Chemical conversion of poly(carbonate) to 1,3-dimethyl-2-imidazolidinone (DMI) and bisphenol A: a practical approach to the chemical recycling of plastic wastes

A method for the chemical recycling of poly(carbonate) (PC) plastic wastes in the forms of bisphenol A (BPA) and 1,3-dimethyl-2-imidazolidinone (DMI) was investigated. Treatment with N,N'-dimethyl-1,2-diaminoethane (DMDAE) of PC pellets or PC wastes, derived from compact discs, in dioxane with/without a catalytic amount of base (e.g. Na2CO3 0.5 mol%) for a short period at 100 degreesC produced DMI and BPA, both in nearly quantitative yields. The aminolysis reaction can be carried out also in DMI, thus saving the use of conventional solvents. A sequential profile of this reaction was verified by examining two model reactions of diphenyl carbonate with N-methylbutylamine and DMDAE, respectively, both proceeded through low-activation energy processes. (C) 2002 Elsevier Science Ltd. All rights reserved.