Manganese complexes ethylene

For asymmetric epoxidation of methylstyrene, dehydronaphthalene, and meta-chlorobenzoic acid in the presence of A-methylmorpholine oxide, Reger and Janda synthesized manganese complexes 33 with the salen ligand bound to the methyl ether of poly(ethylene oxide) [69]. 

Manganese ethylenebis dithiocarbamate complex with zinc salt. See Mancozeb Manganese (II) ethylene di (dithiocarbamate). 

Costas and coworkers have shown recently that manganese complexes based on BPMEN-type ligands (where BPMEN is bis((pyridin-2-yl)methyl)ethylene-l,2-diamine, Figure 11.11) show enhanced activity in the epoxidation of alkenes with H2O2 in the presence of excess acetic add, albeit with lower activity and with a narrower substrate scope than for the pyridyl-tmtacn based systems reported in the same study (see above. Table 11.7) [102]. 

The rate of peroxide decomposition and the resultant rate of oxidation are markedly increased by the presence of ions of metals such as iron, copper, manganese, and cobalt [13]. This catalytic decomposition is based on a redox mechanism, as in Figure 15.2. Consequently, it is important to control and limit the amounts of metal impurities in raw rubber. The influence of antioxidants against these rubber poisons depends at least partially on a complex formation (chelation) of the damaging ion. In favor of this theory is the fact that simple chelating agents that have no aging-protective activity, like ethylene diamine tetracetic acid (EDTA), act as copper protectors. 

A second manufacturing method for acetic acid utilizes butane from the C4 petroleum stream rather than ethylene. It is a very complex oxidation with a variety of products formed, but conditions can be controlled to allow a large percentage of acetic acid to be formed. Cobalt (best), manganese, or chromium acetates are catalysts with temperatures of 50-250 °C and a pressure of 800 psi. 

The complexes [M(CO)5(> 2-C2H4)] [A1C14] (M = Mn, Re) were first prepared by abstraction of the chloride ligand in M(CO)sCl using aluminum-trichloride under ethylene pressure.14 The preparation of [BF4] salts of these cationic pentacarbonylethene complexes of manganese and rhenium proceeds under very mild conditions (1 bar) and gives high yields.6... 

Figure 19. Variation of amount of thermostable polymer from the complex of polyethylene terephthalate, ethylene-diamine, and Mn2+ (from manganese acetate) with milling...

Metal cluster complexes containing vinylidene ligands have been considered as models of species present when olefins or alkynes are chemisorbed on metal surfaces (114). Vinylidene has been detected in reactions of ethylene or acetylene with Fe(100), Ni( 111), and Pt(l 11) surfaces (115), and was shown to be an intermediate by theoretical studies on a manganese surface (116). The facile cleavage of C-H bonds which occurs in these systems, together with hydrogen addition or abstraction, also occurs on metal clusters. Typical of the reactions considered is the hydrogen transfer reaction... 

Preparative procedures for Mn(HS04)278 and manganese(n) malonate dihydrate79 have been published. Ethylene glycol (EG) forms the complexes Mn(EG) An... 

Diethyl(ethylene)tellurourea formed complexes with chromium, molybdenum, tungsten, and manganese carbonyls, in which the tellurium is coordinated to the transition metal1. The solid complexes are moderately stable in air. They do not decompose when stored in the dark at 20° under an inert atmosphere. A toluene solution of the chromium complex at 20° deposited tellurium forming the chromium-carbene complex1. 

The effect of a complex-forming agent on the cation-exchange processes of montmorillonite is well demonstrated in calcium-montmorillonite, manganese(II) ion, and the sodium salt of the ethylene diamine tetraacetic acid (EDTA) system (K6nya and Nagy 1998 Konya et al. 1998). The reactions are illustrated in Figure 2.9. 

Ethylene complexes of transition metals near the beginning of the transition series are now known. A neutral complex was prepared in 1960 by the photochemical displacement of carbon monoxide by ethylene from cyclopentadieny 1-manganese tricarbonyl 156) ... 

Some insight into the mechanisms of the iodine-promoted carbonylation has been obtained by radioactive tracer techniques [17] and low-temperature NMR spectroscopy [18]. The mechanism involves the formation of HI, which in a series of reactions forms with rhodium a hydrido iodo complex which reacts with ethylene to give an ethyl complex. Carbonylation and reductive elimination yield propionic acid iodide. The acid itself is then obtained after hydrolysis. The rate of carboxylation was reported to be accelerated by the addition of minor amounts of iron, cobalt, or manganese iodide [19]. The rhodium catalyst can be stabilized by triphenyl phosphite [20]. However, it is doubtful whether the ligand itself would meet the requirements of an industrial-scale process. 

Copolymerization of an acryloyl-substituted manganese-salen complex with ethylene glycol dimethacrylate and styrene [32] yielded catalysts that showed low enantioselectivity in the epoxidation of styrene by m-CPBA/NMO or iodosylben-zene (PhIO). The influence of porosity and cross-linking degree on activity was explored and the catalysts could be used repeatedly with no loss of activity for at least three cycles. 

Ethylene sulfite reacts with metal carbonyls such as manganese and chromium to form a complex in which the sulfur atom functions as an electron donor and is directly attached to the metal center (83 and 84) (65CB2248). In contrast, 4-vinyl cyclic sulfite reacts with iron nonacarbonyl to form a ir-allyliron complex 85, with the extrusion of SO2 (90SL224, 90SL331). Some of these reactions are summarized in Scheme 20. 

Among such oxidations, note that liquid-phase oxidations of solid paraffins in the presence of heterogeneous and colloidal forms of manganese are accompanied by a substantial increase (compared with homogeneous catalysis) in acid yield [3]. The effectiveness of n-paraffin oxidations by Co(III) macrocomplexes is high, but the selectivity is low the ratio between fatty acids, esters, ketones and alcohols is 3 3 3 1. Liquid-phase oxidations of paraffins proceed in the presence of Cu(II) and Mn(II) complexes boimd with copolymers of vinyl ether, P-pinene and maleic anhydride (Amberlite IRS-50) [130]. Oxidations of both linear and cyclic olefins have been studied more intensively. Oxidations of linear olefins proceed by a free-radical mechanism the accumulation of epoxides, ROOH, RCHO, ketones and RCOOH in the course of the reaction testifies to the chain character of these reactions. The main requirement for these processes is selectivity non-catalytic oxidation of propylene (at 423 K) results in the formation of more than 20 products. Acrylic acid is obtained by oxidation of propylene (in water at 338 K) in the presence of catalyst by two steps at first to acrolein, then to the acid with a selectivity up to 91%. Oxidation of ethylene by oxygen at 383 K in acetic acid in... 

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