Catalysts acetylacetonate

The reaction of methyl propionate and formaldehyde in the gas phase proceeds with reasonable selectivity to MMA and MAA (ca 90%), but with conversions of only 30%. A variety of catalysts such as V—Sb on siUca-alumina (109), P—Zr, Al, boron oxide (110), and supported Fe—P (111) have been used. Methjial (dimethoxymethane) or methanol itself may be used in place of formaldehyde and often result in improved yields. Methyl propionate may be prepared in excellent yield by the reaction of ethylene and carbon monoxide in methanol over a mthenium acetylacetonate catalyst or by utilizing a palladium—phosphine ligand catalyst (112,113). 

Epichlorohydrin Elastomers without AGE. Polymerization on a commercial scale is done as either a solution or slurry process at 40—130°C in an aromatic, ahphatic, or ether solvent. Typical solvents are toluene, benzene, heptane, and diethyl ether. Trialkylaluniinum-water and triaLkylaluminum—water—acetylacetone catalysts are employed. A cationic, coordination mechanism is proposed for chain propagation. The product is isolated by steam coagulation. Polymerization is done as a continuous process in which the solvent, catalyst, and monomer are fed to a back-mixed reactor. Pinal product composition of ECH—EO is determined by careful control of the unreacted, or background, monomer in the reactor. In the manufacture of copolymers, the relative reactivity ratios must be considered. The reactivity ratio of EO to ECH has been estimated to be approximately 7 (35—37). 

Figure 2. Visible light spectra of cobalt acetylacetonate catalysts in benzene...

The anionic nickel acetylacetonate catalyst gives only the cis, cis, trans product. Intermediate catalysts have already been seen to give cis, cis, cis structures which do not terminate but produce cis polybutadiene. This will also be seen later with cobalt iodide. At high temperatures or with strongly cationic systems the cyclic dodecatrienes are isomerized to the most stable trans, trans, trans structure. 

High crosslinking density was reached using BPA/DC, trimethylolpropane trimethacrylate and p-toluenesulfonic acid monohydrate [125]. A composition based on BPA/DC and 2,2-bis[4-(2-hydroxyethoxy)phenyl] propane dimethacrylate with a peroxide initiator and Fe acetylacetonate catalyst contains, moreover, a block... 

Reaction of heteroaromatic thioketones 638 with the carbenoids, generated from phenyliodonium bis(phenylsul-fonyl)methane or bis(arylsulfonyl)diazomethanes in the presence of a copper acetylacetonate catalyst, affords heterocycle-fused [c]thiophenes 639. The reaction involves ring closure of the intermediary thiocarbonyl ylides and elimination of a sulfenic acid (Equation 33) <1995S87>. 

Mechanism of polymerization. The AlEt3/H20/acetylacetone catalyst called also chelate Vandenberg catalyst is a stable and soluble product having the structure presented in Fig. 17. 

C(N02)3 Jr mw (548.74)n, N 23.82%, OB to CO2 -39.36%, amorph solid, mp 75—85°, Sol in acet. The initial polymer is prepd by dropwise addition of the diisocyanate in abs dioxane to a dioxane sob of an equiv amt of the did plus 5x10" mole of ferric acetylacetonate catalyst, over a period of 30 nuns while mamtammg the temp at 40-50°. Polymerization at 50° requires 43 hrs to complete. After acet soln and w pptn, the yield is vacuum dried. Post polymerization nitration is accomplished by sob of the polymer m 100% nitric acid at 0° m the ratio of 1 g polymer to 10ml acid. The nitration is completed upon sob of the polymer in acid. The excess nitric acid is removed at RT by vacuum distn, the polymer is dissolved b acet and pptd m methylene chloride... 

NO2 NO2 0 NO2 -C.N.(CH2)2.N.(CH2)2.N.C.0.CH2.C.CH20-N02 CH2 mw (425.32)n, N 23.06%, OB to CO2 -58.31%, amorph solid, mp 70—80°. Sol m acet. The imtial polymer is prepd by dropwise addition of a sob of the diisocyanate in dimethylforma-mide to a dimethylformamide sob of an equiv wt of diol plus 1x10" mole ferric acetylacetonate catalyst over a period of 15 mbs. Polymerization is completed b 136 hrs at 50°. After dilution with dimethylformamide, the polymer is pptd b w and vacuum dried. Post polymerization nitration is accomphshed by soln of the polymer b 100% nitric acid at 0° b the ratio of 1 g polymer to 15ml acid. Nitration is completed on sob of the polymer. The excess acid is vacuum distd at RT, the polymer is dissolved b acet and pptd in methylene chloride... 

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