Mechanism of Free Radical Halogenation using Bromine
Chain Initiation
light
Br2
2 Br
Chain Propagation
Br
H
H
H
H
H
H
C
C
C
H
H
H
H
H
H
C
C
C
H
H
H
Br2
H
+
HBr
H
H
H
C
C
C
H
H
H
H
Br H
C
C
C
H
H
H
H
Br H
C
C
C
H
H
H
+ Br
H
Chain Termination
Br
Br
H
Br
H
Br2
H
C
C
C
H
H
H
H
H
H
H
H
C
H
H
C
H
C
H
H
H
H
C
H
H
C
H
C
H
H
H
H
H
Relative Reactivity
1 2
3
Chlorination 1
3.5 5
Bromination 1
97

C
H
C
H
H
H H
C
H
C
H
C
H
H
C
H
H
H
1) Please draw the rotational energy diagram for the rotation of 2,3-dimethyl butane around the
C2-C3 bond.
0
60
120
180
240
300
360
Draw the molecule below, convert it to a Newman projection and then rotate it about the C2-C3
bond. Based on your rotations, draw the energy diagram above.
2) Please draw the rotational energy diagram for the rotation of 3-methyl pentane around the C2C3 bond.
0
60
120
180
240
300
360
Draw the molecule below, convert it to a Newman projection and then rotate it about the C2-C3
bond. Based on your rotations, draw the energy diagram above.
1) Please draw the rotational energy diagram for the rotation of 2,3-dimethyl butane around the
C2-C3 bond.
Energy
0
60
120
180
240
300
360
Draw the molecule below, convert it to a Newman projection and then rotate it about the C2-C3
bond. Based on your rotations, draw the energy diagram above.
0
CH3 CH3
H3C
C
C
H
H
120
CH3
H3C
H3C
CH3
CH3
CH3
4
60
H3C
CH3
H
HH
CH3
H3C
CH3
CH3
CH3
H
2
CH3
H3C
H
H3C
H CH3
3
H
H3C
H3C
CH3
H
H3C
CH3
H3C
H
CH3
H
H CH3
H
300
240
180
2
3
1
2) Please draw the rotational energy diagram for the rotation of 3-methyl pentane around the C2C3 bond.
6
5
Energy
4
3
2
1
0
60
120
180
240
300
360
Draw the molecule below, convert it to a Newman projection and then rotate it about the C2-C3
bond. Based on your rotations, draw the energy diagram above.
0
H
H3C
CH3
C
C
H
H
120
CH3
H3C
H
CH3
C2H5
C2H5
6
60
H
CH3
H
HH
CH3
H3C
CH3
CH3
C2H5
H
3
C2H5
H
H
H
H C2H5
5
H
C2H5
H
CH3
H
H
CH3
C2H5
H
CH3
H
H CH3
H
300
240
180
2
4
1
3) What is the ratio of products in the free radical chlorination of bicyclo [2,2,0] hexane?
2°
𝑥
8 3.5
( °)
= ∙
3
100 − 𝑥
2
5
𝑥 = 26.32%
4) What is the ratio of products in the free radical chlorination of 2-methylpropane?
CH3
H3C
C
CH3
1°
𝑥
9 1
( °)
= ∙
3
100 − 𝑥
1 5
𝑥 = 64.29%
H
5) What is the ratio of products in the free radical chlorination of 1,1,3,3tetramethylcyclopentane?
H3 C
CH3
1°
𝑥
12
1
( °)
=
∙
2
100 − 𝑥
6 3.5
𝑥 = 36.36%
CH3
H3C
6) Please name the following compounds,
Acids
O
O
C
C
C
C
HO
OH
Propanoic acid
O
O
C
C
H
C
C
OH
OH
butadioic acid (malic acid)
methanoic acid (formic acid)
COOH
OH
C
C
Br
Benzoic acid
O
C
C
OH
3-bromo-3-hydroxybutanoic acid
Aldehydes and Ketones
O
O
C
C
C
C
C
O
C
C
C
H
C
H
H
Propanal
2-pentanone
OH O
O
C
C
methanal (formaldehyde)
C
Propanone (acetone)
C
C
C
C
3-hydroxybutanone
Alcohols
H
OH
C
C
C
OH
C
C
C
C
C
H
C
OH
H
Propanol
2-pentanol
OH OH
OH
C
C
methanol
C
2-propanol
C
C
C
2,3-butadiol
C
Aromatics
NH2
NO2
CH3
HO
Cl
Toluene
CH3
2-chloro-4-nitrophenol
Br
para methylaniline
Br
H2N
COOH
Br
1,3,5-tribromobenzene
para aminobenzoic acid