Phosphorus evaporation from solutions

Marggraf noticed that, when he dissolved the earth from alum in nitric acid, evaporated the solution, and calcined the residue, he merely regenerated the earth but obtained no Balduin s phosphorus (calcium nitrate). He realized, therefore, that the earth in alum must be different from that in chalk or limestone. He also demonstrated the presence of alumina in clay and in roofing slate (74). 

In addition to thermal decomposition of the substrate, holding the system at elevated temperatures for long times can result in volatilization of desired constituents. As an example, Figure 5 shows the amount of phosphorus loss from In-P solutions in terms of a decrease in the liquidus temperature as a function of baking time at 670 °C (55). This level of evaporative loss is significant and must be accurately accounted for to control subsequent growth. In addition, the evaporating species can be transported downstream to other bins and alter the composition of these melts. 

A mixture of 7.8 g. (0.062 gram atom) of iodine and 1 g. of red phosphorus is put in a flask equipped with an air condenser on which is placed a calcium chloride tube to protect the system from atmospheric moisture. The flask is heated in an oil or metal bath to a temperature of 100°, and 15.6 g. (0.058 mole) of n-octadecyl alcohol is added. The bath temperature is then raised to 180° and held there for 1 hour. The cooled reaction mixture is extracted with petroleum ether (b.p. 70-80°), and the resulting solution is boiled with fuller s earth and filtered. The solvent is evaporated from the filtrate, giving 21.5 g. (97.5%) of n-octadecyl iodide melting at 34.5-35°. 

A mixture of the formamide 1637 (7.81 g, 25 mmol) and phosphorus penta-chloride (5.21 g, 25 mmol) in anhydrous tetrachloromethane (50 mL) was stirred at 50 °C for 30 min. The solvent was then evaporated under reduced pressure and the residue was redissolved in absolute Et20 (200 mL). The solution was stirred at 0-5 °C, and triethylamine (6.07 g, 60 mmol) was very slowly added dropwise. After standing overnight in a refrigerator, the EtaN HCl deposited was filtered off, the solvent was evaporated from the filtrate, and the residue was chromatographed on a silica gel column (EtOAc) yield 83%. 

Sulphonamides. Mix together 1 0 g. of the dry acid or 1 - 2 g. of the anhydrous salt with 2 5 g. of phosphorus pentachloride f and heat under a reflux condenser in an oil bath at 150° for 30 minutes. Cool the mixture, add 20 ml. of dry benzene, warm on a steam bath and stir the solid mass well to extract the sulphonyl chloride filter. Add the benzene solution slowly and with stirring to 10 ml. of concentrated ammonia solution. If the sulphonamide precipitates, separate it by filtration if no solid is obtained, evaporate the benzene on a steam bath. Wash the sulphonamide with a little cold water, and recrystallise from water, aqueous ethanol or ethanol to constant m.p. 

Cyano-17-(2 -tetrahydropyranyloxy)-androst-5-en-3j5-ol Acetate A solution of 10 g of 17-cyanoandrost-5-en-3j5,17-diol 3-acetate in 40 ml of 2,3-dihydropyran is treated at the boiling point with 0.2 ml of phosphorus oxychloride for 1.5 hr. The solution is then diluted with ether, washed with aqueous sodium carbonate, and then water, dried over sodium sulfate and distilled under reduced pressure. The oily residue is crystalhzed from petroleum ether to give 6.7 g of 17a-cyano-17j5-(2 -tetrahydropyranyloxy)-androst-5-en-3) -ol acetate mp 127-130° [a]o —92° (diox). The mother liquor when evaporated to dryness yields an oily residue of 7.1 g which resists crystallization attempts. Subsequent reactions (see below) indicate it to be 17jS-cyano-17a-(2 -tetrahydropyranyloxy)-androst-5-en-3jS-ol acetate. 

Plant samples are homogenized with sodium hydrogencarbonate aqueous solution to prevent decomposition of the analytes during homogenization. Imibenconazole and its primary metabolite, imibenconazole-debenzyl, are extracted from plan materials and soil with methanol. After evaporation of methanol from the extracts, the residues are extracted with dichloromethane from the residual aqueous solution. The dichloromethane phase is cleaned up on Florisil and Cig columns. Imibenconazole and imibenconazole-debenzyl are determined by gas chromatography/nitrogen-phosphorus detection (GC/NPD). 

Lead tetraacetate is added in small quantities, with stirring, to an ice-cold suspension of 11 g. of ethyl 3-(D-arabino-tetrahydroxybutyl)-5-methyl 4-furoate in 100 ml. of benzene plus 40 ml. of glacial acetic acid. Addition is stopped when there is a positive reaction with potassium iodide-starch paper. The mixture is stirred for a further ten minutes, filtered, and the benzene solution washed twice with water. The benzene layer is then dried with anhydrous sodium sulfate, filtered, and the filtrate evaporated to dryness. The residue (6 g.) is mixed with a solution of 7.5 g. of sodium hydroxide plus 20 g. of silver nitrate in 40 ml. of water, and heated for 40 minutes on a steam bath. The aqueous solution is filtered, acidified to Congo Red while being cooled with ice, and the crystals formed are removed by filtration, washed with ice-cold water, and dried over phosphorus pentoxide in the vacuum desiccator yield, 2.2 g. After recrystallization from water, the product has m. p. 234r-235°. 

When magnesium sulphate was omitted from distilled water samples of phosphorus compounds, recovery was variable. Table 12.11 shows yields of a series of standards with and without the magnesium sulphate addition and with and without the final hydrolysis. The magnesium sulphate is used as an acidic solution (after addition to the seawater sample, the pH was about 3) to minimize silicate leaching from the glassware during evaporation. The acid and heating are necessary to hydrolyse any condensed phosphates in the final mixture. 

The creamy suspension is allowed to cool to room temperature, and the electrodes of a pH meter are inserted (Note 4). A solution of 20.5 g. (0.15 mole) of zinc chloride (Note 5) in 75 ml. of water is added dropwise with vigorous stirring over a period of 45 minutes, while the pH is maintained at 7 by the simultaneous dropwise addition of a 4A aqueous solution of sodium hydroxide (Note 6). The mixture is stirred for 1 hour and is then filtered with suction the solid product is dried under reduced pressure over phosphorus pentoxide. The dry material is slurried with 200 ml. of petroleum ether (b.p. 30-60°), and the solvent is decanted. This process is repeated five times, and the combined extract is evaporated at reduced pressure. The yield of almost pure -chlorophenyl isothiocyanate, obtained as a readily crystallizing oil with a pleasant anise-like odor, is 33-35 g. (65-68%), m.p. 44-45°. The product can be recrystallized from the minimum amount of ethanol at 50°. 

The insoluble material was removed by centrifuging at 5000 rpm for 15 min in a Beckman Model No J-6B centrifuge. This extraction with alkali was repeated twice more and the solutions of sodium salts of acids were collected. Humic acids were precipitated from the combined NaOH solutions by adjusting the pH to 1 with 2N HCl slowly with stirring and the mixture was left overnight. The precipitated humic acids were collected by filtration through Whatman IMM paper and washed with O.IN HCl. The filtrates were extracted three times with ethyl acetate and the extracts dried over sodium sulfate and evaporated, the residue constituting the fulvic acids. Buth fulvic and humic acids (precipitates) were air-dried, and then dried in a vacuum desiccator over phosphorus pentoxide at room temperature. 

The compounds may have either the formula H3PO4 (m.p., 40°) or 2H3P04-H20 (m.p., 30°). In a round-bottomed flask of suitable size, place 1 part of white phosphorus and 16 parts of nitric acid of sp. gr. 1.2 together with a few crystals of iodine as a catalyzer. Provide the flask with a reflux condenser, painting the cork with black asphalt paint to protect it from the action of the nitric acid. Heat until all of the phosphorus has dissolved then distill off most of the liquid and pour the residue into an open dish. Evaporate with several additions of concentrated nitric acid to oxidize all lower acids of phosphorus and finally concentrate in a platinum dish until the temperature of the solution reaches 150°. On cooling, if necessary with a freezing mixture, the liquid can be brought to crystallization. The crystals should be dried over phosphorus pentoxide... 

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