Oxidation Characteristics and Products of Butylated Hydroxytoluene in Acidic and Basic Environments

Abstract

Under atmospheric pressure, KOH or HCl solution was added to the butylated hydroxytoluene (BHT) oxidation system to adjust the pH, and the oxidative consumption of BHT was monitored by high performance liquid chromatography (HPLC). To investigate the oxidation properties of BHT under pressurized conditions, the temperature and pressure changes during the oxidation process were monitored using the mini-closed pressure vessel test (MCPVT). The oxidation products of BHT were characterized after crystallization and purification and the possible oxidation pathway was speculated. The results showed that under atmospheric pressure, the degradation rate of BHT was less than 5% when the pH was 4 or 6, indicating good stability. At pH 10, the degradation rate of BHT was up to 59% and the oxidation reaction was rapid. KOH and HCl decreased the initial oxidation temperature of BHT from 133.1 ℃ to 53.0 ℃ and 49.1 ℃ in a pressurized closed container, respectively. 2, 6-Di-tert-butyl-4-hydroperoxy-4-methyl-2, 5-cyclohexanedione and 2, 6-di-tert-butyl-4-methyl-4-(3, 5-di-tert-butyl-4-hydroxyphenyl)-2, 5-cyclohexadien-1-one were produced during the oxidation of BHT in both atmospheric alkaline and pressurized environments. The experimental results suggested that BHT was susceptible to oxidative degradation in alkaline and pressurized environments, producing toxic products, posing safety risks.

Keywords

• butylated hydroxytoluene; food additive; oxidation reaction; mini-closed pressure vessel test; initial oxidation temperature