Which of the following pairs of structures represent the same enantiomer, and which represent different enantiomers?
(a) and
(b) and
(c) and
(d) and

Question

Which of the following pairs of structures represent the same enantiomer, and which represent different enantiomers? (a) and (b) and (c) and (d) and

TestHub · Accepted Answer

Ans. (A) (a) Enantiomers; (b), (c) and (d) are pairs of identical molecules.

Sol. Assign R/S at each centre.

(a) Priorities Br $>$ CN $>$ CH₃ $>$ H: first structure S, second R : enantiomers.

(b) Priorities Br $>$ CO₂H $>$ CN $>$ H: both structures are S : identical.

(c) Priorities OH $>$ CH₂CH₃ $>$ CH₃ $>$ H: both structures are R : identical.

(d) Priorities NH₂ $>$ CO₂H $>$ CH₃ $>$ H: both structures are S : identical.

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