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Organic Chemistry

Scorching goIITian

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1 Oct 2008 09:00:21 IST

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What is the product when 3-Methylbutene is added to HBr ?

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Avirup Dasgupta

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Joined: 30 Jul 2007

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1 Oct 2008 10:58:54 IST

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I think it will form 2bromo,2methyl butane as the major product.

There will most probably be a hydride shift to generate a 3 degree carbocation.

Rate if correct.

Avirup Dasgupta

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1 Oct 2008 11:01:28 IST

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It will form 2bromo,2methyl butane.

Madhusudan Chavan

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1 Oct 2008 17:23:14 IST

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Simce carbocations are prone to rearrangement, therefore, if the structure of the initially formed carbocation permits, it may undergo rearrangement either by a 1,2-hydride shift or by a 1,2-methyl shift to form the more stable carbocation which then undergoes nucleophilic attack by the bromide ion to form the rearranged alkyl halide. Thus 3-methylbut-1ene gives 2-bromo-2-methylbutane.

CH3-CH(CH3)-CH=CH2 adds H+ to give CH3-CH(CH3)-CH+_CH3 this secondary carbocation undergoes 1,2-hydride shift to form more stable tertiary carbocation CH3-C+(CH3)-CH2-CH3 which is attacked by bromide ion to form the product CH3-C-Br(-CH3)-CH2-CH3.

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