BCECE Medical BCECE Medical Solved Papers-2014

  • question_answer
    Compound A \[({{C}_{3}}{{H}_{6}}O)\] undergoes following reactions to form B and C. Identify A, B and C. \[\underset{\begin{smallmatrix}   \\  A \end{smallmatrix}}{\mathop{C\xleftarrow{Zn-Hg/HCl}}}\,\underset{B}{\mathop{{{C}_{3}}\underset{A}{\mathop{{{H}_{6}}}}\,O}}\,\underset{\begin{smallmatrix}   \\  C \end{smallmatrix}}{\mathop{\xrightarrow{{{I}_{2}}/NaOH}V}}\,\]

    A)  \[{{H}_{3}}C-\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}CH{{l}_{3}}CH-C{{H}_{2}}-C{{H}_{3}}\]

    B) \[{{H}_{2}}C=\underset{\begin{smallmatrix}  | \\  H \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{2}}OHC{{H}_{3}}l{{H}_{3}}C-C{{H}_{2}}-C{{H}_{2}}-OH\]

    C)  \[{{H}_{3}}C-C{{H}_{2}}-CHO\,\,\,\,\,CH{{l}_{3}}\,\,\,\,\,{{H}_{3}}C-\underset{\begin{smallmatrix}  | \\  OH \end{smallmatrix}}{\mathop{C}}\,H-C{{H}_{3}}\]

    D)  \[{{H}_{3}}C-\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}\,\,\,\,\,CH{{l}_{3}}\,\,\,\,\,\,{{H}_{3}}C-\underset{\begin{smallmatrix}  | \\  OH \end{smallmatrix}}{\mathop{C}}\,H-C{{H}_{3}}\]

    Correct Answer: A

    Solution :

    The compound reacts with \[{{l}_{2}}/NaOH\], so it must be a methyl ketone and it should give iodoform \[(CH{{l}_{3}})\] in this reaction. \[\therefore A\]is \[C{{H}_{3}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,C{{H}_{3}}\](acetone)                 \[C{{H}_{3}}-\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{\underset{A}{\mathop{C}}\,}}\,-C{{H}_{3}}\xrightarrow{{{l}_{2}}/NaOH}\underset{\begin{smallmatrix}  B \\  yellow\text{ }ppt. \end{smallmatrix}}{\mathop{C{{H}_{3}}}}\,\]                     \[+C{{H}_{3}}COONa+Nal+{{H}_{2}}O\] \[C{{H}_{3}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{\underset{A}{\mathop{C}}\,}}\,C{{H}_{3}}\xrightarrow[\begin{smallmatrix}  (Clemmensens \\  reduction) \end{smallmatrix}]{Zn-Hg/HCl}\underset{\begin{smallmatrix}  propane \\  C \end{smallmatrix}}{\mathop{C{{H}_{3}}C{{H}_{2}}C{{H}_{3}}}}\,\]


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