Which stereoisomer is the meso-form? Why?

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

Answer 1

The #cis# isomer is the meso form.

#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.

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Answer 2

Carter Allen

The meso-form is a stereoisomer with an internal plane of symmetry, resulting in optically inactive compounds.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

Which stereoisomer is the meso-form? Why?

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

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