197
HYDROGENATION OF KETONES AND ESTERS CATALYZED BY Pd/C‒SiO2
Hydrogenation of other considered unsaturated
esters with the С=С bond in the acid and(or) alcohol
part of the molecule was performed in ethanol in the
presence of 5% Pd/C–SiO2. The experimental data
showed that the composition and yield of the reaction
products were determined by the ester structure. For
example, for esters 2c and 2d it was observed that the
introduction of methyl or phenyl substituent at the β-
position with respect to the double bond led to the
increase in the yield of the products of hydrogenation
of methyl esters 9c (71%) and 9d (89%) and decrease
in the yield of the ethyl esters 10c and 10d to 11 and
29%, respectively. In contrast to dimethyl fumarate 2i,
hydrogenation of dimethyl maleate 2j afforded
dimethyl succinate 9j with practically quantitative
yield and high selectivity. High selectivity of the
reaction was observed during hydrogenation of methyl
methacrylate 2b, allyl esters of propanoic 2e and (2E)-
3-phenylacrylic acid 2g, and ethyl ester of oleic acid 2h.
column 30 m × 0.25 mm × 0.25 µm, (phase HP-1MS),
temperature gradient from 50 to 250°С at 12 deg/min.
The reactants with purity of at least 98% were used:
PdCl2, but-3-en-2-one and pent-4-en-2-one, (3E)-4-
phenylbut-3-en-2-one and (1E,4E)-1,5-diphenylpenta-
1,4-dien-3-one, methyl acrylate, methyl methacrylate
(99%), butyl methacrylate (99%) (all from Aldrich),
methyl-(2Е)-but-2-enoate and methyl-(2Е)-3-phenyl
acrylate, allyl esters of propanoic, methacrylic, and
cinnamic acid and dimethyl esters of maleic and
fumaric acids with purity 98%, as well as ethyl ester of
oleic acid prepared via conventional method from
triglyceride of oleic acid [13].
Carbon-silica sorbent (InPTs Pilot, Ufa) was used
as the carrier [14].
Catalyst preparation. Catalyst 5%Pd/C–SiO2 was
prepared as described elsewhere [12]. A mixture of
1.0 g PdCl2, 2.4 mL of conc. HCl, and 6 mL of water
was refluxed during 1.5 h until formation of
transparent solution; 17 mL of water was then added
and thoroughly stirred with 11.4 g of the carbon-silica
carrier. The obtained mass was evaporated on a water
bath and dried in an oven at 100°С. Yield 12.38 g.
The use of heterogeneous catalyst Pd/C–SiO2 for
hydrogenation of unsaturated esters allows single-stage
preparation of methyl esters of saturated acids from
ethyl esters of unsaturated acids or vice versa, ethyl
esters of saturated acids from methyl esters of un-
saturated acids.
Hydrogenation of unsaturated compounds.
Volumetric setup for hydrogenation [15] consisted of
thermostated glass reactor with a jacket and a gas
burette. 10 mL of 95% ethanol, 50 mg of 5%Pd/C–
SiO2 containing 2.5 mg (0.024 mmol) of Pd, 2.34 mmol
of ketone or ester were put in a 30 mL reactor. The
reaction was performed with stirring at atmospheric
pressure and 23±1°С. The volume of consumed hy-
drogen was measured at constant pressure by matching
the levels of a liquid in the burette and in the
equilibrating vessel. After the hydrogenation was
complete (the volume of consumed hydrogen became
constant), 0.20 g (2.34 mmol) of ethyl acetate was
added to the mixture, and the catalyst was filtered off.
The composition and yield of the products were
determined by GLC. Physico-chemical properties of
the prepared compounds coincided with the reference
data [16–18].
In summary, hydrogenation of unsaturated ketones
with a phenyl group at the double carbon-carbon bond
in the presence of the 5%Pd/C–SiO2 catalyst is
accompanied by reduction of the ketone group into the
alcohol one. Hydrogenation of the unsaturated car-
boxylic esters can be accompanied by transesterifica-
tion, depending on the ester structure and the solvent.
EXPERIMENTAL
Spectral studies were performed using the
equipment of Center for Collective Usage “Chemistry”
of Ufa Institute of Chemistry, Russian Academy of
Sciences. The reaction products were identified using a
MAT 95 XP chromato–mass spectrometer (Thermo
Finnigan, Germany) with a TRACE GC 2000 chro-
matograph, software XCALIBUR with NIST-05 mass
spectra library (voltage 70 eV, ionizing chamber
temperature 250°С, direct injection temperature 50–
250°С, heating rate 15 deg/min, the spectra were
recorded over m/z 14 to 550 Da at scan rate 2.5 scan/s).
REFERENCES
1. Lisitsyn, A.S., Parmon, V.I., Dublyakin, V.K., and
Likholobov, V.A., Ross. Khim. Zh., 2006, vol. 50, no. 4,
p. 140.
Composition and yield of the products were
determined by means of GLC using a GC-2014 chro-
matograph (Shimadzu, Japan); conditions: capillary
2. Wang, Ji., Li, Ji., Wang, Y., and Luo, G., Chem. Eng. J.,
2014, vol. 236, p. 293. doi 10.1016/j.cej.2013.09.055
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 2 2018
Akchurin
