A DFT Study of R−X Bond Dissociation Enthalpies of Relevance to the Initiation Process of Atom Transfer Radical Polymerization

Citations Over TimeTop 10% of 2003 papers

Abstract

DFT calculations at the B3P86/6-31G** level have been carried out to derive the bond dissociation energies (BDE) and free energies for a number of R−X systems (X = Cl, Br, I, N3, and S2CNMe2) that have been or can potentially be used as initiators for atom transfer radical polymerization (ATRP). For selected systems, a conformational search was carried out for R−X and R by using semiempirical (PM3) and molecular mechanics (MM+ augmented with appropriately optimized parameters for the radical systems) methods. The MM+ technique is more suited to search for the most stable conformations. The computed energies are in good agreement with the experimentally available BDEs and reveal a small weakening effect caused by the substitution of an α-H atom with a CH3 group. The free energies are used to derive the relative equilibrium constant for the ATRP activation/deactivation process. These are compared with the equilibrium constants that have been determined from ATRP polymerization rates and from model studies of activation−deactivation−termination processes in the absence of monomer. These comparisons reveal the effectiveness of the DFT-computed BDEs for predicting polymerization rates for new monomers in ATRP processes.

Related Papers

• → Polystyrene/clay nanocomposites by atom transfer radical nitroxide coupling chemistry(2012)18 cited
• → Reactions of OH−⋅H2O with NO2(1982)21 cited
• → High level ab initio and density functional theory study of bond selective dissociation of CH 3 SH and CH 3 CH 2 SH radical cations(1998)10 cited
• Synthesis of Polymer Brushes from Flat Surface——Research Progress of Surface-initiated Atom Transfer Radical Polymerization(2006)
• → CO2 DISSOCIATION ON Ni-RICH MULTIMETAL CLUSTER: EFFECT OF Pt AND Mg(2018)