ring formation (carbohydrate pp)

glycosidic bond

A bond formed between the anomeric carbon atom of glucose and the oxygen atom of an alcohol i

oligosaccharide

A carbohydrate composed of 2 to 12 monosaccharide units. are built by the linkage of two or more monosaccharides by O-glycosidic bonds re synthesized through the action of specific enzymes, glycosyltransferases, which catalyze the formation of glycosidic bonds.`

hemiketal

A compound formed by the reaction of a ketone group and a hydroxyl group; for example, the C-2 keto group of the open-chain form of fructose reacts with the C-5 hydroxyl group to form an intermolecular hemiketal.

hemiacetal

A compound formed by the reaction of an aldehyde functional group and a hydroxyl group; for example, the C-1 group of the open-chain form of glucose reacts with the C-5 hydroxyl group to form an intermolecular hemiacetal.

degradation product of cellulose

Cellubiose

Polysaccharides

Complex carbohydrates—polymers of covalently linked monosaccharides

Ring structures of fructose.

Fructose can form both five-membered furanose and six-membered pyranose rings. In each case, both α and β anomers are possible. Beta OH up' alpha OH down

What is a 5-membered sugar ring

Furan (furanose)

Monosaccharides Are Joined to Alcohols and Amines Through

Glycosidic Bonds

the disaccharide of milk

Lactose β-D-Galactopyranosyl-(1 → 4)-α-D-glucopyranose

a hydrolysis product of amylose (starch)

Maltose

What is six-membered sugar ring

Pran (pyranox)

Monosaccharides

Simple carbohydrates are aldehydes or ketones that have two or more hydroxyl groups. The smallest monosaccharides, composed of three carbons, are dihydroxyacetone and D- and L-glyceraldehyde.

table sugar, most abundant disaccharide in nature, synthesized only in plants

Surcrose

D- Fructose ring formation

The open-chain form of fructose cyclizes to a five-membered ring when the C-5 hydroxyl group attacks carbon C-2 of the ketone to form an intramolecular hemiketal. Two anomers are possible, but only the α anomer is shown.

glucose ring formation

The open-chain form of glucose cyclizes when the C-5 hydroxyl group attacks carbon atom C-1 of the aldehyde group to form an intramolecular hemiacetal. Two anomeric forms, designated α and β, can result.

Carbohydrates are

are carbon-based molecules that are rich in hydroxyl (C—OH) groups. Indeed, the empirical formula for many carbohydrates is (CH2O)n—literally, a carbon hydrate

In solution the ring & linear from of monosacchardies are in

equilibrium!

ketone can react with an alcohol to form

hemikatal

what are is the chemical basis for ring formation

in that an aldehyde can react with an alcohol to form a hemiacetal

what is the anomeric carbon

most oxidized C of cyclic monosaccharide. It is chiral (i.e. or ) = anomeric configuration (in ring closer)

cyclization of D-glucose

• Reaction of C- 5 hydroxyl with one side of C-1 gives , reaction with the other side gives