Correlation between bond dissociation energies and spin distribution for the radicals of ethers: A DFT study

The bond dissociation energy (BDE) of the C-H bond at the α-position of 43 ethers was examined in terms of the ability of the ether to form peroxide. Density functional theory (DFT) calculations, based on the B3LYP level, were performed to determine essential factors governing the thermochemical stabilisation of the radicals. Analysis of the structural properties of the radical species suggested that hyperconjugation, resonance stabilisation and ring strain are the main features responsible for thermochemical stability. These effects are well reflected in the spin distribution in the radical species, which assists in the understanding of the trend of BDEs for the ethers. A good correlation was obtained between BDE and spin distribution for the whole set of ethers. Improved correlations were obtained by splitting the data set into subcategories based on structural properties, i.e. saturated acyclic ethers, polyethers and 5-membered cyclic ethers.