Picric acid manufacture

A flow diagram of picric acid manufacture by a method applied in the U S S R is presented in Fig. 120 (after Lebedev [5]). 

The second stage of picric acid manufacture - sulphophenol nitration - is carried out with a mixture of the following composition ... 

Picric acid (manufactured as an explosive) Plcryl chloride Picryl fluoride... 

The picric acid used to make class 2 ammonium picrate shall be made by the nitration of phenol and shall contain no material salvaged from trimmings or from loading operations. Class 2 ammonium picrate shall contain no reworked ammonium picrate made by way of any process other than the phenol nitration process. The irritant contaminants requirement is not applicable to ammonium picrate made from picric acid produced by the nitration of phenol. The color requirement is intended to cover the unavoidable presence of a small amount of the red form of ammonium picrate in admixture with the yellow form. The requirement with respect to irritant contaminants represents a control of the purity of picric acid used in manufacture when this is made by the dinitrochlorbenzene process. The chloroform soluble matter requirement also represents a control of the nature of impurities present in picric acid manufactured by a process other than the nitration of phenol. 

This leaction is lesorted to for the reason that naphthalene forms only the n-nitro-compound with niti icacid. The method, similar to that used for prepaiing aniline from nitiobenzene, cannot, therefore, be employed for the production of /3-n.tphtliyl-.amine. u-Naphthol is mainly used foi the manufacture of yellow and orange colours (Martins and naphthol yellow) by the action of nitric acid, and are similai m constitution to picric acid (see Prep. 107). 

Historically, the outbreak of the first World War provided a stimulus for the industrial preparation of large amounts of synthetic phenol, which was needed as a raw material to manufacture the explosive picric acid (2,4,6-trinitrophenol). Today, more than 2 million tons of phenol is manufactured each year in the United States for use in such products as Bakelite resin and adhesives for binding plywood. 

According to Urbanski (Ref 35. p 473) In the second half of the nineteenth century, Picric Acid was very widely used as a fast dye for silk and wool. The first definite suggestions as to the application of Picric Acid for the manufacture of explosives go back to the early second half of the nineteenth century. They referred... 

Uses Organic synthesis photographic agent manufacture of pesticides, herbicides, explosives, and wood preservatives yellow dyes preparation of picric acid and diaminophenol (photographic developer) indicator analytical reagent for potassium and ammonium ions insecticide. 

T. Urbanski, Chemistry andTechnology of Explosives, Vol. 7, Pergamon Press, Oxford, Manufacture of Picric acid . Chapter XIV, 499-523 (1964). 

Uses. Chemical intermediate in manufacture of dyes, picric acid, lumber preservatives, and diaminophenol hydrochloride (a photographic developer)... 

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. 

Easily fusible mixtures containing picric acid as the chief component were very widely employed in Russia and France during World War I and in the period immediately afterwards. A mixture of 51.5 or 80% picric acid with 48.5 or 20% dinitronaphthalene was used in the U.S.S.R. for filling aerial bombs and manufacturing demolition charges. 

Chloroprene is available commercially on a restricted basis in the United States as crude P-chloroprene with a minimum purity of 95% (Lewis, 1993 DuPont Dow Elastomers, 1997). The principal impurities are dichlorobutene and solvents, with smaller amounts of 1-chlorobutadiene (a-chloroprene), chlorobutenes and dimers of both chloroprene and butadiene. Due to its reactivity, chloroprene is stored at 0°C or below under nitrogen and contains significant quantities of inhibitors, such as phenothiazine, tert-butylcatechol, picric acid and the ammonium salt of A -nitroso-N-phenylhydroxy lamine, to prevent degradation and polymerization (Stewart, 1993). Generally within six weeks of manufacture, crude chloroprene is distilled to produce polymerization grade, which is used within approximately 24 h of distillation. 

Around 1902 the Germans and British had experimented with trinitrotoluene [(TNT) (C7H5N306)], first prepared by Wilbrand in 1863. The first detailed study of the preparation of 2,4,6-trinitrotoluene was by Beilstein and Kuhlberh in 1870, when they discovered the isomer 2,4,5-trinitrotoluene. Pure 2,4,6-trinitrotoluene was prepared in 1880 by Hepp and its structure established in 1883 by Claus and Becker. The manufacture of TNT began in Germany in 1891 and in 1899 aluminium was mixed with TNT to produce an explosive composition. In 1902, TNT was adopted for use by the German Army replacing picric acid, and in 1912 the US Army also started to use TNT. By 1914, TNT (1.4) became the standard explosive for all armies during World War I. 

Explosives and related compounds have become widely recognized as serious environmental contaminants. Among the nitrosubstituted aromatic compounds causing particular concern are 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol (picric acid), and many nitro- and/or amino-substituted aromatics that result from the manufacture and transformation of explosives. The threat posed by the presence of these compounds in soil and water is the result of their toxicity and is compounded by their recalcitrance to biodegradation. 

Wilbrand, in 1863. first prepared tnniiromluenc (TNT). C(,H (CH-.) (NO ),. The material was not manufactured in production quantifies until about 1900. The German military recognized the advantages of TNT as a replacement for picric acid, which they had used earlier. TNT was used extensively during World Wat I and became a standard military explosive. 

Major uses of phenol include production of phenolic resins, epoxy resins, and 2,4-D (regulated in many countries) as a selective solvent for refining lubricating oils in the manufacture of adipic acid, salicylic acid, phenophthalein, pentachlorophenol, acetophenetidine, picric acid germicidal paints, and pharmaceuticals as well as use as a laboratory reagent. Special uses include dyes and indicators, and slimicides. 

The catalytic process for the production of picric acid directly from benzene in one step by the action of nitric acid in the presence of mercuric nitrate has much theoretical interest and has been applied, though not extensively, in plant-scale manufacture. It yields about as much picric acid as is procurable from the same weight of benzene by the roundabout method of sulfonating the benzene, converting the benzene sulfonic acid into phenol, and nitrating the phenol to picric acid—and the benzene which is not converted to picric acid is for the most part recovered as such or as nitrobenzene. The first mention of the process appears to be in the patent of Wolffenstein and Boeters.55... 

Trinitrophenetol or ethyl picrate, m.p. 78°, is prepared by the same methods as trinitroanisol. The explosive properties of the two substances have been studied by Desparmets and Calinaud, and by Desvergnes,72 who has reported the results of the earlier workers together with data of his own and discussions of methods of manufacture and of the explosive properties of mixtures with picric acid, ammonium nitrate, etc. Drop test with a 5-kilogram weight were as follows ... 

From the pamphlet Tetra-Nitro-Aniline Flurscheim, Verona Chemical Company, sole licensed manufacturers for the United States, North Newark, New Jersey, 1917( ), p. 4. Giua, op. dt., p. 317, states that the force of TNA measured in the lead block is 420 compared with picric acid 297. 

No m-nitrotetryl is produced if pure dimethylaniline is used in the usual process for the manufacture of tetryl. The amount of this impurity in the usual process depends upon the amount of monomethylaniline which may be present. A large excess of sulfuric acid tends toward the production of m-nitro compounds, but a reduction in the amount of sulfuric acid is not feasible for this increases the amount of benzene-insoluble material. m-Nitro-tetryl reacts with water, as TNA does the nitro group in the 3-position is replaced by hydroxyl, and m-hydroxytetryl or 2,4,6-trinitro-3-methylnitraminophenol, yellow crystals from water, m.p. 183°, is formed. This substance resembles picric acid and forms explosive salts. It is readily soluble in water, and... 

Many chlorate mixtures, particularly those which contain sulfur, sulfides, and picric acid, are extremely sensitive to blows and to friction. In the Street explosives, later called Cheddites because they were manufactured at Chedde in France, the chlorate is phlegmatized by means of castor oil, a substance which appears to have remarkable powers in this respect. The French Commission des Substances Explosives in 1897 commenced its first investigation of these explosives by a study of those which are listed below, and concluded 35 that their sensitivity to shock is... 

Ammonium picrate (explosive D) is manufactured by the neutralization of a hot aqueous solution of picric acid (2,4,6-trinitrophenol) with aqueous ammonia. 

The heavy metal salts of picric acid are dangerously sensitive, and its major use is for the manufacture of ammonium picrate (Explosive D). 

Uses Picric acid is a white to yellowish, highly flammable crystalline substance. It is used in the manufacture of fireworks, matches, electric batteries, colored glass, explosives, and disinfectants. Pharmaceutical, textile, and leather industries also make use of picric acid. 

The second stage in the manufacture of picric acid is the nitration of the phenolsulphonic acid (sulphophenol) obtained. The simplest reactors used for this process are stoneware jars, tourills , which may be of various size (e.g. 85 cm diameter... 

During World War I a method of manufacture of picric acid was established in the United States. 

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