Structure of the Tetrahedral Intermediate in Methyl Formate Formation

Water has a lower proton affinity than the methanol adduct of the protonated formic acid and the deprotonation to form the tetrahedral intermediate therefore is quite endothermic, by about 23.7 kcal/mol. This is the product of acid-catalyzed methanol addition across the C=O double bond of formic acid. The addition changes the hybridization from sp2 to sp3 and the addition product is a tetrahedral intermediate. In the tetrahedral intermediate, two OH groups, one OR group, and the R-group of the acid are attached to the carbon center.

Figure. The MP2(full)/6-31G* optimized structure of the tetrahedral intermediate in methyl formate formation.