9. Carbohydrates Flashcards
what do all carbohydrates have in terms of stereoisomerism
all carbs have stereogenic centre that must be reversed to generate enantiomers
what are the 2 classifications of sugars
what is it determined by
D/L sugars determined by stereogenic center furtherest from C=O
what are the 2 structures of monosaccharides that exist in equilibrium
open and cyclic
what is the alpha anomer of a monosaccharide
C1 OH and C5 CH2OH are trans
what is the beta anomer of a monosaccharide
C1 OH and C5 CH2OH are cis
what are anomers
2 hemiacetals forms are diastereomers which differ at only one asymmetrical carbon
what is mutorotation
D glucose cyclises reversibly in soln
36 alpha:64 beta mix
what reagents and reactants are required for ether formation from carbohydrates
CH3I/Ag2O
what reagents and reactants are required for ester formation from carbohydrates
(CH3CO)2O
what reagents and reactants are required for glycoside formation from carbohydrates
free OH react to form acetal
hemiacetal + OH-/H+ forms acetal anomers where OH group is replaced by OR group
what reagents and reactants are required for hemiacetal formation from glycosides
H3O+/H+
what reagents and reactants are required for polysaccharide formation from carbohydrates
H+ catalyst
other sugar
what is formed when a carbohydrate reacts with CH3I/Ag2O
ether
what is formed when a carbohydrate reacts with (CH3CO)2O
esters
what is formed when a carbohydrate reacts with H+ catalyst and other sugar
polysaccharide
