Phillips initiator

Commerical polymerizations of ethylene, propene, and other a-olefins are carried out as slurry (suspension) and gas-phase processes [Beach and Kissin, 1986 Diedrich, 1975 Lieberman and Barbe, 1988 Magovern, 1979 Vandenberg and Repka, 1977 Weissermel et al., 1975]. Solution polymerization has been used in the past for ethylene polymerization at 140-150°C, pressures of up to 8 MPa (1 MPa = 145 psi = 9.869 atm), using a solvent such as cyclohexane. The solution process with its higher temperatures was employed for polymerization with the relatively low efficiency early Phillips initiators. (Polyethylene, but not the initiator, is soluble in the reaction medium under the process conditions.) The development of a variety of high-efficiency initiators has allowed their use in lower-temperature suspension and gas-phase processes, which are more advantageous from many... 

Commercial production of PE resias with densities of 0.925 and 0.935 g/cm was started ia 1968 ia the United States by Phillips Petroleum Co. Over time, these resias, particularly LLDPE, became large volume commodity products. Their combiaed worldwide productioa ia 1994 reached 13 X 10 metric t/yr, accouatiag for some 30% market share of all PE resias ia the year 2000, LLDPE productioa is expected to iacrease by 50%. A aew type of LLDPE, compositioaaHy uniform ethylene—a-olefin copolymers produced with metallocene catalysts, was first introduced by Exxon Chemical Company in 1990. The initial production volume was 13,500 t/yr but its growth has been rapid indeed, in 1995 its combiaed production by several companies exceeded 800,000 tons. 

Countries produciug commodity LLDPE and their capacities, as well as production volumes of some U.S. companies, are Hsted iu Table 5. Iu most cases, an accurate estimate of the total LLDPE production capacity is compHcated by the fact that a large number of plants are used, iu turn, for the manufacture of either HDPE or LLDPE iu the same reactors. VLDPE and LLDPE resius with a uniform branching distribution were initially produced in the United States by Exxon Chemical Company and Dow Chemical Company. However, since several other companies around the world have also aimounced their entry into this market, the worldwide capacity of uniformly branched LLDPE resins in 1995 is expected to reach a million tons. Special grades of LLDPE resins with broad MWD are produced by Phillips Petroleum Co. under the trade name Low Density Linear Polyethylenes or LDLPE. 

The first commercial grades were introduced by Phillips Petroleum in 1968 under the trade name Ryton. These were of two types, a thermoplastic branched polymer of very high viscosity which was processed by PTFE-type processes and an initially linear polymer which could be processed by compression moulding, including laminating with glass fibre, and which was subsequently oxidatively cross-linked. 

Hen egg-white lysozyme catalyzes the hydrolysis of various oligosaccharides, especially those of bacterial cell walls. The elucidation of the X-ray structure of this enzyme by David Phillips and co-workers (Ref. 1) provided the first glimpse of the structure of an enzyme-active site. The determination of the structure of this enzyme with trisaccharide competitive inhibitors and biochemical studies led to a detailed model for lysozyme and its hexa N-acetyl glucoseamine (hexa-NAG) substrate (Fig. 6.1). These studies identified the C-O bond between the D and E residues of the substrate as the bond which is being specifically cleaved by the enzyme and located the residues Glu 37 and Asp 52 as the major catalytic residues. The initial structural studies led to various proposals of how catalysis might take place. Here we consider these proposals and show how to examine their validity by computer modeling approaches. 

Phillip B, B Schink (1998) Evidence of two oxidative reaction steps initiating anaerobic degradation of resorcinol (1,3-dihydroxybenzene) by the denitrifying bacteiimn Azoarcus anaerobius. J Bacteriol. 180 3644-3649. 

Both amphetamine and cocaine have also been reported to support intracranial self-administration in the mesolimbic/mesocortical dopaminergic system. Rats will self-administer cocaine into the medial prefrontal cortex (Goeders and Smith 1983). while amphetamine is self-administered into the orbitofrontal cortex of rhesus monkeys (Phillips and Rolls 1981) and the nucleus accumbens of rats (Hoebel et al. 1983 Monaco et al. 1981). These data indicate that the mesolimbic/mesocortical dopaminergic system is involved in the initiation of stimulant reinforcement processes, and this work suggests that the region of the nucleus accumbens, more specifically the mesolimbic dopamine system, may be an important substrate for reinforcing properties of several psychomotor stimulant drugs. 

We appreciate the guidance of Pro . R.W. Lenz in the synthesis of model networks, and the help of Drs. Roberto Russo and Ulku Yilmazer in initial synthesis work. This work was supported in part by a grant from the Center for University of Massachusetts-lndustry Research on Polymers (CUMIRP). We appreciate the donation of the Duragen samples by the General Tire and Rubber Co., the isocyanate samples by the Mobay Chemical Co., and the Butarez samples by the Phillips Petroleum Co. 

Phillips H2/CO = 2 needed due to coking of the catalyst caused by high support acidity or high temperatures in particles resulting from high initial ... 

Use of less sterically hindered examples of 5 in combination with MAO allows for active catalysts for the linear (head-to-head) dimerisation of a-olefins such as 1-butene, 1-hexene, 1-decene and Chevron Phillips C20-24 a-olefin mixture (Scheme 4) [47], The mechanism for dimerisation is thought to involve an initial 1,2-insertion into an iron-hydride bond followed by a 2,1-insertion of the second alkene and then chain transfer to give the dimers. Structurally related cobalt systems have also been shown to promote dimerisation albeit with lower activities [62], Oligomerisation of the a-olefms propene, 1-butene and 1-hexene has additionally been achieved with the CF3-containing iron and cobalt systems 5j and 6j yielding highly linear dimers [23],... 

Histones were initially assumed to form part of an assembly system (Sperling and Bustin, 1974, 1975) for two reasons. First, they are present in chromatin as many copies of a few components. [The mass of the five histones equals that of the DNA (for references, see Phillips, 1971 Hnilica, 1972).] Second, fiber X-ray diffraction studies of chromatin (Luzzati and Nicolaieff, 1959 Wilkins et al., 1959 Pardon et al., 1967 Pardon and Wilkins, 1972) indicated that they are involved in a regular periodic structure. The fact that the histones are highly conserved with respect to their primary structure (Dayhoff, 1972 Wilson et al., 1977), especially the arginine-rich histones H3 and H4, also indicates that they may play a primarily structural role in which each residue is crucial. 

Dissolntion and reduction of crystalline Fe(III) minerals is accelerated by chelation with carboxylate ligands in the presence of Fe(ll) (Zinder et al, 1986 Blesa et al, 1987 Phillips et al, 1993 Kostka and Lnther, 1994). Therefore as soil reduction proceeds and carboxylates formed in oxidation of organic matter accumulate in solution together with Fe +, dissolntion and rednction of crystalline Fe(lll) will commence. Dissolution of oxyhydroxide coatings will therefore lag behind the initial reduction of Fe(lll). 

During the early dust bowl years (1935) they established the oil industry s first research team in Bartlesville, Oklahoma. George Oberfell, hired by Phillips to fight the lawsuit, planned the initial research efforts that involved three main initiatives first, to develop technology to use light hydrocarbons in new ways as motor fuels second, to develop markets for butane and propane and third, to find new uses for the light hydrocarbons outside the fuel market. All three objectives were achieved. 

Gutin PH, Prados MD, Phillips TL, et al. External irradiation followed by an interstitial high activity iodine-125 implant boost in the initial treatment of malignant gliomas NCOG study 6G-82-2. Int J Oncol Biol Phys 1991 21 601-606. 

Initiation hy the Phillips catalyst is not well understood. Both Cr(II) and Cr(III) have been proposed as the active oxidation state of chromium. Initiation involves the formation... 

Both traditional Ziegler-Natta and metal oxide Phillips-type initiators are used in suspension polymerizations (Secs. 8-4a, 8-4j) [Kaminsky, 2001], Both types of initiators are used for ethylene, but only the traditional Ziegler-Natta initiators are used for propene since Phillips-type initiators do not yield stereoselective polymerizations. 

Metallocene initiators reached commercialization near the beginning of the twenty-first century. These initiators probably accounted for about 5% of the total production of HDPE, LLDPE, and PP in 2002. The relative importance of metallocene initiators compared to the traditional Ziegler-Natta and Phillips-type initiators will increase in the future. 

The initiation of polymerizations by metal-containing catalysts broadens the synthetic possibilities significantly. In many cases it is the only useful method to polymerize certain kinds of monomers or to polymerize them in a stereospecific way. Examples for metal-containing catalysts are chromium oxide-containing catalysts (Phillips-Catalysts) for ethylene polymerization, metal organic coordination catalysts (Ziegler-Natta catalysts) for the polymerization of ethylene, a-olefins and dienes (see Sect. 3.3.1), palladium catalysts and the metallocene catalysts (see Sect. 3.3.2) that initiate not only the polymerization of (cyclo)olefins and dienes but also of some polar monomers. 

Bradley, B.P., Phillips, G., Green, L., and Gossop, M. (1989) Circumstances surrounding the initial lapse to opiate use following detoxification. Br J Psychiatry 154 354-359. 

Kiernan and Bowen Explosive. An expl mixt developed by Kiernan Bowen of New Orleans, La, contg Na chlorate 75, turpentine 10, bone-meal 10 dried blood 5%. It was concluded that this expl had no value from a military standpoint because of its low brisance, high degree of sensitivity to impact, and the ease with which it lost turpentine, which resulted in decreased sensitivity to initiating agents Ref A.J. Phillips, Study of Sodium Chlorate Explosive Developed by Kiernan and Bowen , PATR 1277 (April 1943)... 

---