Reexamination of the reaction of 4-chlorophenol with hydroxyl radical

By performing DFT calculations, the reaction of 4-chlorophenol with OH is reexamined to reconcile an experimental finding with a recent theoretical result. The calculated results show that abstracting hydrogen atom in the hydroxyl of 4-chlorophenol by the OH is the most plausible process for forming 4-chlorocaechol intermediate, while adding OH to the aromatic ring is the dominant pathway for forming the hydroquinone. The 4-chlorophenoxyl radical plays a crucial role during the hydroxyl-initiated 4-CP degradation due to its energetic stability and the low barrier involved in the reaction, which supports the experimental finding but differs from the recent theoretical result.