Chemistry Reference
In-Depth Information
10.3
a.
b.
CO
2
H
NO
2
10.4
a.
cyclopropanecarboxylic acid
b.
p
-methoxybenzoic acid
O
10.5
a.
b.
C
CO
2
H
H
c.
d.
O
CH
3
K
a
is 1.8 x 10
-5
for acetic acid and 5.0 x 10
-2
for dichloroacetic acid.
K
a
is larger for
dichloroacetic acid; it is the stronger acid. The ratio is:
10.6
In other words, dichloroacetic acid is 2800 times stronger than acetic acid.
10.7
The negative charge in the benzoate anion cannot be delocalized into the aromatic,
but can be distributed over the two oxygen atoms.
-
O
O
-
C
O
C
O
K
a
for benzoic acid is 6.6 x 10
-5
or 0.66 x 10
-4
. For
o
-,
m
-, and
p
-chlorobenzoic acids,
K
a
is 12.5, 1.6, and 1.0 x 10
-4
, respectively. All three chloro acids are stronger than
benzoic acid. However, the difference is greatest for the ortho isomer since, in this
isomer, the chloro substituent is closest to the carboxyl group and exerts the
maximum electron-withdrawing inductive effect. The effect decreases as the distance
between the chloro substituent and the carboxyl group increases.
10.8
10.9
10.10
The halide can be converted to the corresponding Grignard reagent, which can react
with carbon dioxide to give the carboxylic acid.
