question_answer 1)

  Electrophiles are electron seeking species. Which of the following groups contain only electrophiles?   (a) \[B{{F}_{3}},N{{H}_{3}},{{H}_{2}}O\]                                                 (b)\[AlC{{l}_{3}},S{{O}_{2}},NO_{2}^{+}\] (c) \[NO_{2}^{+},CH_{3}^{+},C{{H}_{3}}-\overset{+}{\mathop{C}}\,=O\]                                               (d) \[{{C}_{2}}H_{5}^{-},{{\overset{\centerdot }{\mathop{C}}\,}_{2}}{{H}_{5}},{{C}_{2}}H_{5}^{+}\] Note: Consider the following four compounds for answering questions 19 and 20: \[\text{I}\text{.}\]\[C{{H}_{3}}-C{{H}_{2}}-C{{H}_{2}}-C{{H}_{2}}-\overset{\overset{\text{O}}{\mathop{\text{ }\!\!|\!\!\text{  }\!\!|\!\!\text{ }}}\,}{\mathop{C}}\,-H\] \[\text{II}\text{.}\]\[C{{H}_{3}}-C{{H}_{2}}-C{{H}_{2}}-\overset{\overset{\text{O}}{\mathop{\text{ }\!\!|\!\!\text{  }\!\!|\!\!\text{ }}}\,}{\mathop{C}}\,-C{{H}_{3}}\] \[\text{III}\text{.}\]\[C{{H}_{3}}-C{{H}_{2}}-\underset{\underset{\text{O}}{\mathop{\text{ }\!\!|\!\!\text{  }\!\!|\!\!\text{ }}}\,}{\mathop{C}}\,-C{{H}_{2}}-C{{H}_{3}}\] \[\text{IV}\text{.}\]\[C{{H}_{3}}-\underset{\underset{\text{C}{{\text{H}}_{\text{3}}}}{\mathop{\text{ }\!\!|\!\!\text{ }}}\,}{\mathop{CH}}\,-C{{H}_{2}}-\underset{\underset{\text{O}}{\mathop{\text{ }\!\!|\!\!\text{  }\!\!|\!\!\text{ }}}\,}{\mathop{C}}\,-H\]

Answer:

  (b, c) In option (a), \[N{{H}_{3}}\] and \[{{H}_{2}}O\]are nucleophiles and in (d) \[{{C}_{2}}H_{5}^{-}\] is nucleophile.