Experiment 5-Protection of a Carbohydrate: Acetal formation from -Methylglucopyr
ID: 1009330 • Letter: E
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Experiment 5-Protection of a Carbohydrate: Acetal formation from -Methylglucopyra noside Reading: Klein 2nd Ed pp 941-943 (acetal formation), 1166-1167 (carbohydrate structure and reactions) Introduction Carbohydrates are a vital part of natural processes: many cellular receptors involve multiple carbohydrates appended to proteins and other biomacromolecules. Synthesizing sugar derivatives is therefore a tremendously important research area in organic chemistry. The problem with sugar chemistry is that all the basic carbohydrates have multiple different alcohol groups, as well as multiple conformations and structures. Experimental techniques that allow selective protection of alcohols in sugar derivatives are an important first step in complex syntheses of polysaccharides. Here, you will perform one of these protections: a selective acetalization of a glucopyranose derivative OH OCH3 catalytic HO OCH3 HO HO OH OH OH CH CH3 H3C Figure 1. Reaction SchemeExplanation / Answer
For the reaction,
Name Formula MW mol-eq mmol amount
a-methylglucopyranoside C7H14O6 194.18 1.0 2.57 500mg
benzaldehyde dimethylacetal C9H12O2 152.19 1.8 4.66 700uL
p-toluenesulfonic acid C7H8SO3 172.20 0.005 0.014 25mg
acetonitrile CH3CN - - - 10mL
triethylamine (Et)3N - 0.03 0.072 2drops
product C14H16O6 280.00
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