Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 5, pp. 815−819.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © L.Ya. Shteinberg, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 5, pp. 785−789.
AND INDUSTRIAL ORGANIC CHEMISTRY
A Study of the Kinetics and Mechanism of Amidation
of 4-Nitrobenzoic Acid with Ammonia, Catalyzed by Boric Acid
in the Presence of Polyethylene Glycol PEG-400
L. Ya. Shteinberg
Institute of Chemical Technology and Industrial Ecology, Scientiﬁ c and Technical Institution,
Rubezhnoe, Lugansk oblast, Ukraine
Received July 27, 2010
Abstract—Kinetics of the reaction of 4-nitrobenzoic acid with ammonia, catalyzed by the system constituted by
boric acid and PEG-400 poly(ethylene glycol), was studied. A catalysis mechanism was suggested, which consists
in original synthesis of incomplete polyethylene glycol borate esters, formation on their basis of 4-nitrobenzoic
acid borate esters, and their further amidation with ammonia.
It has been found previously that the system boric
acid + PEG-400 poly(ethylene glycol) catalyzes forma-
tion of 4-nitrobenzamide (PNBAm) in the reaction of
4-nitrobenzoic acid (PNBA) with ammonia in aprotic
media [1–4]. It has been noted that the catalysis is ef-
ﬁ cient in a wide range of concentrations and various ra-
tios between boric acid and PNBA.
The goal of this study was to examine the kinetics and
mechanism of the catalytic amidation of 4-nitrobenzoic
acid with ammonia at various ratios between boric acid
The reaction of PNBA with ammonia was performed
in 1,2,4-trichlorobenzene, in which the yield of PNBAm
is high, as shown previously in [2, 4] (see the scheme ).
Figure 1 shows kinetic curves of PNBAm accumula-
tion, depending on the concentration of PEG-400 used
at various amounts of boric acid. It can be seen that all
the kinetic curves emerge from the origin of coordinates
and are linear up to high degrees of PNBA conversion
(70–75%). Therefore, with the difﬁ culties in kinetic
measurements and their comparatively poor accuracy
taken into account, the initial rates of PNBAm accu-
mulation were calculated as average values W
from the linear portions of the kinetic curves by the for-
is the initial PNBA concentration (M), a, yield
of PNBAm (%); and τ, reaction duration (h).
Dependences of the initial rates of PNBAm
accumulation on the PEG-400 : boric acid molar ratio
are shown in Fig. 2. It can be seen (curves 1–3) that
about the same variation of the reaction rate is observed
with different amounts of boric acid.
Conditionally, three portions can be distinguished in
the curves. In the ﬁ rst of these, the initial rate of PNBAm