Nitric acid extractive distillation

The demand for concentrated nitric acid 98+% strength, primarily for use in nitration, led to the use of sulfuric acid in the extractive distillation of nitric acid. The maximum boiling azeotrope of 68 wt % nitric acid prevents distilling the 55-60 wt % nitric acid produced in an ammonia oxidation plant (AOP) to a strength greater than 68 wt % unless extractive distillation is used. 

Selenium. Selenium has been determined colorimetrically by formatrion of a diaminobenzidine complex, 420 nm, after an oxidation and distillation (13). Method S-190 for selenium in air extracts the analyte from filters by 0.1 N nitric acid leaching. The nitric acid extracts are aspirated into an argon/hydrogen-air flame, and the absorbance is recorded for the 196 nm analytical line. The method discourages the use of a carbonaceous flame like air-acetyelene. Many analysts use air acetylene because it is convenient. Background correction is required for either flame type. 

From each sample, 10.0 g was taken for the extraction procedure, without drying, in order to avoid chemical transformation (due to heating, oxidation processes, etc.). At the same time, 1.0 g was taken for dry weight determination. Control samples were processed for each extraction step. Reagents of p.a. quality were used only, while the acids used were additionally distilled. Deionized water was used for all purposes. For the desorption of eventually present heavy metals, the complete equipment, including glassware, PVC containers, etc. was pre-treated with diluted nitric acid. Extractions were performed at 2(fC and a soUd/liquid ratio of 1 45. 

Extractions were carried out in 50 ml Nalgene centrifuge tubes with sealable watertight caps. Laboratory vessels were rinsed in dilute nitric acid and distilled water before each use. Analysis of solutions was carried out using a ARL MAXIM simultaneous measurement Induction Coupled Plasma Atomic Emission Spectroscope. 

For dehydrogenation, add this ester to dilute nitric acid (20 ml. of the concentrated acid diluted with 40 ml. of water) and boil the mixture under reflux for about 5 minutes, during which the ester gently efferv esces and Anally gives a clear solution. Cool this solution in ice-w ater, make alkaline with aqueous sodium carbonate solution and extract tw ice with ether (50 ml. for each extraction). Dry the extract with sodium sulphate, filter, and then distil using a small distilling-flask... 

Phenol may be nitrated with dilute nitric acid to 3deld a mixture of o- and nitrophenols the 3deld of p-nitrophenol is increased if a mixture of sodium nitiute and dilute sulphuric acid is employed. Upon steam distilling the mixture, the ortho isomer passes over in a substantially pure form the para isomer remains in the distillation flask, and can be readily isolated by extraction with hot 2 per cent, hydrochloric acid. The preparation of m-nitrophenol from wt-nitroaniline by means of the diazo reaction is described in Section IV,70. 

Aromatic alcohols are insoluble in water and usually burn with a smoky flame. Their boiling points are comparatively high some are solids at the ordinary temperature. Many may be oxidised by cautious addi-tion of dilute nitric acid to the corresponding aldehyde upon neutralis-tion of the excess of acid, the aldehyde may be isolated by ether extraction or steam distillation, and then identified as detailed under Aromatic Aldehydes, Section IV,135. 

The acidic contaminants can also be removed by employing a system that utilizes extractions, precipitation, distillation, and other treatments for rendering the waste stream acceptable for current disposal standards (18—20). First Chemical Corporation uses such a system. Residual nitric acid can be removed by a multistage countercurrent Hquid-Hquid extraction. The nitric acid (ca 25%) is then reconcentrated by distillation for further use. 

Quantitatively, sulfur in a free or combined state is generally determined by oxidizing it to a soluble sulfate, by fusion with an alkaH carbonate if necessary, and precipitating it as insoluble barium sulfate. Oxidation can be effected with such agents as concentrated or fuming nitric acid, bromine, sodium peroxide, potassium nitrate, or potassium chlorate. Free sulfur is normally determined by solution in carbon disulfide, the latter being distilled from the extract. This method is not useful if the sample contains polymeric sulfur. 

The residue is cooled and dissolved in 171 ml. of nitric acid (sp. gr. 1.4) (Note 3), and the solution is warmed for 30 minutes on the steam bath. It is immediately concentrated to complete dryness under reduced pressure (Note 4). The flask is cooled, 300 ml. of benzene is added, and the mixture is refluxed for a short time to render the cake friable. The benzene is removed by decantation, and the cake is pulverized and extracted six times by refluxing it briefly with 300-ml. portions of ether. The combined benzene and ether extracts are filtered and concentrated to a volume of about 225 ml. In the meantime the residual salts are extracted twice by refluxing them vigorously for a short time with 300-ml. portions of benzene. The benzene solutions are separated by decantation and added to the ether concentrate. The distillation is then continued untO about two-thirds of the benzene has been removed, when the benzene solution is poured into a beaker and allowed to cool. The methylsuccinic acid is collected on a filter and is washed by shaking a suspension of it in 150 ml. of chloroform (Note 5). The yield of air-dried product, melting at 110-111 , amounts to 87-93 g. (66-70%) (Note 6). 

Treatment of 3,5-dimethylphenol with dilute nitric acid, followed by steam distillation of the reaction mixture, gave a compound A (C8H9NO3, mp 66°C) in 36% yield. The nonvolatile residue from the steam distillation gave a compound B (CSH9NO3, mp 108°C) in 25% yield on extraction with chloroform. Identify compounds A and B. 

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°. 

Fenchone, Cj Hj O, is found in fennel oil and in the oil of Lavandula Stoechas, in its deirtro-rotatory form, and as laevo-fenchone in oil of thuja leaves. It can be extracted from these oils by treating the fraction boiling at 190° to 195° with nitric acid, or permar anate of potassium, and then steam distilling the unaltered fenchone. 

About 130 cc. of nitric acid (sp. gr. 1.27) is obtained. If desired the oxidation mixture may be diluted with water and the /3-chloropropionic add extracted with ether and distilled. Some material is lost in the water by this procedure. 

Urine (2 1.) in a porcelain basin is evaporated to a syrup on the water bath. The flame is extinguished and the hot syrup is stirred with 500 c.c. of alcohol. After some time the clear extract is decanted and the residue is again warmed and once more digested in the same way with 500 c.c. of alcohol. If necessary, the combined extracts are filtered, most of the alcohol they contain is removed by distillation, and the aqueous-alcoholic residue, after transference to a small porcelain basin, is evaporated to dryness on the water bath. The dry residue is well cooled and is kept in an efficient freezing mixture while two volumes of colourless concentrated nitric acid are slowly added with thorough stirring. After the product has stood for twelve hours, the paste of urea nitrate is filtered dry at the pump, washed with a little ice-cold nitric acid (1 1), again filtered with suction till no more liquid drains off, and suspended in 100-150 c.c. of warm water. To this suspension barium carbonate is added... 

The present procedure represents a modification of two previously published procedures,2 3 and results in a safer, more convenient preparation of the title compound. In Step A, the ratio of reagents has been adjusted to allow for the formation of only pentaerythrityl tetrachloride and trichlorohydrin none of the dichlorinated product is produced. Thus work up of the reaction is easier the product can be filtered rather than extracted, so minimal solvent is used, and the crude products are used in Step B, thus avoiding a tedious distillation. Step B has also been modified to make it safer and more convenient. The crude material from Step A is used, and addition of nitric acid over a longer period reduces the hazards of this step. Previously, it was noted that after the nitric acid was added in one portion and the mixture was heated, "a reaction became apparent, whereupon the flask was lowered rapidly into a waiting cold bath and the operator withdrew. 2 Step C is a more detailed modification of the procedure reported by the Russian workers3 as an improvement to the original method of Mooradian and Cloke.2 The latter used quinoline to catalyze the conversion of tris(chloromethyl)acetic acid to 3-chloro-2-(chloromethyl)propene. 

If the additional substance stays in the residue, the process is called extractive distillation of aqueous solutions. The separations of various alcohols, ethylene glycol, acetic acid, acetone, and nitric acid from water is an example in which extractive distillation has been used or proposed. References (108) and (126) describe processes. 

Nitric acid obtained in standard ammonia oxidation is usually 50 to 70% by weight aqueous solution. Pure nitric acid of 98-99% may be obtained either by extractive distillation or by direct strong nitric (DSN) processes. In the distillation method, concentrated nitric acid of 50-70% is distilled with 93% sulfuric acid in a steam-heated tower. Sulfuric acid acts as a dehydrating agent. The distilled nitric acid vapor is condensed to pure nitric acid, while sulfuric acid absorbing water from 50-70% nitric acid loses its strength to about 70% and collects at the bottom. The 70% sulfuric acid is concentrated back to 93%... 

The topic covered in the 10 papers of the first section is commonly referred to as salt effect in vapor-liquid equilibrium and is potentially of great industrial importance. This salt effect leads to extractive distillation processes in which a dissolved salt replaces a liquid additive as the separating agent the replacement often results in a greatly improved separating ability and reduced energy requirements. Two papers in this volume, those by Sloan and by Vaillancourt, illustrate the use of such processing to concentrate nitric acid from its aqueous azeotrope. Nevertheless, the effect has not been exploited by industry to nearly the extent that would seem to be merited by its scientific promise. 

The Extractive Distillation Process for Nitric Acid Concentration Using Magnesium Nitrate... 

Extractive distillation processes are still widely used for nitric acid concentration. Because the operational and maintenance problems associated with sulfuric acid concentration plants are considerable, and their capital cost substantial, attention has been directed periodically to the use of extractive agents other than sulfuric acid. Phosphoric acid (I) acts like sulfuric acid but poses similar problems of reconcentration. Solutions of certain metallic salts, in particular metallic nitrates, permit similar enhancement of relative volatility and are readily reconcentrated in straightforward evaporation equipment, offering the possibility of a compact integrated concentration process. 

Extractive Distillation of Nitric Acid in the Presence of Metal Salts. The nitrates of magnesium (2,3, 4), lithium (4, 5), potassium, calcium (3, 4), sodium, aluminum, iron (3), barium (4), and zinc (6) have been studied for this purpose, and in general terms it has been found that ... 

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