Acrylic acid ester

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General formula of acrylic acid esters. R is an organyl group.

Acrylic acid esters are esters that are derived from acrylic acid (CH 2 = CH-COOH) and thus have the general formula CH 2 = CH-COOR . R stands for an organyl group . Together with the salts of acrylic acid, the esters belong to the class of acrylates .

Manufacturing

Acrylic esters are produced on an industrial scale by allowing the acrylic acid to react with the corresponding alcohol with the addition of a catalyst. The reaction with lower alcohols ( methanol , ethanol ) takes place at 100–120 ° C under acidic heterogeneous catalysis ( cation exchanger ). The conversion of higher alcohols ( n- butanol, 2-ethylhexanol) is catalyzed in a homogeneous phase with sulfuric acid. Acrylic acid esters of higher alcohols can also be obtained by transesterification of lower esters under catalysis with titanium alcoholates or organic tin compounds (e.g. dibutyltin dilaurate ). Since the esterification is an equilibrium reaction, the reaction products are separated off by distillation in order to increase the conversion . Because of the pronounced tendency of the acrylic acid esters to polymerize, inhibitors (e.g. phenothiazine ) are added to the reaction mixtures and the esterification is carried out under a lean air atmosphere (oxygen content below 20% by volume). In large quantities, inter alia, be methyl acrylate , ethyl acrylate , butyl acrylate , isobutyl acrylate and acrylic acid 2-ethylhexyl ester [acrylate (2-ethylhexyl), 2-EHA ] produced.

Applications

Acrylic esters are often used as dienophiles in the Diels-Alder reaction for the production of cyclic carboxylic esters . The main application of acrylic acid esters is in homo- and copolymers with z. B. acrylic acid, acrylamides, methacrylates , acrylonitrile , maleates , vinyl acetate , vinyl chloride , styrene , butadiene and unsaturated polyesters for adhesives and sealants, varnishes and paints, coatings for textiles, leather, paper and a variety of plastics .

Hexanediol diacrylate , isobornyl acrylate and 2-EHA , among others , are used as reactive diluents .

Individual evidence

  1. ^ A b Hans-Jürgen Arpe: Industrial organic chemistry . 6th edition. Wiley-VCH, Weinheim 2007, ISBN 978-3-527-31540-6 .
  2. ↑ a b Entry on acrylic acid esters. In: Römpp Online . Georg Thieme Verlag, accessed on January 11, 2012.