Question

Diazomethane was photolysed to generate singlet carbine which was treated with cis-2-butene. The main product(s) of the reaction is/are:

• A. cis-1, 2-dimethylcyclopropane
• B. trans-1, 2-dimethylcyclopropane
• C. mixture of $\left(A\right)$ and $\left(B\right)$
• D. Ethylcyclopropane

Answer 1

Answer: (A)

cis-1, 2-dimethylcyclopropane

Solution:- (A) cis-$1,2$-dimethylcyclopropane

$\underset{\text{Diazomethane}}{C{H}_2-\stackrel{+}{N}=N^{-}}\underset{-N\equiv N}{\overset{h\nu }{\to }}\underset{\text{Singlet carbene}\left(\text{Methylene}\right)}{:C{H}_2}$

The addition of methylene would yield trans-$1,2$-dimethylcyclopropane from trans-$2$-butene and cis-$1,2$-dimethylcyclopropane from cis-$2$-butene.