Advices For Studying Organic Chemistry

CH 3 (CH 2 ) 15 CH 2 CH 2 Br (CH^3 )^3 CO CH 3 (CH 2 ) 15 CH CH 2

−K+

(CH 3 ) 3 COH

40 oC 85%

2. Dehydrohalogenation of many alkyl halides yields more than one product:

B −

B

B

(a) H(a)

(a)

(b)

CH 3 CH C

H CH 2

CH 3

Br

(b)

(b)

CH 3 CH C

CH 3

CH 3

H Br −

CH 3 CH 2 C

CH 2

CH 3

H Br −

+

+

+

+

2-Methyl-2-butene

2-Methyl-1-butene

2-Bromo-2-methylbutane

1) When a small base such as ethoxide ion or hydroxide ion is used, the major

product of the reaction will be the more stable alkene.

CH 3 CH 2 O− CH 3 CH 2 CCH 3

CH 3

Br

70 oC

CH 3 CH 2 OH CH^3 CH C

CH 3

CH 3

CH 3 CH 2 C

CH 2

CH 3

+ +

2-Methyl-2-butene

(69%)

(more stable)

2-Methyl-1-butene

(31%)

(less stable)

i) The more stable alkene has the more highly substituted double bond.

2. The transition state for the reaction:

C 2 H 5 O−+

C 2 H 5 O

δ−

CC C 2 H 5 O

H

Br

CC

H

Brδ−

Η ++CC Br−

Transition state for an E2 reaction

The carbon-carbon bond has some

of the characterof a double bond.

1) The transition state for the reaction leading to 2-methyl-2-butene has the