Cooling Filter materials

Xanthylamides. Dissolve 0 25 g. of xanthhydrol in 3-5 ml. of glacial acetic acid if an oil separates (as is sometimes the case with commercial material), allow to settle for a short time and decant the supernatant solution. Add 0-25 g. of the amide, shake and allow to stand. If a crystalline derivative does not separate in about 10 minutes, warm on a water bath for a period not exceeding 30 minutes, and allow to cool. Filter oflF the solid xanthylamide (9-acylamidoxanthen) and recrystallise it from dioxan - water or from acetic acid - water, dry at 80° for 15 minutes and determine the m.p. 

Cyclopropenone prepared in this way is quite pure and suitable for most chemical purposes. It can he repurified by crystallization from 3 volumes of ethyl ether at — 60° using a cooled filtering apparatus. The residual ethyl ether is then removed by evaporation at 1-2 mm. and 0° very pure cyclopropenone is obtained in 60-70% recovery from the above distilled material. 

Turanose Phenylosotriazole. A solution of 15 g. of turanose phenylosazone in 300 cc. of hot water was placed on the steam-bath and a solution of 22 g. of copper siilfate pentahydrate in 150 cc. of hot water was added. The mixture turned a deep cherry-red at once and in a short time (fifteen min.) a red precipitate had formed and the solution had become green. After thirty minutes from the time of addition of the copper solution, the solution was cooled, filtered, and the copper removed as sulfide. The clear light yellow filtrate was neutralized with 45 g. of barium carbonate and the insoluble material removed by filtration. The filtrate was extracted with five 50-cc. portions of ether to remove the aniline, and the aqueous portion was concentrated in vacuo to a thick sirup. The sirup was dissolved in 60 cc. of warm alcohol, filtered to remove a slight turbidity and diluted with 65 cc. of ether. Upon cooling and scratching, the product crystallized as large prisms yield 8.9 g. (72%). The phenylosotriazole was recrystallized from 10 parts of alcohol and when pure showed the melting point 193-194° and rotated [a Jj" + 74.5° in aqueous solution (c, 0.90). 

In a 3-I. round-bottom flask fitted with a reflux condenser, 625 cc. of alcohol (95 per cent), 500 cc. of water, 500 g. of pure benzaldehyde and 50 g. of sodium cyanide (96-98 per cent) are placed. This mixture is then heated and kept boiling for 0.5 hour. In the course of about twenty minutes, crystals begin to separate from the hot solution. At the end of the thirty minutes, the solution is cooled, filtered with suction, and washed with a little water. The yield of dry crude benzoin, which is white or light yellow, amounts to 450 to 460 g. (90-92 per cent theory). In order to obtain it completely pure, the crude substance is recrystallized from alcohol, 90 g. of crude material being dissolved in about 700 cc. of boiling alcohol upon cooling, a yield of 83 g. of white, pure benzoin is obtained, m. p. 1290. 

The impure material is digested in 250ml water with the required amount of Ag-aSO at 60°C until the precipitate appears well settled (about 1 hour). After being cooled, filtered through asbestos, and evaporated, the clear filtrate is evaporated to dryness on the steam bath. It is placed in a dessicator to remove final traces of moisture. The yield is variable, depending on the purify of the MnO and the success of the oxidative fusion, but it should be 30-60g. 

Dissolve lg (0.005 mol) of l-chloro-2,4-dinitrobenzene in 5 ml of rectified spirit with warming and add a solution of 0.5 ml (0.005 mol) of 2-methyl-propane-1-thiol in 5 ml of rectified spirit containing 2 ml of 10 per cent aqueous sodium hydroxide. Heat under reflux for 10 minutes and decant the hot solution from any insoluble material into a clean conical flask. Allow the solution to cool, filter and recrystallise the sulphide twice from methanol. The product is obtained as yellow flakes, m.p. 75-76 °C the yield is 440 mg (35%). 

Example 7.8. Steinhart et al. [288] used the formation of a precursor film to fabricate nanotubes of polymers. For this purpose a porous alumina filter with cylindrical holes of defined size is brought into contact with a polymer melt (Fig. 7.17). This is done at a temperature, where the polymer is liquid, which is significantly above room temperature. The precursor film of the polymer wets the walls of the pores within, typically a few seconds. Before the pores are filled completely the filter is removed from the melt, the sample is cooled to room temperature, and the filter material is dissolved in potassium hydroxide. 

Crude riboflavin, prepared as described above starting with 43.6 g of 2-(o-biphehylazo)-4,5-dimethyl-l-ribityl amino-benzene, is washed with 50 ml of cold ethyl acetate, slurried with 180 ml of methanol at 65°C for thirty minutes. The methanol slurry is cooled to 10°C for thirty minutes, filtered, and the filtered material washed with 40 ml of cold methanol. The methanol washed riboflavin is then slurried with 180 ml of water at 80°C for thirty minutes, the slurry is cooled to 70°C, filtered, and the filtered material is washed with 40 ml of hot (70°C) water. The hot water-washed riboflavin is... 

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