JEE Advanced 2017 · Paper 1 · Chemistry Q7

ChemistryMultiple correct+4 / -2Question 25 of 54

The correct statement(s) for the following addition reactions is(are)

(i) trans-2-butene $\xrightarrow{\ce{Br2/CHCl3}}$ M and N

(ii) cis-2-butene $\xrightarrow{\ce{Br2/CHCl3}}$ O and P

O and P are identical molecules

(M and O) and (N and P) are two pairs of diastereomers

(M and O) and (N and P) are two pairs of enantiomers

Bromination proceeds through trans-addition in both the reactions

Answer and worked solution

Official answer: B, D

Bromine adds anti, through a bromonium ion. (D) is true.

(i) trans-2-butene with anti addition gives meso-2,3-dibromobutane. M and N are the same meso compound.
(ii) cis-2-butene with anti addition gives the racemate, (2R,3R) and (2S,3S). O and P are enantiomers, not identical. (A) is false.

M and O are meso versus chiral, so they are diastereomers. The same holds for N and P. (B) is true and (C) is false.

(B), (D)

Topics:Optical isomerism and chirality Alkenes

JEE Advanced 2017 · Paper 1, Chemistry question 7