Precious Metal Catalysts for Homogeneous Catalysis
Polymethyl methacrylate (PMMA), commonly known under its original trade name Plexiglas and other trade names such as Lucite and Perspex, is a further example for the significant role of homogeneous catalysis. Plexiglas is used for very many products, e.g. for noise protection walls, walls of showers in the sanitary field, aircraft windows, transparent roofing – such as the tent-roof design of the Olympic Park in Munich – and automobile lights.
PMMA is formed by the polymerization of methyl methacrylate (MMA), the methylester of methacrylic acid. MMA is therefore a very important industrial precursor product that is manufactured on a scale of millions of tonnes per annum.
Lucite International has developed a new process for the production of MMA which is known as the Alpha process. Since 2008, up to 120,000 tonnes of MMA have been produced per year by this process in Singapore. Methylpropionate is produced from methanol, carbon monoxide and ethylene. The homogeneous palladium catalyst used in this hydroesterification is based on a palladium phosphane complex. In a subsequent reaction, methylpropionate is transformed into MMA with
The Alpha process is an alternative to producing MMA by means of acetonecyanhydrine (the ACH route) in which the ACH is manufactured from acetone and hydrogen cyanide and subsequently processed to MMA with sulfuric acid and methanol.