In a previous article, we set out four tips for inventors, start-ups, and small businesses to consider before filing for a patent: (1) don’t wait to file your patent application; (2) decide where your invention will be practiced or marketed; (3) hire a patent attorney to prepare, file, and prosecute your patent application; and (4) request a professional prior art search. Those four tips are applicable to any subject matter, including chemical, mechanical, and software inventions.


In this article, we provide three additional tips for consideration before preparing a chemical patent application. Chemical compounds, compositions, formulations, etc. are included in a wide range of technologies, including pharmaceuticals, nutraceuticals, foods, coatings, inks, explosives, OLED components, refractory materials, polymers, dental composites, etc.

1. Determine whether the invention should be claimed as a product, process, or both

The patent statute titled “Inventions patentable” defines the statutory categories of patent-eligible inventions in the United States: “Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.” [i] For chemistry-based patent applications, the two most relevant statutory categories are process and composition of matter, and each category encompasses a couple of subcategories. The process category can be bifurcated into: (i) a process of making a compound, and (ii) a process of using a compound. The composition of matter category can be bifurcated into (a) a compound, and (b) a specific form of the compound (e.g., a composition or formulation containing the compound). In addition, it is possible to claim a chemical invention as a product by process in certain situations where it is more practical to describe a product by how it was made rather than by what it is.


A patent application for chemical inventions is often drafted with an eye toward describing and claiming each of the four subcategories. Sometimes, however, a patent application will be drafted with a focus on one or two specific subcategories. For example, one of the benefits of having a proper prior art search conducted is the acquired knowledge of existing compounds disclosed in the patent and non-patent literature that may be relevant to the patentability of your invention. If a compound is properly described in the prior art literature, then there would be no point in including a claim in your application directed to the existing compound because it would be rejected over the prior art. But maybe the compound was simply mentioned in passing somewhere in the prior art and the reference does not describe a specific form of the compound (e.g., a pharmaceutical composition comprising the compound and a pharmaceutically acceptable carrier) or a specific use of the compound (e.g., a method of treating cancer comprising administering the pharmaceutical composition to a patient in need thereof). In such a scenario, the mere mention of the compound in the reference would not necessarily destroy the novelty of a specific composition or use for the compound. Equipped with a prior art search, a patent attorney can work with you to target one or even all four subcategories of invention.


It should be noted that conducting this analysis prior to the drafting and filing of a patent application will help you avoid unnecessary Office action rejections, an unnecessarily long prosecution timeline, and unnecessary costs for attorney hours spent revising the patent application after-the-fact.


It should also be noted that a product or process claim can be independently patentable with respect to the other. Indeed, examiners at the Patent Office commonly issue “Restriction Requirements,” which are Office actions that propose dividing the pending claim listing into different groups of claims based on their format, and that division process requires the examiner to affirmatively state that the claims are independently patentable from one another. Thus, one chemical invention can be deemed to be two or more independent inventions and each of the inventions can independently support a patent of its own.

2. Identify any key intermediate compounds in the process of making a target compound

Sometimes the preparation of a target compound proceeds through an important intermediate compound. Intermediate compounds may be patentable regardless of whether the target compound or the method of making the target compound is patentable. Thus, patentable intermediate compound claims can provide an additional way of protecting a target compound or an important process of preparing the target compound. Moreover, a patentable claim to an intermediate compound can preclude a third party from preparing the target compound via any process that proceeds through that intermediate.

3. Identify evidence of non-obviousness that can be used to rebut an obviousness rejection

Even when a chemical compound or process or making a compound is novel, it must also be non-obvious over what already exists in the prior art literature. Structural similarly to one or more existing compounds, for example, can often be the basis for an obviousness rejection issued by the Patent Office. Obviousness rejections are the most common rejection issued by the Patent Office, but they can be rebutted by via the submission of objective evidence of non-obviousness. When applicants submit such evidence, the patent examiner must reanalyze the rejection anew and balance the evidence of obviousness against the evidence of non-obviousness. The Manual of Patent Examining Procedure (MPEP) [i] states: “Objective evidence relevant to the issue of obviousness must be evaluated by Office personnel. . . . Such evidence, sometimes referred to as ‘secondary considerations,’ may include evidence of commercial success, long-felt but unresolved needs, failure of others, and unexpected results.” [ii] Objective evidence is based on provable facts, not inventor bias, and the evaluator (e.g., patent examiner, judge) must consider such evidence from the perspective of a person having ordinary skill in the relevant art.


Generally, at the time of filing a patent application evidence of commercial success is not yet available. But the applicant may be aware of evidence derived from the prior art, such as evidence of a long-felt but unresolved need for the invention or evidence documenting the failure of others. Alternatively, a patent applicant may be aware of experimental evidence obtained from the laboratory, such as data or a result that was unexpected compared to data or trends disclosed in the prior art. More often than not, patent applicants rely on evidence of “unexpected results” to rebut an obviousness rejection during patent prosecution. Because such evidence may be the most important factor with respect to whether your invention is patentable or not, we suggest the following.


First, try to acquire experimental data at the time of invention and, if possible, data comparing one or more inventive compounds with one or more compounds considered to be the closest prior art. Conducing such experiments at the time of invention allows you to include the data in the patent application, which allows the patent examiner to factor the results into their initial analysis. Further, as a practical matter, it may be prohibitively expensive to conduct experiments four or five years after the time of invention (i.e., during patent prosecution). And, your employees may depart the company, leaving the laboratory devoid of someone having the ability to carry out important experiments. Second, try to acquire as much data as possible. To be accorded proper weight by a patent examiner, the scope of experimental data must be commensurate with the scope of what is claimed in your patent application. This issue is often raised by examiners when a claim relates to a generic structure (i.e., a genus encompassing dozens or hundreds of compounds) and the experimental data was obtained from only one or two compounds. It is quite difficult to establish a trend with two data points, and without a trend the data may not support a genus of compounds. In other words, if the data shows an unexpected result for one or two specific compounds, then it may not be extrapolatable to hundreds of compounds because chemistry is considered an unpredictable art.


[i] 35 U.S.C. § 101 (emphasis added).

[ii] Although the MPEP is not law, the examining procedures described therein must be followed by the patent examiners at the U.S. Patent & Trademark Office.

[iii] MPEP § 2141.

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