Agitated aniline

To produce a moulding composition, aniline is first treated with hydrochloric acid to produce water-soluble aniline hydrochloride. The aniline hydrochloride solution is then run into a large wooden vat and formaldehyde solution is run in at a slow but uniform rate, the whole mix being subject to continuous agitation. Reaction occurs immediately to give a deep orange-red product. The resin is still a water-soluble material and so it is fed into a 10% caustic soda solution to react with the hydrochloride, thus releasing the resin as a creamy yellow slurry. The slurry is washed with a counter-current of fresh water, dried and ball-milled. 

A 1500-cc. flask is fitted with a reflux condenser, a mechanical stirrer, and a 200-cc. separatory funnel. In the flask arc placed 372 g. (4 moles) of aniline (Note 1), 105 g. (r.25 moles) of sodium bicarbonate (Note 2) and roocc. of water. The flask and contents are then heated on a steam bath to 90-95°, and r27 g. (1 mole) of benzyl chloride (Note 3) is run in slowly from the separatory funnel, vigorous agitation being maintained. The addition of benzyl chloride should take not less than one and one-half to two hours, and the reaction is complete in four hours. 

Decolorize the smear in aniline-xylene, agitating the slide gently until no purple runs from it (the use of a second Coplin jar of aniline-xylene after the majority of blue stain has been removed aids the visual assessment of decolorization). 

Aniline is to be hydrogenated to cyclohexylamine in a suspended-particle agitated-tank reactor at 403 K (130°C) at which temperature the value of k is 90 s 1. The diameter dp of the supported nickel catalyst particles will be 0.1 mm and the effective diffusivity De for hydrogen when the pores of the particle are filled with aniline is 1.9 x 10 9 m2/s. 

The proposed catalyst loading, that is the ratio by volume of catalyst to aniline, is to be 0.03. Under the conditions of agitation to be used, it is estimated that the gas volume fraction in the three-phase system will be 0.15 and that the volumetric gas-liquid mass transfer coefficient (also with respect to unit volume of the whole three-phase system) kLa, 0.20 s-1. The liquid-solid mass transfer coefficient is estimated to be 2.2 x 10-3 m/s and the Henry s law coefficient M = PA/CA for hydrogen in aniline at 403 K (130°C) = 2240 barm3/kmol where PA is the partial pressure in the gas phase and CA is the equilibrium concentration in the liquid. 

Owing to the highly explosive nature of the diazobenzene nitrate, its preparation should never be undertaken except the compound is wanted for research or some special purpose. 20 gms. of aniline are placed in a beaker, well cooled, and boiled-out nitric acid, previously diluted with half its volume of water, oarefully added till the mixture sets to a thick crystalline paste—aniline nitrate. The crystalline mass is filtered off at the pump, and washed with a little cold water. 5 gms. of the moist salt are finely powdered and placed in a small flask with enough water just to cover the substance. The flask is now well cooled in ice-water, and nitrous fumes (for preparation, see p. 513) are led in with frequent agitation until all the aniline nitrate has disappeared. At no time must the temperature of the flask rise above 10°. Should there not be sufficient water to keep all the diazobenzene nitrate formed in solution, its crystalline form will easily enable it to be distinguished from the aniline salt. When the reaction is finished the contents of the flask are poured into 3 times their volume of absolute alcohol, and ether is added to this mixture as long as crystals separate. If too much water has been added to the aniline nitrate from the beginning, a thick aqueous solution of diazobenzene nitrate separates out in place of the crystals. If this occurs, the ether-alcohol is decanted off, and the residue redissolved in absolute alcohol, and reprecipitated with ether. On no account must... 

We should note that the reactor receives an excess of aniline, so that the amidation of methyl(chloromethyl)diethoxysilane is accompanied by the binding of released hydrogen chloride. When introducing aniline, one should keep a close watch on the temperature in the reactor, since the process takes place with the liberation of heat. After aniline has been introduced, the reactive mixture is heated to 135-140 °C within 2-3 hours and agitated at this temperature for 8-8.5 hours. After that reactor 6 is... 

Then, the solution of methyl(phenylaminomethyl)diethoxysilane in the mixture of toluene and aniline is sent by nitrogen flow into distillation tank 12. There a residual pressure of 25-35 GPa is created, cooler 13 is filled with water, the agitator is switched on and the tank is slowly heated. The distilled toluene enters receptacle 14 through run-down box 4 the distillation continues up to 100°C. The toluene in the receptacle is sampled to determine the density (at the density of 0.854-0.870 g/cm3 the distillation is considered complete). The distilled toluene from receptacle 14 is sent in vacuum into batch box 7 and used for another process of amidation. 

Procedure. To the solution of aniline in a 3-ml tapered glass tube add the Na I followed by chloramine-T. Agitate the tube for 1 min then adjust the pH to 11 with NaOH (indicator paper). Extract the labeled aniline with three 1-ml portions of chloroform and evaporate the combined chloroform extracts to dryness under a stream of dry nitrogen. The residual product is dissolved in 100 /aI of 0.1 M HCl. 

A 50-mL single-necked, round-bottomed flask was charged with the 4-fluoro-3-nitrobenzoic acid loaded resin 172, the appropriate amino add ester hydrochloride salt (2 equiv.), and 5% DIEA/DMF. The mixture was agitated at rt for 24 h, filtered, and then the resin was washed with DMF (three times), CH2CI2 (three times), iPrOH (three times) and then again in the same order, and dried to afford enantiomerically pure aniline intermediate 173. 

II.7 moles) of concentrated hydrochloric acid (sp. gr. 1.19), 950 cc. of water, 200 g. (196 cc., 2.15 moles) of aniline, and 2 kg. of ice (Note i). The mixture is agitated by a mechanical stirrer, and, as soon as the temperature drops below 5°, a chilled solution of 156 g. (2.26 moles) of sodium nitrite m a measured volume (700-1000 cc.) of water is introduced fairly rapidly from a separatory funnel, the stem of which projects below the surface of the reaction mixture. The addition should not be fast enough to cause the temperature to rise to 10° or to cause evolution of oxides of nitrogen. The last 5 per cent of the nitrite solution is added more slowly, and the reaction mixture is tested with starch-iodide paper at intervals imtil an excess of nitrous acid is indicated. 

The hydrochloride is prepared semi-continuously in agitated reactors, in which a 33 per cent weight excess of aniline is caused to react with a 32 per cent weight hydrochloric acid solution. The heat generated by the reaction is removed by cooling water circulation in a double shelly... 

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