Alkylation of naphthalene with n-butene catalyzed by liquid coordination complexes and its lubricating properties

With the development of coal chemical industry, large amounts of naphthalene and n-butene are produced, and converting them into high value-added products through alkylation has gained particular importance and interest. In this work, liquid coordination complexes (LCCs) were used as acid catalysts for the first time in the naphthalene alkylation reaction under mild conditions to obtain multi-butylnaphthalenes with high yield. Various reaction conditions were thoroughly investigated. The LCC consisting of urea and AlCl3 showed excellent catalytic performance under optimal reaction conditions, giving 100% conversion of naphthalene and 99.66% selectivity towards multi-butylnaphthalenes. Combining the catalyst properties and catalytic results, a plausible reaction mechanism was proposed. The lubricating properties of the synthesized products were investigated for their potential application as lubricating base oils. The synthesized multi-butylnaphthalenes showed comparable physicochemical properties and tribological performances as the commercial cycloalkyl base oil.