Reactions involving CO2, H2O, and NH3: The formation of (i) carbamic acid, (ii) urea, and (iii) carbonic acid

Abstract
A complete understanding of the synthesis of urea, (NH2)2CO, from NH3, CO2, and H2O remains an unsolved problem. It is considered that the formation of the intermediate ammonium carbamate (or the equivalent carbamic acid) takes place through the interaction of neutral species, and that this part of the synthesis is open to ab initio computations. Such calculations are reported on the formation of carbamic acid from NH3, CO2, and H2O. We have also investigated the formation of carbonic acid from CO2 and H2O showing that the six‐membered ring transition state is non‐planar, in contradiction with earlier reported calculations.