On the reaction CH2O+NH3 -> CH2NH+H2O

We study the energetics of CH2O + NH3 -> CH2NH H2O in the gas phase at the B3LYP and CCSD(T) levels. This reaction is shown to have a sizeable barrier . Ionization of NH? reduces the barrier to about 5 kcal/mol. We also show t hat in water, a proton-catalyzed mechanism yields no barriers in excess of the reaction endothermicity. Since this reaction has been proposed as one o f the steps in interstellar synthesis of glycine, the simplest amino acid, this work suggests that the formation of amino acids is occurring in and/or on interstellar water ice grains, and not in the gas phase. (C) 2001 Elsev ier Science B.V. All rights reserved.