Chemistry - STEREO ISOMERISM Question with Solution | TestHub
Match the list-I to List-II
List - I | List - II |
|---|---|
(P)
| (1) Diastereomers |
(Q)
| (2) Racemic mixture |
(R)
| (3) Meso compounds |
(S)
| (4) gas will evolve |
| (5) An hydride form as product |
Options:
Answer:
Solution:
P. The compound in (P) is a malonic acid derivative with a chiral center. Heating a malonic acid derivative (geminal dicarboxylic acids) causes decarboxylation, releasing CO₂ gas. This is a general reaction for compounds with a -keto acid structure, which is present in malonic acids.
Q. The compound in (Q) is also a malonic acid derivative. Upon heating, it will undergo decarboxylation to evolve CO₂ gas. The resulting product will be a chiral molecule (2-phenylbutane) formed as a racemic mixture because the reaction mechanism involves a non-stereoselective step leading to both enantiomers.
R. The compound in (R) is a cyclic dicarboxylic acid. It has two chiral centers. The specific stereochemistry shown (trans configuration) is chiral and would exist as a pair of enantiomers in a racemic mixture. A cis isomer of the same molecule would be a meso compound and a diastereomer of the trans isomer.
S. The compound in (S) is a dicarboxylic acid with a specific rigid bicyclic structure (cis configuration). This molecule possesses a plane of symmetry, making it an achiral meso compound. Heating dicarboxylic acids that can form a stable five- or six-membered ring anhydride results in anhydride formation. This cis arrangement is suitable for forming a cyclic anhydride product.