question_answer

Which of the following will have a meso-isomer also?

A)  2-chlorobutane

B)  2, 3-dichlorobutane

C)  2, 3-dichloropentane

D)  2-hydroxypropanoic acid

Correct Answer: B

Solution :

 [a]\[=C{{H}_{3}}-\underset{Cl}{\mathop{\underset{|}{\mathop{\overset{*}{\mathop{C}}\,}}\,}}\,H-C{{H}_{2}}C{{H}_{3}}\] One asymmetric carbon atom, forms d- and \[l-\]optical isomers. Meso due to internal compensation [b] Two asymmetric carbon atoms, forms \[d-,l-\]and meso forms. [c]\[C{{H}_{3}}-\underset{Cl}{\mathop{\underset{|}{\overset{*}{\mathop{CH}}}\,}}\,-\underset{Cl}{\mathop{\underset{|}{\overset{*}{\mathop{CH}}}\,}}\,-C{{H}_{2}}C{{H}_{3}}\] Two asymmetric carbon atoms but does not have symmetry. Hence, meso form is not formed. [d] \[C{{H}_{3}}-\underset{OH}{\mathop{\underset{|}{\overset{*}{\mathop{C}}}\,}}\,H-COOH\] One asymmetric carbon atom, meso form is not formed.