Neutralization phosgene

The animal should be bathed with copious amounts of water and a mild soap. Phosgene oxime reacts quickly with tissue and decontamination is not expected to be entirely effective after pain has been produced. Sodium hypochlorite (0.5%) or isotonic sodium bicarbonate can help neutralize phosgene oxime that has not yet reacted with tissue. Bums should be managed with topical silver sulfadiazine and systemic antibiotics as needed (Roberts, 1988). Horses and sheep should receive tetanus prophylaxis. Other species should be vaccinated on a case by case basis. 

The protonation of COClj has been studied by ab initio techniques, using a 4-31G basis set [1073a,1950b] the species [Cl jC=0"-H] is predicted to have a longer C=0 bond, but shorter C-Cl bonds, than the neutral phosgene molecule. 

Carbonates ate manufactured by essentially the same method as chloroformates except that more alcohol is required in addition to longer reaction times and higher temperatures. The products are neutralized, washed, and distilled. Corrosion-resistant equipment similar to that described for the manufacture of chloroformates is requited. Diaryl carbonates are prepared from phosgene and two equivalents of the sodium phenolates or with phenols and various... 

Chemical Reactivity - Reactivity with Water Decomposes, but not vigorously Reactivity with Common Materials No reaction Stability During Transport Stable Neutralizing Agents for Acids and Caustics Can be absorbed in caustic soda solution. One ton of phosgene requires 2,480 lbs. of caustic soda dissolved in 1(X)0 gal. of water Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Properties.—Colourless liquid possessing a sweet smell, b. p. 60—62° sp.gr. 1-498 at 15° very slightly soluble in water non-inflammable. As chloroform slowly decomposes in presence of air and sunlight into phosgene, it is usual to add a little alcohol to the commcicial product, which arrests the change. Pure chloroform is neutral to litmus, has no action on silver nitrate solution and does not discolour concentrated sulphuric acid when shaken with it for an hour or left for a day. 

At the start of interfacial polymerization, bisphenol A is dissolved in methylene chloride, then introduced into a reactor. Phosgene is injected into the reactor as a liquefied gas together with an aqueous solution of sodium hydroxide. The methylene chloride and the aqueous solutions are immiscible polymerization occurs at the interface between them. The reactants are combined in a rapidly stirred reactor as shown in Fig. 20.7. The sodium hydroxide neutralizes the hydrochloric acid that is generated by polymerization, while the organic phase serves as a solvent for the polymer. The organic phase is separated and washed to remove traces of the base or salts after which the solvent is removed. 

Spill/Leak Disposal Isolate the incident scene dress in proper personal protective equipment (see above) do not allow contact with any materials, liquid or gas stop and/or control leak or hazard if possible to do so and control water - use water spray to control vapor and any vapor cloud. Contain product and keep phosgene from entering sewers, streams, or water intakes. Dike surface flow, and depending on the temperature, try to neutralize the product for disposal using agricultural lime (slaked lime), crushed limestone, or soda ash, or sodium bicarbonate. 

The workup for such reactions involves neutralization and concomitant generation of salts such as NaCl, Na2S04, and (NH4)2S04. The ehmination of such waste streams and a reduction in the dependence on the use of hazardous chemicals, such as phosgene, dimethyl sulfate, peracids, sodium azide, halogens, and HF, are primary goals in green chemistry. 

Caution. Phosgene is a highly toxic gas that reacts with water to form HCl and has a characteristic odor of freshly mown hay. It is necessary to carry out this portion of the reaction using standard Schlenk techniques and in a well-ventilated fume hood. Unreacted phosgene can be neutralized with aqueous base. 

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