Chemical dynamics simulations of collision induced dissociation of deprotonated glycolaldehyde

Abstract

First step of formose or Butlerov reaction involves C–C bond formation between two formaldehyde molecules resulting in glycolaldehyde. This reaction happens under basic conditions in solution. A tandem mass spectrometry investigation of dissociation of deprotonated glycolaldehyde in the gas phase, to study the formose reaction in a retro-synthetic point of view, has been reported. In the present work, we have carried out electronic structure theory calculations and quasi-classical direct chemical dynamics simulations to model the gas phase dissociation of the conjugate base of glycolaldehyde. The dynamics simulations were performed on-the-fly using the hybrid density functional B3LYP theory with the 6-31+G∗ basis set under collision induced dissociation (CID) conditions. Trajectories were launched with two different deprotonated forms of glycolaldehyde for a range of collision energies mimicking experiments. Reverse formose reaction was observed primarily from the slightly higher energy isomer via a non-statistical pathway. Intramolecular hydrogen transfer was ubiquitous in the trajectories. Simulation results were compared with experiments and detailed atomic level dissociation mechanisms are presented.