ISSN 1070-3632, Russian Journal of General Chemistry, 2012, Vol. 82, No. 1, pp. 149–152. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © Yu.D. Markovich, T.N. Kudryavtseva, M.I. Brylev, V.Yu. Markovich, I.A. Koroleva, 2012, published in Zhurnal Obshchei Khimii,
2012, Vol. 82, No. 1, pp. 152–155.
Kinetic Parameters of the Intramolecular Condensation
of Diphenylamine-2-carboxylic Acid
under Microwave Radiation
Yu. D. Markovich, T. N. Kudryavtseva, M. I. Brylev, V. Yu. Markovich, and I. A. Koroleva
Southwestern State University, ul. 50 Let Octyabrya 94, Kursk, 305040 Russia
e-mail: kstu-oah@yandex.ru
Received October 28, 2010
Abstract—The cyclization of diphenylamine-2-carboxylic acid under microwave radiation was investigated.
The kinetic parameters of the processes were measured. The use of microwave radiation was found to reduce
the reaction duration and to increase the target product yield. The optimal conditions for processes were
determined.
DOI: 10.1134/S1070363212010240
The investigation of the possibility of using
microwave radiation in the synthesis of various
heterocyclic compounds is an urgent task, as this
method has several advantages over the other types of
activation of the chemical reaction: reducing the
reaction duration, high energetic efficiency of the
process, etc. [1, 2].
Among the affordable ways of getting the majority
of acridones is the cyclization of appropriate acid I in
concentrated sulfuric acid at 90–100°C for 4 h, the
recommended mole ratio of diphenylamine-2-
carboxylic acid : sulfuric acid is from 1:7.5 to 1:9 [4,
5]. It was interesting to compare the reaction rate and
yield for the reactions under the microwave and the
traditional conditions of heating.
The target products of condensation of substituted
diphenylamine-2-carboxylic acid (Ia–Ig) are the
acridones that are used as starting materials in the
synthesis of various drugs [3].
Under both microwave and traditional heating, the
cyclization reaction proceeds according to the scheme:
O
COOH
MW, H2SO4
R
R
N
H
N
H
I
II
R = H (а), 2'-CH3 (b), 3'-CH3 (c), 4'-CH3 (d), 2'-COOH (e), 4'-COOH (f), 2'-NO2 (g).
The use of sulfuric acid as a cyclizing agent favors
phenylamine-2-carboxylic acids we measured the
kinetic characteristics of the reaction. After processing
the chromatograms, we calculated the degree of
consumption of the initial acid I and the degree of
accumulation of the corresponding acridone (α = cI/cI0).
The kinetic curves of consumption of unsubstituted
acid Ia and accumulation of acridone and acrido-
nesulfonic acid in sulfuric acid at 90°C at the
side reactions of sulfonation. As shown by earlier
research [6], the use of microwave radiation increases
the yield of the mono- and disulfo-derivatives
(compounds IV and V, respectively):
To determine the effect of microwave heating on
the intramolecular condensation of substituted di-
149