Cmde preparations

Aloe polysaccharides [93] are obtained from the fleshy leaves of Aloe sp. Cmde preparations of Aloe polysaccharides are especially used in cosmetic and pharmaceutical preparations to be applied to the skin, but have other uses as well. 

The fact that cmde Candida rugosa lipase occasionally exhibits a moderate selectivity particularly on a-substituted carboxylic esters could be attributed to the presence of two isomeric forms of the enzyme present in the cmde preparation [422, 423]. Both forms (denoted as fraction A and B), could be separated by Sephadex chromatography and were shown to possess a qualitatively identical (i.e., identical enantiopreference) but quantitatively different stereoselectivity... 

Titanium trifluoride is prepared by dissolving titanium metal in hydrofluoric acid (1,2) or by passing anhydrous hydrogen fluoride over titanium trihydrate at 700°C or over heated titanium powder (3). Reaction of titanium trichloride and anhydrous hydrogen fluoride at room temperature yields a cmde product that can be purified by sublimation under high vacuum at 930—950°C. 

Commercial soy protein concentrates typically contain 70 to 72% cmde protein, ie, nitrogen x 6.25, dry wt basis. Soy protein isolates are prepared from desolventhed, defatted flakes. A three-stage aqueous countercurrent extraction at pH 8.5 is used to disperse proteins and dissolve water-soluble constituents. Centrifugation then removes the extracted flakes, and the protein is precipitated from the aqueous phase by acidifying with HCl at pH 4.5. 

Acid mixtures are used to oxidize and remove the dark materials. Proper control gives a series of bleached waxes. A white wax requires double refining and reduces the yield to about 30% of the cmde wax input. A series of synthetic waxes is prepared by separating the acids and alcohols produced during saponification of the wax and reesterifying them with acids or alcohols selected to give desired properties of hardness, solubiHty, emulsification, and gloss. 

The high cost of coal handling and preparation and treatment of effluents, compounded by continuing low prices for cmde oil and natural gas, has precluded significant exploitation of coal as a feedstock for methanol. A small amount of methanol is made from coal in South Africa for local strategic reasons. Tennessee Eastman operates a 195,000-t/yr methanol plant in Tennessee based on the Texaco coal gasification process to make the methyl acetate intermediate for acetic anhydride production (15). 

Solvents. Petroleum naphtha is a generic term appHed to refined, pardy refined, or unrefined petroleum products. Naphthas are prepared by any of several methods, including fractionation of distillates or even cmde petroleum, solvent extraction, hydrocracking of distillates, polymerization of unsaturated (olefinic) compounds, and alkylation processes. Naphtha can also be a combination of product streams from more than one of these processes. 

A number of improvements have been made in these syntheses. For example, the use of ethanoHc ferric chloride and zinc chloride produces a good yield of 2-isopropylquinoline [17507-24-3] from isovaleraldehyde (46). The purification of 2-methylquinoline is facHitated through precipitation. A cmde quinaldine—hydrochloride and zinc chloride complex is prepared and then treated with aqueous base (47). 

The manufacture of silver nitrate for the preparation of photographic emulsions requires silver of very high purity. At the Eastman Kodak Company, the principal U.S. producer of silver nitrate, 99.95% pure silver bars are dissolved in 67% nitric acid in three tanks coimected in parallel. Excess nitric acid is removed from the resulting solution, which contains 60—65% silver nitrate, and the solution is filtered. This solution is evaporated until its silver nitrate concentration is 84%. It is then cooled to prepare the first crop of crystals. The mother Hquor is purified by the addition of silver oxide and returned to the initial stages of the process. The cmde silver nitrate is centrifuged and recrystallized from hot, demineralized water. Equipment used in this process is made of ANSI 310 stainless steel (16). 

Reactions with Nitrogen Compounds. Succinimide [123-56-8] mp 126°C, can be prepared by reaction of aqueous solutions of the acid with ammonia (105) or urea (106) (eq. 7). The solution is heated until water and ammonia are no longer evolved and the molten cmde succinimide is purified by fractionation. Alternatively, the cmde product can be recrystaUized from water (105). 

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