Novell isochroman-3-ones for the curing of unsaturated polyesters via Diels-Alder reaction

The synthesis of some new 4-hydroxy, 4-butyloxy, 4-propionyloxy, and 4-acry loyloxy substituted isochroman-3-ones is described. The influence of the su bstitution pattern in position I and 4 on the CO2 elimination, which leads to high reactive ortho-quinodimethanes, is investigated. The saturated comp ounds are used for model reactions with diethyl maleate to study the Diels- Alder reaction and to explain the curing mechanism of unsaturated polyester s. The acrylic ester is copolymerized with styrene to give a reactive copol ymer which can easily cure unsaturated polyesters at 170 degrees C in two m ins without toxic byproducts.