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Topic: Halogenation  (Read 5646 times)

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Offline kelaklub

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Halogenation
« on: May 14, 2006, 02:28:17 PM »
The following reaction is a halogenation reaction and the answer is stated as choice C. Is there a possible typo with the lone hydrogen still being attached to the most substituted isopropyl carbon? Thanks.
« Last Edit: May 14, 2006, 02:49:10 PM by kelaklub »

Offline Albert

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Re: Halogenation
« Reply #1 on: May 14, 2006, 02:39:18 PM »
Answer C is clearly the right one, except for that hydrogen, which is obviously misprinted.

Offline kelaklub

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Re: Halogenation
« Reply #2 on: May 14, 2006, 02:49:45 PM »
That's what I thought. Thanks.

Offline victor

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Re: Halogenation
« Reply #3 on: May 15, 2006, 09:33:33 AM »
is it because that there's no FeBr3 catalyst present?(so Br group will get attached into isopropyl group?)

Offline Albert

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Re: Halogenation
« Reply #4 on: May 15, 2006, 01:00:06 PM »
is it because that there's no FeBr3 catalyst present?(so Br group will get attached into isopropyl group?)

I would just say it's a radical halogenation of an alkane.

Offline Donaldson Tan

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Re: Halogenation
« Reply #5 on: May 15, 2006, 03:09:16 PM »
When there's UV, you gonna have Bromine radicals everywhere. The alkyl group is most susceptible to radical attacks compared to the benzene ring which is reasonance stabilised. Your main product will be (c)
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Offline movies

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Re: Halogenation
« Reply #6 on: May 17, 2006, 02:46:34 PM »
The reason that it goes to that particular position is because the benzyllic radical can be stabilized by the adjacent aromatic ring.  It's the difference between stabilizing an intermediate and stabilizing the transition state that gets you there.

If it was just the difference between the availability of hydrogens on the aromatic ring versus those not on the aromatic ring, you would expect to see bromination on the methyl groups as well.
« Last Edit: May 17, 2006, 02:48:40 PM by movies »

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