• # question_answer The total number of acylic isomers including the stereoisomers with the molecular formula ${{C}_{4}}{{H}_{7}}Cl$ [Pb. CET 2004] A) 11 B) 12 C) 9 D) 10

${{C}_{4}}{{H}_{7}}Cl$ is a monochloro derivative of ${{C}_{4}}{{H}_{8}}$ which itself exists in three isomeric forms. (i) $C{{H}_{3}}-C{{H}_{2}}-CH=C{{H}_{2}}$ : Its possible mono-chloro derivatives are : $C{{H}_{3}}-C{{H}_{2}}-CH=CH-Cl$ 2 isomers : cis and trans forms $C{{H}_{3}}-\underset{Cl\ }{\mathop{\underset{|}{\mathop{\overset{\bullet }{\mathop{C}}\,}}\,H}}\,-CH=C{{H}_{2}}$ optically active (exists in two forms) $ClC{{H}_{2}}-C{{H}_{2}}-CH=C{{H}_{2}}$ (one form) ${{H}_{3}}C-C{{H}_{2}}-\overset{Cl\ }{\mathop{\overset{|}{\mathop{C}}\,=}}\,C{{H}_{2}}$ (one form) (ii) $C{{H}_{3}}-CH=CH-C{{H}_{3}}$ : Its possible monochloro derivatives are : $C{{H}_{3}}-CH=\underset{Cl\ }{\mathop{\underset{|}{\mathop{C}}\,-}}\,C{{H}_{3}}$ Exists in two geometrical forms $C{{H}_{3}}-CH=CH-C{{H}_{2}}Cl$ Exists in two geometrical forms (iii) $C{{H}_{3}}-\underset{C{{H}_{3}}\ \ \ \ \ \,}{\mathop{\underset{|}{\mathop{C}}\,=C{{H}_{2}}}}\,$ : Its possible monochloro derivatives are $C{{H}_{3}}-\underset{C{{H}_{3}}\ \ \ \ }{\mathop{\underset{|}{\mathop{C}}\,=CH}}\,-Cl$ Only one form $ClC{{H}_{2}}-\underset{C{{H}_{3}}\ \ \ \ \ \,}{\mathop{\underset{|}{\mathop{C}}\,=C{{H}_{2}}}}\,$ Only one form Thus, the total acylic isomers forms of ${{C}_{4}}{{H}_{7}}Cl$ are 12.