BCECE Medical BCECE Medical Solved Papers-2013

  • question_answer
    \[A\,\,[{{C}_{6}}{{H}_{10}}{{O}_{3}}\,(keto\text{ }ester)]\,\,\xrightarrow[\Delta ]{NaOH+{{I}_{2}}}\] yellow\[ppt+B\xrightarrow{{{H}^{+}}}\,C\xrightarrow[-C{{O}_{2}}]{\Delta }C{{H}_{3}}COOH\]. Hence, A is

    A)  \[C{{H}_{3}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,C{{H}_{2}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,O{{C}_{2}}{{H}_{5}}\]

    B) \[C{{H}_{3}}C{{H}_{2}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,C{{H}_{2}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,OC{{H}_{3}}\] 

    C)  Both are correct   

    D)  None is correct

    Correct Answer: A

    Solution :

    A gives iodoform test thus A has \[-\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,C{{H}_{3}}\] group. C eliminates \[C{{O}_{2}}\] on heating hence, C has two \[-COOH\] groups at same (gem) position. Since, only [a] has \[-\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,C{{H}_{3}}\] group, therefore, compound A is \[C{{H}_{3}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,C{{H}_{2}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,O{{C}_{2}}{{H}_{5}}\]. \[\underset{A}{\mathop{C{{H}_{3}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,C{{H}_{2}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,O{{C}_{2}}{{H}_{5}}}}\,\xrightarrow[\Delta ]{NaOH/{{l}_{2}}}\underset{yellow\text{ }ppt}{\mathop{C{{H}_{3}}l\,\downarrow }}\,+\]                  \[\underset{B}{\mathop{NaO\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,C{{H}_{2}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,ONa}}\,\]                  \[\downarrow {{H}^{+}}\] \[C{{H}_{3}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,OH\xleftarrow{\Delta }\underset{C}{\mathop{HO\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,C{{H}_{2}}\overset{\begin{smallmatrix}  O \\  || \end{smallmatrix}}{\mathop{C}}\,OH}}\,\]


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