Hazardous reactions with potassium

Derivation Frommonochloroacetic acid by reaction with potassium cyanide followed by hydrolysis. Hazard Strong irritant. 

Phosgene reacts, sometimes violently, with a large number of common inorganic (Chapter 9) and organic (Chapter 10) substances. Hazardous reactions with lithium, sodium, potassium, aluminium, lithium amide, hexa-2,4-diyn-l, 6-diol, propan-2-ol, and hexafluoropropene have been mentioned specifically [1787]. Mixtures of potassium and phosgene are reported to explode when subjected to shock [1913a]. In addition, phosgene... 

HAZARD RISK Combustible when exposed to heat or flame reacts with oxidizing materials moisture causes liberation of sulfuric acid rapid decomposition when heated above 100°C violent reaction with potassium-tert-butoxide vigorous exothermic hydrolysis when reacted with water in the presence of caustic catalysts at temperatures above 50°C decomposes at elevated temperature forming ethyl ether, which is more flammable than the material itself decomposition emits toxic fumes of SOx NFPA code H 3 F 1 R 1. 

EXPLOSION and FIRE CONCERNS noncombustible gas NFPA rating Health 4, Flammability 0, Reactivity 1 hazardous reactions with aluminum, potassium, sodium, and lithium reacts violently with sodium azide, isopropyl aleohol, tert-butyl azido formate, hexadiyn-1,6-diol, and hexfluoroisopropylideneamino lithium emits toxic and corrosive fumes of carbon monoxide and chlorine when heated to decomposition or on contact with water or steam use water spray or neutralize with sodium hydroxide or anhydrous ammonia for firefighting purposes. 

Most hazardous reactions of potassium hydroxide are similar to those of caustic soda and many are well documented (NFPA 1986). Explosions occurred when caustic potash was added to liquid chlorine dioxide (MeUor 1946), nitrogen trichloride, A-nitrosomethyl urea in n-butyl ether (NFPA 1986), and maleic anhydride (MCA 1960). Reaction with phosphorus yields toxic and flammable gas phosphine, which ignites spontaneously. Explosion may occur if impure tetrahydrofuran is heated or distilled in the presence of concentrated caustic potash solution. 

Precaution Violent reaction with potassium Hazardous Decomp. Prods. Heated to decomp., emits very toxic fumes of Cr HMIS Health 3, Flammability 0, Reactivity 1... 

Precaution Incompat. with fluorine, sodium potassium alloy may undergo hazardous reaction with boron, magnesium, or titanium Hazardous Decomp. Prods. Heated above 750 F, dec. to yield highly toxic fumes of F ... 

In response to a statement [1] that alloys of 2 alkali-metals (Li-Na, K-Na) can be prepared in small amounts by beating the solid components together, without heating in the latter case, it was emphasised that the real hazard arises not from reaction of the surface coating of potassium superoxide with potassium, but with residues of oil or organic matter on the potassium which will explode under impaction with the superoxide [2] - [4]. 

The collected papers of a symposium at Dallas, April 1956, cover all aspects of the handling, use and hazards of lithium, sodium, potassium, their alloys, oxides and hydrides, in 19 chapters [1], Interaction of all 5 alkali metals with water under various circumstances has been discussed comparatively [2], In a monograph covering properties, preparation, handling and applications of the enhanced reactivity of metals dispersed finely in hydrocarbon diluents, the hazardous nature of potassium dispersions, and especially of rubidium and caesium dispersions is stressed [3], Alkaline-earth metal dispersions are of relatively low hazard. Safety practices for small-scale storage, handling, heating and reactions of lithium potassium and sodium with water are reviewed [4],... 

The base employed by Brown and Yamashita was the potassium salt of 1,3-diaminopropane, prepared by reaction of potassium hydride with the solvent of the reaction, 1,3-diaminopropane. The reagent is very effective, and yields of isomerically pure products are high, but potassium hydride is hazardous, expensive and difficult to handle. 

Preparation. The original procedure (1, 315-318) for the preparation employed reaction of trimethyloxosulfonium iodide with NaH in DMSO. A newer, less hazardous route involves reaction of trimethylsulfoxonium iodide (Aldrich) with potassium /-butoxide in DMSO at room temperature.1... 

For the preparation of derivatives on a micro scale (at the microgram and picogram levels) reaction with methyl iodide was recommended [510] 100—200 /il of an acetone solution of barbituric acids was mixed with a 3- to 1000-fold molar excess of methyl iodide and refluxed with 3—5 mg of potassium carbonate. After about 30 min, 0.2 /A of the supernatant was injected directly into a column with 3% of OV-225, with temperature programming at 8°C/min from 100 to 240°C. The advantage of the method is that no toxic and hazardous chemicals are used. The method was further modified for the micro-determination of barbiturates in blood [511]. Only 20-25 /d of blood were necessary for the determination, and with the use of a detector sensitive to nitrogen down to 1 ng of barbiturate could be determined in this sample. The derivatization reaction was performed in a micro-refluxer (see Fig. 2.6). 

The reaction of a carboxylic acid with diazomethane is mild and efficient Diazomethane is usually prepared by reaction of potassium hydroxide with N-methyl-A/-nitroso-p-toluenesulfonamide (HAZARD carcinogenic) and used in ether solution since it is volatile, toxic, and explosive.44 Therefore, the method is most suitable for small scale reactions. A useful feature of the reaction is that diazomethane is intensely yellow and the consumption of the reagent is easily detected by the disappearance of the colour. It may be convenient to prepare the diazomethane in situ 45 (Trimethylsilyl)diazomethane is a safer alternative to diazomethane for the preparation of methyl esters and it is commercially available as a 2.0 M solution in hexanes,46 47... 

SAFETY PROFILE Mildly toxic by ingestion. A severe eye irritant. A skin, mucous membrane, and respiratory system irritant. Mutation data reported. Causes dermatitis. Dust is considered to be a significant industrial hazard. A common air contaminant. Violent reaction with maleic anhydride, nitroethane, nitromethane, nitroparaffins, nitropropane, phosphoms. Reaction with polychlorinated phenols + potassium nitrate forms extremely toxic products. See also CALCIUM COMPOUNDS. 

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