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From NCERT Class Chemistry Part 2:

Example 11.5

Write the structures of the major products expected from the following reactions:

(a) Mononitration of 3-methylphenol
(b) Dinitration of 3-methylphenol
(c) Mononitration of phenyl methanoate.

Solution

The combined influence of $\ce{-OH}$ and $\ce{-CH3}$ groups determine the position of the incoming group.

nitration products

Since $\ce{-OH}$ and $\ce{-CH3}$ are o,p-directing groups, shouldn’t the major product be 3-methyl-2-nitrophenol? Why not?

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    $\begingroup$ Weigh inductive, mesomeric and steric effects in the balance. $\endgroup$ – Sir Arthur7 Mar 6 '20 at 7:36
  • $\begingroup$ @SirArthur7 I can’t seem to get the answer right,can you explain it in detail? $\endgroup$ – JjJot Mar 6 '20 at 8:14
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    $\begingroup$ In order for a nitro- group to be attached to a phenyl group, you must have an H atom available next to this carbon atom. If NO2 wants to attack the Carbon number 2, there is no H atom on Carbon 1 or 3. So the reaction is not possible. $\endgroup$ – Maurice Mar 6 '20 at 8:51
  • $\begingroup$ @Maurice why is this necessary $\endgroup$ – JjJot Mar 6 '20 at 15:32
  • $\begingroup$ @Jashanjot : The nitration reaction is due to the ion $NO_2^+$ attrcte $\endgroup$ – Maurice Mar 7 '20 at 19:32
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The product you are suggesting is very unstable as compared to the ones given as answers due to steric factors. Thus it would not be formed.

Since −OH and −CH3 are o,p-directing groups, shouldn’t the major product be 3-methyl-2-nitrophenol? Why not?

The reasoning that hydroxyl and methyl are o,p directing groups is not at supportive as to why 3-methyl-2-nitrophenol should be formed in preference to the ones given as answers. The o,p directing effect just rules out the meta product and steric factor decides among the remaining possibilities here.

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