Title: pro-E, pro-Z
Long Title: IUPAC Gold Book - <i>pro-E, pro-Z</i>
DOI: 10.1351/goldbook.P04867
Status: current

Definition
One of a pair of identical groups $\ce{c}$ attached to a double bond (as in $\ce{abC=Cc2}$) is described as pro-E if, when it is arbitrarily assigned CIP priority over the other group c, the stereodescriptor of the molecule becomes E. The other group $\ce{c}$ is then described as pro-Z.

Related Terms
- CIP priority: https://goldbook.iupac.org//terms/view/C01082
- stereodescriptor: https://goldbook.iupac.org//terms/view/S05976

Source
- PAC, 1996, 68, 2193. 'Basic terminology of stereochemistry (IUPAC Recommendations 1996)' on page 2214 (https://doi.org/10.1351/pac199668122193)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/P04867/html
- json: https://goldbook.iupac.org/terms/view/P04867/json
- xml: https://goldbook.iupac.org/terms/view/P04867/xml

Citation: Citation: '<i>pro-E, pro-Z</i>' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.P04867
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Accessed: 2026-06-30T05:00:10+00:00