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13
CH1012
CHEMISTRY OF SUGARS
• A reducing sugar is one
which gives a
positive test with Tollen’s reagent. These
sugars exist in hemiacetal forms.
positive test with Tollen’s reagent. These
sugars exist in hemiacetal forms.
• A non-reducing
sugar exists only in the acetal
form and does
not reduce Ag+/NH3.
• The -CHO group in monosaccharides is oxidised in the course of the reaction to
a -COOH group the electron provided
(+1 ® +3 + 2e-) reduces Ag+ + e- ® Ag(s)
a -COOH group the electron provided
(+1 ® +3 + 2e-) reduces Ag+ + e- ® Ag(s)
