title: Adenine formation without HCN.
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.
authors.affiliation: Quantum Theory Project, University of Florida , 2234 New Physics Building, Gainesville, 32611 Florida, United States.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Merz
authors.forename: Eduardo C
authors.initials: EC
authors.lastname: Aguiar
authors.forename: Joao Bosco P
authors.initials: JB
authors.lastname: da Silva
mesh_terms: D000225:Adenine / Q000138:chemical synthesis* / Q000737:chemistry; D006856:Hydrogen Cyanide / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D006856:Hydrogen Cyanide; D000225:Adenine