Manipal Engineering Manipal Engineering Solved Paper-2009

  • question_answer
    Arrange the following in the increasing order of their   basic   strengths\[C{{H}_{3}}N{{H}_{2}},\]\[{{(C{{H}_{3}})}_{2}}NH\]\[{{(C{{H}_{3}})}_{3}}N,\,\,N{{H}_{3}}\]

    A) \[N{{H}_{3}}<{{(C{{H}_{3}})}_{3}}N<{{(C{{H}_{3}})}_{2}}NH<C{{H}_{3}}N{{H}_{2}}\]

    B) \[N{{H}_{3}}<{{(C{{H}_{3}})}_{3}}N<C{{H}_{3}}N{{H}_{2}}<{{(C{{H}_{3}})}_{2}}NH\]

    C) \[{{(C{{H}_{3}})}_{3}}N<N{{H}_{3}}<C{{H}_{3}}N{{H}_{2}}<{{(C{{H}_{3}})}_{2}}NH\]

    D) \[C{{H}_{3}}N{{H}_{2}}<{{(C{{H}_{3}})}_{2}}NH<{{(C{{H}_{3}})}_{3}}N<N{{H}_{3}}\]

    Correct Answer: B

    Solution :

    Aliphatic amines are more basic than\[N{{H}_{3}}\]due to\[+I\]effect of alkyl groups. In aqueous medium tertiary amine is less basic than secondary amine because the cation formed by protonation of tertiary amine is less solvated as compared to the cation formed by protonation of secondary amine. Hence, the increasing order of their basic strength is as: \[N{{H}_{3}}<{{(C{{H}_{3}})}_{3}}N<C{{H}_{3}}N{{H}_{2}}<{{(C{{H}_{3}})}_{2}}NH\]


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