MPEP 2173.05(t)
Chemical Formula

Ninth Edition of the MPEP, Revision 10.2019, Last Revised in June 2020

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2173.05(t)    Chemical Formula [R-11.2013]

Claims to chemical compounds and compositions containing chemical compounds often use formulas that depict the chemical structure of the compound. These structures should not be considered indefinite nor speculative in the absence of evidence that the assigned formula is in error. The absence of corroborating spectroscopic or other data cannot be the basis for finding the structure indefinite. See Ex parte Morton, 134 USPQ 407 (Bd. App. 1961), and Ex parte Sobin, 139 USPQ 528 (Bd. App. 1962).

A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented. For example, the claim language at issue in In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970) referred to a chemical compound as a "polypeptide of at least 24 amino acids having the following sequence." A rejection under pre-AIA 35 U.S.C. 112, second paragraph, for failure to identify the entire structure was reversed and the court held: "While the absence of such a limitation obviously broadens the claim and raises questions of sufficiency of disclosure, it does not render the claim indefinite." Chemical compounds may be claimed by a name that adequately describes the material to one skilled in the art. See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972). A compound of unknown structure may be claimed by a combination of physical and chemical characteristics. See Ex parte Brian, 118 USPQ 242 (Bd. App. 1958). A compound may also be claimed in terms of the process by which it is made without raising an issue of indefiniteness.