Kinetics of oxidation of benzyl alcohol with dilute nitric acid

Abstract

The oxidation of benzyl alcohol by dilute nitric acid has been selected for the study as a typical method for the manufacture of industrially important intermediate benzaldehyde. All the reactions have been performed in the absence of any solvent. A catalytic amount of sodium nitrite is essential for the generation of active state of nitrogen. Benzyl nitrite is formed in a substantial amount as an intermediate. The effects of various parameters such as the NaNO₂ loading, nitric acid concentration, temperature, and molar ratio have been investigated. The stoichiometric requirement of nitric acid for benzyl alcohol conversion has also been determined. The probable mechanism for the oxidation of benzyl alcohol using nitric acid is proposed, showing the reversible formation of benzyl nitrite and its irreversible decomposition to benzaldehyde. The mass-transfer resistance has been eliminated for the investigation of kinetics of all the reactions in the consecutive path. The influence of chloro substitution on the oxidation rates of 2-chlorobenzyl, 4-chlorobenzyl, and 2,4-dichlorobenzyl alcohols has been presented.