Doubt by ARPITA SINGH

please explain This.

Answers

Answer by nitesh chaudhary

In singlet carbene, the two unshared electrons are paired in a 𝑠𝑝2sp2 orbital, leaving a vacant p orbital.

A triplet carbene has both electron with same spin and can’t occupy same orbital. So, one electron occupies one of the𝑠𝑝2sp2 orbitals while the other electron occupies the p orbital.

A singlet carbene react with alkene through a concerted electrophilic addition (via transition state) involving empty carbene 𝜋π orbital with filled orbital of double bond and give stereospecific product.

In case of triplet carbene, reaction with alkenes proceeds in two steps (via radical intermediate). The intermediate is also in triplet state and has life time long enough to allow rotation of groups around a single bond before the closure of ring takes place and gives mixture of cis- and trans- product.