Hydrogenation and Skeleton Rearrangements of α-Pinene on Heterogeneous Catalysts

Article abstract of DOI:10.1023/A:1024694327338

Hydrogenation and isomerization of α-pinene on heterogeneous catalysts were studied, and conditions were found for hydrogenation of pinene to cis-pinane on nickel catalysts and for its dehydrogenation to p-cymene on decationized zeolite Y.

Full text of DOI:10.1023/A:1024694327338

Russian Journal of Applied Chemistry, Vol. 76, No. 2, 2003, pp. 234 237. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 2, 2003,
pp. 242 245.
Original Russian Text Copyright
2003 by Bazhenov, Kas’yanova, Bokin, Kutepov, Khazipova, Travkin, Shchadneva, Khusnutdinov, Dzhemilev.
CATALYSIS
Hydrogenation and Skeleton Rearrangements of -Pinene
on Heterogeneous Catalysts
Yu. P. Bazhenov, L. Z. Kas’yanova, A. I. Bokin, B. I. Kutepov, A. N. Khazipova,
E. A. Travkin, N. A. Shchadneva, R. I. Khusnutdinov, and U. M. Dzhemilev
Kauchuk Private Company, Sterlitamak, Bashkortostan, Russia
Institute of Petrochemistry and Catalysis of the Republic of Bashkortostan, Ufa Scientific Center,
Russian Academy of Sciences, Ufa, Bashkortostan, Russia
Received May 14, 2002
Abstract Hydrogenation and isomerization of -pinene on heterogeneous catalysts were studied, and con-
ditions were found for hydrogenation of pinene to cis-pinane on nickel catalysts and for its dehydrogenation
to p-cymene on decationized zeolite Y.
-
Pinene, which is a bicyclic monoterpenoid, is
an important product of wood chemical industry.
Pinene widely occurs in nature; it is present in
containing catalysts for hydrogenation of other or-
ganic substances, commercially produced in Russia.
-
oils obtained from most of coniferous tree species and
is the major component of turpentine. Due to the pres-
ence of a double bond and a strained four-membered
ring, -pinene readily undergoes various transforma-
tions, primarily hydrogenation and skeleton isomeri-
zation [1 3].
EXPERIMENTAL
Experiments on -pinene transformations were per-
formed in a 100-ml isothermal pressure reactor con-
taining a finely dispersed (0.04 0.1 mm) catalyst;
the ideal mixing mode was ensured by vigorous shak-
ing. The amount of loaded -pinene was 50 ml, and
the amount of the catalytic system relative to sub-
strate, c = 1 10 wt %. The temperature in the reactor,
Tr, was varied from 20 to 150 C, and the hydrogen
pressure, p , from 0.2 to 1.0 MPa. Also, hydrogena-
tion of -pinene was studied in a tubular bubbling re-
-Pinene is widely used in industry, in particular,
in production of synthetic camphor, camphene, myr-
cene, fragrances (linalool, citronellol, geraniol, pino-
carveol, myrtenol, etc.), and paint-and-varnish materi-
als [1 3].
c
H
2
The -pinene hydrogenation product, pinane, is
also an important chemical: its autooxidation yields a
stable hydroperoxide used as initiator of low-tempera-
ture copolymerization of butadiene with styrene [4].
actor charged with a pelletized catalyst (V = 100 ml);
the process was performed in a flow of hydrogen, in
the batch mode with respect to -pinene.
c
The IR spectra were recorded on a UR-20 spec-
trometer; samples were prepared as KBr pellets, mulls
Pinane required for preparing the hydroperoxide is
usually synthesized by hydrogenation of -pinene
with molecular hydrogen on metal-containing cata-
lysts [5 10]. In particular, it has been suggested [5, 6]
to use supported Ru- and Pd-containing catalysts for
1
13
in mineral oil, or neat liquids. The H and C NMR
spectra were recorded on a Jeol FXQ spectrometer (90
and 22.5 MHz, respectively) in CDCl solutions; the
3
chemical shifts ( , ppm) are given relative to TMS.
The mass spectra (70 eV) were taken on a Finnigan
MAT-112S gas chromatograph mass spectrometer.
A chromatographic analysis was performed with a
Chrom-5 chromatograph, column length 1.2 m, sta-
tionary phase 5% SE-30 on Chromaton N-AW-HMDS,
carrier gas helium.
-
pinene hydrogenation. Hydrogenation of -pinene
can also be performed on Ni-containing catalysts, but
under more severe conditions: pH2 1.0 MPa and
reaction time no less than 14 20 h [7 10].
Our goal was to find catalysts effecting hydrogena-
tion of -pinene to pinane under mild conditions
(
pH2 0.6 MPa, T 150 C). The major attention was
The reaction was performed with sulfate -pinene
purified by distillation (99.0 wt % purity). The reac-
given to hydrogenation of -pinene on Pd- and Ni-
1
070-4272/03/7602-0234 $25.00 2003 MAIK Nauka/Interperiodica

HYDROGENATION AND SKELETON REARRANGEMENTS OF -PINENE
tion products (pinane, dipentene, terpinolene, cam-
235
phene, p-cymene) were isolated by fractional distilla-
tion in a vacuum (purity no less than 98.0 wt %,
1
according to GLC) and identified by IR, H NMR,
and 13C NMR spectroscopy and by refractive indices,
using reference samples and published data [1 11].
The cis configuration of pinane prepared on the nickel
catalyst follows from the signal pattern given by the
9
10
1.02 1.04 ppm) and C8
gem-dimethyl (C , C ;
methyl groups ( 1.18 ppm) [1 11].
Fig. 1. Variation with time of the conversion of -pinene,
, in its hydrogenation on palladium catalysts (150 C,
x
cis-Pinane (2,6,6-tetramethylbicyclo[3.1.1]hep-
tane). Yield about 100%; bp 166 167 C, n 1.4624.
IR spectrum (thin liquid film), , cm : 750, 790,
pinene
2
0
2
h, p = 0.6 MPa, c = 10 wt %): (1) 2 wt % Pd/Sibunit,
H c
2
D
1
(2) 2 wt % Pd/ -Al O , and (3) 0.5 wt % Pd/ -Al O .
2 3 2 3
8
1
1
50, 950, 995, 1005, 1025, 1045, 1100, 1120, 1150,
exceed 3 5 wt %, with the major transformation prod-
uct being the isomer of -pinene, dipentene. Similar
results were obtained with hydrogen taken instead of
nitrogen. Thus, the concentration of catalytically ac-
tive centers on the surface of these supports is low.
220, 1250, 1275, 1320, 1340, 1360, 1370, 1380,
1
452, 1458, 1465, 2895. H NMR spectrum (CDCl ),
3
1
0
9
,
ppm: 1.02 d (3H, C H ), 1.04 s (3H, C H ), 1.18 s
3 3
8
1
2
5
(
3H, C H ), 1.26 1.36 m (3H, C H, C H, C H),
3
3
4
6
13
1
.66 2.44 m (6H, C H , C H , C H ). C NMR
2 2 2
9
10
spectrum (CDCl ), , ppm: 23.06 (C ), 23.39 (C ),
3
C
However, -pinene showed an unusual behavior on
decationized zeolites of various structural types (mor-
denite, Y) whose surface contains Brønsted (B ) acid
centers with different strengths [13].
8
4
3
6
2
4.17 (C ), 26.83 (C ), 28.52 (C ), 34.25 (C ), 36.25
2
7
5
1
(C ), 39.06 (C ), 41.72 (C ), 48.49 (C ). Mass spec-
trum, m/z (I , %): 41 (100), 35 (86.2), 95 (74.4),
rel
3
6
9 (59.2), 27 (58.7), 82 (57.2), 83 (53.9), 67 (49.3),
9 (49.3), 81 (45).
Found, %: C 86.86; H 13.11.
nene at 150 C, pressure of 0.3 MPa, and c = 10 wt %
reaches 75% in 2 h. The reaction products contain
dipentene, terpinolene, and camphene (1 : 1 : 0.1):
c
C H .
1
0
18
Calculated, %: C 86.88; H 13.12.
p-Cymene (1-methyl-4-isopropylbenzene). Yield
2
0
Mordenite (Y)
about 80%, bp 177 177.57 C, n 1.4624. IR spec-
D
1
+
+
trum (thin liquid film), , cm : 690, 767, 860, 1040,
150 C
1
2
1
095, 1170, 1192, 1520, 1618, 1690, 1820, 2860,
1
915, 3010. H NMR spectrum (CDCl ), , ppm:
3
-
Pinene
Dipentene Terpinolene Camphene
1
0
8
.02 d (3H, C H ), 1.17 s (3H, C H ), 1.25 s (3H,
3
3
9
10
C H ), 2.26 s (3H, C , CH ), 2.66 2.98 m (1H,
3
3
On 50% decationized zeolite Y, whose surface
7
2
3
5
6
C H, CH), 7.06 s (4H, C H, C H, C H, C H, arom.).
contains stronger B centers, -pinene undergoes not
only isomerization, but also dehydrogenation yielding
p-cymene:
1
3
10
C NMR spectrum (CDCl ), , ppm: 20.98 (C ),
3
8
9
7
3
5
2
4.17 (C , C ), 33.79 (C ), 126.26 (C , C ), 135.04
1
4
(
(
(
C ), 145.84 (C ). Mass spectrum, m/z (I , %): 119
100), 134 (23.7), 91 (16.1), 39 (10.1), 120 (9.7), 41
7.6), 27 (6.6), 77 (6.6), 17 (6.6), 65 (6.2).
rel
NaAY
Found, %: C 89.45; H 10.52.
C H .
1
0
14
-Pinene
p-Cymene
Calculated, %: C 89.49; H 10.51.
This reaction may be of considerable practical
interest owing to a high ( 80% based on the initial
Preliminary experiments showed that -pinene
undergoes no thermal transformations under the con-
ditions examined (T 160 C, nitrogen pressure p
-pinene) yield of p-cymene.
0
.8 MPa). In the presence of -Al O , SiO (kieselguhr
When -pinene is heated in an H atmosphere in
2
3
2
2
or KSM synthetic silica gel), or Sibunit [12], used as
supports for the tested catalysts, the maximal conver-
sion of -pinene under the above conditions did not
the presence of Pd- and Ni-containing catalysts sup-
ported by -Al O , SiO , or Sibunit, the major reac-
2
3
2
tion pathway is hydrogenation to pinane:
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 2 2003

236
BAZHENOV et al.
Fig. 2. Conversion of -pinene, x
, on GM-3 catalyst vs. hydrogen pressure p . Reaction time 6 h. c , %: (a) 1.5 and
pinene
H
c
2
(
b) 3. T, C: (a) (1) 150, (2) 100, and (3) 75; (b) (1) 130, (2) 100, and (3) 50.
In production of isoprene, admixtures of acetylenic
hydrocarbons are hydrogenated on nickel silicate cata-
lysts which are prepared by precipitation of basic
nickel(II) carbonate on kieselguhr, followed by filtra-
tion, washing, drying, pelletizing, and reductive de-
composition [15]. The catalysts contain 25 to 50 wt %
nickel.
Ni, Pd
+
H2
CH3
H
-
Pinene
Pinane
Figure 1 shows variation of the -pinene conver-
sion, xpinene, with time on various Pd-containing
Experiments on hydrogenation of -pinene on the
catalyst produced using this procedure by the Kau-
chuk Private Company showed that the complete con-
version of -pinene with quantitative yield of pinane
is attained in 2 h at 150 C and pH2 = 0.6 MPa with
the 0.04 0.1-mm fraction of the catalyst obtained by
crushing the pellets and activated at 400 C in a hy-
drogen flow for 2 h (Table 1).
catalysts. The highest conversion is observed on
2
wt % Pd/Sibunit (IK-53 brand). The highest activity
of this catalyst is probably due to the largest surface
area of the metal. At the same time, all the catalysts
exhibit similar selectivities: The yield of pinane based
on the converted -pinene is 92 95% with all the
catalysts.
Usually, hydrogenation catalysts are subjected be-
fore use to reductive hydrogen treatment. It is known
A still more active powdered nickel-containing cat-
alyst GM-3 was obtained [15] when the drying of
the catalyst mass and its activation in a hydrogen flow
[14] that too high treatment temperatures may affect
the ratio of the hydride and atomic hydrogen species
in the catalyst and hence the catalytic activity. How-
ever, when the hydrogen treatment temperature was
raised from 100 to 300 C, the Pd-containing catalysts
we studied did not show such an effect.
(
400 C, 2 4 h) were combined in a single stage.
The results of hydrogenation on the catalyst prepared
by this procedure are shown in Fig. 2.
As seen from Fig. 2, GM-3 catalyst is more active
than all the catalysts studied previously.
Table 1. Hydrogenation of -pinene on the commercial
Ni/kieselguhr catalyst at pH2 = 0.6 MPa
Gan [15] has shown that the pore volume, overall
specific surface area, and specific surface area of
metallic nickel in GM-3 catalyst are 2 3 times higher
compared to the catalyst prepared by the conventional
xpinene,* wt %
cc, wt %
Tr,
C
, h
3
1
procedure and amount to 0.5 0.56 cm g , 250
2
2
5
5
5
.5
.5
.0
.0
.0
130
4
4
4
4
2
78.0
100.0
45.0
100.0
100.0
2
1
2
1
2
80 m g , and 100 130 m g Ni, respectively.
150
100
130
150
It is known that, after decomposition of basic nickel
carbonate, Ni/kieselguhr catalysts contain a readily
reducible phase of nickel oxide and also nickel hydro-
silicates, which are reduced at temperatures above
300 C. We found that GM-3 catalyst samples pre-
*
(
x
) Conversion of -pinene (selectivity with respect to
pinene
pinane is close to 100%).
pared by reduction in an H flow at 400 450 C for
2
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 2 2003

HYDROGENATION AND SKELETON REARRANGEMENTS OF -PINENE
237
Table 2. Influence of temperature T and time of reduc-
tion of GM-3 catalyst on the conversion of -pinene,
xpinene (100 C, pH2 = 0.3 MPa, hydrogenation time 2 h,
cc = 3.0 wt %)
(2) p-Cymene was prepared in high yield (80%)
by isomerization and dehydrogenation of -pinene on
50% decationized zeolite Y at 150 C for 2 h in the
presence of N (p = 0.3 MPa).
2
T,
C
, h
xpinene, wt %
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3
4
4
4
4
5
5
50
00
00
50
50
00
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RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 2 2003