Q 22P - Organic Chemistry (Mcmurry)

Question

Question: How might you synthesize the following substances from benzene? 

(a) m-Chloronitrobenzene 

(b) m-Chloroethylbenzene 

(c) 4-Chloro-1-nitro-2-propylbenzene 

(d) 3-Bromo-2-methylbenzenesulfonic acid

Step-by-Step Solution

Answer

a.

b.

c.

d.

Step 1: m- nitro chlorobenzene from benzene

1. As the parent benzene is ethylbenzene that is nitration is to occur in the presence of a nitro group is directly added to a benzene ring.
2. Then chloro group is present at the meta position so that nitrobenzene reacts with ferrous chloride 
3. The final product m-chloronitrobenzene is formed as shown:

Formation of m-chloronitrobenzene

Step 2: m-chloroethylbenzene from benzene

1. As the parent benzene is chlorobenzene which is formed by the alkylation of benzene in reacting with in presence of aluminium chloride.
2. Then Bromo group is present at the meta position so that benzene reacts with ferrous chloride for the addition of the Cl group
3. Then followed by which lead to a reduction of aryl alkyl ketone
4. The final product m-chloroethylbenzene is formed as shown:

Formation of m-chloroethylbenzene

Step 3: 4-chloro1-nitro2-propylbenzene from benzene

1. As the parent benzene is propylbenzene which is formed by the alkylation of benzene in reacting with in presence of aluminium chloride.
2. Then chloro group is present at the meta position so that chlorobenzene react with ferrous chloride for the addition of Cl group
3. Then followed by which lead to reduction of aryl alkyl ketone
4. Then nitration occur in the presence of nitrous acid for the addition of nitro group
5. The final product 4-chloro-1-nitro2-propylbenzene is formed as shown:

Formation of 4-Chloro-1-nitro-2-propylbenzene

Step 4: Formation 3-Bromo-2-methylbenzenesulphonic acid from benzene

1. As the alkylation of benzene occurs on reacting with in presence of aluminium chloride.
2. For sulphonation benzene react with sulphuric acid in the presence of
3. Then Bromo group is present at the meta position so that 2-methyl benzene sulphonic acid reacts with ferrous bromide for the addition of the Br group
4. Then followed by which lead to a reduction of aryl alkyl ketone
5. The final product 3-bromo 2-methyl benzene sulphonic acid is formed as shown:

Formation of 3-Bromo-2-methylbenzene Sulphonic acid