摘要:
Purification of acetophenone containing difficultly separable impurities by extractive distillation with a solvent selected from the group consisting of oligomers of 1,2-glycols, said oligomers having from 4 to 9 carbon atoms per molecule.
摘要:
Method for preparing polyols such as diols and triols by the homogeneous catalytic hydroxylation of an olefinic compound by contacting the olefinic compound with an organic hydroperoxide in an aqueous solution at an initial pH above 8 in the presence of a catalytic amount of a water soluble osmium compound as the catalyst.
摘要:
In the process of producing a diisocyanate comprising(a) condensing and rearranging alkyl phenylcarbamate and formaldehyde under acidic conditions to form dialkyl methylene bis(phenylcarbamate) and(b) thermally decomposing the dialkyl methylene bis(phenylcarbamate) to diphenylmethane diisocyanate,the improvement comprises prior to step (b) treating the reaction product of (a) by first distilling the reaction product of (a) under reduced pressure at a temperature below 120.degree. C. until all solvent is removed and 65-85% of the unreacted alkyl phenylcarbamate present is removed, discontinuing the distillation, adding a polar solvent to undistilled distillation residue and selectively crystallizing and separating dialkyl methylene bis(phenylcarbamate) from the distillation residue.