A polycarbonate such as aliphatic/aromatic polycarbonate comprises repeating structural carbonate units of the formula (H-1): ##STR00001## in which R.sup.h is a radical having the formula (H-2): ##STR00002## wherein each of R.sub.11, R.sub.12, R.sub.13, R.sub.14, R.sub.15, R.sub.16, R.sub.17, R.sub.18, R.sub.19, R.sub.20, R.sub.21, R.sub.22, R.sub.23, R.sub.24, R.sub.25, R.sub.26, R.sub.27, and R.sub.28 is independently a hydrogen, a C.sub.1-C.sub.6 alkyl group, or a halogen substituted C.sub.1-C.sub.6 alkyl group. The polycarbonate, and a thermoplastic composition thereof, have improved thermal stability, cost-effectiveness, and exhibit improved manufacturability such as, for example, minimum cyclic carbonate formation and minimum amine acceptor requirement.