Organic Chemistry

Problems 781

47. Fill in the boxes:

a.

b.

48. Give the products of each of the following reactions:

a. f.

b. g.

c. h.

d. i.

e. j.

49. Thiols can be prepared from the reaction of thiourea with an alkyl halide, followed by hydroxide-ion-promoted hydrolysis.

a. Propose a mechanism for the reaction.

b. What thiol would be formed if the alkyl halide employed were pentyl bromide?

50. The only organic compound obtained when compound Z undergoes the following sequence of reactions gives the
    spectrum shown. Identify compound Z.

4

Offset: 0.2 ppm.

10 9 8765 3210

δ (ppm)

frequency

Compound Z

MnO 2

∆

1. phenylmagnesium bromide


2. H 3 O+

(^1) H NMR
thiourea urea
H 2 NNH (^2) ethanethiol
C
H 2 NNH 2
C
S

1. CH 3 CH 2 Br
   2. HO−, H 2 O + CH^3 CH^2 SH

O

2 CH 2 CH COCH 3 CH 3 NH 2

O

+

O

CH 3 OH

HCl

+

CH 3 C CHCCH 3 + HBr

CH 3 O

CH 3 CH 2 COCH 3

O

excess

1. CH 3 CH 2 MgBr


2. H 3 O+

O

+ (CH 3 CH 2 ) 2 NH

catalytic

H+

O

+ (C 6 H 5 ) 3 P CHCH 3

O

+ CH 3 CH 2 NH 2

catalytic

H+

CH 3 CH 2 CCH 3

O

1. CH 3 CH 2 MgBr


2. H 3 O+

N O

H

1. LiAlH 4
   2. H 2 O

C NCH 2 CH 3 H 2 O

HCl

+

CH 2 CH 3

CH 4 CH 3 Br CH 3 CH 2 CH 2 OH

1.

2.

CH 3 OH CH 3 Br CH 3 CH 2 OH

1.

2.