| 摘要 |
A glycol monoester of formula <FORM:1036163/C2/1> wherein x is 2, 3, or 4, and R is H, CH3 or C2H5, and containing some diester as impurity, is purified by contacting an aqueous solution of the monoester with an organic solvent: (1) having a dielectric constant of less than 10 measured at 20 DEG C. using audio-frequencies, preferably of 1.8 to 5, (2) having a solubility parameter <FORM:1036163/C2/2> wherein x and n are 2, 3 or 4 and A is a number from 10 to 11.5, (3) being a normally liquid aliphatic, cycloaliphatic, or aromatic hydrocarbon or their normally liquid chlorinated derivatives, or mixtures thereof, to dissolve out the diester. The aqueous solution preferably contains 25-75% by volume of monoester, together with a solubilizing amount of a C2 to C4 alkylene glycol. The extraction may be batchwise or continuous using a countercurrent extraction process. The solubility parameter d is derived as in "Solubility of Non-electrolytes" by Hildebrand and Scott, 3rd Edition, 1950, pp. 435-9. Suitable solvents include toluene, hexane, heptane, octane, cyclohexane, cyclohexene, ethylcyclohexane, carbon tetrachloride. Solvents suitable in admixture with others to produce the desired properties include benzene, xylene, chlorobenzene, chloroform, ethylene dichloride, perchloroethylene, methylene chloride.ALSO:A glycol monoester of formula <FORM:1036163/C3/1> where x is 2, 3 or 4, and R is H, CH3 or C2H5, is purified from small amounts of the diester by solvent extraction (see Division C2) and a 10 ml. sample of the aqueous esters is mixed with 5 ml. ethyl alcohol, 0.5 ml. of 2% aqueous thiourea and 0.2 ml. of 35% hydrogen peroxide and allowed to polymerize. The polymer produced is a viscous alcohol-soluble liquid if all diester is removed, indicating no cross-linking, or is stringy, partially alcohol-soluble if only part of the diester is removed. |
