Clay plates

The cooled mixture is transferred to a 3-1. separatory funnel, and the ethylene dichloride layer is removed. The aqueous phase is extracted three times with a total of about 500 ml. of ether. The ether and ethylene chloride solutions are combined and washed with three 100-ml. portions of saturated aqueous sodium carbonate solution, which is added cautiously at first to avoid too rapid evolution of carbon dioxide. The non-aqueous solution is then dried over anhydrous sodium carbonate, the solvents are distilled, and the remaining liquid is transferred to a Claisen flask and distilled from an oil bath under reduced pressure (Note 5). The aldehyde boils at 78° at 2 mm. there is very little fore-run and very little residue. The yield of crude 2-pyrrolealdehyde is 85-90 g. (89-95%), as an almost water-white liquid which soon crystallizes. A sample dried on a clay plate melts at 35 0°. The crude product is purified by dissolving in boiling petroleum ether (b.p. 40-60°), in the ratio of 1 g. of crude 2-pyrrolealdehyde to 25 ml. of solvent, and cooling the solution slowly to room temperature, followed by refrigeration for a few hours. The pure aldehyde is obtained from the crude in approximately 85% recovery. The over-all yield from pyrrole is 78-79% of pure 2-pyrrolealdehyde, m.p. 44 5°. 

Ton-papier, n. tinted paper, -platte, /. clay plate earthenware slab, -priifung, /. clay... 

After 30 minutes the solid sulfinic acid is separated on a fritted-glass filter. The sulfinic acid is dissolved from the filter by a mixture of 750 ml. of ether and 750 ml, of methylene chloride. The solution is dried over calcium chloride and evaporated to dryness under reduced pressure (bath temperature 25°) (Note 5). The residue is suspended in 50 ml. of water, and small portions of dilute ammonia are added to the well-stirred suspension until it has a pH of 9 (Note 6). Insoluble impurities are separated by filtration, and 2-nitrobenzenesulfinic acid is precipitated from the filtrate by adding 5-ml. portions of 6N hydrochloric acid with cooling the sulfinic acid precipitated by each portion of acid is separately collected on a Buchner funnel (Note 7). The acid, a pale yellow solid, is dried on a clay plate in a vacuum desiccator over potassium hydroxide pellets, m.p. 120-125° (dec.), weight 9.4-14.9 g. (50-80%). If the 2-nitrobenzenesulfinic acid is to be used for the hydrogenation of the next step high purity is required, and it is generally advisable to reprecipitate the acid once more in the same way (Note 8). 

A Nalgene 15-500 polyethylene bottle (Nalge Co., Rochester, New York) was used. The side arm coming off the shoulder of the bottle is kept well above the liquid level, the constricted tip removed, and the end of the tube connected to a drying tube containing clay plate chips impregnated with concentrated sulfuric acid. 

A laboratory oven (Note 1) is equipped with as many clay plates or enameled pie plates or trays as it will accommodate and is adjusted to operate at 98-99° (Notes 2 and 3). When the temperature has become constant the plates are removed, rapidly covered with a layer (not over 3-4 mm. deep) of pulverized (Notfe 4) hydrated oxalic acid, and then quickly replaced in the oven. The temperature will drop slightly for a few minutes (Note 5). After the oven has regained the temperature for which it was adjusted, it is heated for two hours longer at this temperature. The product is then removed, crushed if slightly caked, and quickly bottled. The yield from 100 g. of hydrated oxalic acid is 69-70 g. (96-98 per cent of the theoretical amount) (Note 6). The product is 99.5-100 per cent pure, as indicated by titration with standard alkali. 

After the reaction mixture is diluted with water, the product is separated by repeated extraction with ether. The ether solution is evaporated and the residual product is dried on an unglazed clay plate. The yield of nitrosocyclohexane dimer is 0.07 gm (26 %), m.p. 116°-117°C after recrystallization from acetone. 

A solution of 2.45 gm (0.019 mole) of A-heptyl-4-hydroxylamine is prepared in 2 AT hydrochloric acid. To this solution is added, with vigorous stirring, bromine water until the bromine color just persists. During this addition a colorless precipitate of the product begins to form. After the addition has been completed, stirring is continued for a short time. Then the product is filtered off, washed with a small quantity of ice-cold water, and dried on an unglazed clay plate yield 1.93 gm (80%), m.p. 46°-48°C. The product may be recrystallized from acetone or distilled under reduced pressure (b.p. 90°-93°C, 0.4 mm Hg). The final melting point is reported as 49°-50°C. 

Diethyl ketone was either purchased from the Eastman Kodak Company and redistilled, or prepared by passing propionic acid slowly over a mixture of manganous oxide and clay plate chips in a tube furnace at 420-440° 3 the apparatus was similar to one described in Organic Syntheses When prepared by this method the ketone was distilled, dried over potassium carbonate, and redistilled b.p. 100-101°. 

Gap spacings 3, 10, and 25 microns were maintained between two standard porous clay plates, ground flat. The largest measured yield was 5.23 cc. per hour, per square foot. 

The mixture remaining in the three-necked flask is stored overnight at 0°. The solid product is then freed of oily contaminants by spreading on clay plates, which are stored in a desiccator. Finally, the solid is washed with 100 ml. of ice water and then dried in a desiccator over phosphorus(V) oxide. The crude product so obtained is recrystallized twice from 10-15 times its weight of n-heptane which has been previously dried over sodium wire. M.P., 144-145°. Yield, based upon (tri-chlorophosphoranylidene)sulfamoyl chloride, is ca. 12 g. (17%). Anal. Calcd. for N3S3O3CI3 N, 14.36 S, 32.87 Cl, 36.36 mol. wt., 292.57. Found N, 14.51 S, 32.44 Cl, 36.84 mol. wt., 300. 

FIGURE 1.1 Schematic illustration of the structure of a crystalline vermiculite. Within the clay plates, the open circles represent oxygen, the closed circles silicon, and the shaded circles magnesium. The oxygen-oxygen separation of the surface layers is about 7 A. In the interlayer region, the open circles represent water molecules and the shaded circles univalent cations. The dotted lines show the unit cell. 

Figure 2.3a is purely a sketch. The exact interaction potential between n-butylammonium-substituted clay plates (or other charged colloidal particles) in solution must incorporate many effects, such as the size of the small ions and the molecular degrees of freedom of the solvent, that are beyond the scope of either the coulombic attraction theory or DLVO theory. However, whatever the complicated functional dependence, the curve must comprise two states of equal thermodynamic potential. Somehow, the valleys in VT, the total potential, must be of equal depth. As discussed previously, in Figure 2.3b we see that the DLVO theory can never account for this experimentally proved phenomenon. 

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