Diazonium salts explosiveness

This group of internal diazonium salts (previously named diazooxides) contains those which are, like many other internal diazonium salts, explosively unstable and shock-sensitive materials. 

Solid diazonium salts are very sensitive to shock when perfectly dry and detonate violently upon gentle heating they are, therefore, of little value for preparative work. Happily, most of the useful reactions of diazonium compounds can be carried out with the readily-acoeasible aqueous solutions, so that the solid (explosive) diazonium salts are rarely requir. ... 

The Lassaigne procedure for detecting nitrogen in organic compounds frequently gives unsatisfactory results with explosive compounds (diazonium salts, polynitro compounds and the like) and with certain volatile nitrogenous substances, such as bases, their acyl derivatives or their salts. These difficulties... 

The reaction of [B qH q] with excess nitrous acid gives an explosive iatermediate that can be reduced to the nonexplosive bis inner diazonium salt l,10-(N2)2B2QHg [66750-86-5] (eq. 42). This diazonium species is a useful synthetic iatermediate. 

Diazotizations should be carried out above room temperature only in cases where a relatively dilute aqueous system (< 1 m amine, < 1 m mineral acid) is used and the diazonium salt formed does not precipitate (Bersier et al., 1971). Diazotization in highly concentrated sulfuric acid may involve a high risk of explosive detonation if carried out at a higher temperature (see Sec. 2.2). 

Thus, in the first case, if the amine is o-aminobenzoic acid, an explosive diazonium salt with a zwitterion structure is obtained ... 

When o-Nitroaniline is treated by sodium nitrite in acid medium and then by an inorganic sulphide, it forms an explosive diazonium sulphide. Note that even though the presence of a nitrated group does not help, it certainly is not a factor that is vital to cause the explosion, since this is a property that is common to all these diazonium salts whatever the nature of the substitution on the ring. The situation is exactly the same with p-nitroaniline. 

The dry salt was more or less explosive, depending on the method of preparation [1], DTA examination of a 15% solution of the diazonium salt in hydrochloric acid showed an exothermic decomposition reaction with the exotherm peak at 65°C. Adiabatic decompositon of the solution at 20° C took 80 min to attain the maximum... 

Addition of the dry diazonium salt to the crude liquid sulfide causes explosively violent interaction. Slow addition of the sulfide to the cooled salt, or dilution with a solvent, moderates the reaction. 

Alkyl and aryl arenediazoates ( diazoethers ) are generally unstable and even explosive compounds. They are produced by interaction of alcohols with (explosive) bis(arenediazo) oxides, or of -blocked phenols with diazonium salts. The thio analogues are similar. Individually indexed compounds are ... 

Several of these internal diazonium salts, prepared by diazotisation of anthranilic acids, are explosive in the solid state, or react violently with various materials. Individually indexed compounds (including analogous sulfonates) are Benzenediazonium-2-carboxylate, 2659 Benzenediazonium-3 or 4-carboxylate, 2661... 

A few diazonium salts are unstable in solution, and many are in the solid state. Of these, the azides, chromates, nitrates, perchlorates (outstandingly), picrates, sulfides, triiodides and xanthates are noted as being explosive, and sensitive to friction, shock, heat and radiation. In view of their technical importance, diazonium salts are often isolated as their zinc chloride (or other) double salts, and although these are considerably more stable, some incidents involving explosive decomposition have been recorded. 

There is a long history of the preparation of explosive solids or oils from interaction of diazonium salts with solutions of various sulfides and related derivatives. Such products have arisen from benzene- and toluene-diazonium salts with hydrogen, ammonium, or sodium sulfides [1,5] 2- or 3-chlorobenzene-, 4-chloro-2-methylbenzene-, 2- or 4-nitrobenzene- or 1- or 2-naphthalene-diazonium solutions with hydrogen sulfide, sodium hydrogen sulfide or sodium mono-, di- or poly-sulfides [l]-[4,7], 4-Bromobenzenediazonium solutions gave with hydrogen sulfide at -5°C a product which exploded under water at 0°C [2], and every addition of a drop of 3-chlorobenzenediazonium solution to sodium disulfide solution... 

Interaction of substituted arenediazonium salts with potassium O. O-diphenylphosphorodithioates gave a series of solid diazonium salts which decomposed explosively when heated dry [10], The unique failure of diazotised anthranilic acid solutions to produce any explosive sulfide derivatives under a variety of conditions has been investigated and discussed [6]. Preparation of diaryl sulfides from interaction of diazonium and thiophenoxide salts led to violent explosions, attributed to presence of some arenediazo sulfide during subsequent distillation of the diaryl sulfides. Precautions are detailed [11]. A safe method of preparation of diaryl sulfides from diazonium tetralluoroborates and sodium benzenethiolate in DMF is now available [12],... 

The products produced by interaction of diazonium salts and iodides are unstable and liable to be explosive in the solid state. They are usually the triiodides, but monoiodides have been isolated under specific conditions from diazotised aniline and o-toluidine. Products prepared from diazotised o-, m- or p-nitroanilmes, m-chloro-, -methoxy-, or -methyl-aniline are too unstable to isolate, decomposing below 0°C. 

Azo-dyes are important in medicinal chemistry in the treatment of Crohn s disease and ulcerative colitis [67], and the Sudan series of azo-dyes are commonly used as microbial stains [68]. Diazonium salts are intermediates in the production route of these useful structures. Diazonium salts are instable and explosive, which imposes... 

CAUTION From this point on, care must be taken never to allow the diazonium salt to become completely dry explosion hazard). 

The Balz-Schiemann synthesis can be applied not only to substituted anilines but also to aminobiphcnyls1,131 or amino-substituted fused polyaromatic compounds, such as naphthalene,1114,119,129 anthracene,136 phenanthrene,1135 acenaphthene,133 fluorene,1,131,134 benzanthracene,130 136 pyrene,136 chrysene,136 fluoranthene,131 fluorenone,1,131 anthra-quinone,1,137,139,140 benzanthrone,1,117,118 phenanthraquinone,138 or xanthone.132 Fluorinated pyridines,1,141"146 methylpyridincs,126,147 149 pyridinecarboxylic acids,150 quinolines,1,151 isoquinolines,152 quinazolone,1 thiazoles,153,154 isothiazoles,156 benzothiazoles,157 thiadiazoles,155 and thiophenes154 can also be obtained from the corresponding aminated heterocycles. Modified Balz-Schiemann methods are recommended for amino nitrogen-containing heterocycles, the diazonium salts of which are rather water-soluble and unstable (a violent explosion was reported for pyridine-3-diazonium tetrafluoroborate).159 These new techniques have also been specially adapted for pyrazol-, imidazol-, or triazolamines which fail to react under classical conditions.158... 

In each case the diazonium salt is isolated as the sparingly soluble tetraborofluorate (292 X = BF4) or perchlorate (292 X = C104) these form hygroscopic colorless to orange, crystalline solids. The tetrafluoroborates are reasonably stable to shock and friction, but the perchlorates are explosive. Acetone and acetonitrile are useful solvents for studying their reactions in solution. 

Diazonium salts are usually colorless crystalline solids, soluble in water, moderately soluble in alcohol, and when dry are violently explosive by percussion or upon heating. 

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