Study On The Synthesis Of Neopentyl Glycol Dimethylacrylate Over Eco-friendly Catalysts

Neopentyl glycol dimethylacrylate (NPGDA) like other multifunctional methacrylates is industrially important monomers for anaerobic adhesives, diluent monomer in dental composites, thread lockers, sealants and components for making soft contact lenses. NPGDA is currently produced by the direct esterification of neopentyl glycol with methacrylic acid using conventional acids as catalysts such as sulfuric acid. However due to it's problems of toxic, contaminative to the environment and the product separation requires tedious work up procedures, it becomes a must to find an eco-friendly alternative.Therefore, in this paper, the process for preparing NPGDA by directly esterification over supporting solid catalysts was employed. The effects of reaction conditions on reaction results were studied. The researching content was as follows:1. Reaction conditions including the molar ratio of acid to alcohol, catalyst concentration, reaction temperature, cyclohexane and polymer inhibitor concentration were particularly studied over H₂SO₄, paratoluenesulfonic acid (PTSA), phosphotungstic acid (HPW) as catalysts. Under the optimum reaction conditions which were the molar ratio was 2.3:1, the amounts of catalyst, inhibitor and cyclohexane were 7 %, 0.75 % and 60 % relatively, reaction temperature was 105℃, reaction time was 90min, a 95.0% yield of NPGDA was obtained over H₂SO₄.2. Reaction conditions including the molar ratio of acid to alcohol, catalyst concentration, reaction temperature, cyclohexane and rotational speed were particularly studied over supporting catalysts including HPW/AC,HPW/SiO2,HPW/TiO2 and PTSA/AC. Under the optimum reaction conditions which were the molar ratio was 2.3:1, the amounts of catalyst and cyclohexane were 8 % and 80 % relatively, reaction temperature was 115℃, reaction time was 120min, a 83.5% yield of NPGDA was obtained over HPW /AC. A 76.0% yield was still obtained after HPW /AC recyclingly used for 4 times.3. The supporting method and quantity were studied. The method of directly vaporizing and the mass ratio of 1:1 of support and pure catalyst were found as the optimum technologies.4.The supporting catalysts were charactered by many methods including FT-IR,SEM,XRD,XPS,TGA,BET and so on. The results showed that the catalysts' activities had much to do with the characters.