Hydroquinone → 2-Ethyl-2-(hydroxymethyl)propane-1,3-diol;prop-2-enoic acid

Participants

Reaction Steps

2.44 kg of trimethylolpropane, 3.93 kg of acrylic acid, 0.5 kg of an acid ion exchanger (Lewatit 3333 of BAYER AG), 9 g of hydroquinone and 1.5 liters of petroleum ether (boiling range 60° to 70° C) were heated under a water separator, whilst stirring, in a 10 liter three-necked flask equipped with a stirrer, water separator and gas inlet tube. At the same time, a constant stream of air saturated with allyl alcohol was passed through the flask at a rate of 2 liters/hour. In total, 16 ml of allyl alcohol were introduced into the esterification mixture in this way. After 80 hours, the reaction mixture had an acid number of 32 and the boiling point had risen to 72° C. The petroleum ether was distilled off, remnants being removed by applying a vacuum of 0.2 mm Hg at a product temperature of 40° C. The esterification catalyst was separated off by filtration and was kept for further use. The trimethylolpropane triacrylate obtained in practically quantitative yield was pale yellowish and clear. The viscosity corresponded to a time of outflow of 20 seconds measured in a DIN cup 4 at 20° C. The product showed no change even on storage for 4 months at 60° C. When used in a UV light-curing printing ink which contained a photoinitiator, the product polymerised at high speed.

Provenance & Evidence