Agents for Classes of Compounds

DRYING AGENTS FOR CLASSES OF COMPOUNDS Dried with 

Calcium sulfate, magnesium sulfate, sodium sulfate. Magnesium sulfate, sodium sulfate. 

Calcium oxide, calcium sulfate, magnesium sulfate, potassium carbonate, followed by magnesium and iodine. 

Calcium sulfate, magnesium sulfate, sodium sulfate. 

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TABLE 11. Class DRYING AGENTS FOR CLASSES OF COMPOUNDS Dried with... 

For many years oral xanthines, shown in Table 2, were the preferred first-line treatment for asthma in the United States, and if the aerosol and oral formulations of P2" go sts are considered separately, as they are in Table 1, this was still the case in 1989. Within this class of compounds theophylline (8), or one of its various salt forms, such as aminophylline [317-34-0] (theophylline ethylenediamine 2 l), have been the predominant agents. Theophylline, 1,3-dimethylxanthine [58-55-9], is but one member of a class of naturally occurring alkaloids. Two more common alkaloids are theobromine (9), isomeric with theophylline and the principal alkaloid in cacao beans, and caffeine, (10), 1,3,7-Trimethylxanthine [58-08-2], found in coffee and tea. 

Low Osmolality Contrast Media. An ideal intravascular CM possesses several properties high opacity to x-rays, high water solubihty, chemical stabihty, low viscosity, low osmolahty, and high biological safety. Low cost and patentabihty are also important for commercial agents. The newer nonionic and low osmolar agents represent an advanced class of compounds in the development of x-ray contrast media. 

With respect to the monoazacrown ethers, Pedersen has utilized some interesting technology which is applicable to this class of compounds. For example, he has used benzylamine as a nitrogen transfer agent. This is accomplished by the sequence shown in Eq. (4.5). In the same report, Pedersen utilized the r-butyloxycarbonyl (tBOC)... 

Because chlorine is more electronegative than carbon, carbon tetrachloride has four polar covalent bonds. But, as pointed out earlier, the molecular symmetry cancels out the electric dipoles of the individual bonds. The result is a nonpolar molecule. Like water, carbon tetrachloride is a good solvent. At one time, it was used as a dry cleaning agent. Water and carbon tetrachloride, however, dissolve entirely different classes of compounds. Carbon tetrachloride forms solutions with nonpolar organic compounds. It is infinitely miscible, for example, with benzene, whereas water and benzene do not mix. 

Biliary Excretion. The effects of significant hepatic extraction as a result of biliary secretion, with or without metabolism, would be expected to follow the same principles just outlined for hepatic metabolism. In fact, a whole class of compounds that serve as biliary contrast agents for radiological examination depend on significant first-pass biliary secretion to be effective. 

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