Question

The compound below is treated with N-bromosuccinimide (NBS) in the presence of light. Draw both resonance structures for the radical produced by reaction of the compound with a bromine atom. Assume reaction occurs only at the weakest C-H bond. • You do not have to consider stereochemistry. • You do not have to explicitly draw H atoms,

Answer 1

N-bromosuccinamide (NBS) is a suitable source for bromide radical in presence of light.

This bromide radical can convinently replce the weakset C—H bond of the alkene. Now the allylic C—H bond is the weakest bond in the alkene compound since the allylic radical is most stable by resonce stabilization.

The products in each case and the mechanism are shown below.

a C-H bonds are agrivatent as shown in the above. O UBT NBS) Oxxon CX-e, we x +Be

FO Both ch' and c-42 are allylic. But after radical formation from call, it produces, 2 radical while che produced i radical Since 2 radical is more stable than 10 radical thung C-A1 bond is the meak est bond. + BP- NI- HBY ( Resonace form) *** x 46,