A thermoplastic composition comprises: a copolycarbonate comprising bisphenol A carbonate units and second carbonate units of the formula (I) and optionally, a bisphenol A homopolycarbonate; wherein the second carbonate units are present in an amount of 10 to 49 mol % based on the sum of the moles of the copolycarbonate and the bisphenol A homopolycarbonate, the copolycarbonate comprises less than 2 ppm by weight of each of an ion of lithium, sodium, potassium, calcium, magnesium, ammonium, chlorine, bromine, fluorine, nitrite, nitrate, phosphite, phosphate, sulfate, formate, acetate, citrate, oxalate, trimethylammonium, and triethylammonium, as measured by ion chromatography, and the thermoplastic composition has a bisphenol A purity of at least 99.6%, or at least 99.7% as determined by high performance liquid chromatography. The thermoplastic composition has a Vicat B120 of 155° C. or higher; and an increase in yellowness index of less than 10 during 1000 hours of heat aging at 155° C.