Structure of Methanol Adduct of Protonated Formic Acid. 2. Conformation

The methanol oxygen atom adds to the electrophilic carbon of the protonated formic acid. In the absence of solvation effects, this addition requires no activation energy and it is exothermic by about 20.2 kcal/mol. The alcohol adduct of the activated carboxylic acid can be seen as the methoxy-O protonated tetrahedral intermediate of esterification.


Figure. The MP2(full)/6-31G* optimized structure of methanol adduct of protonated formic acid. In this conformation, the O-H bond directions are not aligned.