Toxicity phosgene

Suggested Alternatives for Differential Diagnosis Acute respiratory distress syndrome, congestive heart failure, pulmonary edema, AIDS, pneumonia, cardiogenic shock, septic shock, phosgene toxicity, phosphine toxicity, salicylate toxicity with pulmonary edema, influenza, plague, tularemia, and anthrax. 

To quote directly from a very recent, and authoritative, report on phosgene toxicity [1297a] ... 

Institution of Chemical Engineers, "Phosgene Toxicity - A Report of the Major Hazards Assessment Panel Toxicity Working Party", Institution of Chemical Engineers, Rugby, 1993. 

The phosgene toxicity, separation of hydrochloric acid from excess phosgene, and the use of chlorinated solvents as a reaction medium are the major drawbacks of this reaction process. Extensive studies have suggested that carbamate and dicarbamate can serve as environmentally benign precursors for the synthesis of isocyanate and diisocyanate (1-5). Figure 1 illustrates nonphosgene routes for the synthesis of two important diisocyanates [i.e., 4,4 -diphenylmethane diisocyanate (MDI) and toluene diisocyanate(TDI)] via carbonate and carbamate. 

IChemE and U. UK (Institute of Chemical Engineers), Phosgene Toxicity Monograph, report of the major hazards assessment panel toxicity working party, 1993. 

Chloroform undergoes oxidation to the very poisonous phosgene upon exposure to light and air. Commercial specimens are therefore stored in brown bottles and contain 1-2 per cent, of alcohol the latter converts the toxic phosgene into the harmless substance diethyl carbonate ... 

There is a significant difference in the toxicological effects of saturated and unsaturated afiphatic aldehydes. As can be seen in Table 6, the presence of the double bond considerably enhances toxicity. The precautions for handling reactive unsaturated aldehydes such as acrolein, methacrolein [78-85-3] and crotonaldehyde should be the same as those for handling other highly active eye and pulmonary irritants, as, for example, phosgene. 

Toxicity. Sulfur tetrafluoride has an inhalation toxicity comparable to phosgene. The current OSHA standard maximum allowable concentration for human exposure in air is 0.4 mg/m (TWA) (54). On exposure to moisture, eg, on the surface of skin, sulfur tetrafluoride Hberates hydrofluoric acid and care must be taken to avoid bums. One case of accidental exposure of electrical workers to decomposed SF gas containing SF has been cited (108). 

Naphthol is mainly used in the manufacture of the insecticide carbaryl (59), l-naphthyl A/-methyicarbamate/ iJ-2j5 - (Sevin) (22), which is produced by the reaction of 1-naphthol with methyl isocyanate. Methyl isocyanate is usually prepared by treating methylamine with phosgene. Methyl isocyanate is a very toxic Hquid, boiling at 38°C, and should not be stored for long periods of time (Bhopal accident, India). India has developed a process for the preparation of aryl esters of A/-alkyl carbamic acids. Thus l-naphthyl methylcarbamate is prepared by refluxing 1-naphthol with ethyl methylcarbamate and POCl in toluene (60). In 1992, carbaryl production totaled > 11.4 x 10 t(35). Rhc ne-Poulenc, at its Institute, W. Va., facihty is the only carbaryl producer in United States. 

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. 

Carbon tetrachloride [56-23-5] (tetrachloromethane), CCl, at ordinary temperature and pressure is a heavy, colorless Hquid with a characteristic nonirritant odor it is nonflammable. Carbon tetrachloride contains 92 wt % chlorine. When in contact with a flame or very hot surface, the vapor decomposes to give toxic products, such as phosgene. It is the most toxic of the chloromethanes and the most unstable upon thermal oxidation. The commercial product frequendy contains added stabilizers. Carbon tetrachloride is miscible with many common organic Hquids and is a powerhil solvent for asphalt, benzyl resin (polymerized benzyl chloride), bitumens, chlorinated mbber, ethylceUulose, fats, gums, rosin, and waxes. 

Chlorobenzenes are stable compounds and decompose slowly only under excess heating at high temperatures to release some HCl gas and traces of phosgene. It is possible, under certain limited conditions of incomplete combustion or pyrolysis, to form polychlorinated dibenzo-/)-dioxins (PCDDs) and dibenzofurans (PCDFs) from chlorobenzenes (Cm OROCARBONS and cm OROHYDROCARBONS, toxic aromatics). 

Carbazole-9-carbonyl chloride [73500-82-0J M 300.0, m 100-103 , 103.5-104.5 . Recrystd from C6H6. If it is not very pure (presence of OH or NH bands in the IR) dissolve in pyridine, shake with phosgene in toluene, evaporate and recrystallise the residue. Carry out this experiment in a good fume cupboard as COCI2 is very TOXIC, and store the product in the dark. It is moisture sensitive. The amide has m 246.5-247 , and the dimethylaminoethylamide hydrochloride has m 197-198 . [Weston et al. J Am Chem Soc IS 4006 1953.]... 

Phosgene [75-44-5] M 98.9, b 8.2 /756mm. Dried with Linde 4A molecular sieves, degassed and distilled under vacuum. This should be done in a closed system such as a vacuum line. HIGHLY TOXIC, should not be inhaled. If it is inhaled operator should lie still and made to breath ammonia vapour which reacts with phosgene to give urea. 

Caution Since the toxic gas phosgene is employed in this preparation, the reaction should be performed in an efficient hood. The glassware, which may be coated with a solution of phosgene, should be washed before it is removed from the hood. 

Other chlorinated solvents such as tetrachloroethylene or chloroform may be used in place of carbon tetrachloride. Caution The reaction of sulfur trioxide with chlorinated solvents has been reported to give phosgene and other toxic products. Adequate venting of all by-product gases is essential. 

Thermal degradation in contact with flame or red hot surfaces will produce highly-toxic gases, e.g. acid chlorides and phosgene. Reaction with freshly-galvanized surfaces may produce dichloroacetylene, which is also highly toxic. 

Acetyl chloride CH3COCI Colourless, fuming, corrosive liquid Flash point 4°C When heated, emits phosgene Decomposes violently with water to produce heat and toxic fumes MCI... 

Benzoyl chloride C6H5COCI Colourless, fuming, corrosive liquid with a strong odour Combustible flash point 72°C Generates phosgene gas when heated Reacts strongly with water or water vapour, producing heat and toxic/corrosive fumes Use of water must be considered carefully... 

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