Preparation and Property Analysis of Antioxidant of Carbazole Derivatives

Abstract Carbazole derivatives can be used as antioxidants in the lubricating- oil industry. The alkylation of carbazole with bromoisopropane and chlorotert butane catalyzed by anhydrous aluminum chloride was studied. 3,6-di-iso-propylcarbazole and 3,6-di-tert-butylcarbazole were synthesized from dichloromethane and dibromomethane at ,25 ℃ respectively. The effects of reaction time, catalyst dosage, and the molar ratio of carbazole to chloroalkanes were investigated, and orthogonal experiments were carried out. The structures of the carbazole derivatives were characterized by IR and MS. The thermal stability of the synthesized carbazole derivatives was investigated using differential scanning calorimetry (DSC). The carbazole derivatives were added to the lubricating oil with a mass fraction of 0.8%, and the miscibility, stability and oxidation resistance of the mixed system were evaluated using the mechanical stirring method and rotary pressure vessel oxidation test. The DSC results showed good thermal stability for the carbazole derivatives. The mechanical stirring method also proved that the mixture of oil and carbazole derivatives has good solubility and stability. The results of the rotary pressure vessel oxidation test showed that isopropyl and tertbutyl carbazole derivatives increased the oxidation-induction period of the lubricating oil by 1.39 and 1.91 times, respectively.