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Leolynn Cauthron

Reaction of cyclohexene with hydrochloric acid

David Ocame  Follow

Have a look at the mechanism for the dimerization of cyclohexene in strongly acidic medium:

enter image description here

After the attack of a nucleophile (pi bond) on the electrophilic carbocation, we have:

A: joining of the two rings with a bond, and the consequent carbocation (why did it get formed on that position? why not on the adjacent ones?)
B: rearrangement of the carbocation (why did it happen?)
C: loss of a proton to form the thermodynamically most favorable product (most substituted alkene)

The double bond was formed because of the loss of the $\ce{H+}$ ion in step C, formation of a negative charge at that position, and then the delocalisation of that negative charge into the adjacent empty p-orbital (of the $\ce{C+}$ position).

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BBIER? Lighting Manufacturer  Follow

Then through rearrangement the plus charge will shift to 3 degree carbon.

You're nearly there.
I suggest you draw the 3° carbocation out and think a bit more.
Hint: Hyperconjugation

enter image description here

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Crow72  Follow

Then after the said rearrangement, visualize the lose of proton from the second tertiary carbon atom, giving you your desired product.

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Jeff Nelson  Follow
Maybe because the product is stableMore
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Hafizullah Sufi  Follow
Okay, Ill keep that in mind in the futureMore
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Filippo Veronese  Follow
Okay I got my answer. The charge will be delocalised due to empty p orbital. Thank you.More
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Emily Jones  Follow
Why will the tertiary carbon lose the proton? Wont the negative charge become unstable due to the +I effect?More
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