question_answer 17)

For the following compounds, write structural formulae and IUPAC names for all possible isomershaving the number of double or triple bond as indicated: (a) \[{{C}_{4}}{{H}_{8}}\] (one double bond) (b) \[{{C}_{5}}{{H}_{8}}\] (one triple bond)

Answer:

(a)(i) \[C{{H}_{3}}\underset{But-1-ene}{\mathop{C{{H}_{2}}CH}}\,=C{{H}_{2}}\] (ii) \[\underset{But-2-ene\,(cis)}{\mathop{\underset{\begin{smallmatrix} \\ C{{H}_{3}} \end{smallmatrix}}{\mathop{C{{H}_{3}}}}\,\underset{\begin{smallmatrix} \\ - \end{smallmatrix}}{\mathop{-}}\,\underset{\begin{smallmatrix} \parallel \\ C \end{smallmatrix}}{\mathop{C}}\,\underset{\begin{smallmatrix} \\ - \end{smallmatrix}}{\mathop{-}}\,\underset{\begin{smallmatrix} \\ H \end{smallmatrix}}{\mathop{H}}\,}}\,\] (iii) \[C{{H}_{3}}-\underset{\underset{\underset{But-2-ene}{\mathop{\text{H-C-C}{{\text{H}}_{\text{3}}}}}\,}{\mathop{||}}\,}{\mathop{C}}\,-H\] (iv) \[\underset{2-Mrthylprop-1-ene}{\mathop{C{{H}_{3}}-\overset{\overset{\text{C}{{\text{H}}_{\text{3}}}}{\mathop{|}}\,}{\mathop{C}}\,=C{{H}_{2}}}}\,\] (b) (i) \[\underset{Pent-1-yne}{\mathop{C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}-C\equiv CH}}\,\] (ii) \[\underset{Pent-2-yne}{\mathop{C{{H}_{3}}C{{H}_{2}}-C\equiv C-C{{H}_{3}}}}\,\] (iii) \[\underset{3-Methylbut-1-yne}{\mathop{C{{H}_{3}}-\overset{\overset{\text{C}{{\text{H}}_{\text{3}}}}{\mathop{|}}\,}{\mathop{C}}\,-C\equiv CH}}\,\]