Which of the following statements concerning the stereochemistry of 2,3-dichlorobutane is structural — Haloalkanes and Haloarenes Chemistry Question
Question
Which of the following statements concerning the stereochemistry of 2,3-dichlorobutane is structurally and physically true?
💡 Solution & Explanation
2,3-dichlorobutane has two similar stereocenters. Let's review the principles: A) False. Because the two chiral centers have the same substituents, the molecule generates only three stereoisomers: a pair of enantiomers (active) and one meso compound (inactive). B) False. The meso form is optically inactive due to *internal* compensation (the molecule has an internal plane of symmetry that cancels rotation within a single molecule), not external compensation. C) True. A racemic mixture is a 1:1 mixture of the pure (+)-isomer and (-)-isomer. The optical rotation is zero because the rotation of one molecule is exactly canceled by a mirror-image molecule somewhere else in the solution. This inter-molecular cancellation is the definition of *external* compensation. D) False. A meso form is a distinct diastereomer of both enantiomers, but cannot act as an enantiomer to a mixture.