The oxidation of 2-phenyl ethanols by Fe(NO3)3·9H2O in CF3COOH: The dramatic substituent effect

Abstract

2-Phenyl ethanol with various substituents on the phenyl ring was oxidized by Fe(NO3)3·9H2O in the present of trifluoroacetic acid (TFA) at 0°C to room temperature. The product was highly dependent on the electronic properties of the substituent. Weak electron-donating and electron-withdrawing groups (Such as CH3, Cl, Br, and F) afforded good to excellent yields (95 – 64 %) of the corresponding phenylacetic acids. Moderate electron-withdrawing groups (Such as CF3, COOH) resulted in ∼ 50 % yield of the corresponding phenylacetic acids. However, strong electron-withdrawing group (such as NO2 and CN) hindered the reaction, the corresponding phenethyl trifluoroacetate was acquired almost quantitatively. Furthermore, the strong electron-donating group of methoxy highly promoted the oxidation, resulted in nitrated benzaldehydes and benzoic acids in relative low yields.