Cooling content

Tanks cool contents remain liquid. This case is relatively simple and can easily be handled by the equations given earher. 

Tanks cool, contents partially freeze, and solids drop to bottom or rise to top. This case requires a two-step calculation. The first step is handled as in case 1. The second step is calculated by assuming an isothermal system at the freezing point. It is possible, given time and a sufficiently low ambient temperature, for tank contents to freeze solid. 

The cooled contents of the 2S0-ml. flask containing ferrous chloride (Note 6) are added to the cold sodium cyclopentadienide solution while passing a stream of nitrogen through both flasks. The combined mixture is stirred for 1.25 hours at a temperature just below reflux. Solvent is removed by distillation, and the ferrocene is extracted from the residue with several portions of refluxing petroleum ether (b.p. 40-60°). The product is obtained by evaporation of the petroleum ether solution. Ferrocene may be purified by recrystallization from pentane or cyclohexane (hexane, benzene, and methanol have also been used) or by sublimation. The 3ueld is 31-34 g. (67-73%) (Note 7), m.p. 173-174°. 

A four-necked 3-1. flask fitted with a thermometer, reflux condenser, dropping funnel, and mechanical stirrer is charged with 750 ml. of n-hexane, 750 ml. of anhydrous ethyl ether, 104 g. (3.25 moles) of anhydrous methanol, and 370 g. (3.05 moles) of A,A-dimethylaniline. A drjing tube is attached to the outlet of the condenser to prevent moisture from entering the reaction vessel. The dropping funnel is charged with 182 g. (1 mole) of freshly distilled arsenic trichloride, and this is added drop by drop to the well-stirred ice-cooled contents of the reaction flask. The temperature in the flask is maintained at ca. -i-5°. During the course of the addition, a white precipitate of A, A -dimethylaniline hydrochloride is formed. 

KF (2.0 g, 34.4 mmol stored at 110 ,C) was added in one portion to a solution of 6-chloro-2,3-diphenylpyri-do[2,3-/>]pyrazine (7 0.5 g, 1.6 mmol) in anhyd DMSO (5 mL). The mixture was heated for 10 min under vigorous stirring. To the cooled contents of the flask, H2() (20 mL) was added. The organic material was extracted with CHC13, concentrated and recrystallized (hexane) to give a slightly yellow compound yield 241 mg (50%) mp 142-143°C. 

Pour the cooled contents into a 250 ml beaker containing a mixture of 50 g of crushed ice and 50 ml of cone. HCl. Stir the contents with a glass rod ruitil all the aluminium salts get dissolved more or less completely. 

After evaporation, heat the residue at approximately 130 C for about 1 hour in a drying oven or over a sand bath. Moisten the cooled contents of the dish with 5 to 10 ml of cone, hydrochloric acid, and following a reac-... 

After refluxing, cool contents, rinse column residue back into flask with deionized water. 

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