Accurate and Reliable Thermochemistry by Data Analysis of Complex Thermochemical Networks using Active Thermochemical Tables: The Case of Glycine Thermochemistry

Abstract

Active Thermochemical Tables (ATcT) were successfully used to resolve the existing inconsistencies related to the thermochemistry of glycine, based on statistically analyzing and solving a thermochemical network that includes > 3350 chemical species interconnected by nearly 35,000 thermochemically-relevant determinations from experiment and high-level theory. The current ATcT results for the 298.15 K enthalpies of formation are -394.70 ± 0.55 kJ mol^-1 for gas phase glycine, -528.37 ± 0.20 kJ mol^-1 for solid α-glycine, -528.05± 0.22 kJ mol^-1 for β-glycine, -528.64 ± 0.23 kJ mol^-1 for γ-glycine, -514.22 ± 0.20 kJ mol^-1 for aqueous undissociated glycine, and -470.09 ± 0.20 kJ mol^-1 for fully dissociated aqueous glycine at infinite dilution. In addition, a new set of thermophysical properties of gas phase glycine was obtained from a fully corrected nonrigid rotor anharmonic oscillator (NRRAO) partition function, which includes all conformers. Corresponding sets of thermophysical properties of α-, β-, and γ-glycine are also presented.