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4 Mar 2009 21:31:37 IST
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trans-2-phenyl-1-bromocyclopentane +alc. KOH ----------> ????
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4 Mar 2009 22:35:03 IST
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double bond wud be formed in conjugation with the bezene as that would be the most stable product......
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5 Mar 2009 00:28:37 IST
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any more answers??
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yes.. i wud say that the answer is just the opposite.. that is the product in conjugation with benzene ring wont be formed here...i guess answer must be 1-phenylcyclopent-4-ene ....this is because though if double bond in conjugation with bezene wud be more stable product, but for elimination with KOH, u need a hydrogen in trans position.. but phenyl grp is occupying the trans position on one side, but on other side, there is trans hydrogen.. hence, i said that 1-phenylcyclopent-4-ene wud be formed...( plz ignore IUPAC name error if present)
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5 Mar 2009 16:27:23 IST
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i agree with vighnesh............but still any other answers????
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5 Mar 2009 18:34:51 IST
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hey i too think viggi is right.
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5 Mar 2009 18:59:51 IST
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1phenylcyclopentene will b formed
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5 Mar 2009 19:29:31 IST
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3-phenylcyclopentene It is based on E2 Mechanism The general form of the E2 mechanism is as follows:
B: = base
X = leaving group (usually halide or tosylate) In the E2 mechanism, a base abstracts a proton neighboring the leaving group, forcing the electrons down to make a double bond, and, in so doing, forcing off the leaving group. When numerous things happen simultaneously in a mechanism, such as the E2 reaction, it is called a concerted step. if u can understand ok otherwise i will write the reaction
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Rakesh Trikha |
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5 Mar 2009 20:11:03 IST
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The given compound we may regard as a secondary halide, and many sec and tert halides undergo elimination by E1 mechanism. Formation of carbocation is the r.d.s.Thus in this case the proton attached to carbon having phenyl goup is likely to be eliminated, forming a tertiary carbocation, more stable than the other possibility a secondary.This would then eliminate the bromide ion to form 1-Phenylcyclopentene. It has been observed that the dehydrohalogenation of substituted cycloalkyl halides follows the Saytzeff's rule; thus supporting formation of 1-phenylcyclopentene.
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5 Mar 2009 20:46:11 IST
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I think it should be 3-phenylcyclopentene via E2 this question was in AIEEE 2006 QNO. 132 http://www.fiitjee.com/down/sol/achemistry06.pdf
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Rakesh Trikha |
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5 Mar 2009 20:56:39 IST
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@rtrikha sir, plz clarify ur answer. Also , check vighnesh's answer . i think he is right , however the possibility shown by madhusudan sir cannot also be ruled out. E1 may also occur.I m a bit confused. plz clarify this doubt d=stating whether E1 or E2 will be dominating............ i will be thankful.
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7 Mar 2009 12:29:21 IST
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hey anyone clarify my doubt......
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