question_answer 13)

Write structures of different isomers corresponding to the 5th member of alkyne series. Also write IUPAC names of all the isomers. What type of isomerism is exhibited by different pairs of isomers?

Answer:

The molecular formula of the 5th member of alkyne series is \[{{C}_{6}}{{H}_{10}}\]. The possible isomers are: (i) \[H\overset{1}{\mathop{C}}\,\equiv \overset{2}{\mathop{C}}\,-\underset{Hex-1-yne}{\mathop{\overset{3}{\mathop{C{{H}_{2}}}}\,\overset{4}{\mathop{C{{H}_{2}}}}\,\overset{5}{\mathop{C{{H}_{2}}}}\,}}\,{{\overset{6}{\mathop{CH}}\,}_{3}}\] (ii) \[C{{H}_{3}}-C\underset{Hex-2-yne}{\mathop{\equiv C-C{{H}_{2}}}}\,C{{H}_{2}}C{{H}_{3}}\] (iii) \[C{{H}_{3}}C{{H}_{2}}\underset{Hex-3-yne}{\mathop{C\equiv CC{{H}_{2}}}}\,C{{H}_{3}}\] (iv) \[HC\equiv C-\underset{\underset{\underset{3-Methylpent1-yne}{\mathop{\text{C}{{\text{H}}_{\text{3}}}}}\,}{\mathop{\text{ }\!\!|\!\!\text{ }}}\,}{\mathop{CHC{{H}_{2}}}}\,C{{H}_{3}}\] (v) \[HC\equiv C-\underset{\underset{\underset{4-Methylpent-1-yne}{\mathop{\text{C}{{\text{H}}_{\text{3}}}}}\,}{\mathop{|}}\,}{\mathop{C{{H}_{2}}CHC{{H}_{3}}}}\,\] (vi) \[C{{H}_{3}}C\equiv C-\underset{\underset{\underset{4-Methylpent-2-yne}{\mathop{\text{C}{{\text{H}}_{\text{3}}}}}\,}{\mathop{|}}\,}{\mathop{CHC{{H}_{3}}}}\,\] (vii) \[\underset{3,3-Dimethylbut\,-1-yne}{\mathop{HC\equiv C-\underset{\underset{\text{C}{{\text{H}}_{\text{3}}}}{\mathop{|}}\,}{\overset{\overset{\text{C}{{\text{H}}_{\text{3}}}}{\mathop{|}}\,}{\mathop{C}}}\,-C{{H}_{3}}}}\,\] Chain and position isomerism is shown by different pairs.