Question

The synthesis of $3$ - octyne is achieved by adding a bromoalkane into a mixture of sodium amide and an alkyne. The bromoalkane and alkyne respectively are

• A. $BrCH _{2} CH _{2} CH _{2} CH _{2} CH _{3}$ and $CH _{3} CH _{2} C \equiv CH$
• B. $BrCH _{2} CH _{2} CH _{3}$ and $CH _{3} CH _{2} CH _{2} C \equiv CH$
• C. $Br CH _{2} CH _{2} CH _{2} CH _{2} CH _{3}$ and $CH _{3} C \equiv CH$
• D. $BrCH _{2} CH _{2} CH _{2} CH _{3}$ and $CH _{3} CH _{2} C \equiv CH$

Answer 1

Answer: (D)

$CH _{3}- CH _{2}- C \equiv CH \ce{->[{ NaNH ,}]}CH _{3}- CH _{2}- C \equiv C ^{-} Na ^{+}$
$CH _{3}- CH _{2}- CH _{2}- CH _{2} Br + Na - C \equiv C - CH _{2}- CH _{3} \longrightarrow \underset{\text{3 -octyne}}{CH _{3}- CH _{2}- CH _{2}- CH _{2}- C \equiv C - CH _{2}- CH _{3}}$