Russian Journal of Organic Chemistry, Vol. 39, No. 1, 2003, pp. 29 32. Translated from Zhurnal Organicheskoi Khimii, Vol. 39, No. 1, 2003,
pp. 41 43.
Original Russian Text Copyright
2003 by O. Fedevich, Levush, E. Fedevich, Kit.
Effect of the Reaction Products on the Rate of Oxidation
of Crotonaldehyde
1
1
2
1
O. E. Fedevich , S. S. Levush , E. V. Fedevich , and Yu. V. Kit
1
L’vivs’ka politekhnika National University, ul. Sagaidachnogo 14b, L’vov, 79014 Ukraine
2
L’vov State Agrarian University, L’vov, Ukraine
Received February 27, 2002
Abstract Study of the oxidation of crotonaldehyde revealed an appreciable inhibitory effect of the products
on the process. Analysis of the kinetic data obtained over a wide range of reaction conditions (c 1.5 3.3 M,
0
pO2 1 16 atm, T 293 309 K) showed that the overall oxidation process (with account taken of the inhibitory
*
0.6
1
*
effect of the products) is described by the equation: WCA = k cCA (p ) (1 + 0.17 cCA) , where k is
ap
O
ap
2
the apparent rate constant, and cCA is the decrease of the aldehyde concentration by a moment .
Crotonic acid and its esters are used in the prepara-
tion of copolymers for various applications (specialty
rubbers, latexes, adhesives, plastics, modifying agents,
etc.). Some crotonic acid esters are biologically active
compounds which possess insecticide, ascaricide, and
herbicide properties.
reaction mixture still contains no oxidation products)
but also at any stage of the process. The data obtained
are summarized in table. It is seen that the apparent
rate constant for oxidation of crotonaldehyde notably
decreases as the reaction progresses. When the con-
version of crotonaldehyde attains 50%, kap decreases
by about 10 12%. Thus, although Eq. (1) describes
the overall kinetics of the reaction under study with
an accuracy sufficient for practical purposes, it does
not reflect all fine details of this complicated multi-
step process. Decrease in the apparent rate constant
of crotonaldehyde oxidation may be attributed to
inhibitory effect of some reaction products, which is
not taken into consideration by Eq. (1). Insofar as
the inhibitory effect increases as the concentration
of crotonaldehyde decreases, just the latter parameter
can be used to interrelate with the former. Then, the
kinetic equation for consumption of crotonaldehyde
during the oxidation process may be written as
The simplest procedure for the preparation of
crotonic acid is based on oxidation of crotonaldehyde
with molecular oxygen under atmospheric pressure.
The most appropriate medium for the oxidation is
ethyl acetate [1]. The oxidation of crotonaldehyde in
ethyl acetate was studied in detail in [2 4]. It was
shown that the efficiency of crotonaldehyde oxidation
can be increased to a considerable extent by raising
lim
the oxygen pressure to a certain value (p ). This
O
2
limiting oxygen pressure linearly increases as the
temperature rises. Kinetic equations were found which
satisfactorily describe the kinetics of oxidation of
crotonaldehyde with molecular oxygen over a wide
range of temperature (T 286 333 K), concentration
(
c0 1.2 7.6 M), and pressure (p 0.21 16 atm) condi-
*
0.6
1
O2
WCA
=
k
cCA (p ) (1 + ki cCA) . (2)
ap O
2
tions [Eq. (1)]:
Here, k is a constant which takes into account
WCA = k cCA (p )0.6.
CA
i
(1)
ap
O
2
inhibitory effect of the oxidation products, and cCA
is the decrease of the crotonaldehyde concentration by
a moment from the reaction onset. When cCA tends
to zero, Eq. (2) is transformed into Eq. (1).
However, Eq. (1) does not take into account pos-
sible effect of products which accumulate during the
oxidation process. In order to estimate this effect,
the kinetic dependences like cCA = f( ) were converted
( ) by numerical differentiation. As
a result, it became possible to calculate the apparent
reaction rate not only in the initial period (when the
0
.6
*
Let us denote the rate k c (p ) (which does
ap CA
O
2
into WCA
=
not take into account the inhibitory effect of oxidation
product) as Wd (estimated rate). Then, Eq. (2) is
CA
transformed into linear Eq. (3):
1
070-4280/03/3901-0029$25.00 2003 MAIK Nauka/Interperiodica