Questions 11-13- refer to the carbohydrate mannose (open chain and one anomericring configuration of the structure shown below)HOHOHHCHOHHOHOHCH₂OHOHHOHfHOHO-HHOHH11. Draw the open-chain structure of mannose following oxidation of the carbohydrateto an aldonic acid12. Draw the open-chain structure of mannose following oxidation of the carbohydrateto an aldaric acid using NO313. Draw the structure of mannitol

Carbohydrates are polyhydroxy aldehydes or ketones. They can be classified as monosaccharides, oligosaccharides or polysaccharides. Monosaccharides contain a single polyhydroxy aldehyde or ketone unit. In monosaccharides, if the carbonyl group is at the end of the chain, they are called aldose. If the carbonyl group is at any other position, they are called ketose. Monosaccharides with 3, 4, 5, 6 and 7 carbons in their carbon skeleton are called trioses, tetroses, pentoses, hexoses and heptose respectively. If a monosaccharide has a carbonyl group at one end and six carbons in its skeleton, it would be called an aldohexose If a monosaccharide has a carbonyl group at any other position and six carbons in its skeleton, it would be called a ketohexose. Open chain structures for monosaccharides are drawn in Fischer projections. It is the three-dimensional representation of chiral centres on paper. Horizontal lines represent groups projecting towards the reader while vertical lines represent groups projecting away from the reader. Mannose is a monosaccharide, an aldose. Oxidation of mannose with a mild oxidising agent such as hypobromite oxidised the C1 aldehyde group to the carboxylic group to produce mannonic acid, an aldonic acid. Oxidation of mannose with a stronger oxidizing agent like NO3 (in the form of dilute nitric acid) oxidised C1 and C6 to the carboxyl group to produce mannaric acid, an aldaric acid. The structure of the mannitol is given below: