BCECE Engineering BCECE Engineering Solved Paper-2004

  • question_answer
    In the following compound, least number of mono chlorination is possible:

    A) \[C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}C{{H}_{2}}C{{H}_{3}}\]

    B) \[C{{H}_{3}}-\underset{C{{H}_{3}}}{\mathop{\underset{|}{\mathop{CH}}\,}}\,-C{{H}_{2}}-C{{H}_{3}}\]

    C) \[C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{C{{H}_{3}}}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-H\]

    D) \[C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{C{{H}_{3}}}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-C{{H}_{3}}\]

    Correct Answer: D

    Solution :

    Key Idea: Write chlorination reaction for all of them to find which gives of the maximum number of monochlorination product (a) \[C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}C{{H}_{2}}C{{H}_{3}}+C{{l}_{2}}\xrightarrow{UV}\] \[ClC{{H}_{2}}-{{(C{{H}_{2}})}_{3}}C{{H}_{3}}+C{{H}_{3}}-\overset{Cl}{\mathop{\overset{|}{\mathop{CH}}\,}}\,-{{(C{{H}_{2}})}_{2}}C{{H}_{3}}\] \[+\,C{{H}_{3}}-C{{H}_{2}}-\underset{Cl}{\mathop{\underset{|}{\mathop{CH}}\,}}\,-C{{H}_{2}}-C{{H}_{3}}\] \[\therefore \] Total 3 monochlorinated products are formed.                 (b) \[C{{H}_{3}}-\underset{C{{H}_{3}}}{\mathop{\underset{|}{\mathop{CH}}\,}}\,-C{{H}_{2}}-C{{H}_{3}}+C{{l}_{2}}\xrightarrow{UV}\]                 \[ClC{{H}_{2}}-\underset{C{{H}_{3}}}{\mathop{\underset{|}{\mathop{CH}}\,}}\,-C{{H}_{2}}-C{{H}_{3}}\]                                 \[+\,\,C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{Cl}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-C{{H}_{2}}-C{{H}_{3}}\]                                 \[+\,\,C{{H}_{3}}-\underset{C{{H}_{3}}}{\mathop{\underset{|}{\mathop{CH}}\,}}\,-C{{H}_{2}}-C{{H}_{2}}Cl\] \[\therefore \] Total 3-monochlorinated products are                 (c) \[C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{C{{H}_{3}}}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-H+C{{l}_{2}}\xrightarrow{UV}\]                 \[C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{C{{H}_{3}}}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-Cl+C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{C{{H}_{2}}Cl}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-H\] \[\therefore \]Total 2- monochlorinated products are formed                 (d) \[C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{C{{H}_{3}}}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-C{{H}_{3}}+C{{l}_{2}}\xrightarrow{UV}\]                 \[C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{C{{H}_{3}}}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-C{{H}_{2}}Cl\] \[\therefore \] Only one monochlorinated product formed. \[\therefore \](d) is correct answer.


You need to login to perform this action.
You will be redirected in 3 sec spinner