question_answer 70)

  Predict the major product(s) of the following reactions and explain their formation. \[{{H}_{3}}C-CH=C{{H}_{2}}\xrightarrow[HBr]{{{(Ph-COO)}_{2}}}\] \[{{H}_{3}}C-CH=C{{H}_{2}}\xrightarrow{HBr}\]

Answer:

  (i) \[{{H}_{3}}C-\underset{\text{Propene}}{\mathop{\text{CH}}}\,=C{{H}_{2}}+HBr\xrightarrow{{{(Ph-COO)}_{2}}}\] \[\underset{1-Bromopropane}{\mathop{{{H}_{3}}C-C{{H}_{2}}-C{{H}_{2}}Br}}\,\] In presence of organic peroxides, the addition of \[HBr\]to propene follows anti-Markownikoffs rule (or peroxide effect) to form 1-bromopropane (n-propyl bromide). (ii) \[\underset{\text{Propene}}{\mathop{{{H}_{3}}C-CH}}\,=C{{H}_{2}}+HBr\xrightarrow[addition]{Markkownikoff's}\]                                                 \[{{H}_{3}}C-\underset{\underset{2-Bromopropane}{\mathop{\begin{smallmatrix}  | \\  Br \end{smallmatrix}}}\,}{\mathop{CH}}\,-C{{H}_{3}}\]