Trimethylolpropane → 2-Ethyl-2-(hydroxymethyl)propane-1,3-diol;2-methylprop-2-enoic acid

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600 kg of trimethylolpropane, 3348 kg of methyl methacrylate (MMA), 0.1 kg of hydroquinone monomethyl ether as inhibitor and a mixture of 5 kg of calcium oxide and 1 kg of lithium chloride as catalyst are combined in a 6 m3 stirred tank reactor provided with agitator, steam heating, distillation column and condenser and the mixture is stirred while passing in air. To stabilize the column, a total of 151 kg of MMA containing 0.12 kg of hydroquinone monomethyl ether and 0.016 kg of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl in dissolved form are introduced into the column runback during the course of the reaction. The apparatus is heated to a temperature at the bottom of 96° C., with the column initially being operated under total reflux. As soon as the temperature at the top of the column drops below 70° C., the methanol/MMA mixture is taken off at a reflux ratio of 8:1. Above a temperature at the top of the column of 85° C., the methanol/MMA mixture is low in methanol and is collected in a separate vessel for reuse as raw material in the next batch. When a temperature at the bottom of 115° C. has been reached, the reaction is complete and excess MMA is taken off under reduced pressure, with the pressure gradually being reduced to 100 mbar. When no more MMA distills off, the vacuum is broken. The contents of the tank, which comprise the catalyst-containing trimethylpropane trimethacrylate, are admixed with 15 kg of bleaching earth and 5 kg of aluminium silicate (Perlite) as filter aid and freed of the catalyst by washcoat filtration. The filtrate is fed into a continuous evaporator (area: 2 m2) having a rotating wiper system at a pressure of 15 torr and an evaporator temperature of 142° C. A total of 1420 kg of trimethylolpropane trimethacrylate are obtained from the bottom product.

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