Ab initio molecular dynamics study of the reaction of water with formaldehyde in sulfuric acid solution

Ab initio molecular dynamics methods have been used to study the reaction mechanism of acidcatalyzed addition of water to formaldehyde in a model system of an aqueous solution of sulfuric acid. Using the method of constraints we find that an H2O molecule can be added to formaldehyde by a controlled transfer of a catalytic proton from a hydronium ion in acid solution to the carbonyl oxygen. The formation of the CO bond between the carbonyl carbon and the water oxygen occurs at a stage midway in the proton transfer process. The process can be reversed by removing the H+ from the protonated product diol, leading to CO bond breaking at approximately the same stage of proton transfer. This suggests that the kinetics of the acidcatalyzed reaction is governed by a concerted protonation and addition.