Catalysis of the reaction between 4-nitrobenzoic acid and ammonia by boric acid + polyehylene glycol-400

Article abstract of DOI:10.1007/s11167-005-0594-3

Solvent effect on the synthesis of 4-nitrobenzamide by the reaction of 4-nitrobenzoic acid with ammonia in the presence of the catalytic system constituted by boric acid and polyethylene glycol-400 was studied.

Full text of DOI:10.1007/s11167-005-0594-3

Russian Journal of Applied Chemistry, Vol. 78, No. 10, 2005, pp. 1715 1717. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 10, 2005,
pp. 1745 1747.
Original Russian Text Copyright
2005 by Shteinberg.
BRIEF
COMMUNICATIONS
Catalysis of the Reaction between 4-Nitrobenzoic Acid
and Ammonia by Boric Acid + Polyehylene Glycol-400
L. Ya. Shteinberg
Institute of Chemical Technology and Industrial Ecology, Rubezhanskii Krasitel’ Limited
Liability Company, Rubezhnoe, Lugansk oblast, Ukraine
Received April 13, 2005
Abstract Solvent effect on the synthesis of 4-nitrobenzamide by the reaction of 4-nitrobenzoic acid with
ammonia in the presence of the catalytic system constituted by boric acid and polyethylene glycol-400
was studied.
4
-Nitrobenzamide is the synthetic precursor of
-aminobenzamide used for preparing a numbers of
dyes [1].
p-cymene (177 C) > decane (174 C) > white spirit
(155 162 C) > o-chlorotoluene (155 C) > o-xylene
(145 C). At close temperatures, the NBA yield varies
in parallel with the solvent polarity in the order (run
nos. 6, 7, 9) o-dichlorobenzene > 1,2,4-trichloroben-
zene > decane. The same influence of the solvent po-
larity on the NBA yield is observed in amidation un-
der similar conditions in binary mixtures p-cymene-
nitrobenzene (run nos. 13 17). As can be seen, the
NBA yield steadily grows with increasing nitroben-
zene content, and accordingly, solvent polarity.
4
In [2], we showed that the system constituted by
boric acid and polyethylene glycol (PEG-400) effec-
tively catalyzes the synthesis of 4-nitrobenzamide
(
NBA) by the reaction of 4-nitrobenzoic acid (NBAc)
with ammonia in a mixture of 1,2,4-trichlorobenzene
with o-xylene. It was noted that PEG-400 favors dis-
solution of boric acid and homogenization of the re-
action mixture. In this study, we examined this cat-
alytic reaction in various media:
The highest NBA yields were attained in o-di-
chlorobenzene and 1,2,4-thichlorobenzene even with-
out refluxing of the reaction mixture and distillation
of the water released, which is evidently removed
from the reaction zone with excess ammonia (previ-
ously, in catalysis by titanium and boron compounds,
intense azeotropic distillation of the released water
was necessary for obtaining benzanilide [9]).
4
-NO C H COOH + NH
2 6 4 3
NBAc
H BO + PEG- 400
3
3
4
-NO C H CONH + H O.
2 6 4 2 2
NBA
Catalysis by boron compounds of amidation reac-
tions performed in aromatic and aliphatic hydrocarbons,
including hexane, benzene, toluene, cumene, isomeric
xylenes, and trichlorobenzene, was considered in [3 5].
To carry out the reaction of NBA with ammonia, we
took protic and aprotic solvents differing in the polar-
ity and boiling point. The results obtained and dielec-
tric constants of the solvents are listed in the table.
As known [10], boric acid readily reacts with var-
ious alcohols, including glycols, and polyethylene
glycols (HOROH), to give complexes A exhibiting
elevated acidity. Such compounds can serve as acid
catalysts in amidation. An increase in solvent polarity
can favor stabilization of transition state B and acid
catalysis:
As seen, the reaction readily proceeds in various
aromatic and aliphatic aprotic solvents and their mix-
tures. With an increase in the reaction time and cata-
lyst amount, the NBA yield grows becoming almost
quantitative (run nos. 4, 7, 8).
O
O
NBAc + R
B
A
R H+
O
O
O
O
O
+
O
H R
B
R
O
4
-NO C H C
2 6 4
In the series of solvents with low (and similar)
polarity, the yield of the target product varies in paral-
lel with the reaction temperature (run nos. 1 3, 5, 12):
OH
B
B + NH3
NBAm + H O + A.
2
1
070-4272/05/7810-1715 2005 Pleiades Publishing, Inc.

1716
SHTEINBERG
Synthesis of NBAc in various solvents*
H BO , mol %
relative to NBAc
Yield of NBA,
%
*
*
3
3
Run no.
Solvent
T,
C
, h
1
2
3
4
o-Xylene
o-Chlorotoluene
White spirit
2.57
4.45
145
155
155 162
155 162
6.0
6.0
6.0
6.5
0.0
6.0
6.0
6.0
6.0
0.0
6.0
5
5
5
34
34
5
34
34
2
2
3
4
70
95
10
63
92
66
93
79
96
Traces
49
13
13
1
1
5
6
7
8
Decane
1.99
1.99
9.93
3.98
174
174
162 164
170 175
o-Dichlorobenzene
1,2,4-Trichlorobenzene
2
9
3.98
170 175
34
34
0
0
5
9
.0
1
1
1
1
0
1
2
3
Decane***
1,2,4-Trichlorobenzene
p-Cymene
1.99
3.98
2.24
2.24
174
170 175
177
6.0
7.0
6.0
8.0
*
***
177
2
p-Cymene : nitrobenzene :
10 : 1
8 : 1
5 : 1
3.5 : 1
Ethylene glycol
Diethylene glycol
Triethylene glycol
14
15
16
17
18
19
20
5.21
5.89
7.68
177
177
177
8.0
8.0
8.0
8.0
6.0
6.0
6.0
2
2
2
40
59
67
72
0
9.51
177
2
38.66
31.69
23.19
175 180
175 180
175 180
33
33
33
0
0
*
*
In all the experiments, the PEG-400 amount was taken as a half (in moles) of that of boric acid.
*
The values of were taken from [6, 7]; for the mixture of n-cumene with nitrobenzene, the values were calculated using
an additive scheme from the volume fractions of the components [8] (listed in table).
*
**
Filtrate from run no. 6 was taken as a solvent.
Filtrate from run no. 8 was taken as a solvent.
*
***
However, an attempt to obtain NBA in more polar
formed within 2 h after the beginning of the reaction.
Probably, the crystalline NBA precipitate is bound with
a part of the catalyst, which may hinder its interaction
with the reactants and the catalytic reaction as a whole.
solvents, glycols, failed (run nos. 18 20). A TLC
analysis of the reaction mixture showed that NBAc
rapidly (during 1 h) disappeared, but there was no
NBA among the reaction products. Probably, in gly-
cols, NBAc in the presence of boric acid forms glycol
esters, which then do not react with ammonia.
To study the catalyst distribution in the reaction
mixture, we performed experiment nos. 10 and 11, us-
ing as solvents the filtrates from separation of the solid
target product in experiment nos. 6 and 8, respective-
ly, without adding the catalytic system. It was found
that the filtrate showed no catalytic power in decane
A high polarity of the solvent may also favor homo-
genization of the reaction mixture. We found that, in
amidation in low-polar decane (run nos. 5, 6), crystal-
line NBA precipitates already within 2 h. In more
polar o-dichlorobenzene and 1,2,4-trichlorobenzene,
the reaction mixture is homogeneous, amidation pro-
ceeds faster, and crystalline NBA precipitates only
after cooling the reaction mixture to room tempera-
ture after the reaction is complete (run nos. 7 9).
(
run no. 10), i.e., the whole amount of the catalyst
was probably removed from the filtrate with NBA. In
,2,4-trichlorobenzene, the filtrate showed fairly high
1
catalytic power (run no. 11), thus confirming the uni-
form distribution of the catalyst. The degree of NBAc
binding with ammonia can vary with the solvent po-
larity. As known, carboxylic acids form salts with
amines. The reactivity of carboxylate anions and
protonated amines in nucleophilic substitution at
Thus, with decane as a solvent, the reaction pro-
ceeds in the heterogeneous system gas liquid solid,
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 78 No. 10 2005

CATALYSIS OF THE REACTION BETWEEN 4-NITROBENZOIC ACID AND AMMONIA
1717
the carbonyl carbon atom may be substantially low-
ered [11, 12].
acid and ammonia in aprotic solvents at 145 177 C.
Under the reaction conditions, ammonium salt of 4-ni-
trobenzoic acid rapidly decomposes, with ammonia
liberated and no 4-nitrobenzamide formed.
Since NBA is not formed from NBAc ammonium
salt in the presence of the catalytic system [2], it was
of interest to test the stability of this salt under the re-
action conditions.
(2) In polar proton-donor glycols, 4-nitrobenzoic
acid rapidly transforms into unidentified products
without formation of 4-nitrobenzamide.
We found that the NBAC ammonium salt under-
goes no changes on heating to 120 C for 20 h without
solvents or on washing with o-xylene or o-chloroben-
zene at room temperature, followed by filtration and
drying: its melting point remains unchanged. Howev-
er, on heating of the suspension of NBAc ammonium
salt in these solvents to 60 80 C, it decomposes with
liberation of ammonia. Heating of such a suspension
in o-xylene at 145 C for 10 min causes complete de-
composition of the ammonium salt: after cooling, only
NBAc is recovered from the reaction mixture. Prob-
ably, NBAc reacts in the free state but not as am-
monium salt under the reaction conditions, even in
the presence of a large excess of ammonia.
REFERENCES
1
2
. The Chemistry of Synthetic Dyes, vol. 5, Venkatara-
man, K., Ed., New York: Academic, 1971.
. Shteinberg, L.Ya., Zh. Org. Khim., 2003, vol. 39,
no. 7, pp. 1033 1036.
. Swiss Patent 367509.
. Nelson, P. and Pelter, A., J. Chem. Soc., 1965, no. 9,
3
4
pp. 5142 5144.
5
6
. Pelter, A. and Levitt, T.E., Tetrahedron, 1970, vol. 26,
no. 6, pp. 1545 1553.
. Weissberger, A. and Proskauer, E.S., Organic Sol-
vents. Physical Properties and Methods of Purifica-
tion, Riddig, J.A. and Toops, E.E., Eds., New York:
Interscience, 1955.
EXPERIMENTAL
7
8
. Akhadov, Ya.Yu., Dielektricheskie svoistva chistykh
zhidkostei (Dielectric Properties of Pure Liquids),
Moscow: Khimiya, 1989.
. Fialkov, Yu.Ya., Rastvoritel’ kak sredstvo upravleniya
khimicheskim protsessom (Solvent as a Means for
Controlling a Chemical Process), Leningrad: Khimiya,
Boric acid, NBAC, PEG-400, o-xylene, decane,
,2,4-trichlorobenzene, o-dichlorobenzene, and nitro-
1
benzene were of the same quality as in [2, 9, 13].
o-Chlorotoluene and white spirit were vacuum-dis-
tilled. Ethylene glycol, diethylene glycol, and trieth-
ylene glycol were dried over sodium sulfate and vac-
uum-distilled. n-Cymene was washed with sulfuric
acid, water, solutions of potassium permanganate,
sodium hydroxide, and again water, dried over sodium
sulfate, and vacuum-distilled. NBA and ammonium
salt of NBAc were prepared, the mixtures were ana-
lyzed, and the purity of the products was determined
as in [2] with separation of an additional amount of
the target product and vacuum distillation of the sol-
vent from the reaction mixture.
1
990.
9
. Shteinberg, L.Ya, Kondratov, S.A., and Shein, S.M.,
Zh. Org. Khim., 1988, vol. 24, no. 9, pp. 1968 1972.
1
1
1
0. Shvarts, E.M., Vzaimodeistvie bornoi kisloty so spir-
tami i oksikislotami (Reaction of Boric Acid with
Alcohols and Hydroxy Acids), Riga: Zinatne, 1990.
1. Temnikova, T.I., Kurs teoreticheskikh osnov orga-
nicheskoi khimii (Course of Theoretical Foundations
of the Organic Chemistry), Leningrad: Khimiya, 1968.
2. Litvinenko, L.M. and Oleinik, N.M., Organicheskie
katalizatory i gomogennyi kataliz (Organic Catalysts
and Homogeneous Catalysis), Kiev: Naukova Dumka,
CONCLUSIONS
1
981.
(
1) The catalytic system constituted by boric acid
1
3. Shteinberg, L.Ya, Kondratov, S.A., and She-
in, S.M., Zh. Org. Khim., 1989, vol. 25, no. 9,
pp. 1945 1949.
and polyethylene glycol-400 is the most efficient
in synthesis of 4-nitrobenzamide from 4-nitrobenzoic
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 78 No. 10 2005