3o

4. 5. 6. 7. 8. 9.

R. E. Rausch, USA Patent 3598723 (1971); C. A., 76, 359675 (1972). J. R. Kittrel, German Patent 1956715 (1970); C. A., 73, 68265c (1970). C. R. Castor and R. M. Milton, USA Patent 3013987; Ref. Zh., Khim., 1963, 81123p. V. V. Lebedinskii and B. N. Ivanov-Emin, Zh. Obshch. Khim., 13, 253 (1943). M. A. Ryashentseva and Yu. A. Afanas'eva, Zh. Analit. Khim., 16, 108 (1969). J. H. Beard, J. Casey, and R. K. Murmann, Inorg. Chem., i, 495 (1965). Kh. M. Minachev, V. I. Garanin, and Ya. I. Isakov, Usp. Khim., 35, 2153 (1966).

HYDROGENATING PROPERTIES OF RHENIUM CHLORIDES AND SULFIDES

M. A. Ryashentseva, Kh. M. Minachev, UDC 541.128:546.719'131:546.719'226:542.941 and E. P. Belanova

The use of rhenium chloride as an additive to catalysts for the oxidation of acrolein [i], the carboxylation of ethylene or propylene with CO and 02 under pressure [2], and the graft copolymerization of polybutadiene with olefins [3] is described in [1-3].

The catalytic properties of rhenium chloride as such have not been studied. In the present paper we studied the properties of ReCI3 (I) and compared them with the properties of Re2S7 (II) in the hydrogenation of cyclohexene and benzene, and the heterocyclic compounds: thiophene and pyridine.

EXPERIMENTAL METHOD

The starting cyclohexene, benzene, pyridine, and thiophene had the constants given in the literature. Before experiment the cyclohexene and benzene were first dried with zeolite NaA, ignited at 300~ for 5 h. The ReCIa was obtained by decomposing ReCls at 375-400 ~ in a N2 stream [4]. The Re2S7 was obtained as described in [5]. The experiments (3-4 h) were run in an autoclave, in a glass ampul at 160-270 ~ and a H2 pressure of 120-140 atm. The ob- tained catalyzate was filtered from the catalyst and analyzed on an LKhM-8M chromatograph: in the case of cyclohexene, benzene, and thiophene at i00 ~ using a 3 m • 1.5 mm column that was packed with 15% poly(ethylene glycol adipate) deposited on Chromosorb P (60-80 mesh). The pyridine catalyzate was analyzed at 90% in a He stream on a 4-m-long column that was packed with NaCI, which contained 1% of poly(ethylene glycol) and 0.5% KOH.

From the obtained data (see Table i) it can be seen that (I) in an amount less than 1% of the weight of the charged product has a high activity in the reduction of the C=C double bond in cyclohexene. At 200 ~ (pH2 130 atm) the catalyzate analyzes 94% of cyclohexane. A further increase in the temperature up to 240 and 270 ~ leads to a decrease in the yield of cyclohexane. Under the sameconditions the degree of cyclohexene hydrogenation on (II) is ~3 times smaller. Under the selected conditions, even when ~4 times more catalyst is used, the benzene ring is not hydrogenated on either (I) or (II).

Catalyst (I) has a high activity in the hydrogenation of the pyridine ring. The amount of piperidine formed on this catalyst (0.8% of the pyridine weight) at 240 ~ is 32%. In the presence of ReCI5 the total amount of piperidine that is formed under the same conditions is only 2.5%. Catalyst (II) does not catalyze the hydrogenation of pyridine under the same con- ditions. Only when the amount of (II) is increased 20 times (10% of the pyridine weight), at 220 ~ , a pressure of 120-140 atm, and a reaction time of 4-5 h is the complete hydrogena- tion of pyridine to piperidine observed [6]. It is postulated [7] that the activity of (II) in this reaction is due to the presence of H + ions on the catalyst surface, which lead to the formation of pyridinium ions that can be detected in the IR spectra, the hydrogenation

N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Mos- cow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1183-1184, May, 1976. Original article submitted November 17, 1975.

This material is protected by copyright registered in the name o f Plenum Publishing Corporation, 227 West 1 7th Street, New York, At. y. 10011. No part o f this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, wi thout written permission o f the publisher. A copy o f this article is available f rom the publisher for $Z50 .

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TABLE i. Hydrogenating Properties of Rhenium Catalysts; PH2 120-140 atm; 3 h

Starting compounds and catalysts

Cyclohexene, Re3Ct 9

Cyclohexene, RE2S ~

Pyridine, Re3C19

Pyridine, ReC15 Pyridine, Re2S 7 Thiophene, ResC19 Thiophene, Re2S 7

Amount [o-{'}henium in of catalyst in

wt % of'sta~ catalysts, g . �9 mgeompound

I 0,0t 0,8 0,01 0,8 0,01 0,8 0,01 0,8 0,0t 0,8 O,Oi 0,8 0,ol 0,8 0,0t 0,8 0,01 0,8 0,0t 0,8 O,Oi 0,8 0,02 0,8 0,01 0,8 0,06 3,5 0,06 3,5 0,06 3,5

I 'Hydrogenation

T., ~ product, %

t60 Traces t80 2,2 200 94,0 240 90,0 270 87,0 200 27,3 240 50,2 270 59,5 200 9,4 240 32,0 270 48,0 270 2,5 240 0 270 14,8 240 9,9 270 i8,4

rate of which is higher than that of pyridine. Apparently, the hydrogenation of pyridine on (I) proceeds by the same mechanism.

According to [8], (I) and (II) are apparently not reduced to the metal when the C = C dou- ble bond in cyclohexene is reduced. The fact that (I) has a higher activity in this reaction than (II) can be due to the klaster structure of (I) [9], which contains a trinuclear group that is connected by bridges composed of C1 atoms.

As can be seen from Table i, (I) and (II) have a close catalytic activity in the hydrog' enation of thiophene. The assumptions expressed above regarding the mechanism of the hydrog- enation o[ pyridine and cyclohexne are not suitable for the case of the reduction of benzene and thiophene, which probably proceeds by another mechanism.

The authors express their gratitude to L. A. Nisel'son for supplying the ReCIa sample.

CONCLUSIONS

i. It was found that trivalent rhenium chloride has a high activity in the hydrogenation of the C=C bonds in cyclohexene, the pyridine ring, and thiophene at 200-270 ~ , a hydrogen pressure of 130-140 atm, and a reaction time of 3 h.

2. Rhenium(III) chloride has a higher activity than rhenium heptasulfide in reducing the C~C bond in cyclohexane and the pyridine ring.

LITERATURE CITED

i. M. Honda, K. Tanaka, and J. Watanabe, German Patent 2211938, Jan. 27, 1972; C. A., 76, i04381k (1972).

2. W. Caenzler, K. Kabs, and G. Schroeder, German Patent 2237590, Feb. 21, 1974; C. A., 80, 132806d (1974).

3, D. Medema, H. Alkema, and Van Helden, USA Patent 3649709, May 14, 1972; C. A.~ 77, 6963c (1972).

4. D. Brown and R. Calton, Austral. J. Chem., 18, 441 (1965). 5. M.A. Ryashentseva, Kh. M. Minachev, V. V. Dorogov, and N. S. Prostakov, Khiml Geterot-

sikl. Soedin., 1972, 88. 6. M.A. Ryashentseva, Kh. M. Minachev, and N. A. Tsibizova, Izv. Akad. Nauk SSSR, Ser.

Khim., 1973, 1583. 7. M. A. Ryashentseva, Dissertation [in Russian], Moscow (1973). 8. V.I. Nefedov, N. P. Sergushin, and M. A. Ryashentseva, Dokl. Akad. Nauk SSSR, 213,

600 (1973). 9. L.V. Borisova and A. N. Ermakov, Analytical Chemistry of Rhenium [in Russian], "Nauka"

(1974), p. 27.

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