EAMCET Medical EAMCET Medical Solved Paper-2008

  • question_answer
    Which one of the following reactions yield   2E-butene as the major product?

    A)  \[C{{H}_{3}}-C\equiv C-C{{H}_{3}}+Na/N{{H}_{3}}(liq.)\]

    B)  \[C{{H}_{3}}-CH=CH-C{{H}_{3}}+Li/N{{H}_{3}}(liq.)\]

    C)  \[C{{H}_{3}}-C=C-C{{H}_{3}}+Na/N{{H}_{4}}OH\]

    D)  \[C{{H}_{3}}-C\equiv C-C{{H}_{3}}+Pd/BaS{{O}_{4}}\]

    Correct Answer: A

    Solution :

                                    When alkynes are reduced with Li or Na metal in \[\text{N}{{\text{H}}_{\text{3}}}\text{,}\]at low temperature, an anti-addition of hydrogen atoms takes place and traris or E product is obtained. \[{{H}_{3}}C-C\equiv C-C{{H}_{3}}+Na\xrightarrow{Liq.N{{H}_{3}}}\] \[{{H}_{3}}C\_\_\underset{\begin{align}   & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,H \\  & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,2E-butene \\  & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,or \\  & \,\,\,\,\,\,\,\,\,\,\,\,trans-2- \\  & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,butene \\ \end{align}}{\mathop{\underset{|}{\mathop{C}}\,}}\,=\overset{H}{\mathop{\overset{|}{\mathop{C}}\,}}\,-C{{H}_{3}}\]


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