White production

The increase in demand for good quality white products and the reduced consumption of fuel-oil related to pollution controls are going to be important factors in residue processing and heavy oil conversion in the years to come. 

Add in turn benzyl chloride (8 3 g., 8 o ml.) and powdered thiourea (5 gm.) to 10 ml. of 95% ethanol in a 100 ml. flask fitted with a reflux condenser. Warm the mixture on the water-bath with gentle shaking until the reaction occurs and the effervescence subsides then boil the mixture under reflux for 30 minutes. Cool the clear solution in ice-water, filter off the crystalline deposit of the benzylthiouronium chloride at the pump, wash it with ice-cold ethyl acetate, and dry in a desiccator. Yield, 11-12 g., m.p. 170-174°. The white product is sufficiently pure for use as a reagent. It is very soluble in cold water and ethanol, but can be recrystallised by adding ethanol dropwise to a boiling suspension in ethyl acetate or acetone until a clear solution is just obtained, and then rapidly cooling. 

Commercial xanthhydrol may be used, but the pure white product, m.p. 120-121°, obtained by the reduction of xanthone with sodium amalgam (Section VII,16) gives better results. 

A more active product is obtained by the following slight modification of the above procedure. Dissolve the succinimide in a slight molar excess of sodium hydroxide solution and add the bromine dissolved in an equal volume of carbon tetrachloride rapidly and with vigorous stirring. A finely crystalline white product is obtained. Filter with suction and dry thoroughly the crude product can be used directly. It may be recrystallised from acetic acid. 

A large number of salts of sahcyhc acid have been prepared and evaluated for therapeutic or other commercial use. Table 7 hsts those most frequently referenced. Sodium sahcylate has analgesic, antiinflammatory, and antipyretic activities and was used extensively in the sixteenth and seventeenth centuries as a remedy, prepared from natural sources, for arthritis and rheumatism. In the 1990s the salt can be obtained directly from Kolbe-Schmitt carboxylation or by the reaction of sahcyhc acid with either aqueous sodium bicarbonate or sodium carbonate. The resulting mixture is heated until effervescence stops the salt is then isolated by filtration and evaporation to dryness at low temperatures. Generally, the solution must be kept slightly acidic so that a white product is obtained if the mixture is basic, a colored product results. The USP product contains 99.5—100.5% NaC H O (anhydrous). The May 1996 price was 8.15/kg (18). 

The yolk content of good quaHty egg white products is very low, less than 0.03% on a Hquid basis (22). Eat content on a dry basis is then 0.06%. 

S-Dlphanyl-4-methyloxazola (2) a BenzamKlopropiophenona 1 (0 3 g, 1 1 mmoQ was added to concentrated H2SO4 (3 mL) under stimng After 10 mm copious quantities of water were added until the milky white product was completely precptated Filtration and recrystallization from petroleum ether (30-60°C) afforded 0 2 g of 2 (72%), mp B0-81°C... 

Alumina sufficient to adsorb the complete solution is added, then the solvent is removed under vacuum. While benz[a]anthracene, np 157-158°C, sufficiently pure for most purposes, can be obtained by crystallization of the crude product from ethanol-water, filtration" through alumina removes residual, colored impurities, affording a pure, white product. 

If the nitration is caiiied out in accordance with this outline, the product will be crystalline and pale yellow in color. The color is due to traces of dinitrothiophene and the other impurities. Mononitrothiophene has been crystallized by earlier workers from ether, alcohol, benzene, and other solvents. As a rule these solvents fail to yield a snow-white product. It has been found in this work that petroleum ether (b.p. 20-40 ) possesses decided advantages in that by prolonged refluxing it extracts mononitrothiophene but does not readily dissolve the impurities. With petroleum ether, snow-white crystals have been obtained in needles 10 to 20 cm. in length. 

The submitters indicate that N,N-diethylselenourea may be prepared similarly, using diethylcyanamide. In this case, a solution of 50 ml. each of concentrated aqueous ammonium hydroxide and ethanol is used as a solvent. The reaction is carried out at 60°, the solvent being replenished as needed by a solution containing 80 ml. of ethanol and 20 ml. of concentrated ammonium hydroxide. The yield of crude material is 65-80%. Recrystallization from benzene gives a white product, m.p. 117-118°. 

The reaction mixture is filtered with suction and the cake is washed thoroughly with two 200-ml. portions of glacial acetic acid (Note 4). The combined filtrate and washings are evaporated under reduced pressure on the steam bath until a thick oil, which generally partially crystallizes, remains. To purify the crude product, 100 ml. of water is added, and the flask is warmed on a steam bath until the solid melts. The mixture of water and oil is stirred rapidly in an ice bath, and diethyl acetamidomalonate crystallizes as a fine white product. After cooling in an ice bath for an additional hour, the product is collected by filtration, washed once with cold water, and dried in air at 50°. A second crop is obtained by concentrating the mother liquor under reduced pressure. The yield of diethyl acetamidomalonate, m.p. 95-97° (Note 5), is 52-53 g. (77-78%) based on malonic ester. 

The first (white) product has been characterized by X-ray diffraction at —55° and features a linear F-Xe-N group and a planar N atom (Fig. 18.4). " ° On the basis of Raman and F nmr data, the cation of the final (pale yellow) product is believed to be essentially like the V-shaped [Xe2F3]+ cation but with the 2 terminal F atoms replaced by... 

The crystalline crude acid is dried briefly and then recrystallized from acetonitrile to give 32 grams of white product MP 193° to 194.5°C (literature reports 1B9° to 190°C). Concentration of the mother liquor gives an additional 5 grams of material having a MP of 192.5 to 194°C. The 37 grams of material represents an 18% overall yield from benzalde-hyde. 

The crude white product is dissolved in 150 ml of hot petroleum ether (b.p. 60-70°). On cooling, it forms a solid cake which is transferred to a Buchner funnel and rinsed with small portions of cooled petroleum ether. The yield of product, m.p. 75-78°... 

The crude product is usually yellow or orange in color. The color may be readily removed by dissolving the crude product in 200 cc. of hot ethyl alcohol and treating this solution with 5 g. of zinc dust and about 5 cc. of concentrated hydrochloric acid (sp. gr. 1.19). This solution is then filtered and the -bromodiphenyl allowed to crystallize. This gives a white product melting at 89.5-90°. The yield is 20-21 g. (34-35 per cent of the theoretical amount). 

In a 2-1. round-bottomed flask fitted with a reflux condenser protected by a calcium chloride tube 11.5 g. (0.5 gram atom) of finely cut sodium is dissolved in 250 cc. of absolute alcohol. To this solution is added 80 g. (0.50 mole) of ethyl malonate followed by 30 g. (0.50 mole) of dry urea dissolved in 250 cc. of hot (70°) absolute alcohol. After being well shaken the mixture is refluxed for seven hours on an oil bath heated to 1 io°. A white solid separates rapidly. After the reaction is completed, 500 cc. of hot (50°) water is added and then enough hydrochloric acid (sp. gr. 1.18) to make the solution acidic (about 45 cc.). The resulting dear solution is filtered and cooled in an ice bath overnight. The white product is collected on a Buchner funnel, washed with 50 cc. of cold water, and then dried in an oven at 105-1 io° for three to four hours. The yield of barbituric acid is 46-50 g. (72-78 per cent of the theoretical amount). 

A second crystallization from 10 parts of water raises the melting point of the acid to 220°. Any prolonged contact of the hot solution with air will cause some decomposition, notably the formation of traces of />-hydroxybenzaldehydc. The checkers preferred crystallization from 10 parts of glacial acetic acid and 10 parts of 12N hydrochloric acid,6 from which solvent a white product was recovered in 75% yield m.p. 220° (dec.). 

The first product slowly reacts with atmospheric moisture to give an unidentified white product and Cd metal. At low AsFj Cd ratios a brown product, Cd4(AsF6)2. is formed ... 

The product obtained is pure enough for most purposes. Recrystallization from 95% ethanol yields a nearly white product, m.p. 126-127.5°. 

Some slight sublimation is always noticed, and the acid tends to cake. At higher temperatures heavy losses are caused by sublimation, and the caked material is very imperfectly dehydrated there is also some darkening. Under the conditions given a white product is formed. 

The pentamethyl benzene obtained in this way is nearly pure, and one recrystallization from 95 per cent alcohol or from a mixture of equal volumes of alcohol and benzene gives a snow-white product, but the product generally melts over too wide a range for practical purposes. However, if fraction VII is refractionated under diminished pressure and the fraction boiling at i23-i33°/22 mm. (practically all at 127-1290) is collected and recrystallized as in the following paragraph, a product melting quite sharply at 52° (true m.p. 530) is obtained. 

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