Question

The bromination involves so called bromonium ions.Among the given statements identify the one which does not appply:

• A. bromonium ions are 3-membered rings
• B. bromonium ions are intermediates in the formation of halohydrins
• C. bromonium ions are intermediate in the formation of vicinal dibromides by addition of bromides to alkenes
• D. bromonium ions of asymmetrical alkenes are attacked by nucleophiles at the least subtituted alkene c-atom

Answer 1

Answer: (D)

bromonium ions of asymmetrical alkenes are attacked by nucleophiles at the least subtituted alkene c-atom

The bromonium ion is formed when alkenes react with bromine. When the $\pi$ cloud of the alkene (acting as a nucleophile) approaches the bromine molecule (acting as an electrophile), the $\sigma$-bond electrons of $B{r}_2$ are pushed away, resulting in the departure of the bromide anion

Bromonium ions are $3-membered$ rings and an intermediate in the formation of vicinal dibromides by the addition of bromides to alkenes. Cyclic halonium ions undergo nucleophilic attack at the carbon where the positive charge is stabilized more ie, at more substituted carbon.