Which stereoisomer is the meso-form? Why?

trans--1,2-dibromocyclopropane
OR
cis--1,2-dibromocyclopropane

1 Answer
Mar 2, 2016

The #cis# isomer is the meso form.

Explanation:

#trans-1,2-"dibromocyclopane"# generates 2 optical isomers, #R,R#, and #S,S#, where each chiral carbon is bound to halide. It is fairly clear that the #"meso"# has a plane of symmetry bisecting #CH_2# that equates the #cis#-bromine atoms. If you can't see this on paper, then make a couple of models.