Stereochemical Specification

R-7.1.2 The E/Z Convention

In names of compounds, steric relationships around one or more double bonds can be designated by the stereodescriptors Z and/or E , assigned as follows. The sequence-rule-preferred atom or group (see R-7.2.1) attached to one of a doubly bonded pair of atoms is compared with the sequence-rule-preferred atom or group attached to the other of that doubly bonded pair of atoms; if the selected atoms are on the same side of the reference plane (see R-7.1.1) the italic capital letter Z is used as the stereodescriptor; if the selected atoms are on opposite sides, the italic capital letter E is used as the stereodescriptor. These stereodescriptors, placed in parentheses followed by a hyphen, normally precede the whole name; if the molecule contains several double bonds, then each stereodescriptor is immediately preceded by the lower or less primed locant of the relevant double bond.

Examples to R-7.1.2

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