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Chemistry 493B | From Innovation to Industry


Markush Structures

Eugene Markush – Pyrazolone Dye and Process of Making the Same (1924)

In 1925 after Eugene Markush's appeal was upheld, the USPTO officially began allowing instance where a ‘virtual set’ of compounds is considered with R-groups at specified positions selected from a group consisting of a closed listing of potential radical substituents. These structures became know as Markush Claims and allow inventors to patent members of a class of compounds that have a similar function.

Generic type of description of chemicals used to summarize a potentially large set of closely related chemicals in a single condensed representation

  • Core chemical structure and a list of possible substituents (R-Groups)

Four types of R-groups

  • Substituent variation: allows different substituents at a position
  • Position variation: allows different attachment points for a substituent
  • Frequency variation: allowing substituents to occur multiple times
  • Homology variation: using generic expressions covering many specific substituents 
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Simple example of Markush structure representing four specific compounds

Markush Structure Search Tutorials

Tutorial | Understand the Value of a Markush Structure Search

Tutorial | Understand the Types of Markush Searches