CHEM 203 Lecture Notes - Lecture 37: Hemiacetal, Glycosylation, Reducing Sugar
Document Summary
Chemical reactions of monosaccharides: because these compounds contain hemiacetal, oh and. C=o groups, their chemistry reflects that of hemiacetals, alcohols and aldehydes / ketones. Much like a hemiacetal reacts with an alcohol in the presence of acid to form an acetal, so a monosaccharide will react under the same conditions to form a glycoside (riboside, glucoside, fructoside ). Note: the mechanism of glycoside formation is analogous to that seen earlier (notes of nov 27) for the formation of acetals. Reversibility of glycoside formation in aqueous acidic media (glycoside hydrolysis) Note: the mechanism of glycoside hydrolysis is analogous to that seen earlier (notes of nov 26) for the hydrolysis of acetals. Important difference between free sugars (hemiacetal present) and their glycoside derivatives (no hemiacetal present): reducing and non-reducing sugars and the tollens test. Importance of the tollens test in the structural elucidation of natural carbohydrates. Glycosylation of a monosaccharide with another monosaccharide: formation of complex sugars or polysaccharides.
