Question

The number of structural and configurational isomers of a bromo compound, $${C_5}{H_9}Br,$$   formed by the addition of $$HBr$$  to 2 - pentyne respectively are

A. 1 and 2
B. 2 and 4  
C. 4 and 2
D. 2 and 1
Answer :   2 and 4
Solution :
Addition of $$HBr$$  of 2 - pentyne gives two structural isomers (I) and (II)
\[C{{H}_{3}}-C\equiv C-C{{H}_{2}}C{{H}_{3}}\xrightarrow{HBr}\]       \[\underset{\left( \text{I} \right)}{\mathop{C{{H}_{3}}C\left( Br \right)=CHC{{H}_{2}}C{{H}_{3}}}}\,\,\,+\]       \[\underset{\left( \text{II} \right)}{\mathop{C{{H}_{3}}CH=C\left( Br \right)C{{H}_{2}}C{{H}_{3}}}}\,\]
Each one of these will exist as a pair of geometrical isomers. Thus, there are two structural and four configurational isomers.

Releted MCQ Question on
Organic Chemistry >> Alkyl and Aryl Halide

Releted Question 1

Chlorobenzene can be prepared by reacting aniline with :

A. hydrochloric acid
B. cuprous chloride
C. chlorine in presence of anhydrous aluminium chloride
D. nitrous acid followed by heating with cuprous chloride
Releted Question 2

The reaction conditions leading to the best yields of $${C_2}{H_5}Cl$$  are :

A. \[{{C}_{2}}{{H}_{6}}\text{(excess)}+C{{l}_{2}}\xrightarrow{\text{uv}\,\text{light}}\]
B. \[{{C}_{2}}{{H}_{6}}+C{{l}_{2}}\xrightarrow[\text{room temperature}]{\text{dark}}\]
C. \[{{C}_{2}}{{H}_{6}}+C{{l}_{2}}\text{(excess)}\xrightarrow{\text{uv}\,\text{light}}\]
D. \[{{C}_{2}}{{H}_{6}}+C{{l}_{2}}\xrightarrow{\text{uv}\,\text{light}}\]
Releted Question 3

$$n - $$  Propyl bromide on treatment with ethanolic potassium hydroxide produces

A. Propane
B. Propene
C. Propyne
D. Propanol
Releted Question 4

The number of structural and configurational isomers of a bromo compound, $${C_5}{H_9}Br,$$   formed by the addition of $$HBr$$  to 2 - pentyne respectively are

A. 1 and 2
B. 2 and 4
C. 4 and 2
D. 2 and 1

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Alkyl and Aryl Halide


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