Hydrogenation on granular palladium-containing catalysts: I. Hydrogenation of tertiary acetylene alcohols

Article abstract of DOI:10.1023/A:1015536927055

Commercial granular palladium catalyst (0.5% of Pd on γ-Al ₂O₃) was modified by treating with zinc acetate (type 1) or successively with zinc acetate and ammonia (type 2). The treatment significantly increased the hydrogenation selectivity for a triple bond into a double bond: to 85.3-93.1% with the type 1 catalyst and to 96.3-97.8% with the type 2 catalyst. A construction of an autoclave with a fixed bed of the granular catalyst is described.

Full text of DOI:10.1023/A:1015536927055

Russian Journal of Organic Chemistry, Vol. 38, No. 2, 2002, pp. 150 152. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 2, 2002,
pp. 170 172.
Original Russian Text Copyright
2002 by Tolkacheva, Kislyi, Taits, Semenov.
Hydrogenation on Granular Palladium-containing Catalysts:
I. Hydrogenation of Tertiary Acetylene Alcohols
L. N. Tolkacheva, V. P. Kislyi, S. Z. Taits, and V. V. Semenov
Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119992 Russia
Received February 23, 2001
Abstract Commercial granular palladium catalyst (0.5% of Pd on -Al2O3) was modified by treating with
zinc acetate (type 1) or successively with zinc acetate and ammonia (type 2). The treatment significantly
increased the hydrogenation selectivity for a triple bond into a double bond: to 85.3 93.1% with the type 1
catalyst and to 96.3 97.8% with the type 2 catalyst. A construction of an autoclave with a fixed bed of the
granular catalyst is described.
The hydrogenation in agitated reactors is usually
carried out with palladium on carbon or homogeneous
catalysts. The obvious advantage over the above of
the granular palladium catalysts (GPC), e.g., 2% of
Pd on granulated carbon or 0.5% Pd on -Al2O3
(ShPAK-0.5), is in the ease of separation of the reac-
tion mixture from the catalyst. However to the use of
GPC in a common rotating autoclaves stands in the
way the abrasion of the catalysts providing fine
particles hard to filter off and appearing in the pro-
duct as an impurity. In the industry the GPC are
commonly used in upflow reactors but at small-scale
production, from 10 to 1000 g, they are inconvenient
since the process requires prolonged adjustment.
large-scale syntheses. A reactor of 10 l capacity is
shown on Fig. 1a. It is equipped with bottom dis-
charge, manometer, a valve for hydrogen input, and
a capillary for sampling. The pumping of the fluid
through the catalyst bed is ensured by the operation
of a turbo-type agitator and by an efficient motor
(3000 rpm). The flow of the fluid is shown by arrows.
For test experiments with small charge of sub-
stances was manufactured a reactor of 1 l capacity
shown in Fig. 1b. In this reactor is used an agitator
of centrifugal type (the fluid flow is also indicated by
arrows) and vertical and not horizontal position of
catalyst bed: the catalyst is packed into a latticed
bowl. Although it turned out that the construction of
reactor with the turbo-type agitator and horizontal
catalyst bed was somewhat better, in both reactor
types the granulated catalyst did not suffer fragment-
ation (no mechanical abrasion was observed).
We describe here a construction of an agitated
reactor with a fixed bed of GPC and its application to
The said reactors were used in hydrogenation of
acetylene alcohols within the framework of refining
a production process for isophytol preparation, the
key product in the vitamin E synthesis.
I III,
R
=
CH3 (a), Me2C=CHCH2CH2 (b),
Me(MeC=CHCH2CH2)2 (c), Me(CHMeCH2CH2CH2)3
(d).
(a) Reactor of 10 l capacity, (b) Reactor of 1 l capacity.
(1) bottom discharge, (2), hydrogen input valve, (3)
manometer, (4), capillary for sampling, (5), high-
speed motor, (6), fluid level, (7) net with GPC.
Since unmodified palladium catalysts are known
to possess a moderate selectivity with respect to
hydrogenation of the triple and double bonds we
1070-4280/01/3802-150$27.00 2002 MAIK Nauka/Interperiodica

HYDROGENATION ON GRANULAR PALLADIUM-CONTAINING CATALYSTS: I.
Table 1. Hydrogenation of acetylenes Ia d
Compd. Catalyst Convers Selectivity,
151
Pressure,
at
Tempera-
Reaction
time, h
Dilution with
Charge
no.
type
sion, %
%
ture,
C
i-PrOH
typea
Ia
Ib
Ic
Id
1
2
1
2
1
2
1
2
98.2
99.7
97.8
99.1
99.3
98.9
99.1
99.5
93.1
97.8
91.1
96.6
89.7
96.3
85.3
97.5
16 20
16 20
12 16
10 16
10 12
7 10
5 8
24 27
45
26 28
65
25
60
16
6
8.5
3.5
6
4
4
5
A
A
A
A
B
B
B
B
1: 1
1: 1
1: 1
1: 1
24 26
50
1 2
a
A Reactor of 1 l capacity, 400 ml of initial compound, 20 ml of catalyst; B Reactor of 10 l capacity, 3.5 l of initial compound,
120 ml of catalyst.
studied two catalysts prepared from a commercial
catalyst ShPAK-0.5 (0.5% of Pd on the -Al2O3) by
treatment with zinc acetate (type 1) or by successive
treatment with Zn(OAc)2 and gaseous ammonia
(type 2).
Since olefins II under the reaction conditions are
further hydrogenated to compounds III, the yield of
the latter grows (and the selectivity consequently
decreases) with growing conversion of acetylenes I
(and with the overall reaction time). These data are
directly illustrated in Table 2 (hydrogenation on type
1 catalyst). Similarly in the experiment at larger scale
(charge 7 l) at the hydrogenation of compound Ia into
IIa on the type 2 catalyst with conversion of the initial
substrate of 80% the selectivity was 99%, and the
yield with respect to the isolated product after
rectification was 94.4% (taking into account that
some initial compound was recovered). In the
experiment carried out to 99.2% conversion of the
initial compound the selectivity amounted to 97.5%,
the yield of the target product was 96.7% as
determined by GLC, and 92.8% after distillation.
Thus the yield of the target compound with respect to
consumed initial substrate is somewhat higher at con-
version of 80%, and the catalyst under study (type 2)
is comparable in selectivity with homogeneous hydro-
genation catalysts [2] but also possesses the same
advantages as palladium catalysts immobilized on the
polymer supports [3].
The experimental results are presented in Table 1.
As seen, the type 2 catalyst shows considerably
higher selectivity as compared with the type 1 catalyst
(85.3 93.1% for type 1, 96.3 97.8% for type 2).
Both gaseous ammonia and zinc acetate were former-
ly used to poison palladium catalysts [1], but they
were not used in preparation of catalysts, and were
just added into the reactor. We found that the catalyst
prepared by treatment with gaseous ammonia showed
good reproducible activity, and besides these catalysts
were relatively stable (probably the ammonia
molecules were retained in the pores by adhesion
forces).
The experimental conditions are somewhat dif-
ferent. In the series of compounds Ia d the rate of
hydrogen absorption considerably increased: for
instance, under conditions where dimethylethynyl-
carbinol (Ia) was hydrogenated to olefin IIa,
dehydroisophytol (Id) bypassed the stage of isophytol
(IId) and gave at once dihydroisophytol (IIId). There-
fore in the series Ia d the pressure and reaction time
should be reduced. Note that with no agitation the
hydrogen absorption virtually stopped. Thus an
efficient stirring in the reactor type described is
necessary for sufficient hydrogenation rate. Therefore
in hydrogenation of compounds Ic, d the reaction
mixture was diluted with 2-propanol (1: 1) to reduce
viscosity of the solution.
Thus, in comparison of catalysts of types 1 and
2 as the parameter that determined the comparable
conditions we used the degree of conversion (and the
overall reaction time) and not the temperature. Since
the activity of catalyst 2 was somewhat lower than
that of catalyst 1 the comparable time of reaction with
catalyst 2 was attained by applying higher tempera-
ture (by 20 49 C). Although at higher temperature
usually decreases the selectivity, the data in Table 1
show that even at higher temperature the selectivity
on catalyst 2 is better.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 2 2002

152
TOLKACHEVA et al.
Table 2. Variation of selectivity with time of
hydrogenation of compound Ia on type 1 catalyst (23
27 C, 16 20 at)
for 2 h (in 0.5 h the catalyst turned black). Then the
2-propanol was decanted, and the catalyst was dried
at 80 C.
(2) Preparation of the catalyst poisoned with zinc
acetate (type 1). To 100 g of the catalyst prepared as
above was added 0.5 l of 15% solution of Zn(OAc)2,
and the mixture was boiled at reflux for 2.5 h, then
the catalyst was filtered off, washed with distilled
water, and dried at 80 100 C.
Yield of compound, % Selectivity,
Time, Conversion,
%
h
%
IIa
IIIa
1.5
18.6
27.0
48.6
74.7
90.9
98.2
17.9
25.8
46.5
71.2
85.5
91.4
0.7
1.2
2.1
3.5
5.4
6.8
96.2
95.5
95.7
95.3
94.1
93.1
4.5
8
(3) Preparation of the catalyst poisoned with
ammonia (type 2). The catalyst prepared along proce-
dure 2 was placed into a desiccator and evacuated by
a water-jet pump. Then ammonia was introduced into
the desiccator to atmospheric pressure, and the vessel
was left standing for 10 h. The catalyst thus treated
was flushed with air and put into the reactor.
12
14.5
16
At exhaustive hydrogenation of farnesylacetone
(IV) into phyton (V) the problem of selectivity is
lacking, and the catalyst ShPAK-0.5 can be used
without modification. Phyton (V) was obtained with
the help of unmodified catalyst ShPAK-0.5 in 97.8%
yield.
General method of hydrogenation in a reactor
with a fixed-bed catalyst. Into the reactor of 10 l
capacity was charged a cell with 120 g of granular
catalyst, then in a vacuum through the bottom dis-
charge valve was charged into the vessel 7 l of liquid
[2,2-dimethyl-3-butyn-2-ol (Ia) and dehydrolinalool
(Ib) were used without dilution, 3.5 l of dehydro-
nerolidol (Ic) or dehydroisophytol (Id) for hydrogen-
ation were diluted with 3.5 l of 2-propanol]. The flow
of hydrogen was passed into the reactor, the agitator
was switched on, and the reactor was heated to the
required temperature (the catalyst type, temperature
of the process, and hydrogen pressure are listed in
Table 1). As the hydrogen was consumed, it was
added to the initial pressure value. The reaction
mixture in the reactor was sampled through a capil-
lary and analyzed every hour. On completion of the
process the reactor was cooled to room temperature,
and the reaction product was discharged under hydro-
gen pressure. The compound obtained was analyzed
by GLC and subjected to rectification.
EXPERIMENTAL
Chromatographic analysis of compounds IIa d,
IIIa d, IV was carried out on chromatograph
LKhM-8MD (capillary column 25 m, stationary
phase SE-30, 22 C).
REFERENCES
Catalyst preparation. (1) Catalyst on alumina
support for exhaustive hydrogenation. Commercial
catalyst ShPAK-0.5 (0.5% of Pd on -Al2O3) was
placed in a porcelain dish and calcined in a muffle for
2 h at 350 450 C. The catalyst was cooled, placed
into a round-bottom flask equipped with a reflux
condenser and a capillary for hydrogen input. To the
catalyst was poured 2-propanol, the flask was heated
to 70 C, and a hydrogen flow through it was passed
1. Sul,man, E.M., Usp. Khim., 1994, vol. 63, no. 11,
p. 981.
2. Esteruelas, M.A., Lopes, A.M., Oro, L.A., Perez, A.,
Schulz, M., and Werner, H., Organometallics, 1993,
vol. 12, no. 8, p. 1823.
3. Shuikina, A.P., Ednatanova, A.I., Kovaleva, L.S.,
Parenago, O.P., and Frolova, V.M., Kinetika i kata-
liz, 1981, vol. 22, no. 1, p. 177.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 2 2002