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(vii) Name the reagent which on reaction with glucose confirmsthe presence of five hydroxyl groups in glucose : |
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Answer» The REAGENT, which on reaction with GLUCOSE, confirms the presence of five hydroxyl groups in glucose is acetic anhydride, REPRESENTED by the CHEMICAL formula (CH₃CO)₂O. • When glucose is reacted with acetic anhydride, it forms pentacetate, confirming the presence of five hydroxyl (OH) groups in it. • It is a known property of an anhydride to form an ester and an acid on reacting with a compound containing the hydroxyl group. • One OH group produces only one ester (acetate) group. • Therefore, formation of five ester or acetate MOLECULES on reaction of glucose with acetic anhydride confirms that five hyroxyl (OH) groups are present in one molecule of glucose. • The above reaction can be represented as follows : CHO(CHOH)₄CH₂OH (glucose) + 5(CH₃CO)₂O →CHO(CHOCOCH₃)₄CH₂OCH₃O (penta acetyl glucose / penta-acetate) + 5CH₃COOH
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