Nitrating acid mixture, spent

NITRATING ACID MIXTURE, SPENT see ACID MIXTURES, NITRATING... 

Nitrating acid mixture, spent, 5.1, 8 Nitrating acid, mixture, spent, all concentrations, unstable Solids containing corrosive liquids, n.o.s., 8... 

However, the second step of the reaction is relatively slow and the concentration of the nitronium ion is low. Sulphuric acid (7664-93-9), which speeds the reaction and maximizes the nitronium ion concentration, is mixed with nitric acid (nitric acid sulphuric acid, 36 61%) and the two are called mixed acid syn. nitrating acid mixture. Spent nitrating acids mixtures have a lower nitronium ion concentration, a higher water concentration, and some organic matter. 

Nitrating Acid Mixtures, spent 1826 60 Nitrocellulose, with plasticizing substance 2557 32... 

SOLVENT, n.o.s. SPENT MIXED ACID see ACID MIXTURES, SPENT, NITRATING STAIN see PAINTS, ENAMELS, LACQUERS, STAINS, etc. STANNIC CHLORIDE see TIN TETRACHLORIDE 1993 ... 

Acid mixture, spent, nitrating 1826 60 Alkali Metal Amides 1390 40... 

During my Cleveland years, I also continued and extended my studies in nitration, which I started in the early 1950s in Hungary. Conventional nitration of aromatic compounds uses mixed acid (mixture of nitric acid and sulfuric acid). The water formed in the reaetion dilutes the acid, and spent aeid disposal is beeoming a serious environ-... 

Nitration completed, the nitrator contents Me cooled down to 35°C to precipitate picric acid. The mixture is then transferred by means of compressed air (4 atm) to a higher mounted tMik Z (Fig. 120) Mid from there to the centrifuge W1 for separating picric acid from spent acid. For each tank a separate centrifuge is provided. 

This description is based on that given in the Encyclopedia [2]. A continuous stream of glycerine flows through a tubular path to a tubular reaction zone where it meets a stream of precooled nitrating acid. The tubular reaction zone is uncooled, the temperature is controlled by regulating the temperature of precooled nitric acid and also the proportion of nitratic acid to glycerine. It is desirable to cool the mixture of nitrate ester and spent acid to facilitate the separation of the nitrated product. 

Nitration can start from toluene or o-mtrotoluene,/Miitrtttoluenc being isolated as an important intermediate for dyes and medicinal products - (Vol. I, p. 277). Nitration is carried out continuously in a series of nitrators through which the toluene or /> nitrotoluene and the nitrating acids How in a countercurrent. In front of the first nitrator is placed an extraction vessel (not shown on the diagram) in wliich the residua) nitric acid and nitro compounds are extracted from the spent acid by toluene. After extraction, the spent acid/toluenc mixture enters the cooling unit. Toluene which now contains some nitrotoluene and acid is separated from the spent acid and enters the nitrator. The spent acid is sent for distillation. 

As pointed out in Vol. 11, p. 391 numerous attempts have been made introduce continuous methods of cellulose nitration. In addition to those me tioned in Vol. II. the following continuous methods were reported by Iliatl ar Rebel [2] Plunkett [22, Plunkett and McMillan [23], Reinhardt 24, Kai sey (25) described a continuous method with nitric-phosphoric acid mixture and Bergman [26] - nitration of powdered cellulose. Diels and Orth (27) us. spent acid for the first step of nitration followed by the second with fresh mix-acid. 

Preparation. Coned, nitric acid (300 ml.) is chilled in ice and treated with cooling with 300 ml. of coned, sulfuric acid. In a second flask 150 ml. of methanol is cooled in ice to keep the temperature below 10° during cautious addition of 50 ml. of coned, sulfuric acid. One third of the cold nitric-sulfuric acid is placed in each of three 500-ral. Erlenmeyers, and each portion is treated with one third of the methanol-sulfuric acid mixture, added in 2-3 min. with constant swirling. Methyl nitrate separates as an almost colorless oily upper layer. After standing for 15 min. the lower layer of spent acid is separated and quenched with a large volume of water to avoid vigorous decomposition. The combined ester is washed with 25 ml. of ice-cold 22% sodium chloride solution, and the process is repeated with addition of enough alkali to produce a faintly alkaline reaction. The ester is washed free of alkali with ice-cold salt solution, then washed twice with 15 ml. of ice water, dried over calcium chloride, decanted, and used directly. Yield 190-230 g. (66-80%). Distillation is not recommended the crude ester is satisfactory for synthetic purposes. 

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