Concept explainers
Interpretation:
The structure of L-(+)-threose and L-(+)-erythrose is to be represented and the aldotriose, which must be used for the preparation of the above-mentioned compounds in the Kiliani-Fischer synthesis, is to be determined.
Concept Introduction:
▸ The Kiliani-Fischer reaction is used for increasing the number of carbon atoms of an aldose molecule, as a result of the formation of the epimeric aldonic acid.
▸ It is an effective and economic process for the synthesis of monosaccharides by the process of hydrolysis of a cyanohydrin.
▸ Furthermore, it can also be used for the production of epimers of higher aldoses from a lower aldose, that is, a single aldose produces a mixture of two diastereomeric sugars called epimers.
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Organic Chemistry
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- Aldohexoses A and B both undergo Ruff degradation to give aldopentose C. On treatment with warm nitric acid, aldopentose C gives an optically active aldaric acid. B alsoreacts with warm nitric acid to give an optically active aldaric acid, but A reacts to givean optically inactive aldaric acid. Aldopentose C is degraded to aldotetrose D, whichgives optically active tartaric acid when it is treated with nitric acid. Aldotetrose D isdegraded to (+)@glyceraldehyde. Deduce the structures of sugars A, B, C, and D, and useFigure 23-3 to determine the correct names of these sugars.arrow_forwardWhen the gum of the shrub Sterculia setigera is subjected to acidic hydrolysis, one of the water-soluble components of thehydrolysate is found to be tagatose. The following information is known about tagatose:(1) Molecular formula C6H12O6(2) Undergoes mutarotation.(3) Does not react with bromine water.(4) Reduces Tollens reagent to give d-galactonic acid and d-talonic acid.(5) Methylation of tagatose (using excess CH3 I and Ag2O) followed by acidic hydrolysis gives1,3,4,5-tetra-O-methyltagatose.(a) Draw a Fischer projection structure for the open-chain form of tagatose.(b) Draw the most stable conformation of the most stable cyclic hemiacetal form of tagatosearrow_forwardA D-aldopentose A is oxidized to an optically inactive aldaric acid with HNO3. A is formed by the Kiliani–Fischer synthesis of a D-aldotetrose B, which is also oxidized to an optically inactive aldaric acid with HNO3. What are the structures of A and B?arrow_forward
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