Halonium
Ion - Leads to anti Geometry of Addition so trans products.
Holonium
ion intermediates are produced when alkenes react with X2,
X being Cl, Br or I. Halonium ions are positively-charged, three-membered
ring intermediates. Note that nucleophiles, i.e. X- or water, can only
attack from the face of the halonium ion intermediate opposite of where
the X atom is (otherwise they would simply bounce off of the X atom),
a geometry referred t as anti addition, explaining why trans stereochemistry
of addition is always observed in the products of these reactions.
Pictures of the Day CH320M/CH328M
10-6-22
