Water-Soluble Crystals

organic or inorganic, always react with the crystalline substance. Therefore, addition of an acid can increase etch rates as a result of chemical reactions (Sec. 2.4). However, by virtue of their low dielectric constant, which determines the solubility of the substance, their addition also decreases the rate, in the case of organic acids the latter effect is predominent, while in strong inorganic acids the former effect Is predominent. 

Consequently, addition of small amounts of strong acids to slow solvents is found to have a marked favorable effect on the revelation of dislocation etch pits, while In organic acid the etch-pit contrast is poor. 

Addition of trace amounts of ionic salts to slow solvents is found to be equally effective in producing contrasting etch pits as, for example, on the surfaces of alkali halide crystals (see Fig, 6). 

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Water-soluble crystal modifiers such as yellow pmssiate of soda (YPS) (sodium ferrocyanide decahydrate) or ferric ammonium citrate may also be added to some types of salt as anticaking agents. Both are approved by the U.S. Food and Dmg Administration for use in food-grade salt. YPS and Pmssian Blue (ferric ferrocyanide), are most commonly added to rock salt used for wintertime highway deicing. Concentrations of YPS and Pmssian Blue in deicing salt vary, typically in the range of 20—100 ppm. 

Sulfamic acid [5329-14-6] (amidosulfuric acid), HSO2NH2, molecular weight 97.09, is a monobasic, inorganic, dry acid and the monoamide of sulfuric acid. Sulfamic acid is produced and sold in the form of water-soluble crystals. This acid was known and prepared in laboratories for nearly a hundred years before it became a commercially available product. The first preparation of this acid occurred around 1836 (1). Later work resulted in identification and preparation of sulfamic acid in its pure form (2). In 1936, a practical process which became the basis for commercial preparation was developed (3,4). This process, involving the reaction of urea with sulfur trioxide and sulfuric acid, continues to be the main method for production of sulfamic acid. 

A solution of 75 g (Mo mol) of 1,3-propanolamine and 202 g of triethylamine in 100 cc of absolute dioxane Is added dropwise at 25°C to 30°C while stirring well to a solution of 25.9 g (Vio mol) of N,N-bis-( -chloroethyl)-phosphorlc acid amide dichlorlde in 100 cc of absolute dioxane. After the reaction is complete, the product is separated from the precipitated triethylamine hydrochloride and the filtrate Is concentrated by evaporation In waterjet vacuum at 35°C. The residue Is dissolved in a large amount of ether and mixed to saturation with water. The N,N-bis-( -chloroethyl)-N,0-propylene phosphoric acid diamide crystallizes out of the ethereal solution, after it has stood for some time in a refrigerator, in the form of colorless water-soluble crystals. MP 48 C to 49°C. Yield 65% to 70% of the theoretical. 

White or off-white needle-shaped water-soluble crystals. 

Emil Fischer s initial studies [1] focused on dithioacetal formation from a variety of simple aldopentoses, aldohexoses, and aldoheptoses. The products were obtained by simply treating the sugar with an excess of ethanethiol in concentrated hydrochloric acid at low temperature ( 0°C). Many of these dithioacetals have low water solubility, crystallize spontaneously from the reaction mixtures, and can be isolated by simple filtration and washing with odd water. Fischer s key paper [1] also outlined most of the major reaction modes of the diethyl dithioacetal derivatives, later developed in detail, and thus paved the way for subsequent studies into this important class of sugar derivative. 

Properties A naturally occurring complex of biotin isolated from yeast. Mp 228.5C. Water-soluble crystals. The molecule arising from covalent attachment of biotin to a Ly s residue via an amide linkage. 

Hyamine [Rohm Haas], TM for qua-ternary-ammonium-type bactericides, algicides, and fungicides, supplied as water-soluble crystals or aqueous solutions. 

Acid Coupling Process. On the other hand, Chrysoidine Y [532-82-1] (22) (Cl Basic Orange 2 Cl 11270) is an example of a dye produced by acid coupling. Aniline, 9.3 g, is diazotized and the diazo solution is added to a solution of 11 g / /-phenylenedi amine in 200 mL water then the solution is made slightly acidic with hydrochloric acid. The reaction mixture is maintained with stirring until coupling is complete as indicated by spot test where, upon addition of an alkaline solution of 2-naphthol, there is no color change if the diazo is exhausted. The solution is warmed to about 60 °C. A concentrated solution of salt is added (about 120 g). The reaction mixture is then allowed to cool and the dye is filtered and dried. Reddish brown water-soluble crystals are obtained. 

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