CLAS - Chem 109C - Chapter 19
e-mail: benzene4president@gmail.com
website: http://clas.sa.ucsb.edu/staff/terri/
drop-in: M/W/F 10-11, T/R 2-3 and T/R 4-5
New Reactions
I. Electrophilic Aromatic Substitution
A. Halogenation
C. Reduction of Nitro groups
D. Oxidation of Alkyl groups (must contain a
benzyl hydrogen)
E. Formation of Arenediazonium salt
B. Nitration
F. Substitution of Arenediazonium salts
1. Sandmeyer
C. Sulfonation
D. Friedel-Crafts Acylation
2. Phenyl iodide formation
E. Friedel-Crafts Alkylation (potential
carbocation rearrangement)
3. Schiemann
4. Phenol formation
F. Gatterman-Koch
II. Reactions to Benzene Substituents
A. Desulfonation
B. Reduction of Acyl groups
1. Catalytic Hydrogenation
2. Clemmensen
3. Wolff-Kishner
5. De-arenediasonium salt
III. Nucleophilic Aromatic Substitution (strong
deactivating substituent must be ortho and/or para to the
leaving group)
Increasing pKa (if on a phenol)
Reactivity toward Electrophilic Aromatic
Substitution
-NH2, -NHR, -NR2 (most reactive)
-OH, -OR
-NHCOR
-OCOR
-R
-Ar, -CH=CHR
Activating
(more reactive than
benzene)
Ortho/Para
Directors
-H (standard)
-F
-Cl
-Br
-I
-CHO
-COOR
-COOH
-COCl
-C≡N
-SO3H
-NH3+, -NH2R+, -NHR2+, -NR3+
-NO2 (least reactive)
De-activating
(less reactive than
benzene)
Practice Problems
1. Predict the products for the following reactions:
a.
g.
b.
h.
c.
i.
d.
e.
f.
j.
k.
Meta
Directors
2. Rank the following compound in order of increasing
pKa. Explain your reasoning.
I. phenol
II. para-methoxyphenol
III. para-nitrophenol
3. Provide a possible synthesis for the following
compounds starting from benzene:
a. meta-nitrobenzoic acid
b. para-chlorobenzoic acid
c. meta-butylnitrobenzene
d. para-bromostyrene
e. meta-chloroaniline
f. meta-bromophenol
g. meta-dichlorobenzene