Advices For Studying Organic Chemistry

CC CCl

4

CC

Br

CC

Br Br

Br

Br

Br

omoalkene Tetrabromoalkane

Br 2

Br 2

Dibr

CCl 4

CC

Cl 2

CCl 4 CC

Cl

Cl

CC

Cl

Cl

Cl

Cl

Dichloroalkene Tetrachloroalkane

Cl 2

CCl 4

2. It is usually possible to prepare a dihaloalkene by simply adding one molar
   equivalent of the halogen.

Br 2 (1mol) CH 3 CH 2 CH 2 CH 2 CBr CBrCH 2 OH

CClo (^4) (80%)
H 3 CH 2 CH 2 CH 2 CC CCH 2 OH

3. Most additions of chlorine and bromine to alkynes are anti additions and yield
   trans-dihaloalkenes.

0 C

HO 2 CCCCO 2 H Br^2 CC

Br

HO 2 C

CO 2 H

Br

Acetylenedicarboxylic acid (70%)

8.13 ADDITION OF HYDROGEN HALIDES TO ALKYNES

1. Alkynes react with HCl and HBr to form haloalkenes or geminal dihalides
   alide are
   used.

depending on whether one or two molar equivalents of the hydrogen h

1) Both additions are regioselective and follow Markovnikov’s rule: