Process for isolating hydroxypivalic acid from aqueous solution
AssigneeBayer Aktiengesellschaft
InventorsKarl Heinz Neumann, Dieter Heitkamp, Helmut Fiege
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Abstract
Hydroxypivalic acid is obtained from aqueous solutions by removal of the water by azeotropic distillation and subsequent crystallization from a solvent mixture which is composed of a polar and a non-polar component. The distillation is carried out under reduced pressure and at a maximum bottom temperature of 90.degree. C., until a residual water content of at least 0.1% of the total weight of the resulting solution is achieved.
Claims16
A process for isolating hydroxypivalic acid from aqueous solutions by removal of the water by azeotropic distillation and subsequent crystallization of the hydroxypivalic acid from an organic solvent, which comprises (a) adding one or more organic solvents, of which at least one forms an azeotrope with water, to the aqueous solution, (b) distilling off the water under reduced pressure until the resulting solution of the hydroxypivalic acid in the organic solvent(s) has a residual water content of at least 0.1% by weight, based on the total weight of the solution formed, and (c) adjusting the solution formed such that it comprises at least one polar and at least one non-polar solvent and the hydroxypivalic acid crystallizes out of it.
Dependencies are inferred from the claim text.