Patent ID: 7754916

Claim:
A process for preparing an unsaturated carboxylic acid, and esters thereof, from an ammonium salt of a beta-hydroxypropionic acid, said process comprising: a) providing an aqueous solution comprising the ammonium salt of a beta-hydroxypropionic acid; b) converting the ammonium salt of a beta-hydroxypropionic acid to a corresponding beta-hydroxypropionic acid and ammonium cation in aqueous solution; and c) separating the ammonium cation from the aqueous solution, leaving the beta-hydroxypropionic acid in aqueous solution; wherein said converting and separating steps b) and c) are accomplished by a technique selected from the group consisting of: (1) adding a solution comprising a hydrophobic acid and, optionally, an organic solvent, to the aqueous solution, wherein the hydrophobic acid comprises a proton and a conjugate base, is immiscible in water, is capable of forming an ammonium salt which is also immiscible in water, and has an acid dissociation constant (pK a ) which is at least 0.5 less than the acid dissociation constant of the beta-hydroxypropionic acid, to form a multi-phase solution which comprises an aqueous phase comprising the beta-hydroxypropionic acid, which comprises the carboxylic anion and the proton, and a non-aqueous phase comprising a neutralized acid, which comprises the ammonium cation and the conjugate base of the hydrophobic acid, and (2) contacting the aqueous solution comprising the ammonium salt of beta-hydroxypropionic acid with an acid ion exchange resin having an acid dissociation constant (pK a ) which is at least 0.5 less than the acid dissociation constant of the beta-hydroxypropionic acid, to form an aqueous solution comprising the corresponding beta-hydroxypropionic acid and a non-aqueous ammonium cation-containing exchange resin.