512
OBRAZTSOVA, EFIMOV
Hydrogenation of ENB was also performed at
atmospheric pressure in a temperature-controlled
reactor at 30 40 C. The components were also loaded
many-fold; the process was made simpler and shorter;
the high pharmacopoeia quality of the finished prod-
uct and its 100% yield were attained.
in an inert gas atmposphere (N or Ar) to prevent their
2
oxidation with atmospheric oxygen and thus improve
the product quality. After loading the catalyst pre-
pared, ENB, and solvent, the whole system was kept
at the required temperature for 3 5 min and purged
CONCLUSIONS
(
1) A carbon-supported palladium triphenylphos-
phine catalyst was suggested for preparation of Anes-
thesin of high pharmacopoeia quality in a quantitative
yield.
with H for 5 min, after which vigorous stirring was
2
started. After the uptake of the theoretical amount of
hydrogen, the reaction stops. The next portion of ENB
is fully hydrogenated in the same time. The catalyst
can effect hydrogenation of up to 50 portions of ENB
without noticeable loss in the activity.
(
2) Anesthesin is prepared in one step under mild
conditions without by-products. Fifty synthesis runs
can be performed with one catalyst portion, after
which it can be regenerated and reused.
The total amount of converted ENB per gram of Pd
is 29250 g on the average. The yield of Anesthesin
is quantitative (chromatographic analysis data).
REFERENCES
The spent catalyst can be separated, regenerated,
and then reused without noticeable loss in the activity.
1. USSR Inventor’s Certificate no. 609278.
2
. USSR Inventor’s Certificate no. 753069.
The high activity and long life of the suggested
catalyst are due to its structural features. As shown in
3. USSR Inventor’s Certificate no. 492514.
4. US Patent 3037046.
[
9], deposition of palladium on carbon supports fol-
5
. Simonov, A.P., Chuvilin, A.L., Moroz, E.M., et al.,
Abstracts of Papers, II Vsesoyuznaya konferentsiya
Kataliz i kataliticheskie protsessy khimfarmproizvod-
stva (II All-Union Conf. Catalysis and Catalytic
Processes in Production of Pharmaceuticals ), Mos-
cow, October 8 10, 1989, part 2, p. 248.
lowed by reduction with hydrogen results in formation
of cluster complexes in which triphenylphosphine
molecules stabilize palladium particles of definite size
(optimal ratio PPh /Pd 0.4), exhibiting the highest
3
catalytic activity. This allows the hydrogenation rate
and yield of the target product to be considerably
increased; it also ensures long working life of the
catalyst without noticeable loss in the activity.
6
. Klyuev, M.V., Zh. Org. Khim., 1984, vol. 20, no. 9,
pp. 1908 1912.
7. Abdullaev, M.G., Abstracts of Papers, 12-ya Mezhdu-
narodnaya konferentsiya molodykh uchenykh po khi-
mii i khimicheskoi tekhnologii, posvyashchennaya
100-letiyu obrazovaniya Rossiiskogo khimiko-tekhno-
logicheskogo univ. (12th Int. Conf. of Young Scien-
tists on Chemistry and Chemical Technology, Dedi-
cated to the Centennial of Foundation of the Russian
Univ. of Chemical Engineering), Moscow, November
December 1998, p. 90.
The preservation of the catalyst activity is also
favored by mild synthesis conditions (H pressure
1
2
atm; temperature up to 40 C; anhydrous medium;
single-component solvent readily removable by evap-
oration in isolation of the target product). It is also
important that the solvents used are not involved in
side reactions and are not so toxic as, e.g., toluene,
benzene, or methanol used in alternative procedures
8. Morogina, A., Nasibulin, A.A., and Klyuev, M.V.,
[4, 8] (which is very important in preparation of phar-
Neftekhimiya, 1998, vol. 38, no. 4, pp. 277 281.
maceuticals); also, they do not require time-consum-
ing washing of the finished product.
9. RF Patent 2203885.
1
0. Obraztsova, I.I., Efimov, O.A., Simenyuk, G.Yu., and
Min’kov, A.I., in Trudy Mezhdunarodnoi nauchno-
prakticheskoi konferentsii Khimiya XXI vek: novye
tekhnologii, novye produkty (Proc. Int. Scientific and
Practical Conf. Chemistry XXI Century: New
Technologies, New Products ), Kemerovo, December
5 8, 2000, pp. 62 66.
It should be noted that, with ultradispersed dia-
mond used as catalyst support, the hydrogenation rate
appreciably increases [10].
Thus, we have improved the hydrogenation pro-
cess: the service life of the catalyst was increased
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 77 No. 3 2004