Hazards perchlorates

The ion [Cr(CF3-S03)] + can be isolated from a solution of chromium(iii) in 9.IM-CF3 SO3H, but in 7.4M-acid less than 10% of the complex is formed, suggesting the use of CFs SOs" as an indifferent ion instead of the more powerfully oxidizing (and often more hazardous) perchlorate ion. At still higher acid concentrations a bis(trifluoromethylsulphonate) species, thought to be rranj-[Cr(Ha0)4(CF3-SO3)2]+, is formed. 

Because of these hazards, perchloric acid is usually handled under fume hoods with wash-down and air scrubbing capabilities, which are not available on standard laboratory fume hoods. The crystalline form of the acid, which is explosive and shock sensitive, can precipitate on hood surfaces washing down the hood interior solves this problem. 

Triethylsilyl perchlorate. This reagent represents an explosion hazard. ... 

Salts. In addition to the dangers of perchlorate salts, other salts such as nitrates, azides and diazo salts can be hazardous and due care should be taken when these are dried. Large quantities should never be prepared or stored for long periods. 

The fire department blamed the accident on welders cutting in hazardous areas without a fire watch, highly combustible structural components (fiber-glass-resin), high-density storage of highly flammable and detonable material, spilled ammonium perchlorate about the plant, and high w ind conditions. 

Perchloric Acid Fume Cupboards Use of concentrated perchloric acid gives rise to special hazards and these special fume cupboards should be for perchloric acid use only. Contact of hot perchloric acid with organic materials and certain metals (especially copper) can lead to the formation of perchlorates which,... 

Hazards arising from the oxidation of organic compounds are greater when the reactants are volatile, or present as a dust or an aerosol. Liquid oxygen and various concentrated acids, e.g. nitric, sulphuric or perchloric acid, and chromic acid are strong oxidizing agents. The use of perchloric acid or perchlorates has resulted in numerous explosions their use should be avoided when possible (refer to Table 6.5). 

Oxidants more concentrated than air are of greater hazard potxential, and the extent of involvement of the common oxidants Perchloric acid Chlorine Nitric acid Hydrogen peroxide Sulfuric acid METAL CHLORATES... 

Because trifluoromethanesulfonic acid is a stronger acid than perchloric acid, under no circumstances should perchlorate salts be used with the neat acid, because the hot anhydrous perchloric acid so formed represents an extreme explosion hazard, especially in contact with transition metal complexes (or with organic materials). See Perchloric acid Dehydrating agents See other ORGANIC ACIDS... 

Use of the perchlorate salt gives a cleaner product than the tosylate, but is more hazardous. 

Explosion hazards of mixtures of lactose monohydrate with potassium chlorate, potassium nitrate or potassium perchlorate are assessed. 

Perchlorate salts of the azide complexes, and also of the dichloro analogue, may present an explosion hazard. 

Preparative hazard See Perchloric acid Oleic acid... 

The use of the perchlorate anion to precipitate the cobalt complex to determine the yield [1] is deprecated on the grounds of potential hazard [2], though it was not found possible to cause the salt to detonate by pounding, but it will bum if ignited. A spectroscopic assay method is suggested as an alternative to precipitation [3],... 

Most of the numerous and frequent hazards experienced with perchloric acid have been associated with either its exceptional oxidising power or the inherent instability of its covalent compounds, some of which form readily. Although the 70-72% acid of commerce behaves when cold as a very strong, but non-oxidising acid, it becomes an extreme oxidant and powerful dehydrator at elevated temperatures (160°C) or when anhydrous [1],... 

The latent hazards in storing and handling the explosive mixtures of perchloric acid with acetonitrile or dimethyl ether are discussed. 

Treatment of tervalent compounds of antimony with perchloric acid can be very hazardous. 

Cochrane, A. R. G. etal., School Sci. Rev., 1977, 58, 706-708 Hazards of using perchloric acid to hydrolyse DNA are stressed. Perchloric acid can cause ignition of any organic material, even a considerable time after contact. Other acids to effect hydrolysis are suggested. 

Attention is drawn to the hazards involved in the use of perchloric acid in a published method [1] for transesterification of triglycerides with methanol. Alternative acid catalysts and safety precautions are suggested [2],... 

Precautions are necessary to prevent explosions when using the mixed acids to oxidise organic materials for subsequent analysis. The sulfuric acid probably tends to dehydrate the 70% perchloric acid to produce the hazardous anhydrous acid. See Nitric acid, etc., above... 

In view of the ready commercial availability and apparent stability of the hexahy-drate, it is probable that the earlier report of explosion on impact, and deflagration on rapid heating [1] referred to the material produced by partial dehydration at 100°C, rather than the hexahydrate [2], The caked crystalline hydrated salt, prepared from aqueous perchloric acid and excess cobalt carbonate with subsequent heated evaporation, exploded violently when placed in a mortar and tapped gently to break up the crystalline mass, when a nearby dish of the salt also exploded [3]. Subsequent investigation revealed the probable cause as heating the solid stable hexahydrate to a temperature ( 150°C) at which partial loss of water produced a lower and endothermic hydrate (possibly a trihydrate) capable of explosive decomposition. This hazard may also exist for other hydrated metal perchlorates, and general caution is urged [4,5],... 

The hexasolvated complex may be hazardous with respect to detonation. Other metal perchlorates and nitrates solvated with DMSO are explosive. 

Organic materials, Sulfuric acid Analytical Methods Committee, Analyst, 1976, 101, 62-66 Advantages and potential hazards in the use of mixtures of 50% hydrogen peroxide solution and cone, sulfuric acid to destroy various types of organic materials prior to analysis are discussed in detail. The method is appreciably safer than those using perchloric and/or nitric acids, but the use of an adequate proportion of sulfuric acid with a minimum of peroxide is necessary to avoid the risk of explosive decomposition. The method is not suitable for use in pressure-digestion vessels (PTFE lined steel bombs), in which an explosion occurred at 80° C. 

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