Question

Halogenation of which one of the following will yield m-substituted product with respect to methyl group as a major product?

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is C

To determine which compound will yield a m-substituted product upon halogenation with respect to the methyl group, it is essential to understand the directing effects of substituents in aromatic compounds:

1. Aromatic substitutions in benzene rings involve directing effects based on the nature of the substituents.
2. Activating groups, such as alkyl groups (e.g., a methyl group), are usually ortho/para directing.
3. Deactivating groups, such as nitro groups, are typically meta directing.

Now let's analyze the options provided and find the one that will direct a substituent to the meta position with respect to the methyl group:

1. Compound 1:

   

   This compound has both methyl and hydroxyl groups. Hydroxyl is a strong ortho/para director, and methyl is also an ortho/para director, thus not leading to a meta-substituted product.

2. Compound 2:

   

   This compound has a methyl group and a halogen, such as chlorine or bromine. Halogens are ortho/para directing although they are deactivating. Both substituents favor ortho/para, not meta.

3. Compound 3:

   

   This compound has methyl and nitro groups. The nitro group, which is a very strong deactivator, directs the incoming group to the meta position despite the activating effect of the methyl group.

4. Compound 4:

   

   This compound is simply a toluene derivative, where methyl is the principal group, thus directing ortho/para, not meta.

Therefore, upon evaluation, Compound 3 (with a methyl and a nitro group) is the correct answer. The nitro group's strong deactivation effect makes it a meta director, leading to a m-substituted halogenation product. This aligns with the given correct answer.