Nitrophenol salts

A number of salts of picric acid have been described already (Vol. I). Some salts of polynitrophenols and of heavy metals have initiating properties. One of the earliest known substances of this kind is lead picrate. Its high sensitiveness to the action of mechanical impact, however, raised difficulties in its practical utilization. 

Urbanski and Kruszynska [41] made a comparative study of the sensitiveness to impact of lead picrate and other initiating explosives. They found lead picrate to be more sensitive than any other substance. They also examined the decomposition of lead picrate on hot metal plates. On contact with a metal surface heated to 341 °C it explodes after 3 sec, and on one heated to 370°C after 1 sec. 

From their results the authors calculated the activation energy of the thermal decomposition which leads to explosion of this substance, and obtained a value of 55.6 kcal/mole. 

During World War II the Germans employed, on a small scale, cap compositions containing lead picrate for the manufacture of electric fuses giving few gaseous products. 

The lead picrate for this purpose was produced in the following way [42]. Into a stainless-steel reactor equipped with a stirrer of the type used for the manufacture of lead azide and other initiators (cf. Fig. 49) 8 1. of a solution containing 1.44 kg of lead nitrate and 151. of ice water were poured. Fifteen litres of a solution containing 1.5 kg of picric acid were then added. During the reaction the temperature should be maintained between 6 and 10°C. Since the temperature rises with the precipitation of lead picrate, 7-8 more litres of ice water must be poured into the reactor, usually a few minutes after the picrate has begun to precipitate. After 4 hr the liquid was decanted from above the precipitate the latter was transferred to a cloth filter and washed with alcohol (101.) to which an aqueous solution of lead, nitrate (500 ml of a 30% solution) has been added to avoid the dissolution of lead picrate during washing. 2.2 kg of product was obtainable from one batch. 

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Other reactions of aminoguanidine with nitrous acid Cyanamide salts Silver cyanamide Nitrocyanamide salts Nitrophenol salts Lead picrate Lead styphenate Lead stypheratc manufacture... 

The preparation of bis(furoxano)-2-nitrophenol salts is a four-step procedure developed by Fronabarger and his collaborators. It is based on formation of a diazidotri-nitrobenzene intermediate containing a hydrolysable group. This intermediate gives bis(furoxano)-2-nitrophenol by hydrolysis [54]. 

COj liberated. All acids esters which hydrolyse easily, e.g., methyl oxalate (p. 357) salts of amines nitrophenols. 

Nitromersol/777-j5 , y (4) and mercurophen [52486-78-9] (5) are prepared by the same mercuration reaction as phenyhnercuric acetate, only 4-nitro-(9-cresol and o-nitrophenol are used, respectively, iastead of benzene. The second step is reaction with sodium hydroxide to form the anhydride or sodium salt, respectively. 

Iron Reduction. The reduction of nitrophenols with iron filings or turnings takes place in weakly acidic solution or suspension (30). The aminophenol formed is converted to the water soluble sodium aminopheno1 ate by adding sodium hydroxide before the iron-iron oxide sludge is separated from the reaction mixture (31). Adjustment of the solution pH leads to the precipitation of aminophenols, a procedure performed in the absence of air because the salts are very susceptible to oxidation in aqueous solution. 

In this solvent the reaction is catalyzed by small amounts of trimethyl-amine and especially pyridine (cf. 9). The same effect occurs in the reaction of iV -methylaniline with 2-iV -methylanilino-4,6-dichloro-s-triazine. In benzene solution, the amine hydrochloride is so insoluble that the reaction could be followed by recovery. of the salt. However, this precluded study mider Bitter and Zollinger s conditions of catalysis by strong mineral acids in the sense of Banks (acid-base pre-equilibrium in solution). Instead, a new catalytic effect was revealed when the influence of organic acids was tested. This was assumed to depend on the bifunctional character of these catalysts, which act as both a proton donor and an acceptor in the transition state. In striking agreement with this conclusion, a-pyridone is very reactive and o-nitrophenol is not. Furthermore, since neither y-pyridone nor -nitrophenol are active, the structure of the catalyst must meet the conformational requirements for a cyclic transition state. Probably a concerted process involving structure 10 in the rate-determining step... 

Commercial Mononitrophenol. Yel cryst mass mp about 45° mostly ortho- with some para-nitrophenol. Can be prepd by the nitration of phenol with dil nitric acid (1 3) at a temp below 35° (see Ref, p 283). Although it does not possess expl properties and does not gelatinize NC, it has been used as the fuel component of some commercial expls. It forms salts, some of which are weak expls which were used in expl compns, for example, Voight Explosives (qv)... 

It was first prepd by Nietzki and Burckhardt (Ref 2) by the action of S0% nitric acid followed by 63% nitric acid on diquinoyltrioxime, C6H2( OX NOH)3 (Beil 7, 886), at a temp lower than room temp. By neutralizing the soln, a sparingly sol K salt was pptd, which in turn was converted by double decompn into a still less sol Ba salt. From the latter, by the action of a ealed quantity of sulfuric acid, free Tetra-nitrophenol was obtained... 

N.C6H3(0H).S03Na, mw 241.16, N 5.8%, orange-red crysts. Can be prepd by treating the product obtained on sulfonation of phenol with Na nitrate and an excess of sulfuric acid. This salt, which is a mixt of Na o- and p-nitrophenol-sulfonates, was patented in 1911 by A. Voight for use in expl mixts such as Na nitrophenol-sulfonate 22.5 to 25, K or Na nitrate 45 to 65,... 

Perfluoroalkyl carbanions, generated by reversible nucleophilic addition of a fluoride anion to fluoroalkenes, react with dry benzenediazonium chloride in dimethyl formamide, giving phenylazoperfluoroalkanes in 41-53% yield (Dyatkin et al., 1972). The dianion obtained from 1,2-dinitrobenzene with dipotassium cyclo-octatetraenide reacts in a complex way with arenediazonium salts, forming 4-aryl-azo-2-nitrophenol in 46-58% yield (Todres et al., 1988). 

The course of the reaction has not been fully clarified. Hydrolytic and aromatization processes are probably responsible for the formation of colored or fluorescent deriva4 tives (cf. Potassium Hydroxide Reagent). For instance, sevin is converted to a-naphthalkali metal salt of the o-hydroxycinnamic acid pro- duced by hydrolytic cleavage of the pyrone ring is converted from the non-fluorescent cis- to the fluorescent trans-form by the action of long-wavelength UV light (X = 365 nm) [2]. 

Methyl parathion is an organophosphorus insecticide that is commercially produced in the United States and abroad. Methyl parathion, 0,0-dimethyl 0-(4-nitrophenyl) phosphorothioate, is not known to occur as a natural substance (lARC 1983). It is commercially produced by the reaction of 0,0-dimethyl phos-phorochloridothionate and the sodium salt of 4-nitrophenol in acetone solvent (EPA 1974b HSDB 1999 NIOSH 1976 NRC 1977 Worthing 1979). 

Still another method was reported by Schrader 12) (Equation 31). Compounds prepared by the general method of reaction of the chloro esters with the nitrophenol, either in the presence of base or by using a salt of the phenol, are shown in Formula 32. 

This salt of the tfci-p-quinonoid form of 2-hydroxymercurio-4-nitrophenol explodes on heating. 

In the pure state m- and p-nitrophenols are colourless, but the o-com-pound, on the other hand, is yellow. The salts of all three, however, are intensely coloured, the o- and wi-compounds being orange-red and orange-yellow and the p-compound deep yellow. (Use of p-nitro-phenol as an indicator.)... 

An attempt has been made to explain the strong colours of the salts of the nitrophenols as a rearrangement involving the formation of a... 

On various grounds, however, this explanation may be questioned. In particular it may be pointed out that m-nitrophenol behaves like the other two isomers and hence its alkali salts must also be quinonoid in form. But wi-quinones are unknown throughout the whole range of the aromatic compounds. Moreover, there are numerous examples of substances which undergo a deepening in colour when they form salts but cannot change to a tautomeric quinone. Thus the disodium and dipotassium salts of yellowish-brown anthraquinol are deep blood-red in colour (p. 335). 

Finally,- the alkali salts of phenol itself are more deeply coloured than is phenol. This fact cannot indeed be recognised subjectively, but investigation of the absorption of ultra-violet light demonstrates it. Thus it has been found that the absorption by sodium phenoxide much more nearly approaches the subjectively visible part of the spectrum than does that of the free phenol. The difference is so considerable that it provides also a satisfactory explanation of a subjectively perceptible deepening of colour from colourless to yellow. The colour of the salts of nitrophenols is therefore ascribed to the bathychromic (colour-deepening) efEect of salt-formation. 

Rate comparisons for liberation of p-nitrophenol from 10-4 M solutions of amino-acid ester salts in the presence of 5.0 x 10 3 M [323] or [324] at 25.0°Ca... 

Kinetic data for release of p-nitrophenol from amino acid and dipeptide ester salt substrates in the presence of the macrocyclic reagent [3271 ... 

The lead salts of nitromethane, mono-, di- or tri-nitrophenols bum at faster rates (up to 640-fold) than the parent compounds. Lead salts of trinitromethane, trini-trobutyric acid or dinitro-benzoic or -p-toluic acids bum at slightly faster rates (up to 10-fold) than the parent compounds. 

Several metal salts of nitrophenols exhibit very limited thermal stability, especially heavy metal salts, and several instances of explosive decomposition at modest (or even ambient) temperatures have been recorded. Individual entries are ... 

A Flavobacteriumsp. (ATCC 27551), isolated from rice paddy water, degraded parathion to 4-nitrophenol. The microbial hydrolysis half-life of this reaction was <1 h (Sethunathan and Yoshida, 1973 Forrest, 1981). When parathion (40 pg) was incubated in a mineral salts medium containing 5-day-old cultures of Flavobacterium sp. ATCC 27551, complete hydrolysis occurred in 72 h. The major degradation product was 4-nitrophenol (18.6 iig) (Sudhaker-Barik and Sethunathan, 1978a). 

This family of organonitrogen pesticides includes the nitrophenols and their salts, for example, Dinoseb and the substituted dinitroanilines, trifluralin, and nitralin. Figure 3 shows a typical commercial process for the production of a dinitroaniline herbicide [8]. In this example, a chloroaromatic is charged to a nitrator with cyclic acid and fuming nitric acid. The crude product is then cooled to settle out spent acid, which can be recovered and recycled. Oxides of nitrogen... 

Methyl parathion was developed around 1948 when the German technology was discovered after the war. Parathion (the ethyl analog) is not so safe and is used to a lesser extent. Both methyl parathion and parathion are synthesized by reacting the sodium salt of p-nitrophenol with 0,0-dialkyl phosphorochloridothioate, which is made from phosphorus pentasulfide, the alcohol, and chlorine. 

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