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This question is about the structure of products X and Y. According to me, the answer should be only A (as OTs will substitute on benzylic carbon).

But in the answer key, they have given B and D.

Please help.

  • 1
    $\begingroup$ I'd suggest you that, in your future questions and answers, not to abbreviate word for the benefit of most of the readers. Thank you. $\endgroup$ May 20, 2018 at 6:22
  • 1
    $\begingroup$ Done @MathewMahindaratne. Will keep this in mind for future questions... $\endgroup$ May 20, 2018 at 6:24
  • 4
    $\begingroup$ The picture is blurry. Please upload a better quality one/ consider sketching through chemsketch. $\endgroup$
    – Archer
    May 20, 2018 at 6:36

1 Answer 1


There are two replaceable $\ce{H}$s in the starting material, but only 1 equiv of $\ce{TsCl}$ is given. Thus, primary $\ce{-OH}$ will win the battle due to steric reasons, and therefore, B represent the intermediate product X. The second reaction is firstly acid-base reaction between secondary $\ce{-OH}$ and $\ce{H-}$, and then, nucleophilic substitution ($\mathrm{S_N}$2) reaction to replace $\ce{-OTs}$ group by $\ce{H-}$. That leaves D as the product Y, after acid workup.

  • $\begingroup$ So u mean that since the benzylic carbon is sterically hindered, its -OH won't be substituted?? $\endgroup$ May 20, 2018 at 6:48
  • 1
    $\begingroup$ The faster reaction is acid-base reaction. Once, acetic $\ce{H}$ removed from $\ce{-OH}$, it is basically not removable. $\endgroup$ May 20, 2018 at 6:56

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