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Elucidate the structure of glucose. |
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Answer» Solution :(i) Its moleculer formula is found to be `C _ 6 H_ (12) O _ 6 `. (ii) On heating with HI it forms N-hexane suggesting that all the six carbon atoms are linked in a straight chain. ` overset(CHO) overset(|) underset(CH_2OH) underset(|) ((CHOH)_4) overset(HIDelta)tounderset("n- hexane")(CH _3 - CH _2 - CH _2- CH _2- CH_ 2- CH _3 ) ` (iii) Glucose reacts with hydroxylamine to form an oxime. This show it contain carbonyl group. `overset(CHO)overset(|) underset(CH_2OH) underset(|)((CHOH)_4) overset(NH_2OH) to overset(CH= N -OH)overset(|) underset("Oxime")underset(CH_2OH) underset(|)((CHOH)_4)` (v)Inpressureofbrominewater,glucoseundergoesoxidationforminggluconicacid.Thisshowscarbonyl groupisanaldehyde group. `overset(CHO) overset(|) underset( CH_2 OH) underset(|) ((CHOH)_4) overset(Br_2 "water")to overset(COOH) overset(|)underset(CH_2OH) underset(|) ((CHOH) _4)` (v) ACETYLATION of glucose with acetic anhydride gives glucose penta acetate which confirms the presence of five OH groups. (vi) On oxidation with strong oxidising AGENT. like Cone. `HNO_3` it gives saccharic acid. This indicate the presence ofprimaryalcoholic group. Based on the above facts Fischer gave open and ring STRUCTURE for glucose. 
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