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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Fzang on December 11, 2010, 06:14:51 AM

Title: Product of isopropylbenzene + cyclohexene + HF
Post by: Fzang on December 11, 2010, 06:14:51 AM

That is the question I'm given. No drawings, no clues, no nothing.

Previous question was benzoic acid + nitric acid/sulfuric acid which adds a meta-directed nitro-group to the benzoic acid. Simple as that... but the question in topic... I have no idea. Does it mean I add hydroflouric acid to cyclohexene to create some flourocyclohexane which can then (somehow) react with isopropylbenzene.. or what?

I'm clueless. Every other question in this section follows the "A + B with condition C", except the one in topic.

Title: Re: Product of isopropylbenzene + cyclohexene + HF
Post by: Fzang on December 11, 2010, 08:09:22 AM

Maybe this?

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Ff.cl.ly%2Fitems%2F18121N273Z2t3j3k273l%2FScreen%2520shot%25202010-12-11%2520at%25202.13.45%2520PM.png&hash=b38225b2b91f858bc76c4a4bb84821813a50c629)

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Ff.cl.ly%2Fitems%2F1B2p3P0w26233n0y0l0A%2FScreen%2520shot%25202010-12-11%2520at%25202.13.13%2520PM.png&hash=24e02c05cc632ea7fd00054a7330588f9887cc6b)

That would make perfect sense... I think.

If that's the case, could anybody explain the reaction mechanism, showing the intermediates formed?

Title: Re: Product of isopropylbenzene + cyclohexene + HF
Post by: ooosh on December 13, 2010, 04:23:07 AM

Dont you know the mechanism of F-C alkylation?

Title: Re: Product of isopropylbenzene + cyclohexene + HF
Post by: Fzang on December 13, 2010, 06:07:44 AM

HF attaches to the double bond, creating flourocyclohexane.

Flourocyclohexane is converted to cyclohexane-carbocation with AlF₃.

Carbocation reacts o/p with benzene isopropylbenzene.

Proton is removed from the o/p located carbon, restoring charge.

Proton regenerates AlF₄^- to AlF₃ and HF.

Is this correct?

Title: Re: Product of isopropylbenzene + cyclohexene + HF
Post by: Fzang on December 13, 2010, 07:14:00 AM

(Why can't I edit my posts?)

Correction to above. I think HF can create an electrophile/nucleophile by itself without a catalyst. Catalysts are only needed for pure halogens such as Br₂.

Title: Re: Product of isopropylbenzene + cyclohexene + HF
Post by: ooosh on December 14, 2010, 10:48:54 PM

See,you can solve it yourself.

Title: Re: Product of isopropylbenzene + cyclohexene + HF
Post by: cupid.callin on December 15, 2010, 09:14:54 AM

Its pretty simple example of freidal craft's alkylation.
But the ortho product will be in negligible amount due to steric hindrance .