Q 24P - Organic Chemistry (Mcmurry)

Question

Draw and name all of the monochlorination products that you might obtain from the radical chlorination of the compounds below. Which of the products is chiral? Are any of the products optically active? 

(a) 2-methylbutane 

(b) Methylcyclopropane

(c) 2,2-dimethylpentane

Step-by-Step Solution

Answer

a)

                                                     Chlorination of 2-methyl butane

b) 

                                               Chlorination of methyl cyclopropane

c)

                                           Chlorination of 2,2-dimethylpentane

Step-by-Step Solution Step 1: Chiral molecule

A chiral molecule is not superimposable on its mirror image, and a chiral molecule has at least one carbon atom, which is bonded to four different groups.

The achiral molecule is superimposable on its mirror image, and an achiral molecule does not contain a carbon atom bonded to four different groups.

Step 2: a) Chlorination of 2-methyl butane

Chlorination of 2-methyl butane in the presence of light gives the possible four mono chlorination products. Thus, the reaction is as follows:

                                                                Chlorination of 2-methyl butane

Here, the compound 2-chloro-3-methyl butane is a chiral molecule as it has a carbon atom that is bonded with four different groups. Therefore, due to the presence of a chiral center, this molecule is also optically active.

Step 3: b) Chlorination of methyl cyclopropane

Chlorination of methyl cyclopropane in the presence of light gives the possible three products given as follows:

                                               Chlorination of methyl cyclopropane

All the formed compounds are achiral as they do not contain carbon atom which is bonded to four different groups. Therefore, all the formed compounds are optically inactive.

Step 4: c) Chlorination of 2,2-dimethyl pentane

Chlorination of 2,2-dimethylpentane in the presence of light gives the possible 4 monochlorinated products as follows:

                                                             Chlorination of 2,2-dimethylpentane

Here, the compounds 3-chloro-2,2-dimethylpentane and 4-chloro-2,2-dimethylpentane are chiral molecules because they contain chiral carbon atoms. Due to the presence of a chiral center, those compounds are also optically active.