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enter image description here

In this particular question, my answer is (D) as steric hinderance is minimum there, but answer (B) was given due to the electron withdrawing (-M) effect of the nitro group.

Isn't steric hinderance the dominating factor in nucleophilic addition type reactions? Is it that a planar phenyl ring doesn't offer that much steric hinderance?

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  • $\begingroup$ @Jay Yes knew it , but problem was that steric hinderance should've been more dominating factor than this ? $\endgroup$
    – Yash Agrawal
    Commented Sep 14, 2021 at 8:07
  • $\begingroup$ Both are 1° carbon but your view can't be ignored. $\endgroup$
    – Jay
    Commented Sep 14, 2021 at 10:03

1 Answer 1

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The high reactivity of acyl chlorides towards nucleophilic attack is due to the highly polarised situation of the carbon-oxygen/chlorine bonds i.e.

enter image description here

As you have mentioned due to the phenyl ring being planar, the steric hindrance does not overpower the polarising thing.

Now on comparing the reactions -NO$_2$ group's -M effect will be the most successful to make the carbon-oxygen/chlorine bonds more polar as compared to methyl's +I effect.

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  • $\begingroup$ Yes , seems right $\endgroup$
    – Yash Agrawal
    Commented Sep 14, 2021 at 11:12
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    $\begingroup$ I disagree. This paper compares the rates of alcoholysis of various acid chlorides and it is found that acetyl chloride has a much higher rate than p-nitro benzoyl chloride. $\endgroup$
    – Robin Singh
    Commented Sep 15, 2021 at 1:39
  • $\begingroup$ @RobinSingh the paper is not explicitly showing any comparison between p-nitro benzoyl chloride and acetyl chloride. It does talks about ethyl p-nitrobenzoate which is a different compound. $\endgroup$
    – R_Squared
    Commented Sep 15, 2021 at 2:08
  • $\begingroup$ @DivyanshVerma It does lol. Check Table I and II on page 4 $\endgroup$
    – Robin Singh
    Commented Sep 15, 2021 at 4:51
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    $\begingroup$ I don't have access to the whole pdf $\endgroup$
    – R_Squared
    Commented Sep 15, 2021 at 7:13

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