Product drying, completion

For the production of tartar emetic (antimony potassium tartrate [28300-74-5]), potassium bitartrate [868-14 ] and antimony oxide, Sb202, are added simultaneously to water in a stainless-steel reactor. The reaction mixture is diluted, filtered, and collected in jacketed granulators where crystallization takes place after cooling. Centrihiging, washing, and drying complete the process. 

Drying of the poly(vinyl alcohol) is critical to both the color and solubiHty of the final product. Excessive drying temperatures result in high product color and an increase in the crystallinity, which in turn reduces the solubiHty of the product. Drying is initially subjected to a flash regime, where the solvent not contained within the particles is flashed off. This first phase is foUowed by a period where the rate is controUed by the diffusion rate of solvent from the poly(vinyl alcohol) particles. Because the diffusion rate falls as the material dries, complete drying is not practical. The polymer is therefore generally sold at a specification of 95% soHds. 

It is very necessary that the tetrazonium borofluoride be dried completely. If the solid is wet, the decomposition proceeds very vigorously. There is formed at the same time a product of higher melting point (1600) as well as some tar. These products, although not volatile with steam, lower the yield of the 4,4 -difluorobiphenyl very materially. 

The first commercial copper phthalocyanine synthesis, a baking process, involved melting phthalic anhydride with urea at 150°C in the presence of boric acid. Cop-per(II)chloride was then added and the temperature increased to approximately 200°C until the copper phthalocyanine production was completed. The reaction mixture was cooled and the crude product milled. After being washed, first with dilute sodium hydroxide solution and then with dilute sulfuric acid, the material was filtered off and dried. The crude copper phthalocyanine obtained was then... 

Phycotoxins accumulate in fish and shellfish because of the natural feeding habits of the respective organisms, rather than because of food handling or processing practices. The toxins causing the diseases discussed in this chapter are heat stable (Australia New Zealand Food Authority, 2001 Committee on Evaluation of the Safety of Fishery Products, 1991). Complete inactivation of saxitoxin (associated with PSP) requires at least ten minutes of exposure to 260°C dry heat. Brevetoxins (associated with NSP) were inactivated (i.e., to levels below the limit of assay detection using Japanese medaka [Oryzias latipes]) by exposure to 500°C heat for 10 to 15 minutes (Poli, 1988). Complete inactivation required 10 minutes exposure to 2760°C dry heat (Wannamacher, 2000). 

In gravimetric analysis, the final product usually has to be dried completely. This is done by the process of heating to constant mass - heating the substance, allowing it to cool in a dry atmosphere inside a desiccator, then weighing it. The process is repeated until a constant mass is obtained, showing that all the water has been driven off. 

Sulfur trioxide-Dimethylformamide eomplex (SOrDMF). This is a reagent required for this method of LSD production. A completely dry 22 liter flask (round bottom) in an ice cooling bath is fitted with a condenser, stirring device, addition funnel, then is filled with 10-11 liters of... 

The Ter Meer reaction has not been widely exploited for the synthesis of m-dinitroaliphatic compounds. This is partly because the Kaplan-Shechter oxidative nitration (Section 1.7) is more convenient, but also because of some more serious limitations. The first is the inability to synthesize internal em-dinitroaliphatic compounds functionality which shows high chemical stability and is found in many cyclic and caged energetic materials. Secondly, the em-nitronitronate salts formed in the Ter Meer reactions often need to be isolated to improve the yield and purity of the product. Dry em-nitronitronate salts are hazardous to handle and those from nitroalkanes like 1,1,4,4-tetranitrobutane are primary explosives which can explode even when wet. Even so, it is common to use conditions that lead to the precipitation of gem-nitronitronate salts from solution, a process that both drives the reaction to completion and also provides isolation and purification of the product salt by simple filtration. Purification of em-nitronitronate salts by filtration from the reaction liquors, followed by washing with methanol or ethanol to remove occluded impurities, has been used, although these salts should never be allowed to completely dry. 

After addition of 10 mL of dry dichloromethane, the yellow suspension is stirred magnetically for 3h. The solution is filtered away from the silver chloride through a Schlenk frit under an argon atmosphere into another dry Schlenk tube. To the yellow solution trilluoromethane sulfonic acid (0.058 mL, 0.66 mmol) (distilled at 43 °C in vacuo with an oil pump and stored under argon) is added by means of a micropipette. The mixture is stirred for 1 h. A colorless precipitate forms. Precipitation of the product is completed by addition of 10 mL of pentane. The mixture is centrifuged and the solution decanted. The remaining solid is washed twice with 10 mL of pentane, and dried under high vacuum for 4h. Yield 620 mg (89%). 

Preparation.—(1) At one time fuming sulphuric acid was largely prepared by the dry distillation of basic ferric sulphate which had been obtained by submitting ferrous sulphate to atmospheric oxidation and subsequently dehydrating the oxidation product fairly completely ... 

When dressed products are to be examined, a small portion is washed for about 15 minutes under the tap and rubbed vigorously between the fingers meanwhile it is then allowed to dry completely in the air and afterwards tested as above. 

Cool the beaker in a bath of cold water and add 150 ml of cold water. Filter off the crude phenanthraquinone with suction and wash it with water until free from chromium salts. Suspend the solid in 20 ml of rectified spirit and add, with stirring, 20 ml of saturated sodium metabisulphite solution. Break up the lumps of the addition product with a glass rod and allow to stand, with frequent stirring, for 10 minutes. Add 150 ml of water to dissolve the addition product and filter with suction. Reject the precipitate which consists of the impurities present in the phenanthrene. Add saturated sodium carbonate solution to the filtrate until the bisulphite addition product is completely decomposed allow the precipitate to settle for 1 minute, then add a few drops of sodium carbonate solution and note whether any further precipitation occurs. Stir the precipitate for 2-3 minutes, filter with suction, wash with three 20 ml portions of water and drain well. Dry the product between filter papers and then in a desiccator over calcium chloride. The yield of phenanthraquinone, m.p. 206 °C, is 1.4 g (60%). The product may be recrystallised from glacial acetic acid (about 20 ml), but the m.p. is unaffected. 

This product is purified by dissolving with mechanical stirring in a minimum amount (ca. 150 ml.) of a dry chloroform-dry pyridine mixture (5 1 by volume) 4 To this solution, filtered if necessary through a small Buchner funnel to remove any traces of undissolved residue, anhydrous ethyl ether (ca. 300 ml.) is slowly added with mechanical stirring until the product is completely precipitated as a fine white crystalline powder. This is collected on a large Buchner funnel and washed with six 30-ml. portions of absolute ethanol to remove traces of pyridine and chloroform. It is then washed with anhydrous ethyl ether, air-dried, and dried in vacuo for several days over sulfuric acid, care being taken to prevent contact of the product with acid. The yield is 28.0 g. (76.7% m.p. 150 to 151°). 

MAP and DAP fertilizers are made in a granulation process from ammonia and wet-process phosphoric acid. The acid is partially neutralized in a tank reactor. Ammoniation and granulation are completed in a rotary drum. Drying, cooling and product screening complete the process238. 

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