Cyclohexene and benzene are completely hydrogenated to cyclohexane in the presence of Re2(CO)10 at 230~ PH2 = i0 MPa. IR spectroscopy showed that Re2(CO)I 0 is converted to a new Re carbonyl compound during the catalysis. Different compounds are formed in the hydrogenation of cyelohexene and benzene.

Rhenium oxides and sulfides are catalysts for the hydrogenation of the C=C bonds in hydrocarbons but, in most cases, they are less active than the standard hydrogenation catalysts [I]. The hydrogenation of cyclohexene (I) and benzene (II) proceeds completely in the presence of rheniecene hydride (CsHs)2ReH at 180-230~ P~2 " I0 MPa [2,3]. In previous work [4], we showed that (I) and (II) are hydrogenated in the presence of rhenium pentacarbonyl Re2(CO)10, which is inactive in homogeneous hydrogenation reactions up to 200~ Above this temperature, Re2(CO)I 0 decomposes with the formation of a heterogeneous system [5]. In the present work, we studied the catalytic properties of Re2(CO)I 0 in the hydrogenation of (I) and (II) at elevated temperatures and pressure and the composition of the rhenium complexes before and after the catalysis was studied by IR spectroscopy for the identification of Re2(CO)10. EXPERIMENTAL Chemically pure-grade (I) and (II) were used as the starting compounds. A sample of Re2(CO)I 0 was obtained by a modification of the method of Hieber and Fuchs [6]. The reduction of KReO 4 by carbon monoxide was carried out at 280~ in a rotating, copper-lined autoclave over 5-6 h; Pco ~ - 27 MPa. The hydrogenation was carried out in a static system consisting of a 0.15-1iter steel autoclave with a glass insert, in which the catalyst and starting compound were placed. The autoclave was flushed with nitrogen and hydrogen. A given hydrogen pressure was established and a given temperature was reached. The experiment was carried out. The autoclave was then cooled to -20~ About 30 min are required, as a rule, to heat the autoclave to 180-230~ The composition of the catalysis products was determined by gas-liquid chromatography on a 300 x 0.3-cm steel column packed with 15% polyethyleneglycol adipinate on Chromosorb P and by refractometry. The catalyst was analyzed by IR spectroscopy before and after the reaction on a UR-20 spectrometer.