Question

Reaction of (±) 2,3- dibromobutane is slower than meso in which the two methyl groups are ____________

(a) Skew

(b) Anti

(c) Gauche

(d) Partially eclipsed

I had been asked this question in an international level competition.

The origin of the question is Stereoselectivity and Stereospecificity in portion Structure and Stereostructure of Molecules of Engineering Chemistry I

Answer 1

The correct choice is (d) Partially eclipsed

To elaborate: Reaction of (±) 2,3- dibromobutane is slower than meso due to higher transition state in which the two methyl groups are partially eclipsed.