question_answer 12)

Giving justification, categories the following molecules/ions as nucleophile or electrophile: \[H{{S}^{-}},B{{F}_{3}},{{C}_{2}}{{H}_{5}}{{O}^{-}},{{(C{{H}_{3}})}_{3}}N_{\centerdot }^{\centerdot };C{{l}^{+}},\] \[C{{H}_{3}}-C=O,{{H}_{2}}N_{\centerdot }^{{{\centerdot }^{-}}},\overset{+}{\mathop{N{{O}_{2}}}}\,\]

Answer:

(i) Nucleophiles: \[H\overset{{}}{\mathop{\overset{\centerdot \,\centerdot }{\mathop{S}}\,{{_{\centerdot }^{\centerdot }}^{-}}}}\,,{{C}_{2}}{{H}_{5}}\underset{\centerdot \centerdot }{\overset{\centerdot \,\centerdot }{\mathop{O}}}\,{{_{\centerdot }^{\centerdot }}^{-}},{{(C{{H}_{3}})}_{3}}N_{\centerdot }^{\centerdot },{{H}_{2}}\overset{\centerdot \centerdot }{\mathop{N{{_{\centerdot }^{\centerdot }}^{-}}}}\,\] These species have one or more unshared pair of electrons, which can be donated to an electrophile. (ii) Electrophiles: \[B{{F}_{3}},C{{l}^{+}},C{{H}_{3}}-\overset{+}{\mathop{C}}\,=O,\overset{+}{\mathop{N}}\,{{O}_{2}}\] These species have only six valence electrons and hence, can accept a pair of electrons from a nucleophile.