Solvent drying agents

Use Dry-cleaning solvent, vapor-degreasing solvent, drying agent for metals and certain other solids, vermifuge, heat-transfer medium, manufacture of fluorocarbons. 

We may now understand the nature of the change which occurs when an anhydrous salt, say copper sulphate, is shaken with a wet organic solvent, such as benzene, at about 25°. The water will first combine to form the monohydrate in accordance with equation (i), and, provided suflScient anhydrous copper sulphate is employed, the effective concentration of water in the solvent is reduced to a value equivalent to about 1 mm. of ordinary water vapour. The complete removal of water is impossible indeed, the equilibrium vapour pressures of the least hydrated tem may be taken as a rough measure of the relative efficiencies of such drying agents. If the water present is more than sufficient to convert the anhydrous copper sulphate into the monohydrate, then reaction (i) will be followed by reaction (ii), i.e., the trihydrate will be formed the water vapour then remaining will be equivalent to about 6 mm. of ordinary water vapour. Thus the monohydrate is far less effective than the anhydrous compound for the removal of water. 

Liquids or solutions of organic substances in organic solvents are usually dried by direct contact with a solid inorganic drying agent. The... 

Using inorganic salts as precursors, alcohol as the supercritical drying agent, and a batch process a solvent-exchange step was necessary to remove water from the gel. 

Magnesium methylate is used as a drying agent for alcohols and other organic solvents and as an intermediate in various manufacturing processes, eg, for organomagnesium compounds (79), orthocarbonic esters (80), and for oxide coatings. 

Magnesium ethylate is used as a drying agent for organic solvents, as an intermediate for the manufacture of organomagnesium and other organic products, as catalyst in the Tishchenko (85) and other reactions (86—91), in the condensation of esters (92), in alkylation reactions, and in polymeri2ations (84,91). 

Surface Applied Surfactants. Antistat agents can be appHed direcdy to the surface of a plastic part. Usually the antistat is diluted in water or in a solvent. The antistat solution is appHed by spraying, dipping, or wiping on the surface. The water or solvent dries leaving a thin film that attracts moisture. Since it is appHed to the surface, migration through the resin is not a factor. In practice, the quaternary ammonium compounds find the most use. They are soluble in water and effective at low concentrations. 

The first step of the Combes reaction has been reported to occur by merely mixing an aniline and diketone in an alcoholic solvent, or neat, with slight warming. Dilute aqueous acid (2 M HCl), AcOH, ZnCh as well as CaCl2, or other types of drying agents have been used to promote the first step. 

Y. Pico, J. J. Vreuls, R. T. Ghijsen and U. A. Th Brinkman, Drying agents for- water-free intr-oduction of desorption solvent into a GC after on-line SPE of aqueous samples , Chromatogmphia 38 461-469 (1994). 

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