Nitric acid continued

Prepare a suspension of methylene diformamide in acetic anhydride by adding 204 grams of methylene diformamide to 760 milliliters of acetic anhydride while stirring the acetic anhydride. Then cool this mixture to -5 Celsius by means of an ice bath. Now, place 760 milliliters of 99% nitric acid into a flask, and cool to -5 Celsius by means of an ice bath. Afterwards, rapidly add the 99% nitric acid to the methylene diformamide suspension while maintaining the methylene diformamide suspension at -5 Celsius with rapid stirring. After the addition of the 99% nitric acid, continue stirring the reaction mixture at about -5... 

Place 5 ml of tiie blood sample in a 125-ml flask, add 5 ml of the Digestion Mixture, heat, gently at first, then at about 150°. When the solution boils and begins to char, add 2 ml of nitric acid continue to add 1-ml quantities of nitric acid Mid a few (hops of perchloric acid until a clear straw-coloured solution is obtained. Maintain the temperatme until white fumes of sulphur trioxide are evolved and the solution is free from nitric acid. Cool, fransfer quMititatively to a 10-ml volumefric flask, and dilute to volume with water. 

Cool the mixture for a few minutes and detach the air condenser. With a Pasteur pipette, transfer the reaction mixture to a beaker containing 4 mL of ice-cold water. Rinse the conical vial and spin vane with a small amount of water. Cool the mixture in an ice bath until the crystals have formed. If the material oils out rather than crystallizes, scratch the oil vigorously with a spatula until it does crystallize completely. Collect the crude product on a Hirsch funnel under vacuum. Wash it well with cold water (about 5 mL) to remove the nitric acid. Continue drawing air through the solid mass on the Hirsch funnel to help dry the solid. Weigh the solid. 

Evaporate the solution until dense white fumes of perchloric acid are evolved with no brown fumes from the nitric acid. Continue heating until the liquid in the fiask is nearly gone but do not bake the flask dry. 

Procedure for Bromine and Iodine Estimations. Again cover the beaker as before, but before adding the nitric acid add i g. of hydrazine sulphate and heat the solution on the water-bath until evolution of gas ceases. To ensure complete decomposition of an iodate, however, the heating should be continued for i hour. 

Oxidation of benzoin with concentrated nitric acid or by catalytic amounts of cupric salts in acetic acid solution, which are regenerated continuously by ammonium nitrate, yields the diketone benzil ... 

Introduce a solution of 15 g. of the diazo ketone in 100 ml. of dioxan dropwise and with stirring into a mixture of 2 g. of silver oxide (1), 3 g. of sodium thiosulphate and 5 g. of anhydrous sodium carbonate in 200 ml. of water at 50-60°. When the addition is complete, continue the stirring for 1 hour and raise the temperature of the mixture gradually to 90-100°. Cool the reaction mixture, dilute with water and acidify with dilute nitric acid. Filter off the a-naphthylacetic acid which separates and recrys-talhse it from water. The yield is 12 g., m.p. 130°. 

C. Palladium on carbon catalyst (5 per cent. Pd). Suspend 41-5 g. of nitric acid - washed activated carbon in 600 ml. of water in a 2-litre beaker and heat to 80°. Add a solution of 4 1 g. of anhydrous palladium chloride (1) in 10 ml. of concentrated hydrochloric acid and 25 ml. of water (prepared as in A), followed by 4 ml. of 37 per cent, formaldehyde solution. Stir the suspension mechanically, render it alkaUne to litmus with 30 per cent, sodium hydroxide solution and continue the stirring for a further 5 minutes. Filter off the catalyst on a Buchner funnel, wash it ten times with 125 ml. portions of water, and dry and store as in B. The yield is 46 g. 

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-... 

To solve some of the environmental problems of mixed-acid nitration, we were able to replaee sulfuric acid with solid superacid catalysts. This allowed us to develop a novel, clean, azeotropic nitration of aromatics with nitric acid over solid perfluorinated sulfonic acid catalysts (Nafion-H). The water formed is continuously azeotroped off by an excess of aromatics, thus preventing dilution of acid. Because the disposal of spent acids of nitration represents a serious environmental problem, the use of solid aeid eatalysts is a significant improvement. 

The first nitration to be reported was that of beri2ene itself. Mitscher-lich in 1834 prepared nitrobenzene by treating benzene with fuming nitric acid. Not long afterwards the important method of effecting nitration with a mixture of nitric and sulphuric acids ( mixed acid ) was introduced, evidently in a patent by Mansfield the poor quality of early nitric acid was probably the reason why the method was developed. Since these beginnings, nitration has been the subject of continuous study. 

In the commonly used Welland process, calcium cyanamide, made from calcium carbonate, is converted to cyanamide by reaction with carbon dioxide and water. Dicyandiamide is fused with ammonium nitrate to form guanidine nitrate. Dehydration with 96% sulfuric acid gives nitroguanidine which is precipitated by dilution. In the aqueous fusion process, calcium cyanamide is fused with ammonium nitrate ia the presence of some water. The calcium nitrate produced is removed by precipitation with ammonium carbonate or carbon dioxide. The filtrate contains the guanidine nitrate that is recovered by vacuum evaporation and converted to nitroguanidine. Both operations can be mn on a continuous basis (see Cyanamides). In the Marquerol and Loriette process, nitroguanidine is obtained directly ia about 90% yield from dicyandiamide by reaction with sulfuric acid to form guanidine sulfate followed by direct nitration with nitric acid (169—172). 

After the water and nitrogen oxide are driven off, continued heating drives off vapors of nitric acid, additional water, NO2, and some mercury—metal vapor ... 

Nickel sulfate also is made by the reaction of black nickel oxide and hot dilute sulfuric acid, or of dilute sulfuric acid and nickel carbonate. The reaction of nickel oxide and sulfuric acid has been studied and a reaction induction temperature of 49°C deterrnined (39). High purity nickel sulfate is made from the reaction of nickel carbonyl, sulfur dioxide, and oxygen in the gas phase at 100°C (40). Another method for the continuous manufacture of nickel sulfate is the gas-phase reaction of nickel carbonyl and nitric acid, recovering the soHd product in sulfuric acid, and continuously removing the soHd nickel sulfate from the acid mixture (41). In this last method, nickel carbonyl and sulfuric acid are fed into a closed-loop reactor. Nickel sulfate and carbon monoxide are produced the CO is thus recycled to form nickel carbonyl. 

Reactions 8 and 9 are important steps for the Hquid-phase nitration of paraffins. The nitric oxide which is produced is oxidized with nitric acid to reform nitrogen dioxide, which continues the reaction. The process is compHcated by the presence of two Hquid phases consequentiy, the nitrogen oxides must transfer from one phase to another. A large interfacial area is needed between the two phases. 

Fuel Dissolution. In the American and British plants, LWR fuel pieces typically fall directly from the shear into a dissolver basket, which fits inside the dissolver vessel. A soluble poison such as gadolinium is added to the nitric acid to prevent criticahty. The massive end fittings are sometimes separated from the fuel pieces before the latter enter the dissolver. The French have installed continuous rotary dissolvers in the UP3 and UP2-800 plants at La Hague. The units each consist of a dmm rotating within a geometrically favorable slab tank (13). 

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