Cooling ethylene content

An autoclave was charged with palladium acetate (0.0140 g), l,3-bis[bis(2-methoxy-5-methylphenyl)phosphino]propane (0.0398 g), trifluoroacetic acid (0.0499 g), benzothiazole (0.4225 g), and 100 ml of acetone. The solution was then treated with 2497.5 ml of methanol and water (1000 ppm) and then sealed and stirred at 800 rpm. The mixture was heated to 70°C and carbon monoxide and ethylene having a molar ratio of 1 1.8, respectively, added until the internal pressure of the autoclave was 100 bar. The mixture was then stirred for 2 hours while the internal temperature and the internal pressure were maintained at 100 bar and 70°C. After cooling the contents were removed, degassed, filtered, washed with methanol several times, and 51.5 g of product isolated. 

Fig. 18. aEffect of tacticity b. Effect of ethylene content onto the density cooling rate behavior... 

The more or less simultaneously developed Phillips process likewise uses a xylene solution, but at lower pressures (30-50 bar) and temperatures (150°C) and with a partially reduced chromic oxide on aluminum oxide or aluminum silicate as supporting agent. The catalyst, which is used in relatively large quantities (10% of ethylene content), is activated by heating and filtered off after an almost 100% yield of poly(ethylene) has been obtained. The poly(ethylene) precipitates from the cooled solution the solvent, before distillation, still contains low-molecular-weight poly-... 

Foresta T, Piccarolo S and Goldbeck-Wood G (2001) Competition between a and 7 phases in isotactic polypropylene effects of ethylene content and nucleating agents at different cooling rates. Polymer 42 1167-1176. 

A series of ethylene-propylene block copolymers prepared with " C-labelled ethylene was analysed for percentage of ethylene incorporation by radiochemical methods. These samples when scanned at 180 °C gave results that agreed with the radiochemical assay quite well. However, when the cooled samples were scanned, the results from the cold calibration were low in comparison with the known ethylene content. These data are shown in Table 3.1. 

A prepolymer is made first by charging Pluracol E2000 [1000.0 g, 1.0 eq., poly(ethylene oxide), 56 OH, BASF] to a suitable container equipped with a mechanical stirrer and a nitrogen gas inlet. Flush the container with dry nitrogen and add Desmodur W (264.0 g, 2.0 eq., 4,4 -methylene-bis(cyclohexyl isocyanate), 31.8% NCO, Bayer). While maintaining a positive N2 pressure on the reaction mixture, stir and heat at 80°C for 2 h. Cool the product to room temperature and check the NCO content (theory = 3.32 %). It might be necessary to warm the highly viscous prepolymer to take samples for titration. To a portion of this prepolymer (250.0 g, 0.2 eq.), add Dabco T-12 (0.25 g, dibutyltin dilaurate,... 

It is most important that the temperature of the reaction mixture be not allowed to rise prematurely, since if it reaches 50° during the early stages the reaction velocity increases so rapidly that the contents are apt to boil out of the flask. For the same reason it appears necessary that a certain ratio between reacting mass and cooled surface be not exceeded. Runs of twice the above size have been carried out in a 5-I. flask without mishap, but temperature control was difficult and these conditions are extremely hazardous. A run of 4 kg. of ethylene chlorohydrin in a 12-I. flask was attempted, but rapidly went out of control. 

A gaseous alkene was passed into a cooled autoclave containing the complex, initially with agitation, and later without. Later, when the alkene was admitted to a pressure of 5.6 bar at 2°C, a slight exotherm occurred, followed by an explosion. The autoclave contents were completely carbonised. Mixtures of ethylene, aluminium chloride and nitromethane had exploded previously, but at 75°C. 

After that, the reactive mixture is held for 10 hours at 5 MPa. After the synthesis the mixture is cooled, the excess gases are withdrawn and the contents of the autoclave are sampled. In case there is diethylaluminum hydride in the products, they are subjected to additional ethylation by passing ethylene through the reactive mixture at 75 °C and 0.5-1 MPa for 1.5 hours. The mixture from the autoclave is sent into collector 7 and centri-... 

Description Ethylene, initiator and, if applicable, comonomers are fed to the process and compressed to pressures up to 3,100 bar before entering the tubular reactor. In the TS mode, the complete feed enters the reactor at the inlet after the preheater in the TM mode, part of the gas is cooled and quenches the reactor contents at various points of injection. 

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