Heating/cooling methods cold baths

Hexammino - cobaltic Chloride, or Luteo-cobaltic Chloride, [Co(NH3)8]Cl3.—Several methods of preparation have been described. The best method is that of Jorgensen,1 whereby the salt is prepared by warming chloro-pentammino-cobaltic chloride, [Co(NH3)5C l]Cl2. in a pressure flask with 20 per cent, aqueous ammonia and ammonium chloride for several hours with constant shaking. After cooling, the mixture is removed from the flask and ammonia allowed to evaporate. The liquid is then diluted, hydrochloric acid added, and the whole heated on the water-bath, thus changing any aquo-pentammino-chloride into ehloro-pentammino-ehloride. More concentrated hydrochloric acid is added and the mixture cooled and filtered. The residue on the filter consists of ammonium chloride, chloro-pentammino-chloride, and hexammino-cobaltic chloride. Ammonium chloride is removed by treating with a 20 per cent, solution of hydrochloric acid, and the residue is then treated on a filter with cold water in which chloro-pentammino-cobaltic chloride is insoluble and hexammino-cobaltic chloride soluble. The salt is precipitated from its warm solution by the addition of half its volume of concentrated hydrochloric acid. 

Method 2 (from hydrazobenzene). Prepare a solution of sodium hypobromite by adding 10 g. (3-2 ml.) of bromine dropwise to a cold solution of 6-0 g. of sodium hydroxide in 75 ml. of water immersed in an ice bath. Dissolve 9-5 g. of hydrazobenzene (Section IV,87) in 60 ml. of ether contained in a separatory funnel, and add the cold sodimn hypobromite solution in small portions. Shake for 10 minutes, preferably mechanically. Separate the ether layer, pour it into a 100 ml. distilling flask, and distil off the ether by warming gently on a water bath. Dissolve the warm liquid residue in about 30 ml. of alcohol, transfer to a small beaker, heat to boiling on a water bath, add water dropwise to the hot solution until the azobenzene just commences to separate, render the solution clear again with a few drops of alcohol, and cool in ice water. Filter the orange crystals at the pump, and wash with a little 50 per cent, alcohol. Dry in the air. The yield is 8 g. 

Method 1. Dissolve 76 g. of thiourea in 200 ml. of warm water in a 750 ml. or 1 litre round-bottomed flask. Dilute the solution with 135 ml. of rectified spirit and add 126-5 g. of benzyl chloride. Heat the mixture under reflux on a water bath until the benzyl chloride dissolves (about 15 minutes) and for a further 30 minutes taking care that the mixture is well shaken from time to time. Cool the mixture in ice there is a tendency to supersaturation so that it is advisable to stir (or shake) the cold solution vigorously, when the substance crystallises suddenly. Filter off the sohd at the pump. Evaporate the filtrate to about half bulk in order to recover a further small quantity of product. Dry the compound upon filter paper in the air. The yield of hydrochloric acid filter off the sohd which separates on cooling. Concentrate the filtrate to recover a further small quantity. The yield of recrystalhsed salt, m.p. 175° is 185 g. some of the dimorphic form, m.p. 150°, may also separate. 

Nitrosomethylurea. Acetamide method. To a solution of 59 g. of acetamide in 88 g. (28 ml.) of bromine (1) in a 4-litre beaker add dropwise, with hand stining, a solution of 40 g. of sodium hydroxide in 160 ml. of water. Heat the resulting yellow reaction mixture on a steam bath until eflfervescence sets in (2), after which continue the heating for 2-3 minutes. CrystaUisation of the product from the yellow or red coloured solution usually commences immediately. Cool in an ice bath for 1-2 hours, collect the product by suction filtration, wash with a little ice-cold water, and dry in the air. The yield of colourless acetylmethylurea, m.p. 178-180°, is 50 g. 

Method 2. Ethyl p-nitrobenzoate. Place 21 g. of p-nitrobenzoic acid (Section IV,154), 11-5 g. of absolute ethyl alcohol, 3 8 g. of concentrated sulphuric acid, and 30 ml. of sodium-dried A.R. benzene in a 250 ml. round-bottomed flask, fit a reflux condenser, and heat the mixture under reflux for 16 hours. Add 50 ml. of ether to the cold reaction mixture, wash the extract successively with sodium bicarbonate soiution and water, dry with anhydrous magnesium sulphate or calcium chloride, and distil off the solvent on a water bath. Remove the last traces of benzene either by heating in an open evaporating dish on a water bath or in a bath at 100-110°. The residual ethyl p-nitrobenzoate (21 g.) solidifies completely on cooling and melts at 56°. 

Functional property tests were conducted in duplicate. AACC (21) methods were used for the determination of water hydration capacity (Method 88-04) and nitrogen solubility index (NSI) (Method 46-23). Oil absorption capacity was measured by the procedures of Lin et al. (22) and oil emulsification by a modification (22) of the Inklaar and Fortuin (23) method. Pasting characteristics of 12.0% (w/v, db) slurries of the flours and processed products were determined on a Brabender Visco/Amylograph (Method 22-10). The slurries were heated from 30 to 95°C before cooling to 50°C to obtain the cold paste viscosity value. Gelation experiments were conducted by heating 15% (w/v db) slurries in sealed stainless steel containers to 90°C for 45 min in a water bath C3). 

Method A AsF3 and SbCl5 were mixed in amounts indicated in Table 1 and placed in a 3-necked flask equipped with a stirrer, reflux condenser, and thermometer. The haloalkane was then added and the mixture was quickly heated to gentle reflux in a water bath and held under these conditions for 2-4 h, after which time it was cooled and poured into dil HC1. The organic layer was separated, washed with 1 % aq NaOH (x 2) and H20, dried (CaCl2), and fractionated. When the product had a bp below rt, the reflux condenser was connected to a cold trap (— 78 CC). The condensate in the trap was evaporated through a caustic scrubber and recondensed. 

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