Synthesis of cyclohexylideneacetonitrile on zeolites

Article abstract of DOI:10.1023/A:1012313503421

Condensation of cyclohexanone with acetonitrile on zeolites with different carcass structures was studied. The highest yield of cyclohexylideneacetonitrile (80 wt %) at a 98% selectivity of the process was attained with NaX zeolite containing 0.5 wt % KOH. Factors responsible for different catalytic activities and selectivities of zeolites are discussed.

Full text of DOI:10.1023/A:1012313503421

Russian Journal of General Chemistry, Vol. 71, No. 5, 2001, pp. 756 758. Translated from Zhurnal Obshchei Khimii, Vol. 71, No. 5, 2001,
pp. 806 808.
Original Russian Text Copyright
2001 by Kozlov, Rusak.
Synthesis of Cyclohexylideneacetonitrile on Zeolites
N. G. Kozlov and M. F. Rusak
Institute of Physical Organic Chemistry, Belarussian National Academy of Sciences, Minsk, Belarus
Received September 9, 1999
Abstract Condensation of cyclohexanone with acetonitrile on zeolites with different carcass structures
was studied. The highest yield of cyclohexylideneacetonitrile (80 wt %) at a 98% selectivity of the process
was attained with NaX zeolite containing 0.5 wt % KOH. Factors responsible for different catalytic activities
and selectivities of zeolites are discussed.
Cyclohexylideneacetonitrile (I) is used as an inter-
mediate in synthesis of phenylacetonitrile whose de-
rivatives show biological activity [1]. Condensation
of carbonyl compounds is usually performed in the
liquid phase in the presence of alkali metal amides
catalysts decreases. The zeolites NaX and NaY are
characterized by a higher content of these centers than
the high-silica zeolite NaTsVM. In the presence of
NaX, the yield of I at 240 C was 71 wt %, at the
reaction selectivity of 89%. With NaTsVM, the reac-
[
2, 3]. A disadvantage of this process is a poor (41%) tion under the same conditions was more selective,
yield of nitrile I and formation of a dimeric by-prod-
uct. Compound I can also be prepared in the presence
of a heterogeneous catalyst (35% KOH on Al O sup-
but the yield of the target product did not exceed
52 wt %. With increasing temperature to 280 C, the
conversion of cyclohexanone increased, and the selec-
tivity with respect to nitrile I decreased.
2
3
port). The yield of the target product on this catalyst
was 78%, and the process selectivity, 98% [1].
In zeolite systems, the chemical transformations
occur to a large extent inside crystal cavities. There-
fore, the steric factor should be taken into account
when developing a selective catalyst. Namely, the
critical size of reactant molecules should not exceed
the size of the opening of large cavities in the zeolite
structure. Our data suggest that the most suitable type
of zeolites exhibiting the highest activity in conden-
sation is faujasite in which the size of the zeolite
channels is 8 10 . Erionite with the channel size of
Recently, there has been a trend toward the use of
zeolites in fine organic synthesis [4, 5]. The structural
features of zeolites and the possibilities of varying in
a wide range their molecular-sieve properties allow
not only increase in the product yield but also solution
of many environmental and service problems in in-
dustrial synthesis [6].
In this work we examined the possibility of using
zeolites for condensation of cyclohexanone with ace-
tonitrile. We expected that the Na forms of the zeo-
lites, exhibiting the properties of solid bases, would
be active in the reaction. Furthermore, we expected
that their catalytic effect would be very selective,
since these zeolites contain no strong acid centers
responsible for occurrence of side reactions. Experi-
ments were performed with samples having different
carcass structures and different SiO /Al O ratios.
3
5
is unsuitable for this process.
Reaction of cyclohexanone with acetonitrile on
zeolite can be represented as follows:
NaX
=
O + CH C N
=CHC N.
3
H2O
Water released in the reaction is adsorbed by the
zeolite. Therefore, the adsorption capacity of zeolite
can also affect the yield of nitrile I. It is known [7]
that the capacity depends on the free volume deter-
mined by the amount of water in the fully hydrated
crystals. The intracrystalline volume filled with water
can amount to 50% of the crystal volume. After dehy-
dration of zeolite, the free volume is filled with mole-
cules of other substances. Among the examined zeo-
lites, faujasite NaX has the largest free volume
2
2
3
Here we report the results of the experiments ob-
tained under the following conditions: feed space
1
velocity 0.2 h , molar ratio cyclohexanone : aceto-
nitrile 1 : 4, temperature 220 280 C. The major reac-
tion product with all the zeolites is nitrile I. With re-
spect to the activity, the zeolites can be ranked in the
following order: NaX > NaY > NaM > NaTsVM >
NaE. With increasing silicate ratio, determining the
content of base centers in zeolites, the activity of the
3
3
(0.5 cm cm ).
1
070-3632/01/7105-0756$25.00 2001 MAIK Nauka/Interperiodica

SYNTHESIS OF CYCLOHEXYLIDENEACETONITRILE ON ZEOLITES
Catalytic activity of zeolites in condensation of cyclohexanone with acetonitrile
757
Conversion of
cyclohexanone,
wt %
Yield, %
Catalyst
SiO /Al O
2 3
T,
C
Selectivity, %
2
compound I
other products
NaX
3.0
200
20
29
49
79
80
82
41
72
74
3
26
43
71
68
66
39
64
65
3
3
6
8
12
16
5
89
88
89
85
81
86
89
87
96
96
95
71
72
75
96
96
94
98
98
97
2
240
250
280
NaY
NaE
NaM
4.5
6.5
220
2
2
40
50
8
9
220
0.1
0.3
0.5
8
14
16
1
2
3
1
1
2
2
40
50
9
9
12
28
62
66
24
52
58
77
81
87
11
20
48
50
22
50
51
76
80
76
10.0
33.0
220
2
2
40
50
NaTsVM
220
2
2
40
50
0.1% KOH/NaX
0.5% KOH/NaX
1.0% KOH/NaX
240
240
240
3.0
2
+
We suggested that replacement in NaX of the Na
KOH/NaX were prepared by application of the calcu-
lated amounts of aqueous KOH solutions on NaX
zeolite preliminarily calcined at 500 C. For example,
+
ions (r 0.98 ) by the larger K ions (r 1.33 ) would
not only enhance the basicity but also affect the
molecular-sieve properties and increase the process 0.15 g of KOH was dissolved in 40 ml of H O, and a
2
selectivity. The table shows that introduction of
15-g portion of the zeolite was impregnated with this
solution. The mixture was evaporated with stirring
under a drying lamp and then dried at 120 C. The
catalyst of the composition 1 wt % KOH/NaX was
thus obtained. To study the catalytic activity, zeolites
0
9
.5 wt % KOH into NaX increases the selectivity to
8%. With this catalyst we examined the influence
of the reaction mixture composition and feed space
velocity on the yield of nitrile I. The optimal reaction
conditions were found: 240 C, molar ratio cyclohex-
anone : acetonitrile 1 : 3, feed space velocity 0.1
1
0
.15 h ; under these conditions the yield of I was
as high as 80 wt % (see figure). Further increase in the
KOH content in the zeolite to 1 wt % is not appropri-
ate, since the yield of the target product decreases.
Apparently, at a KOH content higher than 0.5 wt %
the effective size of the lattice openings decreases,
which complicates adsorption of water.
Our results show that with NaX zeolite the conden-
sation of cyclohexanone with acetonitrile can be per-
formed without introducing large amounts of alkali
into the catalyst, which will improve the industrial
process for production of cyclohexylideneacetonitrile.
EXPERIMENTAL
Yield of cyclohexylidineacetonitrile I as a function of
the (1) molar ratio cyclohexanone : acetonitrile and (2) feed
space velocity v.
As catalysts we used zeolites NaX, NaY, NaM,
NaE, and NaTsVM. Catalysts containing 0.1 1.0 wt%
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 5 2001

758
KOZLOV, RUSAK
were pressed in pellets and then crushed to a grain
size of 2 3 mm. Experiments were performed in a C=CH bond at 1670 cm .
vertical flow-through catalytic unit. A quartz reactor
bands of the C N bond at 2240 cm 1 and of the
1
20 mm in diameter was charged with 10 ml of the
REFERENCES
catalyst. Before the experiment, the catalyst sample
was activated for 2 h at 500 C in a nitrogen flow.
A 22.3-g portion of a mixture consisting of 9.9 g of
cyclohexanone and 12.4 g of acetonitrile, placed in a
dosing unit, was fed from the top by gravity at a space
1
. Kozlov, N.S., Kozintsev, S.I., and Kacherovskaya, F.B.,
USSR Inventor’s Certificate no. 1498756, 1987,
Byull. Izobret., 1989, no. 29.
. Vishnyakova, T.P. and Karidze, A.A., Zh. Obshch.
Khim., 1969, vol. 39, no. 1, pp. 210 213.
2
3
4
1
velocity of 0.15 h at atmospheric pressure. The
. Vartanyan, R.S., Vartanyan, L.V., and Vartanyan, S.A.,
Arm. Khim. Zh., 1977, vol. 30, no. 9, pp. 784 787.
reaction temperature was 240 C. In the course of the
experiment, samples were taken for analysis at 30-min
intervals. The experiment was performed for 4 h. The
results obtained after catalyst operation for 2 h are
listed in the table. The reaction products were frac-
tionated in a vacuum. The fraction with bp 73 74 C
. Isakov, Ya.I., Isakova, T.A., and Minachev, Kh.M.,
Izv. Akad. Nauk SSSR, Ser. Khim., 1989, no. 3,
pp. 608 631.
. Kikhtyanin, O.V. and Ione, K.G., in Organicheskii
sintez na tseolitnykh katalizatorakh (Organic Synthesis
on Zeolite Catalysts), Novosibirsk, 1990, pp. 137 141.
. Ione, K.G., in Tseolitnyi kataliz v reshenii ekologiche-
skikh problem (Catalysis with Zeolites in Solution of
Environmental Problems), Novosibirsk, 1991, pp. 3 6.
. Breck, D.W., Zeolite Molecular Sieves: Structure,
Chemistry and Use, New York: Wiley, 1974. Trans-
lated under the title Tseolitovye molekulyarnye sita,
Moscow: Mir, 1976, p. 73.
5
6
7
5 mm Hg), n2 1.4775, d4 0.9420 [8], containing
5
20
(
D
98% nitrile I, was isolated.
The purity of the product was determined by GLC
with a Chrom-5 chromatograph (2 2000-mm glass
column, stationary phase Apiezon L on Chromaton
N-AW-DMCS, 0.16 0.20 mm).
The IR spectrum of I was taken with a Specord
1
M-80 spectrophotometer in the range 400 4000 cm .
8. Bailey, W.Y. and Daly, J.J., J. Am. Chem. Soc., 1959,
The spectrum contains the characteristic absorption
vol. 81, no. 20, pp. 5397 5399.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 5 2001