Process for the production of glycidyl methacrylate

#The invention is directed to a process for the production of glycidyl methacrylate by transesterification of methyl methacrylate with glycidol in the presence of a polymerization inhibitor and a transesterification catalyst.

#Glycidyl methacrylate is an interesting compound for polymer chemistry where it finds particular use in the coating sector, especially for the production of powder-coatings.

#It is already known to produce glycidyl methacrylate by transesterification of methyl methacrylate with glycidol in the presence of a polymerization inhibitor and phosphine compounds as transesterification catalysts (Japanese published application No. 72/38421. Although the phosphine compounds dissolve homogeneously in the reaction mixture, however, in the known process the glycidol added is only reacted to a maximum of about 80 percent.

#The following examples further explain the process of the invention.

#There were present in a 1 liter three necked flask, 500 grams (5 moles) of methyl methacrylate and 74 grams (1 mole) of glycidol as well as, as polymerization inhibitor, 0.5 grams of 2,4-dimethyl-6-tert.butyl phenol. Then there was added 0.55 grams (8.5 millimoles) of potassium cyanide and the mixture heated to 70.degree. to 80.degree. C. There were immediately distilled off over a 20 cm. packed column (Raschig rings, 6 mm diameter) at a pressure of 200 Torr, the methanol formed together with methyl methacrylate at a reflux ratio of 3:1. Air was introduced via a capillary during the reaction. After 2 hours reaction time, the glycidol transformation was 98.0% and the glycidyl methacrylate yield 94.7%. Both values were determined gas chromatographically. After filtration of the contents of the flask, the residual methyl methacrylate and unreacted glycidol were distilled off via a thin layer evaporator under vacuum. The resultant crude glycidyl methacrylate was again distilled at 10 Torr (B.P..sub.10 ; 74.degree.-75.degree. C.). The glycidyl methacrylate was obtained as a colorless liquid (Purity >>97%) in a yield of 122 grams (86% of theory).

#As described in Example 1, there were reacted 74 grams (1 mole) of glycidol with 500 grams (5 moles) of methyl methacrylate under addition of 0.5 grams of 2,4-dimethyl-6-tert.butylphenol as inhibitor and 0.55 grams of potassium cyanate (6.8 millimoles) added as catalyst. After 3 hours, the glycidol reaction amounted to 95% and the glycidyl methacrylate yield to 91.6%. The yield of pure product was 82%.