Water catalysts

Nylon-11. This nylon is produced from 11-aminoundecanoic acid, which is derived from castor oil. The acid is polymerized by heating to 200°C with continuous removal of water. Catalysts such as phosphoric acid are frequentiy used. There is no appreciable amount of unreacted monomer left in the product. 

The remainder of these formulations consists of water, catalyst (e.g. sulphuric acid) and stabiliser... 

Fell and Bari (89) also studied the rhodium-catalyzed reaction. A rho-dium-N-methylpyrrolidine-water catalyst system was very effective for producing the propane-1,2-diol acetate directly. The best yields (>90%) of product of about 9 1 alcohol aldehyde ratio were obtained in the region of 95°-l 10°C. This range was very critical, as were other reaction parameters. Rhodium alone gave the best yield of aldehyde (83%) at 60°C. Triphenylphosphine as cocatalyst induced the decomposition of the aldehyde product. 

Caution The catalyst is extremely pyrophoric when exposed to the air in a dry condition it should be kept wet with solvent at all times. The catalyst (Raney 2800 Grade Active Nickel Catalyst in Water) is purchased from Davison Chemical, and is weighed out while it is wet. The catalyst is washed by suspension in methanol and decanted to remove water. It is further washed with ethyl acetate prior to use. The checkers obtained similar results with Raney nickel (50% slurry in water) catalyst purchased from Aldrich Chemical Company, Inc. 

Nakaniwa.N., Ozaki,K., Furukawa,J. Study of diethylzinc/water catalyst system Makromol. Chem. 138, 197 (1970). 

Practical interest in high-molecular-weight poly (propylene oxide) centers in its potential use as an elastomer (19). Copolymerization of propylene oxide with allyl glycidyl ether gives a copolymer with double bonds suitable for sulfur vulcanization. Table IV shows the properties of elastomers made with a copolymer prepared with a zinc hexacyano-ferrate-acetone-zinc chloride complex. Also shown are the properties of elastomers made from partially crystalline copolymers prepared with zinc diethyl-water catalyst. Of particular interest are the lower room-... 

As in the ethylene oxide system kinetics are complex and do not lend themselves to exact interpretation (19). The boron fluoride — water catalyst system appears to be most effective at a boron fluoride/water ratio of about three, a surprising and probably fortuitous similarity to the efficiency of this catalyst in the isomerization of some hydrocarbons (20). At low water concentrations the number of polymer molecules formed equals the number of water molecules added and chain transfer may be assumed, though it has not actually been demonstrated. There is some indication of a maximum molecular weight of 15,000—20,000 at — 20° C but the present data are inadequate to establish this point. The order in monomer appears to be first at low water concentrations rising to second at higher water levels, but it seems quite possible that this apparent change in order is due to some factor such as catalyst destruction. 

Rhodium(I) complexes immobilized on silica using 3-(3-silylpropyl)-2,4-pentanedio-nato ligands (38) show good activity in the hydrosilylation of 1-octene with HSi(OEt)3 at 100°C60. The immobilized Rh catalysts are prepared by (i) reaction of (EtO)3Si(CH2)3C(COMe)2Rh(CO)2 with untreated silica (Catalyst A), (ii) reaction of Rh(acac)(CO)2 (acac = acetylacetonato = 2,4-pentanedionato) with silica modified by [(EtO)3Si(CH2)3C(COMe)2] prior to the complexation (Catalyst B), (iii) reaction of [Rh(CO)2Cl]2 with a polycondensate of [(EtO)3Si(CH2)3C(COMe)2] , Si(OEt)4 and water (Catalyst C) and (iv) sol-gel processing of (EtO)3Si(CH2)3C(COMe)2Rh(CO)2 and Si(OEt)4 (Catalyst D). The Catalysts A and B show ca three times better activity than their homogeneous counterparts, while the Catalyst D exhibits only low activity and the Catalyst C is inactive60. 

One can note, in this connection, that styrene oxide undergoes polymerisation in the presence of aluminium isopropoxide which involves a selective cleavage of the Ca-0[CH(Ph)—O] bond [47]. On the other hand, polymerisation of styrene oxide with the diethylzinc-water catalyst was found to proceed via 0,8-0(0142—0) bond scission [48],... 

Another interesting monomer for copolymerisation with carbon dioxide is isomeric 2-butene oxide. In copolymerisation in a ternary comonomer system consisting of 2-butene oxide, 1-butene oxide and carbon dioxide with the diethylzinc-water catalyst, m-2-butene oxide was incorporated in the copolymer, while trans-2-butene oxide hardly underwent an enchainment [230]. Thus, the smaller steric hindrance for the r/.v-isomer than for the irans-isomer throughout the coordination copolymerisation with carbon dioxide is to be taken into account. 

For the catalyst system NdV/EASC/DIBAH the impact of water on monomer conversion, Mw, polydispersity and cis- 1,4-content was systematically studied (Table 16) [191], With increasing amounts of water catalyst activity passes through a maximum whereas Mw and Mw/Mn pass through a minimum. It has to be mentioned, however, that the overall effect of water on reaction rate and polymer properties are relatively small. In this study it is also shown that water has no influence on cis-1,4-contents [ 191],... 

Just about the same time Japanese workers (107) polymerized this dialdehyde with boron trifluoride etherate, p-toluene sulfonic acid, and titanium tetrachloride as well as with aluminum triethyl-water catalyst systems. Completely insoluble products were obtained with the cationic catalysts, whereas partially soluble materials were isolated with the latter initiator. On the basis of infrared evidence, the above structure was assigned to the soluble product. In spite of the fact that ether linkages were found by infrared analysis in the cationic product, the authors concluded that its structure was different from that of the soluble polymer obtained with organometallic catalyst. The structure of the soluble fraction was assumed to be ... 

Ru4H4 (T 6-C6H6)4]2+ 60 bar, 90°C arenes as substrate similar [35] performance as in water catalyst [45] solution could be reused several times, product isolated by distillation or decantation. 

A continuous solution process [61] has been developed and is operated in the USSR (now CIS). Copolymerization is performed in 10-12 wt% comonomers solution in isopentane or other C5-C7 hydrocarbons, at temperatures between -90 and -50° C, initiated by an aluminum alkyl halide/water catalyst. The catalyst is eliminated by adding a low amount of methanol to the reactor effluent stream, and the polymer is extracted by contacting the solution with hot water and steam. Further operations are similar to those of slurry process. 

Within the scope of systematic investigations on basic reactions in industrial silicone syntheses in the system - alkoxysilane, silanol, siloxane, alcohol, water, catalyst, solvent - after previous investigations on the equilibrium of the silanol alkoxysilane heterocondensation and the reverse siloxane cleavage with alcohol (Eq. 1) [1]... 

Catalyst Preparation. Catalyst preparation consisted of the exchange of nickel or cobalt nitrate for the sodium cation. Ratios of nickel or cobalt to sodium of 20 1 were used for maximum exchange and the ion exchanged zeolite pellets were leached with deionized water. Catalyst preparations were reduced for 16 hours at 400°C in a stream of hydrogen. Similar procedures have been reported (5, 6). 

For example, Soga et al. > found, by examining propylene polymerization in toluene in the temperature range 0-65 °C with an apparently soluble catalyst such as tetrabenzylzirconium, that the isotactic index and the polydispersity of the polymer increased as the polymerization temperature increased. Furthermore, the value of Q > 30 was much greater than that predicted for homogeneous active centres. From these results the authors concluded that the catalyst should be made up of small invisible colloid-type particles. The same interpretation is valid for the surprising results (Q 40) obtainedfor polyethylene, in Isopar solution at 200 °C, with the originally soluble tetrabenzylzirconium-water catalyst. 

Kinetic studies [32] with a diethylzinc/water catalyst showed two distinct rates. A relatively fast rate in the first 5—10% of polymerization... 

In the case of the aluminium alkyl/water catalysts important differences are observed [34] if the aluminium alkyl/water reaction is carried out in a hydrocarbon solvent or in ether solvent. Further important... 

Biphasic (water-catalyst and substrate) media. The ratio of autoxidation to oxydehydrogenation depends on substrate, T and 02 pressure... 

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