E–Z notation

Notation in organic chemistry for double bonds

E–Z configuration, or the E–Z convention, is the IUPAC's preferred method of describing the absolute stereochemistry of double bonds in organic chemistry. It is an extension of cis–trans isomer notation (which only describes relative stereochemistry) that can be used to describe double bonds having two, three or four substituents. E–Z notation can only be used when neither atom of the double bond has two identical atoms or substituent groups attached to it.

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