1. Direct oxidation with air or oxygen: Amine oxides are prepared by oxidizing tertiary amines with an oxidizing agent. There are two synthetic routes. The reaction formula is as follows: R1R2R3N + O2 → R1R2R3N → O. Oxygen or air is passed into a high-pressure reactor containing water, alcohol solvent, and tertiary amine. The reaction is carried out at 100-150℃ and 15-70MPa for 16-64 hours to obtain an amine oxide product with a content of 30%-80%. 2. Preparation using nitrogen peroxide or peroxidized organic acids as oxidizing agents: The reaction formula is as follows: R1R2R3N + H2O2 → R1R2R3N → O. The tertiary amine is dissolved in water (or alcohol solvent), and a small amount of citric acid and its salt and disodium EDTA are added. The temperature is raised to 60-70℃, and an excess of 30% hydrogen peroxide is added dropwise. The reaction is maintained at this temperature for 1 hour, then the temperature is further raised to 75-80℃ and the reaction continues for 3 hours. The temperature is then lowered to 60℃, and a calculated amount of sodium bisulfite is added to decompose residual oxygen. The resulting liquid product has an active ingredient content of 30%. The tertiary amine conversion rate can reach over 98%. The added citric acid acts as a hydrogen peroxide stabilizer, and disodium EDTA acts as a metal ion chelating agent; both also act as catalysts to improve the tertiary amine conversion rate.
