Q71E - Organic Chemistry (Mcmurry)

Question

How would you synthesize the following compounds from benzene? Assume that ortho and para isomers can be separated.

Step-by-Step Solution

Answer

Synthesis of Compound A from benzene

For the formation of ortho bromo para nitro toluene from benzene firstly make aren’t benzene that is toluene by reacting the benzene with methyl chloride in presence of aluminium chloride now nitro is at para nitration is done in the presence of nitrous acid and followed by bromination in presence of ferrous bromide to add bromide at the ortho bromination because para is already filled.

Nitration is done before bromination because if bromination done first then para position is occupied by the Br ion but as per product formation nitro is present at para.

Mechanism for compound A formation

The steps followed as:

1. Parent benzene is formed that is toluene
2. Nitration occurs so nitro present at para
3. Bromination so Br occupy ortho position
4. o-bromo p- nitro toluene formed

Synthesis of Compound B from benzene

The steps followed as:

1. Acylation of benzene occurs on reacting with (CH₃)₂ CHCOCI
2. Chlorination in the presence of CI_2, FeCI₃ 
3. Reduction of the carbonyl in the presence of H₂/Pd,C
4. Sulphonation in the presence of SO_3,H₂SO₄