摘要:
A process for the preparation of an .alpha.,.beta.-unsaturated C.sub.3 -C.sub.6 carboxylic acid of greater than 98% purity, which combines fractional distillation and melt crystallization procedures.
摘要:
This invention is a method for removing certain carbonyl containing impurities from .alpha.,.beta.-unsaturated carboxylic acid ester with an aqueous solution of a bisulfite or dithionite salt.
摘要:
This invention provides a method for reducing carbonyl-containing impurities in .alpha.,.beta.-unsaturated carboxylic acid esters by treatment of the ester with one or more of a selected phenylenediamine and an acid.
摘要:
The invention provides a continuous process for producing a pure grade of acrylic acid having residual aldehyde levels under 10 parts per million. The process applies two groups of amines sequentially and continuously in selectively reducing acrolein and furfural and may be advantageously conducted in the presence of maleic acid and maleic anhydride impurities.