Each of the following is a Fischer projection of 2,3-dihalobutane type compounds with CH3 at the top and bottom. Which represent meso compounds?

2,3-dibromobutane: C2 has left H, right Br; C3 has left H, right Br

2,3-dichlorobutane: C2 has left Cl, right H; C3 has left Cl, right H

2,3-dibromobutane: C2 has left H, right Br; C3 has left H, right Br

2,3-dibromobutane: C2 has left H, right Br; C3 has left Br, right H

2,3-dichlorobutane: C2 has left Cl, right H; C3 has left Cl, right H

2-bromo-3-chlorobutane: C2 has left H, right Br; C3 has left H, right Cl

MolSynapse / Question bank / Stereoisomerism / Fischer, Newman and sawhorse projections

JEE Main levelOne or more correct optionsDifficulty 2 of 3st100

Each of the following is a Fischer projection of 2,3-dihalobutane type compounds with $CH X_{3}$ at the top and bottom. Which represent meso compounds?

A2,3-dibromobutane: C2 has left H, right Br; C3 has left H, right Br
B2,3-dibromobutane: C2 has left H, right Br; C3 has left Br, right H
C2,3-dichlorobutane: C2 has left Cl, right H; C3 has left Cl, right H
D2-bromo-3-chlorobutane: C2 has left H, right Br; C3 has left H, right Cl

Answer: A, C

A meso compound needs identical groups on the two centres and an internal mirror plane, which in a Fischer projection means identical groups on the same side. Options A and C meet this and are (2S,3R)-dibromo and (2R,3S)-dichloro meso forms. In option B the groups are on opposite sides, giving a chiral (R,R) or (S,S) compound. Option D has two different halogens, so no mirror plane is possible.

Practice Stereoisomerism More on Fischer, Newman and sawhorse projections

Previous questionNext question

Each of the following is a Fischer projection of 2,3-dihalobutane type compounds with CHX3​ at the top and bottom. Which represent meso compounds?

Answer: A, C

More questions on Fischer, Newman and sawhorse projections

Each of the following is a Fischer projection of 2,3-dihalobutane type compounds with $CH X_{3}$ at the top and bottom. Which represent meso compounds?