Portmess Homework Q&S 117

Portmess Homework Q&S 117 - mixture of cis and...

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( e ) For the 1,1-dimethylpropyl cation to be formed by a process involving a hydride shift, the starting alcohol must have the same carbon skeleton as the 1,1-dimethylpropyl cation. Although the same carbon skeleton is necessary, it alone is not suf f cient; the alcohol must also have its hydroxyl group on the carbon atom adjacent to the carbon that bears the migrat- ing hydrogen. Thus, 3-methyl-1-butanol cannot form a tertiary carbocation by a single hy- dride shift. It requires two sequential hydride shifts. ( f ) 2,2-Dimethyl-1-propanol can yield a tertiary carbocation by a process involving a methyl shift. 5.36 ( a ) Heating an alcohol in the presence of an acid catalyst (KHSO 4 ) leads to dehydration with formation of an alkene. In this alcohol, elimination can occur in only one direction to give a
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Unformatted text preview: mixture of cis and trans alkenes. Br CHCH 2 CH 3 CHCH 3 Br CH OH KHSO 4 heat Cis trans mixture CH 3 CH 3 H 1 CH 3 C CH 3 1 1 CH 3 C 2,2-Dimethyl-1-propanol CH 2 CH 2 CH 3 O H H CH 3 CH 3 CH 3 C CH 2 OH CH 3 H H 1 CH 3 CHCH CH 3 CH 3 CHCH 2 CH 2 OH CH 3 H CH 3 C 1 1 1 3-Methyl-1-butanol CH 2 CHCH 3 O H H CH 3 CH 3 CCH 2 CH 3 CH 3 C H H 1 2 H 2 O CH 3 CH 3 OH CHCH 3 H CH 3 C CH 3 C 1 1 CH 3 3-Methyl-2-butanol CHCH 3 CH 2 CH 3 1 CH 3 HOCH 2 CCH 2 CH 3 H CH 3 CCH 2 CH 3 H H 1 HO H CH 2 CH 3 CCH 2 CH 3 1 CH 3 2-Methyl-1-butanol H CH 3 C CHCH 3 CH 3 CH 3 CCH 2 CH 3 1 CH 3 CH 3 OH HOCH 2 CCH 2 CH 3 has same carbon skeleton as H and STRUCTURE AND PREPARATION OF ALKENES: ELIMINATION REACTIONS 111...
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This note was uploaded on 09/20/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.

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