Reactions Catalyzed by Pentacyanocobaltate(II)

Kwiatek, Jack

doi:10.1080/01614946808064700

Cited by 91 publications

(61 citation statements)

References 75 publications

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“…The 0.5 order rate dependence on hydrogen pressure is typical of hydrogen activation by homolytic addition, which is usually observed in the hydrogenation promoted by cobalt catalyst precursors. 25 The activation energy calculated from these data, by plotting ln k vs. 1/T (Figure 3), is 33.8 kJ mol -1 . All these results, associated with the selectivity, strongly suggest that the mechanism of the hydrogenation reaction for the cobalt complex dissolved in the ionic liquid is the same as in general accepted for cobalt cyanide complexes dissolved in water.…”

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confidence: 99%

Selective hydrogenation of 1,3-butadiene by transition metal compounds immobilized in 1-butyl-3-methyl imidazolium room temperature ionic liquids

Consorti¹,

Umpierre²,

Souza³

et al. 2003

J. Braz. Chem. Soc.

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Os complexos [Co(acac) 2 ], [Co(acac) 3 ], [Fe(acac) 3 ] e [Ni(acac) 2 ] (acac = acetilacetonato) dissolvidos em tetrafluoroborato de 1-butil-3-metilimidazônio (1), trifluorometanosulfonato de 1-butil-3-metilimidazólio (2) ou hexafluorofosfato de 1-butil-3-metilimidazólio (3), catalisam a hidrogenação de 1,3-butadieno em butenos em sistema catalítico tipicamente bifásico. A conversão do 1,3-butadieno, a seletividade e a freqüência de rotação (TOF) são fortemente dependentes do metal de transição e do líquido iônico. Para [Co(acac) 2 ] dissolvido em 1, estudos cinéticos sugerem que a reação ocorre no meio líquido iônico, com uma energia aparente de ativação de of 33.8 kJ mol -1 . A solução iônica do catalisador pode ser recuperada e reutilizada várias vezes sem mudanças perceptíveis na atividade e seletividade da reação.The compounds [Co(acac) 2 ], [Co(acac) 3 ], [Fe(acac) 3 ] and [Ni(acac) 2 ] (acac = acetylacetonate) dissolved in 1-butyl-3-methyl imidazolium tetrafluoroborate (1), trifluoromethanesulphonate (2) or hexafluorophosphate (3) catalyze the reduction of 1,3-butadiene into butenes in a typical two-phase catalytic reaction. The 1,3-butadiene conversion, the selectivity and turnover frequencies (TOF) are strongly dependent on the nature of the transition metal catalyst precursor and the ionic liquid. For [Co(acac) 2 ] dissolved in 1, kinetic studies strongly suggest that the reaction takes place in the ionic solution bulk, having an apparent activation energy for the overall process of 33.8 kJ mol -1 . The recovered ionic catalyst solution can be reused several times without any significant changes on activity and selectivity. Keywords: biphasic hydrogenation, ionic liquids, dienes, cobalt catalysts IntroductionThe hydrogenation of dienes to mono-olefins has several potentially useful applications in industry. In applications where only moderate selectivity is required heterogeneous catalysts excel due to their easy separability from reaction products by decantation or filtration, and the catalyst can be recycled. 1-5 Transition metal catalyst precursors are known to hydrogenate dienes to olefins under homogeneous conditions. 1,2 In these cases, however, C=C bond isomerization reactions are also operative decreasing the selectivity to hydrogenation products. 6 Moreover, the separation of the products from the reaction mixture and recovery of the catalyst represent disadvantages of these homogeneous catalytic reactions. [3][4][5] The catalytic system formed by dissolving cobalt cyanide in water is highly specific and active (compared with the homogeneous systems) for the hydrogenation of conjugated dienes. 7 Given the restriction that the cobalt catalyst is rapidly deactivated, this aqueous system remains the best catalyst for the hydrogenation of dienes as far as selectivity is concerned.Room temperature molten salts (or ionic liquids) have been demonstrated to be the immobilizing agents of choice for various organometallic catalyst precursors. 8 In these reactions, the catalysts maintain their m...

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Selective hydrogenation of 1,3-butadiene by transition metal compounds immobilized in 1-butyl-3-methyl imidazolium room temperature ionic liquids

Consorti¹,

Umpierre²,

Souza³

et al. 2003

J. Braz. Chem. Soc.

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“…Activation of molecular hydrogen by aqueous solutions of cobalt(I1) salts and cyanide ion was first reported by Iguchi (1942a,b;Kwiatek, 1967). Since then numerous examples of the catalytic hydrogenation of various organic and inorganic substrates by these aqueous, aqueousalcoholic, and alcoholic solutions have been reported.…”

Section: Pentacyanocobaltate( Ii) Systemmentioning

confidence: 98%

Use of Transition Metal Complexes as Selective Hydrogenation Catalysts

Lyon¹,

Rennick²,

Burmeister³

1970

Product R&D

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“…Catalysis by a variety of metal complexes including those of Pt, Pd, Rh, Ru, Ir, Os, Cr, and Co has been demonstrated (34). Particular attention has been given to the catalytic properties of (<£3P)3RhCl, the so-called Wilkinson catalyst (35)(36)(37), Pt(II)-SnCl2 complexes (38), and [Co(CN)5] 3 " (39,40). Many detailed studies have been carried out, and some comparisons with heterogeneous hydrogénation catalysis have been made (41,42).…”

Section: Reductionsmentioning

confidence: 98%

Homogeneous Catalysis: Progress, Problems, and Prospects

Stern¹

1971

Origin and Refining of Petroleum

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Research in catalysis by coordination complexes has resulted in the discovery of many new reactions and the development of several important industrial processes. Close parallels to heterogeneous and biocatalysis are indicated. Progress in reaching a detailed understanding of homogeneous catalytic reactions has been slower. Problems encountered are that nonisolable catalytic species may form in situ, kinetic studies often provide only limited mechanistic information, observed rates and products are affected strongly by media and catalyst compositions, and analogies between apparently closely related systems are frequently invalid. Difficulties in commercialization include containment of corrosive systems and product isolation from liquid media. These problems appear resolvable by currently available means. It is expected that continued research will lead to new applications and will contribute substantially to improved understanding of catalytic phenomena in general."p\uring the past decade homogeneous catalysis has progressed from an interesting novelty to its present status as a recognized field. In the interval a great deal has been said and written concerning the subject, much of it well beyond the scope of this discussion which is limited to an indication of what has been accomplished, an outline of the problems which have been encountered, and a forecast of future prospects.In the strictest sense, homogeneous catalysis involves catalytic reactions occurring in a single phase. However, as currently used, the term implies only that at least a portion of a particular reaction is known or suspected strongly to occur in the coordination sphere of a metal (most frequently a transition metal). Activation of substrates and likely the steric course of the reaction are then consequences of bonding in an in- 197Downloaded by UNIV OF CALIFORNIA SAN DIEGO on June 4, 2015 |

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Reactions Catalyzed by Pentacyanocobaltate(II)

Cited by 91 publications

References 75 publications

Selective hydrogenation of 1,3-butadiene by transition metal compounds immobilized in 1-butyl-3-methyl imidazolium room temperature ionic liquids

Selective hydrogenation of 1,3-butadiene by transition metal compounds immobilized in 1-butyl-3-methyl imidazolium room temperature ionic liquids

Use of Transition Metal Complexes as Selective Hydrogenation Catalysts

Homogeneous Catalysis: Progress, Problems, and Prospects

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