Phosgene production

The metabolism of carbon tetrachloride proceeds via cytochrome P-450-dependent dehalogenation (Sipes et al. 1977). The first step involves cleavage of one carbon-chlorine bond to yield Cl- and a trichloromethyl free radical, which is then oxidized to the unstable intermediate trichloromethanol, the precursor of phosgene. Hydrolytic dechlorination of phosgene yields C02 and HC1 (Shah et al. 1979). Although there are similarities in the metabolism of chloroform and carbon tetrachloride, metabolic activation of chloroform produces primarily phosgene, whereas the level of phosgene production from... 

Osterwalder U. Continuous process to fit batch operation safe phosgene production on demand. Symp. Pap.—Inst. Chem. Eng., North West. Branch. Rugby, U.K. IChemE, 1996 6.1-6.6. 

As a result, no temperature increase due to the exothermal chemical process was observed. With this single-channel reactor, a phosgene productivity of 3.5 kg per year is projected for continuous operation. 

Phosgene Production of plastics, pesticides, chemicals Edema... 

Estanased fram acetic add and phosgene production stadstics. 

Breakdown confidential, worldwide phosgene production is estimated of phosgene to range from 6 to 8 millions tons/year. onsuniption The breakdown of phosgene consumption is the follo-... 

Chlorinated hydrocarbons mixed with an excess of air. l emperatures corresponding to maximum phosgene production. Measured in mg of COCl per g of chlorinated hydrocarbon. 

In particular for liquid phosgene production, noncondensable impurities shouid be... 

Manufacture of dichlorine is generally by the electrolysis of brine, although electrolysis of aqueous HCl or catalytic oxidation of dry HCl may be employed [2165]. As mentioned above, complete reaction of the dichlorine must be ensured, as this is an undesirable impurity in the phosgene product [437,1488], particularly where the material is to be used for high specification polycarbonates or isocyanates. 

The metering operation is considered to be critical with regard to the economics of the plant. If the metering of the reactants is not controlled within precise limits, then excess of carbon monoxide must be used to prevent dichlorine contamination of the final product. This is wasteful not only of carbon monoxide, but also of phosgene product in the condenser... 

The converters used for phosgene production are normally of simple design, consisting of tubular heat exchangers to remove the heat formed from the reaction. The reaction normally operates at atmospheric pressure, although at higher pressures (2-12 atm) smaller reaction vessels may be used, liquefaction for shipment is unnecessary, and the output for a given mass of catalyst is increased [285]. 

Fig. 14 A packed-bed microreactor used for phosgene production by Jensen et al. (A) top view (B) interleaved inlets (C) catalyst filter. (From Ref.t f)...

The non-phosgene production of isocyanates takes place through thermolysis of the corresponding carbamate. The carbamate synthesis may involve several... 

Sciuto et al. (1995) showed that postexposure treatment of rabbits with NAC prevented a reduction in GSH induced by phosgene. Production of leukotrienes LTC4, D4 and E4 was also reduced. 

Several examples will illustrate the use of technical innovation to provide greener products and processes. These are elimination of CC14 waste during phosgene production production of Tyvek envelopes from waste Smart automo-... 

The manufacturing process has remained essentially the same since it was introduced in the 1920s. The reaction, carried out in the vapor phase, is nearly quantitative and the phosgene product is recovered by condensation and purification [1]. 

Despite the apparent simplicity of the chemistry, the commercial production of phosgene is carried out by a relatively small number of large chemical companies that have developed the know-how to handle the toxic and corrosive phosgene product. Because of its extreme toxicity, most production is captive for immediate use in downstream processes. There is no on-site storage of phosgene, and the phosgene inventory in downstream processes is minimized. 

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