Adama Agan Ltd. v Kumiai Chemical Industry Co., Ltd. [2025] APO 41

Patent Applicant: Kumiai Chemical Industry Co., Ltd.

The opposition is unsuccessful. Subject to appeal, I direct the application proceed to grant.

I award costs according to Schedule 8 against the applicant, Kumiai Chemical Industry Co., Ltd. up until the day the amendments were allowed (4 April 2024), and against the opponent, Adama Agan, Ltd. from that date onwards.

1. Patent application 2020300922 (the application) was filed by Kumiai Chemical Industry Co., Ltd. (the applicant) on 30 October 2020 under the provisions of the Patent Cooperation Treaty and claiming priority from JP 2019-198600 which was filed on 31 October 2019. The application entered national phase on 30 May 2022 and, following examination, acceptance of the application was advertised on 5 January 2023.

1. A notice of opposition under section 59 of the Patents Act 1990 (the Act) was filed by Epiphany Law on 4 April 2023. An amendment to the notice of opposition under regulation 5.15, identifying the opponent as Adama Agan Ltd (the opponent) was allowed on 6 November 2024.

1. The statement of grounds and particulars was filed on 4 July 2023 and identifies as grounds of opposition entitlement, manner of manufacture, novelty, inventive step, utility, sufficiency, best method, support and clarity. At the hearing grounds of inventive step and sufficiency were pressed.

1. The applicant proposed post-acceptance amendments to the specification on 17 November 2023. These were allowed unopposed on 4 April 2024. This decision is in relation to the specification as amended.

1. Evidence in support, consisting of a declaration by Professor James Hanley Clark (Clark) dated 2 October 2023 and accompanied by exhibits JHC-1 to JHC-13, was filed on 4 October 2023. No evidence in answer was filed by the due date of 5 January 2024 and the applicant's request for an extension of time to file evidence was refused on 19 February 2024.

1. On 17 April 2024 the applicant filed a declaration by Professor Christopher John Easton (Easton) dated 16 April 2024 and accompanied by exhibits to CJE-1 to CJE-14 and requested that the Commissioner consult this material under regulation 5.23. A delegate of the Commissioner was not satisfied that it would be appropriate to do so, and, following the applicant's request to be heard on this position, advised the parties that the matter would be considered as part of the substantive hearing.

1. The operation of regulation 5.23 was considered in Merial Limited v Bayer Intellectual Property GmbH:

"I conclude that a decision under regulation 5.23 must have regard to the nature of the information and whether the information is likely, if not certain, to change the outcome of the opposition in a significant way."[1]

1. Subsequently, the delegate in Reflex Instruments Asia Pacific Pty Ltd v Minnovare Limited[2] elaborated on relevant factors to consider:
   • the circumstances leading up to the evidence not being filed earlier
   • what the evidence shows
   • whether the information is likely to be crucial to the delegate's decision
   • the public interest in having the information considered
   • the balance of convenience of the parties if the information is considered.

1. In the present circumstances the evidence in question is essentially the evidence in answer filed out of time. The applicant was unsuccessful in gaining an extension of time under regulation 5.9 to file the evidence and so, prima facie, the circumstances leading up to the late filing of the evidence do not weigh in favour of consulting the evidence under regulation 5.23. Similarly, given the significant inconvenience to the opponent of the evidence being consulted, I consider that the balance of convenience also weighs against consulting the evidence.

1. On the other hand, the questions of what the evidence shows and whether it is likely to be crucial to the decision are very weighty factors (which in turn impact on the public interest consideration).

1. The applicant's primary position at the hearing was that it was not necessary to consult the Easton declaration, because the opponent has not discharged its onus to make out the grounds of opposition. However, two categories of documents annexed to Easton were the subject of discussion at the hearing.

1. Annexure CJE-12 to Easton is a bundle of four articles of which Professor Clark is an author. These relate to synthesis of sulfoxides from sulfides using (1) sodium chlorite, preferably catalysed by manganese(III) acetylacetonate in acetone in the presence of alumina, (2) ferric nitrate and silica gel, (3) sodium chlorite catalysed by manganese(III) in an aprotic solvent in the presence of alumina and (4) calcium hypochlorite and moist alumina.

1. In the applicant's submission these demonstrate that Professor Clark does not always consider hydrogen peroxide as a first option for sulfur oxidations, and I understood the applicant to attach some significance to their omission from his evidence (i.e. in circumstances where an article more similar to the claimed process was included). The opponent noted that these articles are directed to the production of sulfoxides rather than sulfones and as such any criticism of Professor Clark based on their omission is misplaced.

1. It does not appear to be in dispute that there are many conditions under which a sulfide may be oxidised to a sulfoxide or a sulfone. The articles in question were published in 1996 and 1997 and relate to production of sulfoxides rather than sulfones. (While I note that the article Professor Clark did exhibit also relates primarily to production of sulfoxides, it does include a discussion of optimum reaction conditions for production of sulfones.) It is not apparent that they call into question Professor Clark's evidence as to what he would have done at the relevant date when seeking to convert a sulfide to a sulfone, or otherwise impact the outcome of an inventive step analysis.

1. The applicant also submitted that the full chapter of Patai's Chemistry of Functional Groups (Patai), provided as annexure CJE-13 to Easton, should be consulted. This is because a skilled addressee would read the chapter as a whole and so it is appropriate that it be considered as a whole, rather than simply the extract provided in the evidence in support (as Exhibit JHC-5). As above, it does not appear to be in dispute that there are a range of conditions under which a sulfoxide may be oxidised to a sulfone. It is not apparent to me that the full chapter of Patai is relevant to whether or not a specific set of conditions would be arrived at with a reasonable expectation of success; the applicant did not identify any specific content in this regard. It follows that I do not consider it necessary to consider either annexure CJE-12 or CJE-13 under regulation 5.23.

1. As to the balance of the Easton declaration, while the evidence is clearly relevant, as will become apparent from the reasons that follow, ultimately I agree with the applicant that it is not necessary to consult it to resolve this opposition. I therefore decline to consult the Easton declaration under regulation 5.23.

1. The application was filed after 15 April 2013 and therefore the amendments to the Act brought about by the Intellectual Property Laws Amendment (Raising the Bar) Act 2012 (the Raising the Bar Act) apply to it. This includes section 60(3A) of the Act, which provides that the Commissioner may refuse an application if satisfied on the balance of probabilities that a ground of opposition exists. It is the opponent who carries the onus of proof.

1. The specification includes six figures and ends with 27 claims and states that the invention "relates to a process for producing a sulfone derivative useful as a herbicide",[3] the derivative being a compound of formula (5), wherein R1, R2, R3, R4 and R5 are defined in the specification:

The process described involves oxidation of a corresponding sulfide using hydrogen peroxide and a metal catalyst.

1. Before construing the specification, I note the comments of Middleton J in Eli Lilly and Company Limited v Apotex Pty Ltd:

"It is well settled that the Court should, from the outset, approach the task of patent construction with a generous measure of common sense. The Court must place itself in the position of a person skilled in the relevant art, being the subject matter of the patent. From this perspective, the patent is to be read as a whole, in the context of the specification and in light of the prevailing common general knowledge and state of the relevant art at the priority date." [4]

1. It is well established that many of the issues in an opposition are answered by reference to the person skilled in the art:

"He is the person to whom the patent is addressed and who must construe it. He is the person whose knowledge will determine whether a patent is novel. He is the person who will judge whether a patent is obvious."[5]

1. The hypothetical skilled person works in the field with which the invention is connected and is a non-inventive person or team likely to have a practical interest in the subject matter of the invention.[6]

1. The parties are largely in agreement that the skilled addressee would include an organic chemist with experience in synthetic organic chemistry and industrial-scale processing.[7]

1. Professor Clark is a Senior Professor at the University of York specialising in green and sustainable chemistry, and is also a consultant in the field of green and sustainable chemistry to chemical and allied industries.[8] He stated that he has over 45 years' experience working in the field of chemistry, and his "research interests lie in the field of green and sustainable chemistry, with a particular focus on synthetic organic chemistry and the design/development of cleaner chemical protocols including work on solvents and catalysis."[9] Professor Clark noted that throughout his research career he has had a strong emphasis on working with industry.[10]

1. Professor Clark indicated that he read and complied with the Federal Court of Australia Expert Evidence Practice Note and that he had no conflict of interest and no financial interest in either party in the matter.

1. However, the applicant noted that at the time Professor Clark made his declaration the opponent was a "strawperson", Epiphany Law, such that there is a lack of clarity around Professor Clark's independence from the current opponent. The applicant also noted that there was no indication of whether Professor Clark had been involved with this patent family previously (for example, in other jurisdictions), and raised a concern that he was advised that he was acting for an opponent (i.e. he knew he was trying to invalidate a patent).

1. The applicant submitted that Professor Clark's specialisation in green and sustainable chemistry means that his knowledge and experience has a different focus to that of the notional skilled addressee - noting that the specification makes no reference to environmental concerns or considerations.[11] Relatedly, the applicant submitted that in choosing an expert with a paper titled 'Selective oxidation of sulfides to sulfoxides using 30% hydrogen peroxide catalyzed with a recoverable silica-based tungstate interphase catalyst', the opponent has "selected a witness who is more likely to have their mind turn to the possibility of using hydrogen peroxide and a tungsten-based catalyst in oxidising a sulfide".[12]

1. Ultimately, whatever the opponent's motivations for engaging Professor Clark, he is clearly experienced in the field of organic chemistry, and I am satisfied that he has a background that enables him to understand the specification and provide evidence in relation to it. I have no reason to doubt that he has complied with the Expert Evidence Practice Note. Accordingly, I will assess his evidence in the usual manner. However, I note that contemporaneous documentary evidence may be of assistance when assessing whether a particular approach or understanding is idiosyncratic.

1. At the outset I note that there are several embodiments described in the specification. I have referenced below only those passages that are relevant to the claimed embodiment.

1. The background of the specification explains that sulfone derivatives of formula (5) are known to have herbicidal activity, with pyroxasulfone "well known as a superior herbicide."[13] I note that the claims relate specifically to a process for producing pyroxasulfone.

1. The specification refers to Reference Example 3 in WO 2004/013106 A1 as disclosing a process for preparing pyroxasulfone via oxidation of the corresponding sulfide with m-chloroperoxybenzoic acid (mCPBA):[14]

1. However, the specification indicates that this process has problems, including a poor yield and inefficient preparation of starting materials, and that it is not practical for industrial scale production:

"...in the process for producing the compound of the formula (5) from the compound of the formula (4), m-chloroperoxybenzoic acid (mCPBA) disclosed in WO 2004/013106 A1 (Patent Document 2) is expensive for industrial use and has problems in handling and waste. Therefore, the process for producing described in WO 2004/013106 A1 (Patent Document 2) is not practical for production on an industrial scale."[15]

1. The specification also notes that there is a possibility of a sulfoxide impurity (formula (6)) remaining in the sulfone product, with the possibility of reduced quality and crop injury, such that a process in which the oxidation proceeds sufficiently that there is substantially no sulfoxide product present is desired (noting that the sulfoxide impurity is difficult to separate from the desired sulfone).[16]

1. Set against this background, the specification relevantly states that an embodiment of the invention relates to:

"a process for producing the compound of the formula (5) from the compound of the formula (4) that affords a product containing the compound of the formula (6) in a sufficiently low percentage, is superior in yield, advantageous for the production on an industrial scale, and industrially advantageous."[17]

"the present inventors have found that, in the process for producing the compound of the formula (5) from the compound of the formula (4), even when an excessive amount of hydrogen peroxide is used in a reaction system of a hydrogen peroxide-tungsten catalyst, the compound of the formula (6), which is a reaction intermediate that is not completely oxidized, surprisingly remains in a product (see Reference Examples). On the other hand, it has been found that the oxidation reaction can be sufficiently advanced by performing the reaction with hydrogen peroxide in the presence of a metal catalyst in a mixed solvent composed of water and a certain organic solvent. Based on these findings, the present inventors have accomplished a production process in which substantially no compound for the formula (6) remains in the target product."[18]

1. The "advantageous effects" of the invention are explained as follows:

"the present invention provides a process for producing the compound of the formula (5) (sulfone derivative: SO2 derivative) from the compound of the formula (4) (sulfide derivative: S derivative), wherein the proportion of the compound of the formula (6) (sulfoxide derivative: SO derivative) in the product is sufficiently low, the yield is superior, and the process is advantageous for production on an industrial scale. The compound of the formula (5) produced by the process of the present invention contains substantially no compound of the formula (6) that can cause the loss of quality as a herbicide and crop injury, and therefore it is useful as a herbicide.

The process of the present invention can be implemented on a large scale using low-cost materials, and is superior in economic efficiency, and is suitable for production on an industrial scale."[19]

1. The specification then provides a consistory statement reflecting claim 1 in its present form:

"According to one aspect, the invention provides a process for producing a compound of the formula (5), the process comprising the following step iii, wherein the reaction step iii is performed in the presence of organic solvent(s) having an acceptor number of 0 to 50 and a water solvent, wherein the organic solvent for the reaction step iii is one or more organic solvents selected from alcohols, nitriles, carboxylic acid esters and amides:

(step iii) a step of reacting a compound of the formula (4) with hydrogen peroxide in the presence of a metal catalyst, wherein the metal catalyst is selected from a tungsten catalyst, a molybdenum catalyst and a niobium catalyst, to produce the compound of the formula (5):

1. As noted above, a "sufficiently low" proportion of the SO derivative is desired, and this is described as follows:

"For example, in the reaction mixture after the reaction in the step iii, the ratio of the compound of the formula (6) (SO derivative) is preferably 10% or less, more preferably 5% or less, still more preferably 3% or less, further preferably 2% or less, and further preferably 1% or less."[21]

1. The specification indicates that the hydrogen peroxide can be in any form as long as the reaction proceeds, with preferred forms including a 10-70 wt% aqueous solution, such as a 30 or 35 wt% aqueous solution.[22] Similarly, any amount of hydrogen peroxide may be used as long as the reaction proceeds noting that:

"...from the viewpoint of yield, suppression of by-products, economic efficiency, safety, risk, etc., the amount of the hydrogen peroxide used in the step iii is, for example, 2 mol or more, preferably 2 to 8 mol, ... based on 1 mol of the compound of the formula (4) (raw material)."[23]

1. The specification states that "[t]he metal catalyst may be any metal catalyst as long as the reaction proceeds."[24] Numerous catalysts which may be used are listed, and it is indicated that the metal is preferably a transition metal. Preferred examples of catalysts "[f]rom the viewpoint of yield, suppression of by-products, economic efficiency, etc." are identified.[25]

1. The specification notes that the reaction may be performed in the presence of an acid catalyst, and the decision of whether or not to use such a catalyst can be made by the person skilled in the art.[26] Similarly, the person skilled in the art can determine whether or not to use a phase transfer catalyst.[27]

1. Any solvent that allows the reaction to proceed may be used. Examples of such solvents are said to include organic solvents with an acceptor number from 0 to 50.[28] The specification states:

"...from the viewpoint of yield, suppression of by-products, economic efficiency, etc., preferred examples of the solvent in the reaction in the step iii include combinations of one or more (preferably one or two, more preferably one) organic solvents selected from aromatic hydrocarbon derivatives, halogenated aliphatic hydrocarbons, alcohols, nitriles, carboxylic acid esters, ethers, ketones, amides, ureas, sulfoxides and sulfones with a water solvent in any ratio."[29]

1. The reaction time and temperature are "not particularly limited"[30], nor is the order of adding the raw materials, oxidising agent, catalyst, solvent, etc.[31]

1. Example 2 describes a number of reactions according to the method broadly described, some parameters of which I have summarised in the table below. The SO impurity was measured via HPLC of the reaction mixture.

Tetrabutylammonium hydrogen sulfate, phenyl phosphate

Tetrabutylammonium hydrogen sulfate, phenyl phosphate

Tetrabutylammonium hydrogen sulfate, phenyl phosphate

Tetrabutylammonium hydrogen sulfate, phenyl phosphate

Tetrabutylammonium hydrogen sulfate, phenyl phosphate

1. Following these examples, the specification reports Comparative Examples 2-1 to 2-6, where similar processes to those in the preceding examples were applied to compounds structurally similar to the compound of formula (4). The specification states that:

"for the similar compounds other than the compounds of the formula (4), the reaction was not completed, a large amount of the SO derivative as a reaction intermediate remained, decomposition occurred, and/or the yield was low. Surprisingly, the process of the present invention was specifically effective only for the compounds of the formula (4)."[32]

1. Comparative Example 2-7 reports production of the pyroxasulfone from the corresponding sulfide using sodium tungstate dihydrate, aqueous hydrogen peroxide and methyl isobutyl ketone. After reacting for 7 hours, 10% or more of the sulfoxide intermediate remained.[33]

1. The specification also includes a Reference Example where pyroxasulfone is obtained via reaction of the corresponding sulfide with sodium tungstate dihydrate, acetic acid and aqueous hydrogen peroxide, which is said to be a reproduction of Example 9C in JP 2013-512201 A.[34] The specification states that:

"...even after adding an excess amount of hydrogen peroxide and aging for 16 hours, the compound (6-a), which is a reaction intermediate, remained no less than 5.0%. In addition, even after purification, the ratio of the compound (6-a) did not decrease. It has been confirmed that it is difficult to purify the compound of the formula (5) by separating the compound of the formula (5) from the compound of the formula (6)."[35]

It is also noted that because this process involves generation of a "dangerous organic peracid (peracetic acid)", heating should be avoided.[36]

1. Claim 1, directed to a process of producing a compound of formula (5), is the only independent claim:

A process for producing a compound of the formula (5), the process comprising the following step iii, wherein the reaction step iii is performed in the presence of organic solvent(s) having an acceptor number of 0 to 50 and a water solvent, wherein the organic solvent for the reaction step iii is one or more organic solvents selected from alcohols, nitriles, carboxylic acid esters and amides:

(step iii) a step of reacting a compound of the formula (4) with hydrogen peroxide in the presence of a metal catalyst, wherein the metal catalyst is selected from a tungsten catalyst, a molybdenum catalyst and a niobium catalyst, to produce the compound of the formula (5):

1. Claims 2-12 define specific embodiments of the process of claim 1.

1. Claim 13 defines the product produced by the process of any one of claims 1-12. Claims 14, 15, 16, 17 and 18 define the product of claim 13 comprising, respectively, 5% or less, less than 5%, 3% or less, 2% or less and 1% or less of the compound of formula (6):

1. Claim 19 defines the process of claim 1 further comprising a step of producing the compound of formula (4). Claims 20-23 define specific embodiments of this step. Claim 24 defines the process of any one of claims 19-23 further comprising a step of producing a precursor for the step of producing the compound of formula (4), and claims 25-27 define specific embodiments of this step.

1. While no lack of clarity in the claims is asserted by the opponent, it is useful to consider some aspects of claim 1.

Organic solvent(s) having an acceptor number of 0 to 50

1. The specification provides the following definition of acceptor number:

"Herein, regarding the acceptor number, the following document can be referred to, for example, Christian Reichardt, 'Solvents and Solvent Effects in Organic Chemistry', 3rd, updated and enlarged edition, WILEY-VCH, 2003, p. 25-26

The definition of the acceptor number utilizing 31P-NMR chemical shift values are described in the above document, which is incorporated into the present invention by reference.

Examples of the solvent having a specified acceptor number are described in the above document, which are incorporated into the present document by reference, but are not limited thereto. The acceptor numbers of typical solvents are as follows:

hexane: 0.0, ethyl acetate: 9.3, acetonitrile: 18.9, butanol: 32.2, ethanol: 37.1, acetic acid: 52.9, and water: 54.8"[37]

"A solvent's acceptor number is the measure of its Lewis acidity and is based on the 31P-NMR chemical shift of a triethyl phosphine oxide probe in the solvent, which is sensitive to the solvent's environment. Higher acceptor values generally indicate greater Lewis acidity."[38]

1. It is apparent that claim 1 requires that the reaction is carried out in a solvent mixture that includes one or more of an organic solvent selected from alcohols, nitriles, carboxylic acid esters and amides having an acceptor number of 0 to 50 and a water solvent. Notably, acetic acid is not an organic solvent within the scope of the claim.

1. As noted above, the specification indicates that "[t]he metal catalyst may be any metal catalyst as long as the reaction proceeds." [39] Preferred tungsten catalysts include tungstic acid and salts thereof, metal tungsten, tungsten oxide, tungsten carbide, tungsten chloride, tungsten sulfide, phosphotungstic acid, silicotungstic acid and salts thereof, and mixtures thereof.[40] Preferred molybdenum catalysts include molybdic acid and salts thereof, metal molybdenum, molybdenum oxide, molybdenum carbide, molybdenum chloride, molybdenum sulfide, molybdenum bromide, phosphomolybdic acid, silicomolybdic acid and salts thereof, and mixtures thereof.[41] Preferred niobium catalysts include niobic acid and salts thereof, metal niobium, niobium carbide, niobium oxide, niobium chloride, niobium nitride, niobium silicide, niobium boride, and mixtures thereof.[42]

1. Subsection 7(2) states that an invention is taken to involve an inventive step unless it would have been obvious to a person skilled in the art in light of the common general knowledge (whether in or out of the patent area) before the priority date of the relevant claim when considered alone or together with the information mentioned in subsection 7(3).

1. Subsection 7(3) defines the relevant information as:

The information for the purposes of subsection (2) is:

(a) any single piece of prior art information; or

(b) a combination of any 2 or more pieces of prior art information that the skilled person mentioned in subsection (2) could, before the priority date of the relevant claim, be reasonably expected to have combined.

1. Nicholas J provided a succinct statement of principles relevant to assessing inventive step in Hood v Bush Pharmacy Pty Ltd:

"Section 7(2) of the Act uses the word 'obvious' in the course of describing what must be established before an invention can be held not involve an inventive step. Something may be 'obvious' in light of the common general knowledge, or the common general knowledge coupled with the relevant s 7(3) information, if it is 'plain or open to the eye or mind, something which is perfectly evident to the person thinking on the subject' or something which 'would at once occur to anyone acquainted with the subject and desirous of accomplishing the end'.

An invention may also be obvious in light of the common general knowledge if the person skilled in the art faced with the same problem as the inventor would have taken as a matter of routine whatever steps might have led from the prior art to the invention, whether they be the steps of the inventor or not or (using the language of the 'modified Cripps question') if the person skilled in the art would be directly led as a matter of course to take such steps in the expectation that doing so might well produce a useful or better alternative to the prior art. However, a claimed invention is not obvious merely because the person skilled in the art would consider that it was 'worthwhile to try'."[43]

1. It is important to note the requirement for a reasonable expectation of success. This is explicit in the expectation that an approach "might well" succeed, and implicit in the characterisation of steps as those to be taken as a matter of routine.[44] However, success need not be guaranteed: "the relevant test is not knowing that steps will or would or even may well work, but merely expecting that the steps may well work."[45] Further, it is possible that the skilled person might be directly led to try more than one alternative expecting that each may well produce a useful or desired result.[46]

1. However, being led to try more than one alternative should be distinguished from a wide-reaching variation of parameters or exploration of a field; the plurality in Aktiebolaget Hässle v Alphapharm Pty Ltd referred with approval[47] to the observations of Judge Rich in In re O'Farrell[48] in rejecting such an "obvious to try" approach to inventive step:

"The admonition that 'obvious to try' is not the standard under s103 has been directed mainly at two kinds of error. In some cases, what would have been 'obvious to try' would have been to vary all parameters or try each of numerous possible choices until one possibly arrived at a successful result, where the prior art gave either no indication of which parameters were critical or no direction as to which of many possible choices is likely to be successful. ... In others, what was 'obvious to try' was to explore a new technology or general approach that seemed to be a promising field of experimentation, where the prior art gave only general guidance as to the particular form of the claimed invention or how to achieve it."[49]

1. Importantly, where a claim is directed to a combination of known integers obviousness is not established merely by identifying each of those features in the prior art or the common general knowledge - the question is whether the combination of those features is obvious.[50] This is highlighted in Minnesota Mining and Manufacturing Co v Beiersdorf (Aust) Ltd:

"An allegation of want of inventive step is not made out by saying you may take one or two, or twenty-one or twenty-two, prior publications and then select from them appropriate extracts or pieces of information, which will add up to the invention claimed and so demonstrate that it was obvious. So to proceed is to mistake the nature of an invention and the nature of the objection of obviousness. The question is, is the invention itself obvious, not whether a diligent searcher might find pieces from which there might have been selected the elements which make up the patent. If this were not so, there could never be a valid patent for a new combination of old integers. The proper question is not whether it would have been obvious to the hypothetical addressee who was presented with an ex post facto selection of prior specifications that elements from them could be combined to produce a new product or process. It is rather whether it would have been obvious to a non-inventive skilled worker in the field to select from a possibly very large range of publications the particular combination subsequently chosen by the opponent in the glare of hindsight and also whether it would have been obvious to that worker to select the particular combination of integers from those selected publications. In the case of a combination patent the invention will lie in the selection of integers, a process which will necessarily involve rejection of other possible integers. The prior existence of publications revealing those integers, as separate items, and other possible integers does not of itself make an alleged invention obvious. It is the selection of the integers out of, perhaps many possibilities, which must be shown to be obvious.

It is in relation to this process that the misuse of hindsight is most common. When once an idea or an object or a process or a combination, admittedly novel, has been published, it is very easy to say after perhaps months of search and study in the Patent Office and the public libraries that the integers into which the patent might be dissected could be found scattered amongst the prior documents by a person who already knew the solution to the problem and therefore knew what to look for and what to discard. But that process does not demonstrate lack of an inventive step. The opening of a safe is easy when the combination has been already provided." [51]

1. Common general knowledge is the background knowledge and experience available to all those working in the relevant art:

"The notion of common general knowledge itself involves the use of that which is known or used by those in the relevant trade. It forms the background knowledge and experience which is available to all in the trade in considering the making of new products, or the making of improvements in old, and it must be treated as being used by an individual as a general body of knowledge."[52]

1. However, it is not enough that information is recorded in a document, even if that document is widely circulated - it is only part of the common general knowledge when it is generally known and accepted:

"...information does not constitute common general knowledge merely because it might be found, for example, in a journal, even if widely read by persons in the art ... Reference in this regard is made to the words of Luxmoore J in British Acoustic Films (1936) 53 RPC 221 at 250, cited by Lehane J in Aktiebolaget Hässle v Alphapharm Pty Ltd (1999) 44 IPR 593; [1999] FCA 628 at 605 [39]:

In my judgment it is not sufficient to prove common general knowledge that a particular disclosure is made in an article, or series of articles, in a scientific journal, no matter how wide the circulation of that journal may be, in the absence of any evidence that the disclosure is accepted generally by those who are engaged in the art to which the disclosure relates. A piece of particular knowledge as disclosed in a scientific paper does not become common general knowledge merely because it is widely read, and still less because it is widely circulated. Such a piece of knowledge only becomes general knowledge when it is generally known and accepted without question by the bulk of those who are engaged in the particular art; in other words, when it becomes part of their common stock of knowledge relating to the art."[53]

1. While there is no expert evidence concerning knowledge of pyroxasulfone itself, based on the description of it in the specification as "well known as a superior herbicide", I will proceed on the basis that it was part of the common general knowledge. It is not apparent that the prior art process for preparing pyroxasulfone via oxidation (using mCPBA) of the sulfide was common general knowledge.

1. Turning to the common general knowledge regarding the process of oxidation of sulfides to sulfones, Professor Clark explained that it is "typically a two-step process in which the sulfide is oxidised to the corresponding sulfone via a sulfoxide intermediate".[54] He indicated that oxidation of sulfide to sulfoxide is "generally quite easy", but oxidation from the sulfoxide to sulfone is more demanding. It requires an excess of oxidant and often "more forcing conditions such as elevated reaction temperatures and/or catalysis."[55]

1. I note Professor Clark's observation prior to providing evidence regarding particular reagents to be used:

"It is important to emphasize that that the reagents that the skilled person or team would seek to use will depend on a number of factors, not least the properties of the starting sulfide material which I touch on below."[56]

1. With respect to oxidants for this transformation, Professor Clark said:

"While a variety of oxidants can be used to transform sulfides to sulfoxides and sulfones, the initial one that comes to mind as being most frequently used is aqueous hydrogen peroxide, which offers the advantages that it is cheap, environmentally friendly, and readily available reagent. One big advantage of using hydrogen peroxide as an oxidant is that it produces water as its only by-product and therefore does not require any post-oxidation work up to remove by-products or cause unnecessary side reactions. It is these properties of hydrogen peroxide that lend it to being called a 'green' oxidant due to its lack of toxic by-products, and thus has stimulated the development of useful procedures for the hydrogen peroxide oxidation of sulfides to sulfoxides and sulfones, especially with the use of various types of metal-based catalyst systems."[57]

1. When asked to elaborate on the use of hydrogen peroxide as an oxidant for the production of sulfones from sulfides, Professor Clark said:

"Whilst hydrogen peroxide is one of the most common and routinely used oxidants for this transformation, especially from an environmental and safety point of view, it is a mild oxidizing agent and when used on its own, especially at the 30% to 35% concentrations, is typically slow in transforming sulfides to their corresponding sulfoxide and sulfone. ...more forcing conditions are often used and the activity of hydrogen peroxide can be increased by altering the reaction conditions, such as increasing the reaction temperatures and/or times, altering the reaction medium, and/or employing the use of catalysts, particularly metal catalysts.

...I would look to use reaction temperatures that enhance the reaction rate as much as possible so as to provide a good yield of the sulfone target product in a reasonable amount of time. Bearing in mind, however, it is a balancing act in that hydrogen peroxide can be more susceptible to decomposition at higher temperatures which can reduce the amount of oxidant available for the transformation."[58]

1. It is apparent that various other oxidants are known for use in sulfide to sulfone transformations.[59] Professor Clark noted this, but stated that these have various limitations relative to hydrogen peroxide:

"Oxygen, particularly ambient air, is cheap and naturally abundant oxidant that can also be used to prepare sulfones. However, oxidation reactions using oxygen/air as the oxidant are often difficult to control and are energy intensive, often requiring higher temperatures than similar systems using other oxidants, such as hydrogen peroxide.

Peracids (or peroxy acids) are another group of oxidants that are commonly used to prepare sulfoxides and sulfones. Peracids contain an acidic -OOH group, and are typically formed in-situ by reacting the corresponding carboxylic acid with hydrogen peroxide. An example of this is peracetic acid which is the reaction product of acetic acid and hydrogen peroxide. Other peracids commonly used to oxidise sulfides to their corresponding sulfoxide and/or sulfone include m-chloroperbenzoic acid (m-CPBA). Despite their strong oxidising properties, peracids such as m-CPBA are typically more expensive than hydrogen peroxide or ambient air. Additionally, oxidation of sulfides using peracids can regenerate the corresponding carboxylic acid as a by-product, which often needs to be removed via work-up with a suitable base to neutralise it generating a salt waste and/or other post-oxidation processing steps producing undesired wash streams. Such work-up with a base may increase the risk of base catalysed side reactions at one or more functionals groups of the target sulfone product. In contrast, using hydrogen peroxide produces water as the only by-product and therefore does not require any specific post-oxidation removal/work-up considerations."[60]

1. Professor Clark explained that inclusion of a catalyst can improve sulfone yield, and that the requirement for a catalyst will largely depend on the oxidant being used.[61] He stated that "around 90% or more of all reactions in industry are catalysed to make them commercially viable."[62]

1. Professor Clark particularly referred to the use of catalysts in combination with aqueous hydrogen peroxide:

"Transition metal catalysts are well reported for use in hydrogen peroxide oxidation reactions, including sulfide to sulfone transformations. A wide range of transition metals can be used, including tungsten, molybdenum, titanium, manganese and iron-based catalysts. Of these, I am most familiar with tungsten-based catalyst systems which have been widely developed for sulfide oxidation reactions with hydrogen peroxide..."[63]

1. When asked to discuss whether a solvent or co-solvent would be used when oxidising sulfides to sulfoxides and sulfones, Professor Clark said:

"For aqueous hydrogen peroxide systems, there is typically a substantial amount of water present. ...most organic sulfide substrates are not soluble or sparingly soluble in water, and consequently a large excess volume of aqueous hydrogen peroxide would be required to solubilise enough of the sulfide starting material in order to react with the peroxide and achieve commercially acceptable yields of the target sulfone product.

The most common approach to address this phase issue would be to solubilize the sulfide substrate in a suitable water-miscible co-solvent which in turn improves its solubility in the aqueous phase and improves access to the oxidant species. ...

Typical water-miscible solvents that can be used in the above monophasic system include the common alcohols, such as methanol, ethanol, propanol, butanol and the like, which are polar but relatively inert. ... Other co-solvents I am familiar with include acetonitrile and other small nitriles, acetone and other small ketones, esters, some amides, and acetic acid..."[64]

1. Professor Clark also explained the considerations involved if adopting a biphasic system and noted that transformations with other oxidants, such as mCPBA, would typically be carried out in relatively non-polar organic solvents, such as dichloromethane, chloroform or toluene.[65]

1. While it is apparent from the above that Professor Clark has a clear and pronounced preference for hydrogen peroxide, which has been criticised by the applicant, it is apparent from the discussion in Patai, the content of which I understand the parties to agree, and which I accept, is common general knowledge, that hydrogen peroxide is a commonly used oxidant in transformations of sulfoxides to sulfones:

"Hydrogen peroxide was used to oxidize sulphoxides to sulphones at an early stage in the development of organosulphur chemistry and has remained the reagent of choice for everyday laboratory oxidations of this type. Typically, an excess of 30% hydrogen peroxide in water is employed at room temperature, often with a co-solvent such as an alcohol or acetone.

Slight variations of this method using reflux temperatures and a foam-emulsion system have been used industrially since the oxidant is cheap and readily available and yields are usually above 70%.

In the presence of metal catalysts, hydrogen peroxide oxidations proceed in improved yields. The most common catalyst is an iron(II) salt which produces the well-known Fenton system or reagent. Dimethyl sulphoxide is oxidized to the sulphone using this system although a range of unwanted side-products such as methanol and methane are produced. Diphenyl sulphoxide does not react using this reagent due to its insolubility and in all cases some iron(III) is formed by other side reactions.

Iron(III) salts also activate the oxidation of sulphoxides by hydrogen peroxide in dry acetonitrile although the yields are typically lower than for the iron(II) system. ...

Sodium tungstate has also been used as a catalyst in the oxidation of dimethyl sulphoxide to the sulphone. The kinetics of this reaction have been studied in great detail and it has been shown that oxygen transfer to the sulphoxide takes place via two peroxytungstic acid species (HWO5 ̄ ) and HWO8 ̄ )."[66]

1. I note here that the reference in Patai does not suggest that sodium tungstate is used particularly frequently, in industrial settings, or in preference to other metals, focusing rather on the fact that the kinetics of the transformation have been of the subject of study.

1. Consistent with long-standing use of hydrogen peroxide, in a publication from the 1960s, 'New catalysts for the oxidation of sulfides to sulfones with hydrogen peroxide',[67] it is observed that "[t]he oxidation of sulfides to sulfones is most generally carried out utilizing 30% hydrogen peroxide in glacial acetic acid." I note, however, that such reaction conditions can be distinguished from those of the present claims, as acetic acid is not within the scope of the solvents of the present claims, and such reactions "strictly involve oxidation by peracetic acid".[68]

1. Various other prior art publications in evidence also reference hydrogen peroxide, among other oxidants (such as peracids, bleach, permanganate and oxygen), as useful in oxidation of sulfides to sulfoxides and sulfones.[69] I note also that Patai states, in relation to the oxidation of sulfoxides, that "[p]rocedures involving a wide range of oxidizing agents are well established...",[70] and consistent with this various oxidants are discussed:

"Nitric acid is one of the most common, and cheaper, oxidants used in organic chemistry. It will oxidize sulphoxides to sulphones in good yields if heated under reflux for several hours which should be contrasted with the mild conditions required with this reagent to oxidize a sulphide to the corresponding sulphoxide."[71]

"Oxygen, in the air, is probably the cheapest, most readily available oxidant and so it is not surprising that industrial processes using this reagent for the oxidation of sulphoxides has been patented."[72]

1. Accordingly, I am satisfied that the relevant common general knowledge includes the knowledge that hydrogen peroxide is one of (many) oxidants which may be used to oxidise sulfides to sulfones, optionally in the presence of a metal catalyst, and often in the presence of water and a cosolvent such as acetone or an alcohol. Various suitable metal catalysts, including tungsten based catalysts, would be known to the skilled person. It is apparent that various other oxidants and associated conditions would also be known to the skilled person.

1. The appropriate starting point for the problem to be solved in the inventive step analysis was discussed in AstraZenca AB v Apotex Pty Ltd, where the majority of the Full Court explained that:

"If the problem addressed by a patent specification is itself common general knowledge, or if knowledge of the problem is s 7(3) information, then such knowledge or information will be attributed to the hypothetical person skilled in the art for the purpose of assessing obviousness. But if the problem cannot be attributed to the hypothetical person skilled in the art in either of these ways then it is not permissible to attribute a knowledge of the problem on the basis of the inventor's 'starting point' such as might be gleaned from a reading of the complete specification as a whole."[73]

1. The applicant drew my attention to Burley J's observations regarding the context in which inventive step is to be considered:

"The High Court in Lockwood Security Products Pty Ltd v Doric Products Pty Ltd (No 2) [2007] HCA 21; 235 CLR 173 (Lockwood No 2) at [127] explained that, in answering the question of obviousness, the information referred to in s 7(3), like that part of the prior art base which is the common general knowledge, is considered for a particular purpose. That purpose is to look forward from the prior art base to see what the skilled person is likely to have done when faced with a problem similar to that which the patentee claims to have solved with the claimed invention."[74]

1. The opponent noted that the claims do not define any particular yield of pyroxasulfone (i.e. that might form part of the problem) and referred to the observation in Nichia regarding formulation of an appropriate Cripps question in an analogous circumstance:

"...Graham J noted that it would not be right to include a limitation to therapeutic qualities in the question because claim 1 made no reference to such qualities. This does not mean, however, that Graham J proceeded on the basis that the Cripps question should be posed by reference to an expectation that the steps in question might well produce a result which was not a useful drug or useful alternative."[75]

1. Following a discussion of a number of cases, Jagot J (with whom Besanko and Nicholas JJ agreed) concluded in Nichia that:

"...the prior art and the claimed invention in the context of the specification as a whole are relevant to the appropriate formulation of the Cripps question in a given case. A 'useful alternative' is one which is useful compared to the prior art in the field of the invention."[76]

1. I understand the applicant's position to be that the problem is to be considered in view of the fact that the method relates to a known and commercially valuable herbicide, and as such a useful alternative must be useful in an industrially applicable context - a useful alternative would not be something that produced lower yields than known methods. In this respect, the applicant submitted that the problem set for Professor Clark, to make pyroxasulfone, was broader and simpler than the true problem.

1. Despite this, I take the opponent's position regarding the problem to be broadly similar to the applicant's; that is, to develop an industrially applicable means of making pyroxasulfone. The need for a good yield is implicit in this problem, and insofar as the skilled person would understand that oxidation of a sulfide to a sulfone is a two-step process, where the first step is easier than the second, the skilled person would be aware that steps might need to be taken to avoid achieving more sulfoxide intermediate than is desirable. I note here, that although there is no evidence that the indication in the specification that the sulfoxide intermediate caused crop injury and was difficult to remove was part of the common general knowledge, it appears unnecessary for this to be the case for the skilled person to appreciate that the sulfoxide intermediate should be minimised.

1. However, the opponent emphasised that the skilled person need not have an expectation that they would be able to achieve the high yields/purity of pyroxasulfone defined in dependent claims, simply that they could produce a useful alternative to current processes. In that respect, the opponent submitted that Professor Clark's approach to considering how to make pyroxasulfone on an industrial basis is appropriate. I am satisfied that the development of an industrially applicable means of producing pyroxasulfone is an appropriate formulation of the problem in view of the claims.

1. Professor Clark explained that he was asked to consider hypothetical reaction conditions for the below transformation, including what oxidant and any other reagents/reaction conditions he would consider appropriate, based on what he understood the common general knowledge to be at 31 October 2019.

1. Professor Clark's response is framed around what he would do "[i]f [he] was going into the laboratory tasked with the above transformation".[77] I note here that elsewhere in his evidence he distinguishes between laboratory and industrial settings, referring to the journal Green Chemistry as providing articles that focus on "industrial and laboratory processes", so it is not apparent to me that Professor Clark is here considering the preparation of pyroxasulfone specifically in an industrial context. However, it would seem that various factors that clearly informed Professor Clark's views concerning this process (such as ease of handling and reagent price) are relevant to industrial contexts.

1. I also note that it seems to me that Professor Clark's lack of awareness of the prior art method for preparation of pyroxasulfone in itself does not mean his evidence cannot be considered in answering the question, from the perspective of the notional skilled person, of whether the skilled person would be directly led to try the claimed invention in the expectation that it might well provide a useful alternative to the prior art.

Inventive step in light of common general knowledge

1. In response to the question set out above at [86], Professor Clark said:

"In terms of the oxidant, I would start with aqueous hydrogen peroxide as the oxidant which offers the advantages that it is cheap, environmentally friendly, and readily available reagent. ... I would use a stoichiometric excess (such as 2.5 equivalents or more) of aqueous of [sic] hydrogen peroxide in the concentration of 30% to 35% ...

...I would expect the sulfide substrate to be sparingly soluble in the aqueous hydrogen peroxide phase. ... I would therefore look to increase its solubility by using a water miscible co-solvent. At this point, I would consider what type of system was going to be used, namely whether the desired system is a monophasic or biphasic system. Generally speaking, and as I have discussed above, a monophasic (i.e. a single phase) system is more efficient for heat transfer and mixing of reagents and typically provides faster reaction rates given the substrate, oxidant and other reagents are in the same phase. So designing a single-phase system would be my preferred approach.

Based on this preference, I would explore using a suitable water-miscible co-solvent which can adequately solubilise the sulfide substrate yet is polar enough to be miscible with the aqueous phase of the hydrogen peroxide, such as ethanol or one of the other common alcohol solvents, such as methanol, propanol or butanol.

As I mentioned above, the transformation from sulfide to sulfone typically requires catalysis. I would initially consider tungsten-based catalysts, particularly sodium tungstate owing to its aqueous solubility and proven track-record in sulfide oxidations. Suitable molybdenum-based catalysts or even titanium- or possibly iron-based catalysts would also be appropriate."[78]

1. The following scheme is a summary of the reaction conditions Professor Clark would "initially consider suitable":[79]

1. He stated that he "would expect that such reaction conditions would be [sic] provide the sulfone derivative in a high yield."[80]

1. Evidently, Professor Clark, prior to reviewing the specification, arrived at a process falling within the scope of the claims (noting that ethanol, methanol, propanol and butanol are all solvents within the scope of the organic solvent of claim 1), and on this basis the opponent submits that claim 1 and various appended claims lacks inventive step in light of the common general knowledge alone.

1. However, it is important to recall that the notional skilled person is not a reference to a specific person:

"The notional person is not an avatar for expert witnesses whose testimony is accepted by the court. It is a pale shadow of a real person - a tool of analysis which guides the court in determining, by reference to expert and other evidence, whether an invention as claimed does not involve an inventive step."[81]

1. As such, evidence of Professor Clark's approach is not an answer in itself to the question of obviousness. Idiosyncratic knowledge or preferences of a skilled person are relevant to the weight that can be attached to their evidence. While it seems reasonably clear that the components of the claimed reaction method, individually, are part of the common general knowledge (and I note the opponent's submission regarding the consistency of Professor Clark's preference for aqueous hydrogen peroxide with the indication in Patai that it is a "reagent of choice"[82]), the question is whether the notional skilled person would be directly led to their use, in combination, with an expectation of achieving an industrially useful process for the preparation of pyroxasulfone.

1. It is useful to recite here a summary of the difficulties the applicant identified with Professor Clark's evidence[83] (some of which I have already addressed above), which in essence I take to be addressing the question of whether the notional skilled person, as distinct from Professor Clark, would be led to the claimed combination:

• Professor Clark was not provided with information about pyroxasulfone beyond its structure and that it is a biologically active compound, and did not request further information. He was not advised of the concern regarding the sulfoxide derivative.
• Professor Clark's evidence was guided towards selection of hydrogen peroxide because of both his specific research interests and his instructions.
• Professor Clark did not explain any basis for expecting a commercially useful outcome when using hydrogen peroxide to produce pyroxasulfone.
• Professor Clark's "simplistic" presentation of hydrogen peroxide as a universally favoured oxidant for oxidising sulfides is inconsistent with the evidence.
• Professor Clark did not explain why he did not consider alternative oxidants, or base his decision on consideration of the properties of the sulfide.
• Professor Clark selected alcohol as the solvent despite the common general knowledge indicating that acetic acid would generally be used.
• Professor Clark did not support his decision to use a catalyst, and particularly a tungsten catalyst.

1. Consideration of both Professor Clark's evidence, and the contemporaneous evidence to which he refers, is helpful in considering some of these points. Professor Clark referred early in his evidence to his publication 'Selective oxidation of sulfides to sulfoxides using 30% hydrogen peroxide catalyzed with a recoverable silica-based tungstate interphase catalyst' (Karimi et al.), published in 2005.[84] In this paper, the impact of the substrate on the oxidation is described:

"...under the described reaction conditions even hindered diaryl sulfides furnished the corresponding sulfoxides in good to excellent yields...

On the other hand, when using the protocol for the oxidation of dialkyl sulfides, the formation of the corresponding sulfones was observed along with sulfoxides almost simultaneously. Decreasing the amount of either catalyst 1 or H2O2 did not affect the concomitant formation of sulfoxides and sulfone."

This is suggestive of a lack of control over the particular product achieved upon application of the same reaction conditions to different substrates, with the applicant particularly noting the lack of any explanation by Professor Clark in his declaration for why hydrogen peroxide favoured the production of sulfoxides from some sulfides and sulfones for others, or why one or the other result would be expected for pyroxasulfone.[85]

1. Karimi et al. also refers to the use of tungsten catalysts:

"Very recently, the elegant work of Noyori and co-workers has shown that a combination of Na2WO4/C6H5PO3H2 and a quaternary ammonium hydrogen sulfate as an acidic phase transfer catalyst can be effectively applied for selective oxidation of sulfide to sulfoxides or sulfones using 30% H2O2 under halide-free conditions. Although using this protocol represents considerable progress the protocol needs homogeneous reaction conditions, and therefore the catalyst is difficult to recover and reuse. Since the replacement of current homogeneous oxidation procedures for the production of fine chemicals by environmentally acceptable protocols based on recoverable catalysts is one of the major tasks in green chemistry, solid oxidation catalysts are called to play a crucial role to accomplish this issue."

1. I take this observation to be consistent with the applicant's submission that addition of a catalyst adds expense and complication to the hydrogen peroxide oxidation, which is inconsistent with various advantages identified by Professor Clark as supporting the use of hydrogen peroxide, that is, it being cheap, environmentally friendly, and not requiring post-oxidation work up to remove by-products.[86] I note that Professor Clark mentions solid phase catalysts, in particular titanium-containing zeolites, and that they may be recovered via filtration,[87] but does not otherwise refer to catalyst recovery. I consider potential challenges with catalyst use to form part of the consideration in the selection of a combination of reaction parameters which is not particularly clearly elucidated in the evidence.

1. The applicant also submitted that, without reasoning from any closely analogous sulfide structure showing how effective the claimed reaction conditions might be in achieving the desired sulfone, there is no reason to expect that peroxide alone, or with heating, might not be effective (that is, rather than incorporating the complication of a catalyst with attendant added expense and processing). That is, there is no reason to assume that the skilled person would proceed directly to the claimed combination where simpler reaction parameters may well be effective. More generally, I think this submission goes to a question of whether there is predictability of the efficacy of hydrogen peroxide oxidations to achieve pyroxasulfone specifically. I will note here Professor Clark does not elaborate in any detail on the reason why he felt that the reaction conditions he arrived at would be successful in relation to pyroxasulfone - in this regard it would appear that the process he arrived at is largely agnostic to the specific properties of the starting material (other than with respect to solvent choice[88]), despite his indication that the properties of the starting material are one of the factors on which a skilled person would base reagent selection.[89]

1. The evidence, including Professor Clark's express statement concerning the need to have regard to the starting sulfide material, does indicate some degree of unpredictability in efficacy. For example, in EP 1334956 A2 the background section states that:

"There have been reported processes of preparing sulfone or sulfoxide compounds by the reaction of hydrogen peroxide with sulfide compounds.

For example, J. Org. Chem., 28, 1140 (1963) discloses a process of preparing 2-phenylsulfonylethanol by the reaction of 2-phenylmercaptoethanol with hydrogen peroxide in the presence of a sodium tungstate. However, said method was not effective for other less reactive sulfides other than 2-phenylmercaptoethanol, which is rather reactive sulfide."[90]

1. To similar effect the applicant referred to variable yields in EP 1364946 A1. It is apparent from this document that quite diverse yields are achieved when oxidising structurally similar sulfides to the corresponding sulfones (for example, Examples 2, 6, 12 and 20 relate to broadly similar reaction conditions and structures, but yields range from 53% to 93%).[91] In addition D4 demonstrates a significant difference in yield even between ostensibly similar reaction conditions applied to the same substrate (i.e. tungsten versus tungsten boride, ethanol versus methanol) which is consistent with this conclusion.[92]

1. On the other hand, I note the opponent's observation of instances in the cited prior art where reactions were "largely insensitive to structural changes".[93] This, and the long history of the use of hydrogen peroxide with catalysts to oxidise sulfides to sulfones,[94] could be seen as pointing towards a general expectation of success which would be applicable to the present circumstances. Certainly, there appear to be multiple examples with various compounds where hydrogen peroxide is an effective means of oxidising sulfides to sulfones. I also acknowledge, as set out previously, that Patai supports the frequent use of hydrogen peroxide.

1. Overall, however, I understand the evidence to reveal a measure of unpredictability. Added to this, the specification itself reveals a significant difference in efficacy between the Comparative and Reference Examples, despite structural similarities. While not shown to be part of the common general knowledge as such, this contemporaneous evidence is consistent with Professor Clark's evidence that it is necessary to have regard to the properties of the starting sulfide and reinforces the weight I attach to this point.

1. On balance, in view of the above, and noting the results shown in the specification, and the absence of any explanation of these results by Professor Clark, or explanation of why he would expect success in any particular circumstance, I do not consider the evidence to support a conclusion that results from one sulfide can be readily extrapolated to another. This makes it difficult to conclude that a skilled person could a priori form an expectation that an industrially useful process would be achieved with any particular oxidant (and associated reaction conditions) and substrate combination. I note here that I agree with the opponent that the requirement is not an expectation of achieving the yields defined in the dependent claims, rather an expectation of an industrially useful process/useful alternative more generally (as opposed to a reaction that merely proceeds in some, perhaps minimal, measure). However, it would appear that the exercise to be undertaken, in view of the large number of well-known oxidants and, where appropriate, catalysts, is in the nature of "vary[ing] all parameters or try[ing] each of numerous possible choices" until arriving at success, in the manner cautioned against by Judge Rich.

1. That Professor Clark settled quickly upon the claimed combination does not, in view of the evidence regarding the many oxidants and reaction conditions suitable for sulfide to sulfone conversions that are part of the common general knowledge, persuade me that this is a case where the common general knowledge alone points the notional skilled person in a particular direction where success might be achieved. I emphasise here that it is not a criticism of Professor Clark to observe that his approach reflects parameters with which he was obviously personally familiar based on his own research to which he referred in his evidence. However, I agree with the applicant that while the claimed reaction conditions might be included in an experimental program, this does not equate to an expectation that they will solve the relevant problem, or to a conclusion that they are a combination of conditions, out of many possibilities, to which the skilled person would be relevantly "directly led".

1. On balance, I am not satisfied that it has been established that the notional skilled person, in view of the common general knowledge alone, would, when seeking an industrially useful process for the production of pyroxasulfone, be directly led to the claimed combination of reaction parameters. The case for lack of inventive step in light of the common general knowledge alone is not made out.

Inventive step in light of prior art documents and common general knowledge

1. The opponent submitted that claim 1 and various appended claims lack inventive step in light of the following prior art documents and the common general knowledge:

D6: Jeyakumar et al. 'Simple and efficient method for the oxidation of sulfides to sulfones using hydrogen peroxide and a Mo(VI) based catalyst', Catalysis Communications 10 (2009) 1948-1951 (Exhibit JHC-12)

1. D1 discloses the preparation of various sulfone-containing isoxazoline derivatives with herbicidal effect and selectivity. While the compounds of D1 are structurally similar to pyroxasulfone, pyroxasulfone does not fall within the scope of the Markush structure of D1 (because the isoxazoline in D1 is substituted by a haloalkyl). D1 indicates that a sulfone derivative can be produced by reacting the corresponding sulfide with an oxidising agent "in an appropriate solvent in the presence or absence of a catalyst".[95] A range of solvents (including halogenated hydrocarbons, ethers, amides and alcohols) and oxidising agents (including mCPBA, hydrogen peroxide, peracetic acid, potassium permanganate and sodium periodate) are said to be suitable. Sodium tungstate "and the like" is said to be a suitable catalyst.[96] The exemplified conditions for this transformation in D1 are mCPBA and chloroform.

1. In relation to this document Professor Clark said:

"I consider this document discloses the recited oxidation conditions and sulfide substrates of claim 1. I also do not consider that oxidising sulfides to their corresponding sulfones using hydrogen peroxide in water and the recited organic solvents, particularly the common alcohols, in the presence of metal catalysts is at all new."[97]

"since the experimental data in the Opposed Application does not provide sufficient foundation to for the conclusion that that differences in yield of the sulfoxide intermediate in the target sulfone product are attributable to the recited organic solvents, rather than to other reagents and/or reaction conditions, D1 discloses the claimed oxidation conditions and sulfide substrates of claim 1. Oxidising sulfides to their corresponding sulfones using hydrogen peroxide in water and the claimed organic solvents in the presence of metal catalysts was a very common approach in the Filed at the time..."[98]

1. Ultimately, I do not consider D1 to extend meaningfully beyond the common general knowledge[99] - it generally discloses suitable oxidation conditions but does not specifically direct towards or exemplify the conditions defined in the present claims. Accordingly, the reasoning above in relation to the common general knowledge applies equally to D1.

1. D2 discloses a method for preparing 5,5-disubstituted-4,5-dihydroisoxazole-3-thiocarboxamidine salts as intermediates for the preparation of, among other things, pyroxasulfone. In the context of a general scheme for the preparation of pyroxasulfone, D2 indicates that "[t]he final oxidation of the sulfur to the sulfone (f) is employed, for example, in EP 1 405 853 [D1]".[100]

1. In particular, Example 9(C) of D2 recites dissolution the relevant sulfide in acetic acid and sodium tungstate dihydrate, followed by addition of hydrogen peroxide to afford the corresponding sulfone. However, as noted by Professor Clark, use of acetic acid as solvent means that this is a different oxidant system - peracetic acid[101] - to that defined in the present claims and the document otherwise refers to oxidising reagents generally.

1. The opponent referred to Professor Clark's statement, having considered both D2 and the specification, that he considered "using the recited organic solvents in place of acetic acid with hydrogen peroxide and sodium tungstate represents a logical alternative and common system choice, particularly from a lack of by-product perspective"[102] in submitting that this change is obvious. However, while this change is explicable in hindsight, D2 itself provides no particular suggestion as to what parameters of the example might be productively changed and it is not apparent to me that the skilled person would be directly led to the claimed combination in the absence of hindsight. I also note that the specification indicates that the claimed process achieves markedly better results than when the conditions of D2 are replicated. I am not satisfied that it has been established that the claims lack inventive step in light of D2.

1. D3 is said by Professor Clark to be "very similar to [D1]",[103] although pyroxasulfone falls within the general structure disclosed in D3 and is exemplified.[104] He continued:

"The commentary for each of the steps is essentially identical to [D1], including with regard to choice of oxidant and solvents. However, one difference between the two documents is that there does not appear to be any reference to metal catalysts being used with the oxidant..."[105]

1. While the opponent submitted that the use of metal catalysts in oxidation reactions involving hydrogen peroxide was commonly known,[106] it is not apparent that D3 on its face, or based on the evidence of Professor Clark, provides any particular teaching towards the claimed reaction conditions or meaningfully extends beyond the information which is part of the common general knowledge. The reasoning in relation to D1 and the common general knowledge also applies to D3.

1. The opponent indicated that D4-D6 are key pieces of prior art. Each of these shows the use of the claimed reaction conditions, although, as I will discuss below, none of the reaction products are particularly similar to pyroxasulfone. I also note that to the extent that a combination of these documents could be said to show substrate insensitivity of the claimed process there is no basis to combine these documents as provided for by section 7(3)(b).

1. D4 discloses a method for preparing sulfone or sulfoxide compounds by reaction of a sulfide with hydrogen peroxide in the presence of a metal oxide catalyst. Professor Clark stated that "[t]he main focus of this document appears to be the use of a metal oxide catalyst which is made in-situ by reacting a metal or metal compound with hydrogen peroxide."[107] The metal in the metal oxide catalyst to be used is selected from tungsten and molybdenum, and various organic solvents which may be combined with water, such as ethers, alcohols and nitriles, are disclosed.[108] Various possible sulfide substrates are disclosed, and Professor Clark said:

"the reaction appears to be largely insensitive to structural changes and any sulfide compound is believed to be suitable for oxidation by the hydrogen peroxide/metal oxide catalyst system discussed in this document..."[109]

1. I take the opponent's position to be that because the reaction is described as insensitive to structural changes, it would be a matter of routine to apply this method to the preparation of pyroxasulfone, although I note that Professor Clark made no particular reference to this.

1. The examples of D4 relate to 2,8-dioctyloxydibenzothiophene, diphenyl sulfide and benzo[b]thiophene and many of the examples of D4 provide a high (>90%) yield of the relevant sulfone, with the opponent drawing attention to this. However, while Example 4 (relating to diphenyl sulfide) reports a yield of 99% diphenyl sulphone, Examples 8 and 9, which are said to be carried out "in a similar manner as in Example 4" but with tungsten boride and molybdenum in place of tungsten, respectively, and methanol in place of ethanol, report yields of 69% and 89% respectively. Given my conclusion regarding the variability of results between sulfide substrates above, and the variability apparent in the examples of D4 itself, I am not persuaded that the notional skilled person would be directly led to apply the method(s) of D4 with an expectation of arriving at an industrially applicable means of making pyroxasulfone.

1. D5 discloses the preparation of statins via a Julia-Kocienski reaction between an aldehyde and a sulfone derivative in the presence of an alkaline metal alkoxy base.[110] D5 discusses conditions for preparation of the sulfones of interest via oxidation of the corresponding sulfide. Specifically, oxidation "in manners known in the art" such as via hydrogen peroxide, peracids, bleach and permanganate is disclosed, and it is said that oxidation can be carried out in the presence of an appropriate catalyst, such as (among others) salts of oxides of vanadium, cerium, manganese, molybdenum and tungsten, or organic catalysts.[111] Various suitable solvents, such as dichloromethane, acetonitriles, alcohols and toluene are disclosed.[112]

1. Example 2 of D5 discloses oxidation of a sulfide to sulfone via both mCPBA in dichloromethane (with a 20% yield) and aqueous hydrogen peroxide with sodium tungstate in methanol (with a 57% yield at small scale and 41% yield when scaled up). At the hearing the opponent drew attention to the higher yield achieved with hydrogen peroxide/sodium tungstate than mCPBA, even at scale.

1. The sulfide of D5 is structurally dissimilar to that of the present claims and Professor Clark did not comment on his expectations when applying the method of D5 to other sulfides, including in an industrial context. In view of the disclosure of D5 on its face and the lack of evidence as to how a skilled person would proceed on the basis of the disclosure, I am not satisfied that lack of inventive step in light of D5 and the common general knowledge is made out.

1. D6 discloses a method for the oxidation of sulfides to sulfones using ammonium heptamolybdate and aqueous hydrogen peroxide in methanol. D6 states that this method provides "excellent yields within short time, also sensitive functional groups such as allyl, vinyl, propargyl, alcohol, ketone, ester, pyridine and nitrile are found to be tolerated."[113] Yields of approximately 90% were achieved for a range of substrates, with the exception of an oxime which was deprotected under the reaction conditions.[114] Professor Clark observed that "the catalytic aqueous hydrogen peroxide system investigated for selective sulfide oxidation to sulfones was largely substrate independent."[115]

1. I accept that the method of D6 may be "obvious to try". However, the onus in this proceeding is on the opponent, and, having indicated that it is necessary to consider the properties of the starting sulfide, Professor Clark makes no specific observation concerning the appropriateness of this method to the production of pyroxasulfone, which does not appear to have a particular structural similarity to any of the exemplary sulfones in D6. In these circumstances, I do not consider that the opponent has discharged its onus; on balance, I am not persuaded that the skilled person would be directly led to the claimed invention in light of D6.

1. Given the above conclusions, it is not necessary to address the opponent's submissions concerning appended claims 19-23. The ground of inventive step is not made out.

1. Section 40(2)(a) requires that the claimed invention be described in a manner which is clear enough and complete enough for the invention to be performed by a person skilled in the relevant art. To satisfy this requirement, it is necessary that, "given what is contained in the specification, the person skilled in the art can readily perform the invention without undue burden or experimentation beyond ordinary steps of trial and error, or the need for further invention."[116]

1. The approach adopted by the Deputy Commissioner in Evolva SA[117] and subsequently by various delegates of the Commissioner when considering compliance with section 40(2)(a) was cited by the opponent and has not been criticised by the Federal Court:[118]

What does the specification disclose to the skilled person?

Does the specification provide an enabling disclosure of all the things that fall within the scope of the claims, and in particular:

(a) Is it plausible that the invention can be worked across the full scope of the claim?

(b) Can the invention be performed across the full scope of the claim without undue burden?

1. The applicant observed that plausibility is a low threshold test designed to prohibit speculative claiming, referring to the decision of the UK Supreme Court in Warner-Lambert Company LLC v Generics (UK) Ltd,[119] where Lord Sumption (with whom Lords Reed and Briggs agreed) said (in relation to a patent directed to a second medical use) that the test is relatively undemanding, but that "the specification must disclose some reason for supposing that the implied assertion of efficacy in the claim is true."[120] He went on to say:

"...although the disclosure need not definitively prove the assertion that the product works for the designated purpose there must be something that would cause the skilled person to think that there was a reasonable prospect that the assertion would prove to be true."[121]

1. The applicant submitted that plausibility most usually or directly applies to the ground of support rather than sufficiency, and this is consistent with, for example, Nicholas J's discussion of Warner-Lambert in the context of the support consideration in ToolGen Incorporated v Fisher (No 2).[122] Nevertheless, insofar as support and sufficiency are often two sides of the same coin,[123] it would seem that consideration of plausibility can play a role in assessing whether the specification provides the enabling disclosure required by section 40(2)(a).

1. The opponent's case on sufficiency is limited to claims 14-18. As noted previously, these are product by process claims defining the product produced by the process of any one of claims 1-12, comprising 5% or less, less than 5%, 3% or less, 2% or less and 1% or less of the sulfoxide compound of formula (6), respectively.

1. In written submissions the opponent referenced Professor Clark's evidence that the specification lacks proper comparative data that would support a conclusion that the use of certain solvents are responsible for low sulfoxide yields,[124] and to the effect that it is a "mixed bag" as to what solvents, catalysts, and/or reaction conditions achieve the claimed results:

"...I do not consider that the experiments in the Opposed Specification provide an adequate foundation for concluding that differences in yield of the sulfoxide intermediate in the target sulfone product are attributable to solvent rather than other reagents and/or reaction conditions, which appears to be what is being put forward by the Opposed Specification. Instead, it all appears to be a mixed bag as to what solvents, catalysts, sulfide derivatives and/or reaction conditions can achieve the desired effect."[125]

1. In view of this, the opponent submitted that "it is not plausible that the claims can be worked across their breadth, having regard to the number of variables (such as, for reaction conditions, catalysts and solvents) which may be used in the process claimed in claim 1."[126]

1. At the hearing I also took the opponent's position to be that because all the reaction conditions are important there cannot be confidence that the high yields defined in claims 14-18 can be achieved across the scope of the claimed process, such that there is an undue burden on the skilled person to work out what is required to achieve that threshold.

1. The applicant submitted that Professor Clark's evidence regarding the lack of sufficiently rigorous testing does not align with the plausibility question. The applicant also pointed to the examples as providing broad support for the claims - demonstrating a broad range of solvents and each of the metal catalysts. In the applicant's submission there is no evidence to suggest that anything within the claims would not work.

1. I note at the outset that the specification has been amended since Professor Clark provided his evidence. The claims as accepted defined a process of preparing a much broader range of sulfones, compared to the current limitation to pyroxasulfone, and also defined the use of any metal catalyst, compared to the current definition of tungsten, molybdenum and niobium catalysts. Notably, this limitation to the metal catalysts aligns with the exemplified processes having lower levels of sulfoxide impurities. In view of this, I think Professor Clark's evidence, to the extent it refers to a mixed bag of sulfide derivatives and catalysts, has diminished force, and I agree with the applicant that the specification provides a relatively broad range of examples that achieve the results defined by claims 14-18.

1. Given that not every example in the specification achieves the level of sulfoxide impurity defined by claims 16-18 (that is, 3% or less), I accept the opponent's submission that it is not plausible that every combination of reaction conditions in claim 1 will result in production of products with the claimed low levels of sulfoxide impurity. However, the relevant question here is whether it is plausible that claims 14-18 can be worked across their full scope. This is a different question to whether every method within the scope of claim 1 will lead to the result claimed by these dependent claims. That the scope of the reaction conditions by which the products of these claims may be achieved is more limited than claim 1 does not in itself mean that the claims cannot be worked across their full scope. While I note that D4 provides an example of where tungsten boride gave quite different results to both tungsten sulfide and tungsten,[127] it is not apparent to what extent this can be extrapolated to mean that there would be difficulties in relation to pyroxasulfone, or that it would be an undue burden to resolve them. Similarly, it is not apparent that variations to reaction conditions, such as temperature and duration, would be beyond routine experimentation for the skilled person. On the evidence before me I cannot be satisfied that it is implausible that these claims can be worked across their full scope, or, to answer the broader sufficiency question, that it would be an undue burden to do so.

1. The opponent has not established that the specification is insufficient.

1. It is usual in matters before the Commissioner that costs follow the event. In the present case the opponent sought its costs regardless of the outcome, noting the applicant's conduct with respect to the regulation 5.23 material.[128] The applicant submitted that costs should follow the event.[129]

1. While I am not persuaded that a variation of costs is warranted in view of the applicant's (unsuccessful) regulation 5.23 request, I note that the application was amended after the evidence in support was filed. When requesting a stay of the opposition the applicant submitted that the amendments were "substantive in nature" and "directly responsive to and resolve alleged deficiencies" in the opposition.[130] In these circumstances, I consider that the applicant can be taken to have essentially conceded that there was some merit to the opposition up to the point the amendment was made. Accordingly, I will award costs according to Schedule 8 against the applicant up until the day the amendments were allowed (4 April 2024), and against the opponent from that date onwards.

[1] [2015] APO 16 at [24].

[2] [2017] APO 8 at [52].

[4] [2013] FCA 214; 100 IPR 451 at [139].

[5] Root Quality Pty Ltd v Root Control Technologies Pty Ltd [2000] FCA 980 at [70].

[7] Opponent's written submissions at [23], applicant's written submissions at [50].

[11] Applicant's written submissions at [41].

[12] Applicant's written submissions at [45].

[34] This is a family member of CA 2781404 A1, discussed below as D2.

[43] [2020] FCA 1686 at [116]- [117] (with citations omitted).

[44] Generic Health Pty Ltd v Bayer Pharma Aktiengesellschaft [2014] FCAFC 73; 314 ALR 91 at [71].

[45] Nichia Corporation v Arrow Electronics Australia Pty Ltd [2019] FCAFC 2 at [99] ('Nichia').

[47] [2002] HCA 59; 212 CLR 411 at 442-443, [76] ('Alphapharm').

[48] (1988) 853 F 2d 894.

[49] Ibid at 903 (with citations omitted).

[50] Minnesota Mining and Manufacturing Co v Beiersdorf (Aust) Ltd [1980] HCA 9; 144 CLR 253 at 293 ('Minnesota Mining'), Alphapharm at 429, [41].

[53] Ranbaxy Laboratories Limited v AstraZeneca AB [2013] FCA 368; 101 IPR 11 at [217].

[66] Patai at page 973 (with references omitted).

[69] EP 1405853 A1 (Exhibit JHC-7, 'D1') at [0046]-[0059], WO 2012/098049 A1 (Exhibit JHC-11, 'D5') at page 7, lines 8-18.

[71] Patai at page 971 (with references omitted).

[73] [2014] FCAFC 99 at [203].

[74] Hanwha Solutions Corporation v REC Solar Pte Ltd [2023] FCA 1017 at [340].

[81] AstraZeneca AB v Apotex Pty Ltd [2015] HCA 30 at [23].

[82] Opponent's written submissions at [101].

[83] Applicant's written submissions at [112].

[85] Applicant's written submissions at [131].

[90] EP 1334956 A2 (Exhibit JHC-10, 'D4') at [0003]-[0004].

[91] EP 1364946 A1 (Exhibit JHC-9, 'D3').

[92] D4, Example 4 - sulfone yield 99.0%, Example 8 - sulfone yield 31.0%.

[98] Opponent's written submissions at [124] (with references omitted).

[99] I note that Professor Clark observes that "the information on the oxidation conditions did not contain anything too surprising and largely reflects oxidants and reagents that were well known and typically used for the transformation of sulfides to sulfones well before the publication date of this document" at [75].

[106] Opponent's written submissions at [140].

[108] D4 at [0007]-[0016], [0019].

[112] D5, page 7, line 20 - page 8, line 2.

[116] Perfect Day, Inc. v Commissioner of Patents [2025] FCA 270 at [147] (with references omitted).

[117] [2017] APO 57 at [45].

[118] See, e.g. Cytec Industries Inc. v Nalco Company [2021] FCA 970 at [143]- [146].

[119] [2018] UKSC 56 ('Warner-Lambert').

[122] [2023] FCA 794.

[123] Jusand Nominees Pty Ltd v Rattlejack Innovations Pty Ltd [2023] FCAFC 178 at [222].

[126] Opponent's written submissions at [181].

[127] D4 at [0085], [0088], [0089].

[128] Opponent's written submissions at [183].

[129] Applicant's written submissions at [232].

[130] Applicant's correspondence of 20 November 2023.