Process for recovering noble products in a process for producing dialkylaminoalkyl (meth) acrylates

A process for manufacturing a dialkylaminoalkyl(meth)acrylate of formula (I):

• H2C═C(R′i)-C(O)—O-A-N(R′2)(R′3) (I)
• in which:
• R′i is a hydrogen atom or a methyl radical
• A is a linear or branched C1-C5 alkylene radical
• R′2 and R′3, which may be identical or different, each represent a C1-C4 alkyl radical, by transesterification reaction between an amino alcohol of formula (II):
• HO-A-N(R′2)(R′3) (II)
• in which A, R′2 and R′3 are as defined above,
• and a light alkyl(meth)acrylate of formula (III):
• CH2═C(R′i)-COOR′4 (III)
• in which R′i is as defined above and R′4 represents the methyl or ethyl radical;
• said process comprising following steps:
• a) submitting a mixture comprising a compound of formula (III), an amino alcohol of formula (II), a transesterification catalyst, and at least one polymerization inhibitor, to transesterification to form a mixture comprising (meth)acrylic ester (I), the unreacted compounds (II) and (III), the catalyst, the polymerization inhibitor, Michael adducts resulting from reactions of addition on the (meth)acrylic double bonds, and other heavy compounds;
• b) distilling the mixture of products to recover, at the top, a stream comprising a major fraction of the required (meth)acrylic ester (I) and light products, comprising a minor fraction of Michael adducts and heavy products, but free or substantially free from catalyst, and leaving, at the bottom, a heavy fraction comprising the catalyst, the polymerization inhibitor, the Michael adducts and the heavy compounds, with a minor fraction of the required (meth)acrylic ester (I) and amino alcohol and traces of light products;
• c) purifying the overhead stream, giving the purified dialkylaminoalkyl (meth)acrylate (I);
• d) submitting at least a proportion of the heavy fraction to a process for recovery of the noble products comprising the steps of (i) adding at least one antifouling agent and optionally a viscosity-reducing compound;
• (ii) submitting the mixture to a sufficient temperature and to distillation conditions for cracking the Michael adducts into their constituent components;
• (iii) recovering the noble products in the form of a stream of distillate, and of a final residue that is sufficiently fluid to be transported by pump;
• e) recycling, to the purification step c), at least a proportion of said stream of distillate comprising at least one compound selected from (meth)acrylic ester (I), amino alcohol (II) or alkyl(meth)acrylate (III);
• f) disposal of the final residue.