Triphenyl phosphite, cobalt complex

PC sH,g, Triphenyl phosphite, cobalt complex, 29 178 iron complexes, 28 171,29 159 nickel complex, 28 101 ruthenium complex, 26 178 03PC2 H2, Tris(4-methylphenyl) phosphite, ruthenium complex, 26 277,278,28 227 03P2RhC2,H45, Rhodium(I), (acetato)car-bonylbis(triisopropylphosphine)-, 27 292... 

C1bHi5As, Arsine, triphenyl-iron complex, 26 61 C H 5OjP, Triphenyl phosphite ruthenium complex, 26 178 CuHijP, Phosphine, triphenyl-cobalt complex, 26 190—197 cobalt-gold-ruthenium, 26 327 gold complex, 26 90, 325, 326 gold-manganese complex, 26 229 iridium complexes, 26 117-120, 122-125, 201, 202... 

Cobalt complexes find various applications as additives for polymers. Thus cobalt phthalocyanine acts as a smoke retardant for styrene polymers,31 and the same effect in poly(vinyl chloride) is achieved with Co(acac)2, Co(acac)3, Co203 and CoC03.5 Co(acac)2 in presence of triphenyl phosphite or tri(4-methyl-6- f-butylphenyl) phosphite has been found to act as an antioxidant for polyenes.29 Both cobalt acetate and cobalt naphthenate stabilize polyesters against degradation,73 and the cobalt complex of the benzoic acid derivative (12) (see Section 66.4) acts as an antioxidant for butadiene polymers.46 Stabilization of poly(vinyl chloride)-polybutadiene rubber blends against UV light is provided by cobalt dicyclohexyldithiophosphinate (19).74 Here again, the precise structure does not appear to be known. 

The preparations described here are developed from published work by Malatesta et al.5 and from more recent studies in the contributors own laboratory.2 The cobalt and nickel complexes are prepared by reduction of the corresponding metal nitrates with sodium tetrahydroborate in the presence of excess ligand, whereas the syntheses of the rhodium and platinum complexes involve simple ligand exchange processes. The preparative routes are suitable for use with triphenyl- or p-substituted triphenyl phosphites reactions involving o- or m-substituted triphenyl phosphites give much reduced yields of products which are difficult to crystallize and are very air-sensitive. These features probably reflect the unfavorable stereochemistry of the o- and m-substituted ligands. 

Triphenyl phosphite (15.5 g., 0.050 mole) is added to a solution of cobalt(II) nitrate hexahydrate (2.91 g., 0.010 mole) in ethanol (60 ml.). Sodium tetrahydroborate (1.0 g.) is dissolved in warm ethanol (25 ml.) and the solution cooled rapidly to room temperature. The sodium tetrahydroborate solution is added dropwise over a period of 10 minutes to the well-stirred cobalt nitrate solution. The purple color of the cobalt(II) salt rapidly discharges, and a pale yellow precipitate deposits. After stirring for a further 10 minutes the product is filtered off, washed with ethanol, and dried in vacuo. Yield is 11.0 g. (85%). The product may be further purified by dissolving in the minimum volume of benzene and reprecipitating by drop-wise addition of methanol. Anal. Calcd. for C72H61C0O12P4 C, 66.48 H, 4.74 P, 9.52. Found C, 66.60 H, 4.47 P, 9.21%. The tri-p-tolyl phosphite complex can be prepared (85% yield) by an analogous route. Anal. Calcd. for C84H85C0O12P4 C, 68.64 H, 5.84. Found C, 68.74 H, 5.92%. 

POCisHis, Phosphine, triphenyl-, oxide cerium complexes, 23 178 P03C3H, Trimethyl phosphite chromium complexes, 23 38 cobalt and rhodium complexes, 25 162-163... 

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. 

PO2WC2SH21, Tungsten, dicarbonyl(T) -cyclopentadienyl)hydrido(triphenyl-phosphine)-, 26 98, 28 7 PO3C3H, Trimethyl phosphite, cobalt and rhodium complexes, 28 283, 284 iron complexes, 26 61, 28 171, 29 158 nickel complex, 28 101 P03C,H,5, Triethyl phosphite, iron complexes, 26 61, 28 171, 29 159 nickel complexes, 28 101,104-106 P03C,H2, Isopropyl phosphite, nickel complex, 28 101... 

In commercial practice, all PET is made using an antimony compound for the final polycondensation stage. The transesterification reaction between DMT and the glycol is catalysed by salts of manganese, zinc, calcium, cobalt, or other metals. At the end of the ester-interchange stage, when essentially all of the methanol has been evolved, the transesterification catalyst is converted to a catalytically inactive and substantially colourless form by reaction with a phosphorus compound such as triphenyl phosphate or phosphite. Polyesters of 1,4-cyclo-hexanedimethanol and DMT or TA are made using complex titanium catalysts. 

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