How are chemical formulas treated in patent claims?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

Chemical formulas in patent claims are generally treated as definite and non-speculative, unless there is evidence to the contrary. The MPEP 2173.05(t) states:

“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.”

This means that patent examiners and courts generally accept chemical formulas as presented, without requiring additional proof of their accuracy.