3
$\begingroup$

I encountered a weird question in an exam. The statement says that instead of radical substitution, cyclopropane undergoes electrophilic addition reaction in sunlight.

I know that all saturated compounds give substitution reactions in sunlight but the answer key states that electrophilic addition takes place.

I couldn't find any source to prove this. Any help with an explanation and a verified source would be appreciated.

$\endgroup$
1
2
$\begingroup$

It should say "in addition to" rather than "instead of".

Cyclopropane suffers badly from ring strain. The bond angles in the ring are 60° rather than the normal ~109.5° when carbon makes four single bonds. In the absence of light, when in contact with $Cl_2$ or $Br_2$ the ring will break and addition occur.

In sunlight, both the expected substitution reactions and the addition reaction will occur.

Can't find the reference I thought I remembered, but here's a site or two discussing it:

https://www.chemguide.co.uk/organicprops/alkanes/halogenation.html

https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_General_Chemistry_(Petrucci_et_al.)/27%3A_Reactions_of_Organic_Compounds/27.07%3A_Reactions_of_Alkanes

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.