In 1-chloroprop-1-ene(E), if we add HBr, where will the proton add to, C1 or C2? I am asking this because I can't decide whether mesomeric as well as negative inductive effect of Cl will dominate or hyperconjugation of methyl group at C2 carbon, which in turn will decide the position of the formed carbocation.

  • $\begingroup$ Chlorine in chlorobenzene is an ortho, para-director. What does that tell you? $\endgroup$ – user55119 May 17 '20 at 23:48
  • $\begingroup$ @user55119,But also, chlorine deactivates the ring. Therefore, it is a bit confusing that whether hyperconjugation (which only stabilises carbocation) will dominate, or +M and -I by chlorine. $\endgroup$ – B.Anshuman May 18 '20 at 3:54
  • $\begingroup$ The +M effect is dominant here over hyperconjugation. Hyperconjugation is dominant over +M when number of alpha hydrogen is more than 9. I think this gives you a hint what can be the answer to your question. $\endgroup$ – Bitthal Maheshwari May 18 '20 at 5:31
  • $\begingroup$ Simply follow the experimental results. $\endgroup$ – user55119 May 18 '20 at 12:31

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