Markush structure

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Markush structures (-R) are chemical symbols used to indicate a collection of chemicals with similar structures. They are commonly used in chemistry texts, and also in patent claims.

Markush structures are depicted with R groups, in which the side chain can be a structure type, e.g. 'cyclohexyl'.[1] This more general depiction of the molecule, versus detailing every atom in the molecule, is used to protect intellectual property. The company which files the patent makes a general claim for the usage of the molecule without revealing to their competitors the exact molecule for which they are declaring a useful application.[2]

example Markush structure

In Patents[edit]

They are named after Dr Eugene A. Markush, founder of the Pharma Chemical Corporation in New Jersey. He was involved in a legal case that set a precedent for generic chemical structure patent filing.[1] The patent filing was US Application 611,637, filed January 9, 1923. Markush was awarded a patent from the US Patent Office for “Pyrazolone Dye and Process of Making the Same” on August 26, 1924.[2][3]

In describing a chemical, a Markush structure allows the patent-holder to list several active/effective structural formulas. Patent applicants are required to reveal their best known embodiment implementing their invention [4] and patent claims can be rejected or invalidated as indefinite if they are too vague.[4]

See also[edit]


  1. ^ a b Barnard, John M. (28 Oct 2009). "Markush Structure Searching" (PDF). Royal Society of Chemistry Retrieved 15 Jan 2014. 
  2. ^ a b Gardner, Steve; Vinter, Andy. "Beyond Markush – Protecting Activity not Chemical Structure" (PDF). Retrieved 15 Jan 2015.  External link in |website= (help)
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  4. ^ a b