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Chapter 20 693
Copyright © 2017 Pearson Education, Inc.
55.
O
HO
OH
O
O
O
NH
C
CH
3
CH
3
O
O
HO
COO
CH
2
OH
CH
2
OH
O
HO
OH
O
COO
hyaluronic acid
NH
CO
_
_
O
HO
56.
She can take a sample of one of the sugars and oxidize it with nitric acid to an aldaric acid or reduce it with
sodium borohydride to an alditol. If the product is optically active, the sugar was d-lyxose; if the product is
not optically active, the sugar was d-xylose.
HO H
HO H
CH
2
OH
H OH
D
-lyxose
HNO
3
COOH
HO H
HO H
COOH
H OH
optically active
H OH
HO H
CH
2
OH
H OH
D
-xylose
HNO
3
COOH
H OH
HO H
COOH
H OH
optically inactive
HO H
HO H
CH
2
OH
H OH
D
-lyxose
CH
2
OH
HO H
HO H
CH
2
OH
H OH
optically active
H OH
HO H
CH
2
OH
H OH
D
-xylose
CH
2
OH
H OH
HO H
CH
2
OH
H OH
optically inactive
1. NaBH
4
2. H
3
O
+
1. NaBH
4
2. H
3
O
+
C
H O
C
H O
C
H O
C
H O
57.
+
+
+
+
C
H
R
NH
C
H
R
O
C
H
R
C
H
H
R
O
NH
C
H
H
R
C
H
O
H
H
R
C1 H
H
2
O
B
OH
B
NH
2
NH
2
NH
3
C
H
OH
R
H B
+