Question

In attempting to synthesize cyclohexane from benzene, they somehow got methylcyclopentane. Can anyone write out probable steps going from benzene to methylcyclopentane with HI at 275 degrees C?

https://upload.wikimedia.org/wikipedia/commons/d/d9/CyclohexaneBerthelot.svg

https://en.wikipedia.org/wiki/Cyclohexane#Early_failures

Answer 1

This should be reaction of rearrangement.
In the first place, you add H+, and you for a carbo cataion, and as the structure now is instable, when you rise up the T, it shoud break and rearrange in more stable way.

Answer 2

But HI works also ad a reducent agent 2HI--> I2 + H2, where H2 will also make weaker all the structure. So that's why u cant use another acid as HBr or HCl, cuz of their redox potential.

Answer 3

Oh, so does that mean HI has a high redox potential and HBr and HCl have a low redox potential?

Answer 4

Try to think about the eletconegativity: for Clorine use to riduce a lot, Br little bit less, and I has pretty low tendence to reduce, so it easyer for I to get reoxidated, while i think you will be in touble if you will try to reoxidate Cl- in Cl2

Answer 5

I would like to see the mechanism for this step by step.