Process for the manufacture of butyl acrylate by direct esterification

Abstract

In this esterification, catalysed by H.sub.2 SO.sub.4, the crude reaction mixture comprising ester, butanol, acrylic acid, BuSO.sub.4 H and traces of H.sub.2 SO.sub.4 is obtained; BuSO.sub.4 H is hydrolysed (in R2) to H.sub.2 SO.sub.4 using pure water or water generated during the reaction; after hydrolysis, the medium is separated by settling (in D2) into an organic phase containing ester, butanol and part of the unconverted acid; and an aqueous phase containing H.sub.2 SO.sub.4 and the remainder of the unconverted acid; the organic phase is washed under alkaline conditions in order to neutralize the acrylic acid to alkaline acrylate which is soluble in the aqueous phase and then the neutralized organic phase is washed with water; the acid present in alkaline salt form in the aqueous phase from the 1st basic neutralization is regenerated by addition of the acidic aqueous phase (8) resulting from the separation by settling (in D2) of the hydrolysis stage; the acid (10) thus regenerated in this aqueous phase is extracted (in C5) by a solvent chosen from butanol, butyl acrylate or a mixture of butyl acrylate and butanol; the organic phase (13) obtained at the head of the extraction column (C5), containing mainly acid and butanol or ester, or a mixture of butanol and ester, is recycled to the esterification reactor (R1); the aqueous phase (15) recovered at the foot of the column (C5) is conveyed as feed to a distillation column (C6) for recovering butanol (16) at the head, for the purpose of recycling it upstream and of discarding the spent aqueous liquors, which are virtually free from organic pollution.