3
$\begingroup$

Find the product of the following reaction

enter image description here

Note that the carbon marked as a star is a special labelled carbon which may be considered as a $\ce{C-14}$ isotope

The given answer is (c)

Why would the product in option (b) form ? I know that it proceeds via SN2 mechanism but is there some sort of benzyne reaction where we would get the product in option (b) ?

$\endgroup$
1
  • 4
    $\begingroup$ It is similar to dow's process, which takes place via Sn Benzyne mechanism $\endgroup$
    – Jayadithya
    Jun 13 at 8:55
6
$\begingroup$

The point is, as mentioned in the comment by @Jayadithya, that given the reaction conditions, the explicit «marking» a carbon atom as $\ce{^{13}C}$ (instead of the typical $\ce{^{12}C}$ / $\ce{^{13}C}$ according to the general isotopic distribution for this element) does not introduce a significant site selectivity for the reaction of the intermediate benzyne:

enter image description here

Thus, one anticipates an equal molar ratio of products formed along pathway a), and b). It is not the kinetic H-D isotopic effect you may observe e.g., with the $S_N2$ reactions

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.