Handling of phosgene

Personnel protection and safe handling of phosgene 3.1.5.1 Safety procedures for chemical processing plants... 

Personnel engaged in the handling of phosgene should be trained to recognize its odour... 

The problems raised by the handling of phosgene and the hazards this.entails have led to the development of different methods to synthesize TDI. Mitsui Toatsu Chemicals in Japan has developed a process based on the carbonylation of dinitrotoluenes in the presence of an alcohol. The catalyst employed to do this is palladim-on-charcoaL It operates in the presence of ferric chloride and pyridine. The diurethane (or dicarbamatc) of the alcohol used is obtained ... 

Waste Disposal. Because of its low Boiling poiat and high, toxicity, measures must be taken to prevent the entrance of phosgene iato drains or sewers. If recycle of phosgene is not feasible, phosgene waste can be handled by one of the decomposition methods mentioned above, ie, caustic scmbbiag, moist activated carbon towers, or combustion. 

N,N-Dimethylisobutyramide (Gavrilov, N. Koperina, A. Klutcharova, M. Hull., soc. Chim. France 1945, 12, 773) was converted to l-chloro-N,N,2-11 imrUiylproponylaraine according to the procedure of Org. Synth. 1979, 55, 26, In nl% yield, bp 118-121 C. Freshly-distilled oxalyl chloride was used iir.iKiid of phosgene. The propenylamine should be handled carefully in a vytltii i 1.0 avoid its rapid hydrolysis by moisture. 

Phenyl iso-thiocyanate, 642,643 Phenylthioureas, 422, 655 Phenylurea, 644, 645 Phenylurethanos, 264 Phloroacetophenone, 727, 736 Phosgene, 185 Phosphoric acid, 189, 284 Phosphorus, detection of, 1043 Phosphorus, red, purification of, 193 Phosphorus oxychloride, 367 Phosphorus pentabromide, 489, 492 Phosphorus pentachloride, 799, 822, 974 Phosphorus pentoxide, handling of, 407 Phosphorus tribromide, 189, 492 Phosphorus trichloride, 367 Phosphorus trisulphide," 836 Phthalamide, 983 Phthalein test, 681 ... 

Although it will not be possible to dispense with some of these reagents entirely, their industrial use is likely to be confined to a small group of experts who are properly equipped to handle and contain these materials. In some cases, catalytic alternatives may provide an answer, such as the use of catalytic carbonylation instead of phosgene and solid acids as substitutes for hydrogen fluoride. 

Care and precautions Precautions and strict management are necessary in the handling of perchloroethylene. It should not be used around an open flame, welding arc, intense ultraviolet light source, or smoke. Like most solvents containing chlorine, perchloroethylene also breaks down and releases very hazardous compounds such as phosgene, hydrochloric acid, and chlorine. 

Among the most useful of these azolides is l,l -carbonyldiimidazole (253). This compound is extremely reactive towards nucleophilic reagents because the carbonyl group is subject to electron withdrawal from both sides. Also, although it is very rapidly hydrolyzed by water at room temperature with vigorous carbon dioxide evolution, tihe compound is crystalline, and much more easily handled than phosgene which has similar reactivity. In the formation of 1-acylimidazoles compound (253) reacts in equimolar proportions with a carboxylic acid in an inert solvent to give practically quantitative yields. This reaction comprises a two-step mechanism (Scheme 145) in which the carboxylic acid reacts initially... 

Disulfuryl fluoride is a clear colorless liquid with a boiling point of 51°. Its vapor pressure over the temperature range —28 to 43° follows the equation logioP(mm.) = 8.015— 1662/T. It has an inhalation toxicity of the same order as that of phosgene, and should be handled only in a well-ventilated area. Its thermal decomposition to sulfur trioxide and sulfuryl fluoride is not very appreciable below 200° but is rapid at 400-500°. In the presence of metal fluorides such as ceaum or sodium fluoride, however, its decomposition point is considerably low er. It hydrolyzes rather slowly to give fluorosulfuric acid. It is not very soluble in cold concentrated sulfuric acid or fluorosulfuric acid, but is soluble in acetonitrile, ethyl ether, carbon tetrachloride, monofluorotrichloromethane, and benzene. 

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