Reactivity Comparison of Five- and Six-Membered Cyclic Carbonates with Amines: Basic Evaluation for Synthesis of Poly(hydroxyurethane)

摘要

The reaction of six- and five-membered cyclic carbonates, 5-(2-propenyl)- 1,3-dioxan-2-one (I) and 4-(3-butenyl)-1,3-dioxolan-2-one (2) with hexylamine and ben- zylamine was carried out in N,N-dimethylacetamide at 30, 50, and 70 DC. The six- membered cyclic carbonate 1 proceeded quantitatively with hexylamine at 30 DC for 24 h, while the five-membered cyclic carbonate 2 converted in 34%. The reaction rate constants at 50 DC are evaluated as follows; 1.42 Ilmol .h (I with hexylamine) > 0.29 Ilmol .h (I with benzylamine) > 0.04 Ilmol .h (2 with hexylamine) > 0.01 Ilmol .h (2 with benzylamine). The activation energies in the reactions of 1 and 2 with hexylamine were estimated to be 10.1 and 24.6 kJ/mol, respectively. The ring-strain energy was calculated by the semi-empirical method using the PM3 Hamiltonian. The ring-strain energy of the six-membered cyclic carbonate was 2.86 kca1/mol larger than that of five-membered one.