Explain aboutthe structure of Fructose . (OR) Elucidate the structure

1.	Explain aboutthe structure of Fructose . (OR) Elucidate the structure of Fructose .
Answer» Solution :(i) ELEMENTAL analysis and molecularweight determinationof FRUCTOSE show thatit has themolecularformula `C_(6)H_(12)O_(6)`. (ii) Fructoseon reducing with HI and red phosphorus givesa mixture of n - hexane (majorprodcut) and 2 - iodohexane(minor product) . This reactionthatthesixcarbon atoms in fructoseare ina straight CHAIN. (iii) Fructosereacts with`NH_(2)OH` and HCN . It Shows the presence of carbonylgroup in themolecules of fructose . (iv)Fructosereactswithacetic anhydride inn the presence of phyridine to form penta acetate .Thisreactionindicatesthe presence of fivehydroxylgroup in a fructosemolecule. (v) Fructose is notoxidized bybrominewater . This rules outthe possibilityof presence of analdehyde (-CHO) group. (vi)Partial reduciton of fructosewith sodium amalganand waterproduces mixtureof sorbitol andmannitol whichareepimers at second carbon. New asymmericcarbon is formedat C - 2. Thiconfirmsthe presenceof keto group. (vii) On oxidation withnitricaicd,it gives glycolic acid and tartaricacids whihcontainssmallernumberof carbon atoms thanin fructose . This shows thata ketogroupis present in C- @ . Italosshownthe presenceof 10 alcoholicgroups atC - 1and C - 6 . From the above reactionthe structureof fructose is .

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