1070-4272/03/7612-1955 $25.00 C 2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 12, 2003, pp. 1955!1957. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 12, 2003,
Original Russian Text Copyright + 2003 by Trakhanov, Kruk, Maksimuk.
AND INDUSTRIAL ORGANIC CHEMISTRY
Base-Catalyzed Autocondensation of Cyclohexanone
P. K. Trakhanov, V. S. Kruk, and Yu. V. Maksimuk
Research Institute of Physicochemical Problems, Belarussian State University, Minsk, Belarus
Received May 6, 2003
Abstract-Autocondensation of cyclohexanone in air at 1193137oC, catalyzed with a solid alkali, was studied.
Cyclohexanone is an intermediate in industrial
organic synthesis. Its characteristic feature is tendency
to undergo autotransformations yielding a series of
products . In synthesis of caprolactam  and adip-
ic acid , autocondensation is a side reaction, where-
as in the first step of industrial synthesis of 2-phenyl-
phenol (a bactericide) [43 6] or 2-cyclohexylcyclohex-
anol (a fragrance) , this is the principal process.
To improve the existing processes involving cyclo-
hexanone and develop new ones, it is appropriate to
study the kinetic features of its autocondensation,
primarily with the aim to obtain input data for simu-
lation of flowsheets and process equipment.
The condensation is nonselective and yields a mix-
ture of isomers; the resulting compounds with double
bonds are not quite stable. Therefore, not all of the
products of deep autocondensation of cyclohexanone
have been identified. Compounds I!III have been
studied in most detail [1, 8310].
Formation of condensation products containing
three and more rings was considered in . The
autocondensation is reversible, and, at elevated tem-
peratures, compounds II and III are hydrolyzed back
to cyclohexanone in the presence of water. The ki-
netic (in the range 1803290oC) and thermodynamic
characteristics of this reaction, which is very important
for processing by-products from caprolactam produc-
tion , have been considered previously .
Data on liquid-phase autooxidation of cyclohex-
anone under various conditions are summarized in
Table 1. It is seen that the major influence on the
reaction rate is exerted by the temperature and cata-
lyst. Virtually no data are available for the interval
from 80 to 210oC in which the majority of industrial
processes are performed. In this study, we examined
the kinetics of cyclohexanone autocondensation in air
at 1193137oC, catalyzed with a solid alkali.
The kinetics of liquid-phase aldol condensation of
cyclohexanone was studied in a laboratory installation
consisting of a round-bottomed three-necked glass
flask fully immersed in a thermostat with silicone oil.
Table 1. Kinetics of liquid-phase autocondensation of cyclohexanone
T, oC ³ Catalyst/solvent ³ Other conditions ³Analytical method ³ References
25 ³ Aqueous NaOH ³Analysis of aqueous and organic layers ³ IR ³ 
30370 ³Alcoholic or aqueous-alcoholic KOH³Preliminary purging with argon ³
H NMR ³ 
80 ³ 3/3 ³Under N
, ³ GLC ³ 
³in the dark, ³³
³with removal of water ³³
1193137 ³ KOH(cr.)/3 ³In air, with removal of water ³ GLC ³ This work
210+ 0.5 ³ Al, Fe oxides/decalin ³Under N
, without removal of water ³ GLC ³ 
(0.6 MPa)³³ ³³
DPPH is 1,1-diphenyl-2-picrylhydrazyl (inhibitor of radical reactions).