Very toxic

Hydrogen sulphide is a colourless gas, b.p. 213 K, with a most unpleasant odour the gas is very toxic, but the intense odour fortunately permits very minute concentrations of the gas to be detected. 

CAUTION Carry out the preparation in an efficient fume cupboard (hood) since diazomethane is very toxic. 

Diazomethane. CA UTION. Diazoniethane is very toxic its preparation should be carried out only in a fume cupboard (hood) provided with a powerful exhaust system. The use of a screen of safety glass is recommended. 

An alkaloid present in tobacco a very toxic compound sometimes used as an insecticide)... 

Dorex is very toxic (see Table 2) and must be handled with extreme care. Because it may produce severe dermatitis on moist skin, it is difficult to use in hot, humid climates inhalation of the dust or spray may irritate the mucous membranes. Whereas symptoms may include a flushed face, tachycardia, headache, vertigo, and hypotension, it does not produce the typical cyanide effect. 

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. 

Phenol fumes are irritating to the eyes, nose, and skin. According to the National Institute for Occupational Safety and Health (NIOSH), exposure to phenol should be controUed so that no employees are exposed to phenol concentrations >20 mg/m, which is a time-weighted average concentration for up to a 10-h work day, 40-h work week. Phenol is very toxic to fish and has a nearly unique property of tainting the taste of fish if present in marine... 

Methyl amyl ketone, derived from the crossed aldol condensation of -butyraldehyde and acetone, is used predominandy as a high soHds coatings solvent. It is also employed as a replacement for the very toxic 2-ethoxyethyl acetate [111 -15-9J. 

Ammonium cyanide may be prepared in solution by passing hydrogen cyanide into aqueous ammonia at low temperatures. It may also be prepared from barium cyanide and ammonium sulfate, or calcium cyanide with ammonium carbonate. It may be prepared in the dry state by gentiy heating a mixture of potassium cyanide or ferrocyanide and ammonium chloride, and condensing the vapor in a cooled receiver. Ammonium cyanide is soluble in water or alcohol. The vapor above soHd NH CN contains free NH and HCN, a very toxic mixture. 

Ben2oate esters, like most organic esters, are not very toxic. They are not absorbed through the skin as rapidly as alkyl esters but are more potent physiologically. They are also moderate skin irritants. The oral LD qS (mouse) for methyl- to butyUiydroxy ben2oates range between 8 and 5 g/kg. 

Insecticide methomyl is a very toxic pesticide and is highly soluble in water (57.9 g/1). It has a low sorption affinity to soil and can cause groundwater and surface water contamination in agricultural areas. Solubilities of methomyl in different solvents are in methanol 1000 g/1, in aceton 730 g/1, in ethanol 420 g/1, in isopropanol 220 g/1, in toluene 30 g/1. 

Wash with cone H2SO4, then Na2C03 soln, dry with anhydrous Na2C03, and finally pass through a 50cm column of activated alumina before distn. Alternatively, wash with 10% ferrous sulfate soln to remove peroxides, then H2O, dry with CaS04, and dist in vac. Add 0.2% of catechol to stabilise it. VERY TOXIC. 

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.]... 

Ethyl trifluoromethanesulfonate [425-75-2] M 178.1, b 115 /atm, 118-120 /atm, d 1.378, Hp 1.336. The ester reacts slowly with H2O and aqueous alkali. If its IR has no OH bands (-3000 cm" ) then purify by redistillation. If OH bands are present then dilute with dry Et20 and shake (carefully) with aqueous NaHC03 until effervescence ceases, then wash with H2O and dry (MgSOa), filter, evaporate and distil the residue under slight vacuum then at atmospheric pressure in a N2 atmosphere. IT IS A POWERFUL ALKYLATING AGENT, AND THE FUMES ARE VERY TOXIC - CARRY ALL OPERATIONS IN AN EFFICIENT FUME CUPBOARD. [Gramstad and Hazeldine J Chem Soc 173 7956 Howells and McCown Chem Rev 77 69 1977.]... 

Mercury(II) trifluoroacetate [13257-51-7] M 426.6. Recrystd from trifluoroacetic anhydride/trifluoroacetic acid [Lan and Kochi J Am Chem Soc 108 6720 7986]. Very TOXIC and hygroscopic. 

Creeps/melts very reactive in air/water. Difficult to process very toxic. 

Cautionl Hydrogen selenide is very toxic. This preparation should be carried out in a well-ventilated hood. The operator should wear rubber gloves. The apparatus should be screened from any bright light. 

Cyanogen chloride (Chlorine cyanide) CNCI Poisonous liquid or gas Vapour highly irritating and very toxic Colourless liquid with a strong irritating smell Boiling point 1 3°C Vapour density 2.1... 

The packaging of certain dangerous chemicais (e.g. those iabeiied toxic , very toxic or corrosive must be fitted with chiid-resistant ciosures, or tactiie danger warnings (for the biind) if soid to the pubiic. 

Contact with acids liberates very toxic gas... 

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