Nitric acid, anhydrous distillation

Nitric Acid, Anhydrous. Prepared by distillation of coned nitric acid with coned sulfuric acid by treating so -dium or potassium nitrate with 100% H2S04 and removing HN03by distillation by fractional crystallization of coned HN03, Review of preparation and properties of pure HNOy Stern et a/, Chet i. Rev, 60, 185-207 (I960), See also Niiric Acid. 

Anhydrous HNO3 can be obtained by low-pressure distillation of concentrated aqueous nitric acid in the presence of P4O10 or anhydrous H2SO4 in an all-glass, grease-free apparatus in the dark. The molecule is planar in the gas phase... 

A three-necked round-bottom flask is fitted with a dropping funnel, a thermometer, and a magnetic stirrer and is heated in a water bath to 30°. Tetralin (1.32 g, 0.01 mole) and 50 ml of 3.5 Anitric acid solution are placed in the flask and brought to temperature. Ceric ammonium nitrate (21.9 g, 0.04 mole) is dissolved in 100 ml of 3.5 N nitric acid, and the solution is added dropwise to the reaction mixture at a rate such that the temperature does not rise and only a pale yellow color is evident in the reaction mixture. At the completion of the reaction (1 to 2 hours), the mixture should be colorless. The solution is cooled to room temperature, diluted with an equal volume of water, and extracted twice with ether. The ether solution is dried with anhydrous sodium sulfate, filtered, and the ether is evaporated. The residue may be distilled to yield a-tetralone (bp 113-11676 mm or 170749 mm) or may be converted directly to the oxime, which is recrystallized from methanol, mp 88-89°. 

A. Dinitrodurene.—A solution of 13.4 g. (0.1 mole) (Notes 1,2) of durene (p. 32) in 100 cc. of chloroform is added to 75 cc. of concentrated sulfuric acid in an 800-cc. beaker provided with a thermometer and an efficient mechanical stirrer. The mixture is cooled to io°, and 16 g. (10.7 cc.) of fuming nitric acid (sp. gr. 1.5) (Note 3) is added drop by drop, with stirring, from a 125-cc. separatory funnel, the mixture being cooled in an ice-salt bath and the nitric acid added at such a rate that the temperature does not rise above 50° (about fifteen minutes is required for the addition). As soon as all the acid has been added the mixture is poured into a separatory funnel, the sulfuric acid layer is removed and the upper chloroform layer is immediately (Note 4) run into 500 cc. of 10 per cent sodium carbonate solution. The sulfuric acid layer is discarded because it contains very little dinitrodurene. Four portions are nitrated and the combined chloroform solutions are washed twice with 2.5 per cent sodium carbonate solution, dried over night with 30 g. of anhydrous calcium chloride, filtered, and the chloroform distilled off until crystals of dinitrodurene begin to appear. At this point four times the volume of hot 95 per cent ethyl alcohol is added (about... 

Sodium Nitrotetrazolate Dihydrate (NaNT) Anhydrous aminotetra-zole (8.48 g, 0.10 mol) and copper sulfate pentahydrate (0.2 g, 0.8 mmol) were added to a solution of nitric acid (9 mL, 65 %) in distilled water (60 mL). This was added to a pre-cooled solution of sodium nitrite (20.8 g, 0.30 mol) and cupric sulfate pentahydrate (11 g, 0.044 mol) in distilled water (100 mL). The solution was maintained at 15 to 18 °C during the addition by means of a cool water bath. After addition, the solution was stirred for 30 min at the same temperature... 

Preparation of Anhydrous Nitric Acid. Put 50 g of sodium nitrate into retort 1 made from refractory glass (see Fig. 80) and pour in 100 ml of a 98% solution of sulphuric acid. Carefully heat the retort with the flame of a burner and distil oS a 90-95% nitric acid solution into receiver 4 cooled by a mixture of water and ice. Garry out distillation until the nitrogen oxides in the retort disappear. 

Fig. 91. Apparatus for preparing anhydrous nitric acid (distillation in vacuum)...

When the concentrated acid is exposed to the air it imbibes moisture and if mixed with water it absorbs a sensible amount of heat, owing to the formation of another hydrate of much greater persistency, This stable liydrate contains four equivalents of water, and one of nitric acid (HO, NO, 3 Aq.) it hea a specific gravity of 1 424, and is composed of sixty per cent, of anhydrous aoid, and forty of water. This hydrate has a higher boiling point than the protokydrato, and distils at 250° unaltered. 

Anhydrous Nitric Acid. One hundred per cent nitric acid may be prepared by distillation of a mixture of concen-... 

Analysis of the compound for platinum is accomplished gravimetrically by reduction of a known weight of the anhydrous salt to metallic platinum with formic acid.3 For the determination of chloride, 0.3 g. of the anhydrous salt is dissolved in 40 ml. of distilled water containing 250 mg. of hydrazine sulfate the solution is boiled gently until platinum metal is formed and coagulated. Then, without removal of the platinum, the solution is made 1 f in nitric acid and is titrated potentiometrically with standard 0.2 F silver nitrate solution. Anal. Calcd. for Na2PtCl6 Pt, 42.99 Cl, 46.88. Found Pt, 42.78 Cl, 46.73. 

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