Bruice - Chimica Organica

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798 Chapter 25
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29. The hemiacetal is formed by reaction of the primary alcohol with the aldehyde.
O O
HO
HO
CH 3 H
H
O
H
30. a. Chenodeoxycholic acid is missing the OH group on the C ring (at the top of the molecule) that cholic
acid has.
b. Notice that because the methyl and hydrogen at the juncture of the A and B rings are on the same side,
we know that the A and B rings are cis fused. The three OH groups are all in axial positions.
CH3
CH 3
HO
H
COOH
H
A
B
HO
OH
31. O
O
O
O
O
N
+
−
O
O
O
P
32. If stearic acid were at C-1 and C-3, the fat would not be optically active.
Therefore, stearic acid must be attached to adjacent OH groups (C-1 and C-2 or C-2 and C-3).
O
O
O
O
O
O