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(This question is from a dubious source)

Friedel-Crafts Acylation of benzene with 1-chloro 2,2-dimethyl propanone

The reaction taking place here is Friedel-Crafts acylation of benzene with 1-chloro 2,2-dimethyl propanone (pivaloyl chloride?). To me, the options seem most peculiar. When the $\ce{C} - \ce{Cl}$ is broken, it gives rise to a carbocation at the carbon of $\ce{C}=\ce{O}$ bond.

According to my teacher, $\ce{C+}=\ce{O}$ now leaves with the electrons of the adjacent $\ce{C}-\ce{C}$ bond, giving rise to a stable tertiary butyl carbocation. This leads us to $\ce{PhCMe3}$.

Edit 2: this is the same reaction: Unusual Friedel–Crafts alkylation with pivaloyl chloride

Considering that the t-butyl group is para-directing, the options still don't seem right to me. If this conversion to a t-butyl carbocation happens once, can it not happen again? Would we simply not get two t-butyl groups para to each other?

(I still doubt multiple substitution is even possible)

Edit 3: as of 24/2/2024 this question has been confirmed to be of poor quality. See reasons in comments.

zxen
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  • According to the person who gave me this question, the answer is B. – zxen Feb 21 '24 at 08:50
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    tBu group is similar to Me and electron-donating and so activating and p-directing – Waylander Feb 21 '24 at 08:57
  • See the answer to this SE question https://chemistry.stackexchange.com/questions/38454/unusual-friedel-crafts-alkylation-with-pivaloyl-chloride – Waylander Feb 21 '24 at 11:48
  • @Waylander thanks, that's the same reaction - but it concludes with only tert-butyl benzene. – zxen Feb 21 '24 at 12:32
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    I strongly suspect that you would get at least some of the 1,4-di-tert-butyl benzene in the reaction mixture, possibly the major component. The acylium species is not going to stop being a source of tBu+ and the t-Bu-benzene is more activated than benzene itself. – Waylander Feb 21 '24 at 13:10
  • All right, my teacher confirms this is a poor question. The alternatives listed as the possible products are all incredibly minor. – zxen Feb 22 '24 at 09:36
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    You'd get pretty much zero C, little D, but if you got B, then A would also be present and I second what Waylander said. – Mithoron Feb 23 '24 at 16:44

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