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15.

 

Which is the least stable in these structures if the radical carbon is changed to a carbanion?

(answer is A, pay attention to sign of charge!)

16.

 

The major monobromination product in the following reaction is

(CH

3

)

3

CCH

2

CH

3

+   Br

2

products

h

n

(CH

3

)

3

CCH

2

CH

2

Br

(CH

3

)

3

CCHCH

3

Br

(CH

3

)

2

CCH

2

CH

3

Br

(CH

3

)

2

CCH

2

CH

3

CH

2

Br

(a)

(b)

(c)

(d)

(e) none of the above

The answer is (C) because selectivity is high for bromination which prefers to attach the weaker C-H
bond.

17.

 

According to the following energy profile, the rate of reaction from A to B is determined by

E

reaction coordinate

A

B

C

(a)  the energy of A only
(b)  the energy of B only
(c)  the energy difference between C and A
(d)  the energy difference between B and A
(e)  the energy of C only

The answer is C (activation energy)

Comments:

Organic chemistry (questions with answers)

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