Nitric Acid Direct Decomposition

A novel, mild system for the direct nitration of calixarenes has been developed using potassium nitrate and aluminum chloride at low temperature. The side products of decomposition formed under conventional conditions are not observed in this system, and the p-nitro-calixarenes are isolated in 75-89% yields.17 Such Friedel-Crafts-type nitration using nitryl chloride and aluminum chloride affords a convenient system for aromatic nitration.18 Nitryl chloride was previously prepared either by the oxidation of nitrosyl chloride or by the reaction of chlorosulfonic acid with nitric acid. However, these procedures are inconvenient and dangerous. Recently, a mixture of sodium nitrate and trimethysilyl chloride (TMSC1) has been developed as a convenient method for the in situ generation of nitryl chloride (Eq. 2.6). 

Mercury fulminate is relatively resistant to the action of dilute acids, in particular to that of nitric acid, but concentrated acids cause decomposition. Thus, under the influence of nitric acid decomposition occurs with evolution of NO, CO, acetic acid and mercuric nitrate. Under the influence of concentrated hydrochloric acid free fulminic acid is evolved (with an odour resembling that of hydrogen cyanide) as well as the decomposition products hydroxylamine hydrochloride, formic acid, mercuric chloride (Carstanjen and Ehrenberg [32] Scholl [33]). Mercury fulminate explodes on direct contact with concentrated sulphuric acid. 

Nitric acid is manufactured at the present day by one of three processes (i) By the direct oxidation of nitrogen in the electric arc as indicated in connection with the fixation of nitrogen (ii) By oxidation of ammonia as indicated in connection with that compound and (iii) By the decomposition of sodium nitrate with sulphuric acid. Some chemical changes involved in the third reaction have just been discussed. The plant employed consists of (i) the distilling apparatus (ii) the condensing system (iii) the receiving vessel (iv) the bleaching system and (v) the absorption apparatus. 

The simplest reaction for the destruction of N2O is shown in Eq. (9.21). Unfortunately many catalysts for this reaction are sensitive to water. And nitric acid plant tail gases contain 0.5 to 1.0% water. This means relatively high temperatures (> 400°C) are needed to make Direct Decomposition of N20 possible221. 

The SCR of N20 with hydrocarbons is an exothermic reaction and the adiabatic temperature rise is 30 to 100°C, depending on the concentration of added hydrocarbon. In an existing nitric acid plant, the expander is usually designed to work at a very well-defined temperature, so the heat of the N20 removal reaction has to be removed. A tail gas cooler can be used for this purpose. Direct decomposition of N20 produces only 3 to 5°C of heat so cooling of the gases before they enter the expander is normally not necessary with this process221. 

The cyclohexadiene derivative (V), formed by addition of a nitric acid molecule, is very unstable and it is difficult to speak about a definite direction of the decomposition reaction of the compound V. 

Alkylphosphinic acids should also be considered as compounds in which the alkyl is directly attached to phosphorus, since they have been obtained by the oxidation of primary alkylphosphines with fuming nitric acid. (CH3)2=PO-OH is hardly an acid, but rather resembles a higher aliphatic alcohol in its waxy appearance and melting-point (76° C.). This compound sublimes without decomposition. 

Sample Solution Transfer 9 mL (10 g) of sample into a 250-mL Erlenmeyer flask, and add 15 mL of water, 5 mL of nitric acid, and 2 mL of sulfuric acid. Mix, and heat gently on a hot plate to initiate and maintain a vigorous decomposition. When decomposition is complete, place a small, stemless funnel in the mouth of the flask, and continue as directed for the Standard Solution, beginning with and heat until strong fumes of sulfuric acid evolve. ... 

For the determination of beryllium, different organic materials were destroyed by low temperatur ashing or pressure decomposition with nitric acid/hydrofluoric acid in a Teflon tube. Interfacing elements were masked or pre-extracted at pH 9 the beryllium trifluoracetyl-acetonate was formed and extracted into benzene. The concentration of Be(tfa)2 solutions is possible From biological fluids such as urine beryllium is directly extracted as Fe(tfa)2 Direct dissolution-chela-... 

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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