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Chapter 17 571
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46.
a. Three
deuteriums would be incorporated into palmitic acid, because only one CD
3
COSR is used in the
synthesis.
b. Seven
deuteriums would be incorporated into palmitic acid, because seven
-
OOCCD
2
COSR are used
in the synthesis (for a total of 14 Ds), and each
-
OOCCD
2
COSR loses one deuterium in the dehydra-
tion step (14 Ds
-
7 Ds
=
7 Ds).
47.
It tells you that an imine is formed as an intermediate. Because an imine is formed, the only source of
oxygen for acetone formation is H
2
18
O.
CH
3
NHR
O CH
2
_
+
CH
3
NHR
CH
2
+
H
H
18
CH
3
NHR
CH
3
+
H
2
18
O
18
CH
3
CH
3
O
O
+
CO
2
+
RNH
3
C
C
C
C
C
O
If decarboxylation occurred without imine formation, most of the acetone would contain
16
O. There
would be some
18
O incorporated into acetone because acetone would react with H
2
18
O and form a hydrate.
The
18
O would become incorporated into acetone when the hydrate reforms acetone.
CH
3
O CH
2
_
_
CH
3
CH
2
H
CH
3
CH
3
CH
3
CH
3
+ CO
2
C CH
3
OH
CH
3
OH
18
+ H
2
O
C
O
C
O
C
O
C
C
O
H
2
18
O
H
18
18
O
O
48.
OH
a.
c.
e.
b.
d.
OH
CH
3
CH
2
CH
2
CH
2
CH
3
OCH
2
CH
3
CH
2
R
OR
'
CH
2
OH
CH
CH
3
HO
C
O
C
O
C
O
C
O
C
O
C
O
C
O