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576 CARBOHYDRATES
22.16
L-(+)-Ribose
HO
HO
H
H
HO H
L-(+)-Arabinose
H
HO
OH
H
HO H
L-(−)-Xylose
HO
H
H
OH
HO H
L-(+)-Lyxose
H
H
OH
OH
HO H
OH OH OH OH
OH OH OH OH
22.17 Since d-(+)-galactose yields an optically inactive aldaric acid, it must have either structure
III or structure IV.
III
H
H
OH
OH
H OH
H OH
HNO3
IV
H
HO
OH
H
HO H
H OH
Optically inactive
H
H
OH
OH
H OH
H OH
Optically inactive
H
HO
OH
H
HO H
H OH
HNO3
OOH OOHOH OH
OH OHO OH OHO
A Ruff degradation beginning with III would yield d-(−)-ribose
III
H
H
OH
OH
H OH
D-(−)-Ribose
H2O2 
Fe2(SO4)3
Br2 
H2O
OH
OH
A Ruff degradation beginning with IV would yield d-(−)-lyxose: thus, d-(+)-galactose must
have structure IV.
IV
HO
HO
H
H
H OH
D-(−)-Lyxose
H2O2 
Fe2(SO4)3
Br2 
H2O
OH
OH
22.18 d-(+)-glucose, as shown here.
H
HO
H
H
OH
H
OH
O
H
The other γ-lactone
of D-glucaric acid
H
H
OH
H
OH
O
OH
O
Na-Hg Na-Hg
H
HO
OH
H
H OH
H OH
H
HO
OH
H
H OH
H OH
D-(+)-Glucose
O
pH 3-5
O HO
O HO OH
OH OH OH