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Chapter 20 697
Copyright © 2017 Pearson Education, Inc.
65.
Let
A
=
the fraction of d-glucose in the
a
-form and
B
=
the fraction of d-glucose in the
b
-form.
A
+
B
=
1
B
=
1
-
A
specific rotation of
A
=
112.2
specific rotation of
B
=
18.7
specific rotation of the equilibrium mixture
=
52.7
specific rotation of the mixture
=
specific rotation of
A
*
fraction of d-glucose in the
a
-form
+
specific rotation of
B
*
fraction of d-glucose in the
b
-form
52.7
=
112.2
A
+
1
1
-
A
2
18.7
52.7
=
112.2
A
+
18.7
-
18.7
A
34.0
=
93.5
A
A
=
0.36
B
=
0.64
This calculation shows that 36% is in the
a
-form and 64% is in the
b
given in Section 20.10.
66.
Let
A
=
the fraction of d-galactose in the
a
-form and
B
=
the fraction of d-galactose in the
b
-form.
A
+
B
=
1
B
=
1
-
A
specific rotation of
A
=
150.7
specific rotation of
B
=
52.8
specific rotation of the equilibrium mixture
=
80.2
specific rotation of the mixture
=
specific rotation of
A
*
fraction of galactose in the
a
-form
+
specific rotation of
B
*
fraction of galactose in the
b
-form
80.2
=
150.7
A
+
52.8
1
1
-
A
2
80.2
=
150.7
A
+
52.8
-
52.8
A
27.4
=
97.9
A
A
=
.280
Therefore, 28% is
a
-d-galactose and 72% is
b
-d-galactose.
67.
C
C
N
H O
R
H
O
C
H
R
HO
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