Question

What is isotopomer?

Answer 1

Isotopomers (from isotope + isomer) are isomers with isotopic atoms, in which there is the same number of each isotope but the isotopes are in different positions.

Explanation:

There are two types of isotopomers.

(a) Constitutional isotopomers

Consider 1-(`""^2"H"_1`)propane and 2-(`""^2"H"_1`)propane:

`"CH"_3"CH"_2"CH"_2[""^2"H"]` and `"CH"_3"CH"[""^2 "H"]"CH"_3`

These are constitutional isotopomers because the deuterium atoms are attached at different positions on the propane chain.

(b) Stereoisotopomers

These are isotopomers in which the isotopes are connected to the same atoms but point in different directions in space.

(i) Geometric stereoisotopomers

(`Z`)- and (`E`)`"-CH"_3"CH=CH"[""^2"H"_1]` are geometric stereoisotopomers
of 1-(`""^2"H"_1`)propene.

(ii) Optical stereoisotopomers

(`R`)- and (`S`)`"-CH"_3"CH"[""^2"H"_1]"OH"` are enantiomeric optical stereoisotopomers
of 1-(`""^2"H"_1`)ethanol.