question_answer

Two aldopentoses A and B give the same osazone derivative. A is oxidised to an optically active aldoric acid by dilute nitric acid. Ruff degradation of B gave a tetrose which was similarly oxidised to an optically active aldaric acid. Assign the structure of A and B from the following list.  (a)                                         (b)                     (b) (c)                                           (d)              

A) \[BrC{{H}_{2}}-C{{H}_{2}}-CH=C{{H}_{2}}\]          

B) \[{{C}_{2}}{{H}_{5}}-CHBr-C{{H}_{3}}\]

C) \[{{C}_{2}}{{H}_{5}}-C{{H}_{2}}-C{{H}_{2}}Br\]                   

D) \[Br-C{{H}_{2}}-C{{H}_{2}}-CH=C{{H}_{2}}\]

Correct Answer: C

Solution :

 A and B have same osazone derivative, it means configuration at C-3 and C-4 is the same.