question_answer

  Write the reactions of D-glucose which cannot be explained by its open chain structure.                 [3]

Answer:

  D-glucose exists in two anomeric forms, in cyclic forms. Open structure has following drawbacks (i) It does not form addition compounds with  and Grignard reagent thus, indicating absence of ?CHO group.             [1] (ii) It does not give Schiff's test.                     [1] (iii) Pent acetate of glucose does not react with hydroxyl ammine.                                   [1] All these facts can be explained if we take cyclic structure. glucose differs in configuration about numeric carbon.