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I have a question in my chemistry workbook, and the solution to the question is different from what I think it is.

The question is what is the product of the reaction between 1-cyclohexyl-1-propyne and excess of HBr. The structure I think we get is 2,2-dibromopropyl cyclohexane. However, not only is it not present in the options, but the given answer is 1,1-dibromopropyl cyclohexane.

According to the Markownikov rule, the carbocation formed should be the most stable. I used hyperconjugation to check the stability, and I am pretty sure my structure has more alpha-hydrogens. Is there a reason this happens, or is my book just dumb?

*My IUPAC naming might be wrong so here are the images of the structures that I am talking about:

My structure: enter image description here

Given structure: enter image description here

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    $\begingroup$ My structure and Given structure are both the same structure, namely (2,2-dimethylpropyl)cyclohexane. $\endgroup$
    – Maurice
    Commented Jul 1 at 19:42
  • $\begingroup$ Please explain. Those Me's are figmentary [sic] bromines so there is a 1,1 or 2,2-dibromopropyl cyclohexane. Were they methyls one would be a propyl, two would be a sec-butyl. The question is the direction of addition and possibly interaction of the cyclohexyl group. The second addition might involve a proton shift. $\endgroup$
    – jimchmst
    Commented yesterday

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