Question

What is the hybridisation of carbon atoms in \(CH_{2}=CH-CN\) (Acrylonitrile)?

• A. \(C_{1}=sp^{3},\;C_{2}=sp^{3},\;C_{3}=sp\)
• B. \(C_{1}=sp^{2},\;C_{2}=sp^{2},\;C_{3}=sp\)
• C. \(C_{1}=sp^{2},\;C_{2}=sp,\;C_{3}=sp^{2}\)
• D. All carbon atoms are \(sp^{2}\) hybridised.

Hint:

Remember these hybridisations: \[ \boxed{ \begin{aligned} C=C &\rightarrow sp^2\\ C\equiv C &\rightarrow sp\\ C\equiv N &\rightarrow sp\\ C-C &\rightarrow sp^3 \end{aligned} } \] In nitriles (\(-C\equiv N\)), the carbon atom is always \(sp\)-hybridised.

Answer 1

The Correct Option is B

In acrylonitrile ($CH_2=CH-CN$), each vinyl carbon participates in a $C=C$ double bond and two single bonds, giving both $sp^2$ hybridization. The carbon of the cyano group forms a $C\equiv N$ triple bond plus one single bond, giving it $sp$ hybridization; so the hybridizations along the chain are $sp^2$, $sp^2$, $sp$.