Term: diastereotopic https://doi.org/10.1351/goldbook.D01685 Definition: Constitutionally equivalent atoms or groups of a molecule which are not symmetry related. Replacement of one of two diastereotopic atoms or groups results in the formation of one of a pair of diastereoisomers. In the example below the two hydrogen atoms of the methylene group C-3 are diastereotopic. D01685.png Related Terms: 1) prochirality (http://doi.org/10.1351/goldbook.P04859). 2) enantiotopic (http://doi.org/10.1351/goldbook.E02083). 3) heterotopic (http://doi.org/10.1351/goldbook.H02815). 4) diastereoisomers (http://doi.org/10.1351/goldbook.D01679). 5) methylene (http://doi.org/10.1351/goldbook.M03881). Image: Not defined (https://goldbook.iupac.org/img/inline/D01685.png) Source: PAC, 1996, 68, 2193. 'Basic terminology of stereochemistry (IUPAC Recommendations 1996)' on page 2206 (https://doi.org/10.1351/pac199668122193) Citation: 'diastereotopic' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.D01685 License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.