question_answer

(a) Give the mechanism of the following reaction \[2\,C{{H}_{3}}C{{H}_{2}}OH\xrightarrow[413\,K]{Dil.\,{{H}_{2}}S{{O}_{4}}}\,C{{H}_{3}}C{{H}_{2}}OC{{H}_{2}}C{{H}_{3}}\] Does this reaction follow \[{{S}_{N}}1\] or \[{{S}_{N}}2\] pathway? (b) Describe hydroboration-oxidation reaction with the help of an example.

Answer:

                (a) Refer to page 11/48. The reaction occurs by \[{{S}_{N}}2\] mechanism. (b) \[{{B}_{2}}{{H}_{6}}\xrightarrow{\,}2\,B{{H}_{3}}\] \[\underset{\text{Propene}}{\mathop{3\,C{{H}_{3}}CH\,=\,C{{H}_{2}}}}\,+B{{H}_{3}}\xrightarrow{{}}\]\[\underset{\text{Tri-n-propylborane}}{\mathop{{{(C{{H}_{3}}\,C{{H}_{2}}C{{H}_{2}})}_{3}}B}}\,\] \[\underset{\text{Tri-n-propylborane}}{\mathop{{{(C{{H}_{3}}C{{H}_{2}}C{{H}_{2}})}_{3}}}}\,B+3\,{{H}_{2}}{{O}_{2}}\xrightarrow{O{{H}^{-}},\,{{H}_{2}}O}\]\[\,\underset{\text{Propan-1-ol}}{\mathop{3\,C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}OH}}\,+\underset{\text{Boric}\,\,\text{acid}}{\mathop{{{H}_{3}}B{{O}_{3}}}}\,\]