Nitric And Sulfuric Acids

Before moving on into the manufacture of some of the really good explosives, it would be best to make the reader familiar with the two ingredients which will be used over and over in the processes described here. They are nitric and sulfuric acid. A familiarity with these two substances will take much of the mystery out of explosive manufacture. 

Nitric acid is the key, indispensable ingredient in the manufacture of the explosives found in this book. The sulfuric acid can often be made do without, if one is willing to use, a greater amount of the most concentrated nitric acid, and accept a lower yield of product in the process. Not so with the nitric acid. Only nitric acid in the specified or higher strengths will give that desired product. 

Nitric acid can be obtained in reasonably large amounts, by anyone who does not look like a refugee from the local insane asylum or drunk tank, at drug stores or chemical supply outlets. In most cases, a drug store will have to send out for it, and small chemical suppliers may have to also. Fuming nitric acid is less likely to be on the shelves than the standard concentrated nitric acid. 

To make this good quality high strength acid, the following materials are needed concentrated sulfuric acid, sodium nitrate, and dry ice. Also required is a distilling kit with ground glass joints and a vacuum adapter so the product can be distilled under a vacuum. The best vacuum source is an aspirator (cost 10) because the acid fumes, will not harm it, and the water flow will flush them down the drain. 

Some bubbling will begin in the 2000 ml flask as nitric acid begins to boil out. Heat should be applied from the hot plate to keep the process going. A good, but not violent rate of boiling is 

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The element is a steel-white metal, it does not tarnish in air, and it is the least dense and lowest melting of the platinum group of metals. When annealed, it is soft and ductile cold-working greatly increases its strength and hardness. Palladium is attacked by nitric and sulfuric acid. 

The overall reactivity of the 4- and 5-positions compared to benzene has been determined by competitive methods, and the results agreed with kinetic constants established by nitration of the same thiazoles in sulfuric acid at very low concentrations (242). In fact, nitration of alkylthiazoles in a mixture of nitric and sulfuric acid at 100°C for 4 hr gives nitro compounds in preparative yield, though some alkylthiazoles are oxidized. Results of competitive nitrations are summarized in Table III-43 (241, 243). For 2-alkylthiazoles, reactivities were too low to be measured accurately. 

An other example is the oxidation of 4-(hydroxymethyl)thiazole with a mixture of nitric and sulfuric acids at -5°C (24, 27). 

Nitration Phenols are nitrated on treatment with a dilute solution of nitric acid in either water or acetic acid It IS not necessary to use mixtures of nitric and sulfuric acids because of the high reactivity of phe nols... 

The practical problems He ia the separatioa of the chlorine from the hydrogea chloride and nitrous gases. The dilute nitric acid must be reconcentrated and corrosion problems are severe. Suggested improvements iaclude oxidation of concentrated solutions of chlorides, eg, LiCl, by nitrates, followed by separation of chlorine from nitrosyl chloride by distillation at 135°C, or oxidation by a mixture of nitric and sulfuric acids, separating the... 

Sir Joseph Swan, as a result of his quest for carbon fiber for lamp filaments (2), learned how to denitrate nitrocellulose using ammonium sulfide. In 1885 he exhibited the first textiles made from this new artificial sHk, but with carbon fiber being his main theme he failed to foUow up on the textile possibihties. Meanwhile Count Hilaire de Chardoimet (3) was researching the nitrocellulose route and had perfected his first fibers and textiles in time for the Paris Exhibition in 1889. There he got the necessary financial backing for the first Chardoimet silk factory in Besancon in 1890. His process involved treating mulberry leaves with nitric and sulfuric acids to form cellulose nitrate which could be dissolved in ether and alcohol. This collodion solution could be extmded through holes in a spinneret into warm air where solvent evaporation led to the formation of soHd cellulose nitrate filaments. 

Nitration with mixed nitric and sulfuric acids provides 79% yield of 3-nitro-2,6-difluoropyridine [5860-02-1], bp 218—220°C (414). 

Nitronaphthalene. 1-Nitronaphthalene is manufactured by nitrating naphthalene with nitric and sulfuric acids at ca 40—50°C (37). The product is obtained in very high yield and contains ca 3—10 wt % 2-nitronaphthalene and traces of dinitronaphthalene the product can be purified by distillation or by recrystaUization from alcohol. 1-Nitronaphthalene is important for the manufacture of 1-naphthalenearnine. Photochemical nitration of naphthalene by tetranitromethane in dichioromethane and acetonitrile to give 1-nitronaphthalene has been described (38). 

Organic Reactions. Nitric acid is used extensively ia iadustry to nitrate aHphatic and aromatic compounds (21). In many iastances nitration requires the use of sulfuric acid as a dehydrating agent or catalyst the extent of nitration achieved depends on the concentration of nitric and sulfuric acids used. This is of iadustrial importance ia the manufacture of nitrobenzene and dinitrotoluene, which are iatermediates ia the manufacture of polyurethanes. Trinitrotoluene (TNT) is an explosive. Various isomers of mononitrotoluene are used to make optical brighteners, herbicides (qv), and iasecticides. Such nitrations are generally attributed to the presence of the nitronium ion, NO2, the concentration of which iacreases with acid strength (see Nitration). 

Alcohols and glycerols are nitrated by esterification ia a mixture of concentrated nitric and sulfuric acids. This reaction is of importance ia the production of nitroglycerin from glycerol and nitrocellulose from cellulose. 

Cellulose nitrate (pyroxylin) [9004-70-0], made from cellulose and a mixture of nitric and sulfuric acids, is called gun cotton and is used in explosives. Nitrates of lower DS find some appHcation in coatings and adhesives. 

Nitrobenzotrichloride is also obtained in high yield with no significant hydrolysis when nitration with a mixture of nitric and sulfuric acids is carried out below 30°C (31). 2,4-Dihydroxybenzophenone [131 -56-6] is formed in 90% yield by the uncatalyzed reaction of benzotrichloride with resorcinol in hydroxyHc solvents (32) or in benzene containing methanol or ethanol (33). Benzophenone derivatives are formed from a variety of aromatic compounds by reaction with benzotrichloride in aqueous or alcohoHc hydrofluoric acid (34). 

MO calculations of the cinnoline ring system show that the relative order of reactivities for electrophilic substitution is 5=8>6 = 7>3 4. This is confirmed experimentally, as nitration of cinnoline with a mixture of nitric and sulfuric acids affords 5-nitrocinnoline (33%) and 8-nitrocinnoline (28%). Similarly, 4-methylcinnoline gives a mixture of 4-methyl-8-nitrocinnoline (28%) and 4-methyl-5-nitrocinnoline (13%). 

When cinnoline 1-oxide is treated with nitric and sulfuric acids or potassium nitrate in sulfuric acid, 4-nitrocinnoline 1-oxide is obtained in yields ranging from 3-64% depending on the reaction conditions. With a mixture of fuming nitric and sulfuric acids, the corresponding 4-nitro-, 4,5-dinitro- and a small amount of the 5-nitro-cinnoline derivatives are obtained. 

Both 4-nitrocinnoline 1-oxide and the 5-nitro isomer give 4,5-dinitrocinnoline 1-oxide when treated with fuming nitric and sulfuric acids. Cinnoline 1-oxide also reacts with benzoyl chloride/silver nitrate to give 3-nitrocinnoline 1-oxide in 71% yield. 

Nitration of cinnoline 2-oxide takes a different course. With nitric and sulfuric acids or with potassium nitrate and sulfuric acid a mixture of 8-nitrocinnoline 2-oxide, 6-nitrocinno-line 2-oxide and 5-nitrocinnoline 2-oxide is obtained, while with benzoyl nitrate in chloroform only a low yield (1.5%) of the 5-nitro derivative is obtained. 

Indole can be nitrated with benzoyl nitrate at low temperatures to give 3-nitroindole. More vigorous conditions can be used for the nitration of 2-methylindole because of its resistance to acid-catalyzed polymerization. In nitric acid alone it is converted into the 3-nitro derivative, but in a mixture of concentrated nitric and sulfuric acids 2-methyl-5-nitroindole (47) is formed. In sulfuric acid, 2-methylindole is completely protonated. Thus it is probable that it is the conjugate acid which is undergoing nitration. 3,3-Dialkyl-3H-indolium salts similarly nitrate at the 5-position. The para directing ability of the immonium group in a benzenoid context is illustrated by the para nitration of the conjugate acid of benzylideneaniline (48). 

Anodic protection against acids has been used in a number of processes in the chemical industry, as well as during storage and transport. It is also successful in geometrically complicated containers and tubings [12], Carbon steel can be protected from nitric and sulfuric acids. In the latter case, temperature and concentration set application limits [17]. At temperatures of up to 120°C, efficient protection can only be achieved with concentrations over 90% [ 18]. At concentrations between 67 and 90%, anodic protection can be used at up to 140°C with CrNi steels [19]. 

Nitroglycerin (NG) production provides a good example of the reductions in inventory that can be achieved by redesign. It is made from glycerin and a mixture of concentrated nitric and sulfuric acids. The reaction is very exothermic if the heat is not removed by cooling and stirring, an uncontrollable reaction is followed by explosive decomposition of the NG. 

The first electrophilic substitution reaction studied in the isoxazole series was the nitration of 3,5-dimethylisoxazole reported by Morgan and Burgess in 1921.The reaction occurs smoothly on heating with mixed nitric and sulfuric acids at 100°C and leads to the 4-nitro derivative in 86% yield. 

Similar to the alkylation and the chlorination of benzene, the nitration reaction is an electrophilic substitution of a benzene hydrogen (a proton) with a nitronium ion (NO ). The liquid-phase reaction occurs in presence of both concentrated nitric and sulfuric acids at approximately 50°C. Concentrated sulfuric acid has two functions it reacts with nitric acid to form the nitronium ion, and it absorbs the water formed during the reaction, which shifts the equilibrium to the formation of nitrobenzene ... 

Dinitrotoluenes are produced hy nitration of toluene with a mixture of concentrated nitric and sulfuric acid at approximately 80°C. The main products are 2,4- and 2,6-dinitrotoluenes ... 

Aromatic rings can be nitrated by reaction with a mixture of concentrated nitric and sulfuric acids. The electrophile is the nitronium ion, N02+, which is generated from HNO3 by protonation and loss of water. The nitronium ion reacts with benzene to yield a carbocation intermediate, and loss of H+ from this intermediate gives the neutral substitution product, nitrobenzene (Figure 16.4). 

The use of mixed acid (mixt of nitric and sulfuric acids) as a nitrating agent was first described in 1846 by Muspratt Hoffman (Ref 1). The sulfuric acid in their mixt was considered to be a dehydrating agent , a view first advanced by Spindler (Ref 4) and developed further by Markovnikov (Ref 7) Sapozhnikov (Ref 8). The modern concept of the role of sulfuric acid in mixed... 

In the purification of TNT the following impurities have to be removed (1) traces of nitric and sulfuric acids (2) unsymmetrical isomers (3) products of incomplete nitration (4) byproducts (tetranitromethane, trinitrobenzene, nitrobenzoic acids, nitrocresols, etc)... 

Sol in w, alk, carbon disulfide, chlf, nitric and sulfuric acids... 

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