The synthesis of the bisesterdiamide T2T-dimethyl (one-and-a-half repeating unit of nylon 2,T) (benzoic acid, 4,4′-[1,2–ethanediylbis(iminocarbonyl)] bis-dimethyl ester, CAS no 7060-10-8) has been studied using dimethyl terephthalate (DMT) and 1,2-diaminoethane (DAE) as starting materials. T2T-dimethyl was synthesised in a solvent mixture of toluene/methanol at 65°C employing lithium or sodium methanolate as a catalyst. The progress of reaction was followed as function of time using liquid chomatrography and endgroup titrations. The products were analysed using 1H NMR, 13C NMR and differential scanning calorimeter. A high yield was obtained (90%), and after recrystallisation from NMP, the product was found to be of high purity. The pure T2T-dimethyl obtained had a melting onset of 312°C and a melting enthalpy of 165 J/g. T2T-dimethyl was also synthesised in absence of a catalyst at 100°C and using m-xylene as solvent and at a high concentration of reactants. The yield of this reaction was relatively low (34%). The addition of phenol to the reaction mixture had little effect on the yield and purity of the product.
- Dimethyl terephthalate