Elf Atochem S.a.

Norbert Richard

Michel Fauconet

Marc Esch

Patrice Hurtel

Charles Hazan

Nadine Colin

Patrick Delafin

The present invention relates to the manufacture of a dialkylaminoalkyl (meth)acrylate by transesterification of methyl or ethyl (meth)acrylate with an amino alcohol. The transesterification catalyst is chosen from tetrabutyl, tetraethyl and tetra(2-ethylhexyl) titanates. The reaction is carried out in a stirred reactor at 90-120&deg; C., after which the crude reaction mixture is sent to a tailing column (C ), the flow from the top of this column is sent to a topping column (C ) and the flow from the bottom of this column si then sent to a final rectification column (C ). A dialkylaminoalkyl (meth)acrylate of high purity is obtained in this way.

Process for the continuous manufacturing of dialkylaminoalkyl (METH) acrylates having a critical order of steps

To recover these noble products consisting of acrylic acid monomer, acrylic ester monomers and alcohols, a thermal cracking is performed in the absence of catalyst on a mixture of heavy distillation residues originating, on the one hand, from the manufacture of acrylic acid and, on the other hand, from the manufacture of the esters, the light fraction originating from the dissociation reactions is continuously vaporized during the cracking operation and this light fraction is distilled in order to recover, after condensation, the required products. The process according to the invention may consist in conducting the cracking of the mixture of heavy residues, optionally preheated, in a reactor (R1); feeding a distillation column (C1) with the light cracking products; recovering the required mixture of light noble products at the head of column (C1); recycling the flow recovered at the foot of column (C1) into the reactor (R1); recovering the heavy residue from the reactor (R1) and sending it to a removal treatment, if appropriate after having diluted it with a part of the flow recovered at the foot of column (C1), the remainder of the said flow being recycled into the reactor (R1). Figure to be published: FIG. 1

Process for recovery of the light noble products present in the

An alkyl (meth)acrylate is prepared by a direct esterification (in 1) of (meth)acrylic acid by the corresponding alcohol, catalysed by H.sub.2 SO.sub.4. To the crude reaction mixture (C.sub.1) comprising the desired ester, alcohol, (meth)acrylic acid, alkyl hydrogen sulphate and traces of H.sub.2 SO.sub.4, there is added (in 3) a base to neutralize the acidic species, the resulting salts passing into the aqueous phase (A.sub.1), which is separated from the organic phase (O.sub.1) containing the desired ester. The light products (L.sub.1) containing the alcohol are recovered (in 4) from the aqueous phase, and the waste waters (W.sub.2) are expelled. A hydrolysis is carried out (in 8) of the alkyl hydrogen sulphate present in the aqueous phase (A.sub.1) obtained after the separation which is carried out after neutralization (in 3), to form the alcohol and H.sub.2 SO.sub.4 in this phase, the acidic species resulting from the hydrolysis are neutralized by introduction of a base .into the medium, and the resulting aqueous phase (A.sub.3) is directed to the step for recovery of the alcohol. Pollution of the waters (W.sub.2), attributable to the alkyl hydrogen sulphate, is thus avoided.

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Creutz Wald, France

Norbert Richard