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110th Anniversary: The Epoxidation of Polybutadiene via Reaction-Controlled Phase-Transfer Catalysis

Li Xu, Bo-Geng Li, Suyun Jie, Zhisong Li, Zhiyang Bu
Industrial & engineering chemistry process design and development 2019 v.58 no.29 pp. 13085-13092
catalysts, catalytic activity, emulsions, energy, epoxidation reactions, epoxides, hydrogen peroxide, polymerization, process design, rubber
By using an aqueous H₂O₂ solution and the reaction-controlled phase-transfer catalyst CPC-PW₄O₁₆, polybutadiene (PBD) was epoxidized quantitatively and efficiently up to an epoxy ratio of 20 mol %. During the epoxidation, the catalyst first interacted with H₂O₂ to generate an amphiphilic intermediate, which made the reaction mixture become a two-phase emulsion. The epoxidation of PBD occurred in the interface of two phases. With the consumption of H₂O₂, the catalyst was self-precipitated out of the emulsion, thereby becoming recyclable. The starting material of PBD can be either the commercial block rubber or the original rubber solution directly from the polymerization reactor. When using the latter, many processes consuming time and energy in preparation of PBD solid rubber and in preparation of EPBD could be removed. The recycle test indicated that the activity of catalyst still remained high, compared with the fresh one.