Kenneth M. Merz Jr., Eduardo C. Aguiar and Joao Bosco P. da Silva. Adenine Formation without HCN
J. Phys. Chem. A 2014, 118, 3637-3644., 2014-05-05
Abstract: From a historic point of view adenine was always presumed to be the product of HCN pentamerization. In this work a new mechanism for adenine synthesis in the gas phase without HCN is proposed. The concept of retrosynthetic analysis was employed to create a tautomer of adenine, which can be reached from previously observed interstellar molecules C3NH and HNCNH and its isomer H2NCN. MP2/6-311++G(2d,2p) calculations were performed to calculate the Gibbs free energy of the minimum and the transition state (TS) structures involved in the six step mechanism. This new mechanism requires a smaller number of steps, the reaction energy is twice as exergonic, and the rate determining TS is lower in energy than the corresponding
ones proposed elsewhere in the literature.