Additional theoretical research has helped further understanding of substituted isocyanate species. In 1994, Mcallister and Tidwell performed comprehensive structural and isodesmic reaction analyses on a large selection of substituted isocyanates, with the goal of theoretically motivating the discovery of novel isocyanate derivatives. Their work highlights many insightful features of a diverse range of RNCO species, but is not connected to any particular reaction mechanisms. In the past decade, a series of studies by Konovalov and coworkers predicted the quantum mechanical features of the R 1 NCO + R 2 OH (R 1 , R 2 =Ph, CH 3 , H) reactions in various conditions, including solvent effects and cooperative catalysis with the B3LYP/6-311++G(df,p) method. However, their small sample size precludes a deep understanding of how substituents generally influence the reaction energetics. Our pre-liminary computations also indicate water + HNCO reaction energies differs by more than 1 kcal mol -1 between the CCSD(T)/cc-pVQZ and B3LYP/cc-pVQZ levels of theory computed on the same geometries. This discrepancy between DFT and CCSD(T) in the simplest of cases exemplifies the need for rigorous ab initio methods to draw meaningful conclusions from theoretical study of more complex H 2 O + RNCO reactions.