Advices For Studying Organic Chemistry

reaction.

2. If the alkene is unsymmetrical, the halogen ends up on the carbon atom with the

1) trical.

i) The more highly substituted carbon atom bears the greater positive charge

because it resembles the more stable carbocation.

ii) Water attacks this carbon atom preferentially.

greater number of hydrogen atoms.

The intermediate bromonium ion is unsymme

CCH 2

HC

H 3 CC

3 Br

H 3 C CH 3

CH 2 H 3 CCCH 2 Br

OH 2

CH 3

H 3 CCCH 2 Br

OH

CH 3

Br +

(^2) δ+ OH 2
δ+
−H+
(73%)
iii) The greater positive charge on the 3° carbon atom permits a pathway with a
lower free energy of activation even though attack at the 1° carbon atom is less
hindered.

The Chemistry of Regiospecificity in Unsymmetrically Substituted

Bromonium Ions: Bromonium Ions of Ethene, Propene, and

2-Methylpropene

1. When a nucleophile reacts with a bromonium ion, the addition takes place with
   Markovnikov regiochemistry.

1. In the formation of bromohydrin, bromine bonds at the least substituted carbon
   (from nucleophilic attack by water), and the hydroxyl group bonds at the more
   substituted carbon (i.e., the carbon that accommodated more of the posit e
   charge in the bromonium ion).
   2

iv

. The relative distributions of electron densities in the bromonium ions of ethane,