Elf Atochem S.a.

Atofina

Arkema Inc.

Jacqueline Bessalem

Michel Fauconet

Alain F Riondel

Christian Lacroix

Nathalie Hess

Stephane Lepizzera

2-Ethylhexyl acrylate is manufactured according to a process for the direct esterification of acrylic acid with 2-ethylhexanol catalysed by sulphuric acid, the acrylic acid subjected to the esterification being stabilized by at least one stabilizing agent, the said esterification being followed by the neutralization by a base of the crude reaction mixture (B1) obtained, the resulting salts passing into the aqueous phase (A1) of the said mixture, the organic phase (O1) and the aqueous phase (A1) resulting from this neutralization being separated and the 2-ethylhexyl acrylate being recovered from the organic phase (O1). To suppress the emulsions which appear during the said neutralization, the stabilizer or stabilizers of acrylic acid is/are chosen with the exclusion of hydroquinone, in the absence of which the aqueous phase of the process is stabilized before and/or during the neutralization.

Process for the manufacture of 2-ethylhexyl acrylate

Butyl acrylate is prepared by reacting acrylic acid and butanol in a reactor in the presence of an esterification catalyst the water formed being entrained by distillation in a column () in the form of a heteroazeotropic mixture with butanol mixture following condensation, being separated in a decanter () to give an upper, organic phase which is recycled to the top of the distillation column () and a lower, aqueous phase which is drawn off. The reaction is conducted with deferred introduction of part of the butanol at the top of the distillation column () or to the decanter () or to the reactor (), the butanol/acrylic acid molar ratio being initially between 0.5 and 1 before rising to between 1 and 1.5 following the completion of the deferred introduction of the butanol.

Process for preparing butyl acrylate by direct esterification

2-Ethylhexyl acrylate is obtained by esterification of acrylic acid (AA) with 2-ethylhexanol (2-EtHexOH), in the presence of at least one stabilizer for AA, with H SO as catalyst, the crude reaction mixture (B1) obtained comprising the desired acrylate, 2-EtHexOH, AA, 2-ethylhexyl hydrogensulphate (2-EtHexSO H), traces of H SO and impurities. (B1) is washed with water in an extraction column C2 to remove, at the bottom, the aqueous phase (A1), the top organic phase (O2) being sent to a topping column C3 to obtain, at the top, the AA and the 2-EtHexOH, which are recycled to the esterification, the topped desired acrylate being sent to a distillation column C4, from where it exits, purified from the heavy products; a stage of hydrolysis of the 2-EtHexSO H present in (A1) being carried out to form, in this phase, 2-EtHexOH and H SO , the acidic entities resulting from the hydrolysis being neutralized by introduction of a base into the medium, and the resulting aqueous phase (A3) being sent to the recovery of the 2-EtHexOH in a distillation column C1.

An acrylic acid ester is manufactured by reaction of the said acid and an alcohol chosen from C.sub.5 or above primary and secondary aliphatic monoalcohols, in the presence of an acid as esterification catalyst and of a polymerization inhibitor, the alcohol being capable of forming a heteroazeotrope with water, the water formed by the esterification reaction being entrained by distillation in a column in the form of a heteroazeotropic mixture with the alcohol, which mixture, containing an amount of unreacted acrylic acid, is then subjected, after condensation, to a separation in order to give an upper organic phase which is recycled to the head of the distillation column and a lower aqueous phase which is withdrawn; according to the invention, an extraction (for example in an extraction column EC) of the acrylic acid contained in the condensed heteroazeotropic mixture (M) intended for phase separation with an esterifying-alcohol-rich mixture, and the acrylic acid thus extracted is returned to the head of the distillation column (DC), as a constituent of the recycled organic phase, with an increase in the level of reflux into the distillation column (DC) relative to the natural reflux.

Process for the manufacture of alkyl acrylates by direct esterification

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.

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Saint-Avold, France

Jacqueline Bessalem