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Show how an aldohexose can be used to synthesize 2-ketohexose. |
Answer» Solution : Here aldohexosereacts with one molecule of phenylhdrazine which CONDENSES with the aldehyde group to give phenylhydrazone. When warmed with axcess of phenyl hydrazine, the secondary alcoholic group ADJACENT to the aldehyde group is oxidised by another molecule of phenylhydrazine, to a ketonic group. With this ketonic group, the third molecule of phenylhydrazine condenses to GIVEN OSAZONE. The phenylhydrazinyl group is transferred from osazone to `C_6H_5CHO` giving `C_6H_5CH=N.NHC_6H_5` and a dicarbonyl compound called an osone. The more reactive aldehyde group of the osone is reduced, not the less reactive keto group and it give the 2-ketohexose. |
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