Hydrogenation of substituted olefins with certain complex organo-metallic catalysts

Kalechits, I. V.; Липович, В. Г.; Шмидт, Ф. К.

doi:10.1016/0031-6458(66)90007-4

Cited by 2 publications

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“…It follows from these observations that the decomposition products of lithium aluminum hydride appearing under the influence of cobalt do no block the entire surface of the Co(0) nanoclusters, due may be to a lower degree of decomposition of LiAlH 4 . The comparison of the yield of hydrogen in the reaction of LiAlH 4 with Co(acac) 2 and Ni(acac) 2 shows that the yield of hydrogen per one mole of the metal is about 1.5-2 smaller for the former. However, we cannot exclude also other possible causes of the observed results.…”

Section: Nmmentioning

confidence: 97%

“…Comparison of the catalytic properties of systems based on Co(acac) 2 and Ni(acac) 2 obtained at the action of lithium aluminum hydride shows their fundamental difference. Nickel catalyst is formed only after the activation with a proton-donor substance regardless of the catalyst system composition [10], whereas for Co(acac) 2 the composition in the range 5 ≤ LiAlH 4 /Co ≤ 12 not requires an additional proton-donor compound for the formation of a hydrogenation catalyst.…”

Section: Nmmentioning

confidence: 97%

“…2. UV spectra of Co(acac) 2 (1) and the reaction system of Co(acac) 2 -nLiAlH 4 for n = 2 (2), 6 (3), and 15 (4). c Co = 8.3 mM, benzene-THF (10:2), T = 30°C.…”

mentioning

confidence: 99%

“…The nanoparticles are stabilized by an excess of LiAlH 4 or LiAlH(t-BuO) 3 , as well as by the products of their catalytic decomposition under the action of cobalt in the reduced state. At the ratio LiAlH 4 / Co> 12 to obtain the particles active in catalysis their activation by a proton-donor compound is required.The study of the Ziegler systems based on the transition metal complex compounds combined with the organic hydride compounds of the metals from I-III groups in the hydrogenation catalysis has been carried out since the second half of XX century and is continued now [1][2][3][4]. Despite such a long period of study and industrial applications of these systems, in particular, in the process of hydrogenation of polymers [5], some aspects of the formation and nature of the catalytically active species require further research of fundamental nature.…”

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confidence: 99%

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Formation of the cobalt hydrogenation catalysts at the action of lithium aluminum hydride and lithium tri(tert-butoxy)aluminohydride and their properties

et al. 2012

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The interaction of Co(acac) 2(3) with LiAlH 4 or LiAlH(t-BuO) 3 was studied using NMR, UV, IR, ESR spectroscopy, electron microscopy, and volumometry. The basic stages of formation of cobalt catalysts for hydrogenation were suggested. The formation of the nanoparticles that are active in the hydrogenation process is shown to occur at a ratio of reagents 5 ≤ Red/Co ≤ 12. The nanoparticles are stabilized by an excess of LiAlH 4 or LiAlH(t-BuO) 3 , as well as by the products of their catalytic decomposition under the action of cobalt in the reduced state. At the ratio LiAlH 4 / Co> 12 to obtain the particles active in catalysis their activation by a proton-donor compound is required.The study of the Ziegler systems based on the transition metal complex compounds combined with the organic hydride compounds of the metals from I-III groups in the hydrogenation catalysis has been carried out since the second half of XX century and is continued now [1][2][3][4]. Despite such a long period of study and industrial applications of these systems, in particular, in the process of hydrogenation of polymers [5], some aspects of the formation and nature of the catalytically active species require further research of fundamental nature. This concerns, above all, establishing all the functions of the I-III groups metal compounds in the processes of formation and operation of the Ziegler type catalyst.To date, experimentally has been shown that the coreagents in the Ziegler type systems are involved in the formation of hydride or an organic derivative of the transition metal, reduction of the transition metal compound, most often to the metal in the zero oxidation state, formation of adducts with the reduced form of the transition metal of the type of acid-base interaction, and stabilization of nanoparticles [6-8]. However, some aspects of this problem have not yet been substantiated experimentally. These include the role of the decomposition reactions of the I-III group metal compounds catalyzed by the transition metals [8,9].We have previously shown [10] that in the formation of nickel-based hydrogenation catalysts using lithium aluminum hydride LiAlH 4 , the function of the latter is not limited to the reduction of the nickel precursor. The tetrahydroaluminate anions adsorbed on the surface act as a stabilizer of the nickel nanoparticles. Besides, the tetrahydroaluminate anions and probably products of catalytic decomposition of LiAlH 4 occupying the vacant positions on the surface may act as catalyst poisons. Therefore, the resultant nanoparticles are active in the hydrogenation only when they are activated by a proton-donor compound. In contrast to nickel, the palladium catalysts active in the hydrogenation are formed under the action of LiAlH 4 without activation with alcohol or water at a ratio of LiAlH 4 /Pd < 10 [11].These results have generated the need to study the cobalt-containing catalytic systems, formed by using LiAlH 4 and its alkoxy derivative LiAlH(t-BuO) 3 as the reducing agent, in the hydrogenation processes. A...

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Section: Nmmentioning

confidence: 97%

Section: Nmmentioning

confidence: 97%

“…2. UV spectra of Co(acac) 2 (1) and the reaction system of Co(acac) 2 -nLiAlH 4 for n = 2 (2), 6 (3), and 15 (4). c Co = 8.3 mM, benzene-THF (10:2), T = 30°C.…”

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confidence: 99%

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