Long-chain double SO₃H-functionalized Brønsted acidic ionic liquids catalyzed selective alkylation of phenol andp-cresol with tert-butanol

Abstract

A simple, efficient, and selective approach for the tert-butylation of phenol and p-cresol using two double SO 3 H-functionalized long-chain Brønsted acidic ionic liquids as recyclable catalysts is reported. Under optimum reaction conditions, 89.4% conversion of the phenol and 73.7% selectivity of 2,4-tert-butyl-phenol and 93.2% conversion of the p-cresol and 89.2% selectivity of 2-tert-butyl-p-cresol were obtained. Two ionic liquids could be recovered readily and their catalytic activity almost completely retained after five recycles.

An Efficient and Mild Method for the Alkylation of p-Cresol with tert-Butyl Alcohol

“…In addition, titania modified with a 12-tungstophosphoric acid (TPA/TiO 2 ) catalyst was prepared by Kumbar et al, and surface area, XRD, 31 P MAS NMR, XPS, NH 3 -TPD, and FTIR pyridine adsorption were employed to characterize these catalysts, and an 82% conversion of p-cresol and an 89.5 selectivity of 2-tert-butyl-p-cresol were obtained under the optimized reaction conditions [38]. Long-chain double SO 3 H-functionalized Brønsted acidic ionic liquids were synthesized, and the catalytic performances for the alkylation of p-cresol were investigated; an 89.4% conversion of the phenol, a 73.7% selectivity of 2,4-tert-butyl-phenol, a 93.2% conversion of p-cresol, and an 89.2% selectivity of 2-tert-butyl-p-cresol were obtained by Li et al [39]. Additionally, the alkylation of p-cresol with MTBE to synthesize 2-tert-butyl-pcresol was investigated, and a mesoporous and strong acid catalyst UDCaT-1 was prepared by Yadav et al The ratio of p-cresol and MTBE was 1:1; the reaction temperature was set as 100 • C, and a 45% conversion was obtained [40].…”

Alkylation of Phenol and tert-Butyl Alcohol Catalyzed by Deep Eutectic Solvents under Mild Conditions

“…Alkylation of phenol (PhOH) with tert -butyl alcohol (TBA) to synthesize tert -butyl phenol is one of the most significant Friedel–Crafts reactions in the chemical industry . As an important raw material, tert -butyl phenol was usually used for the preparation of fine chemicals, ultraviolet absorbents, antioxidants, fuel stabilizers, agrochemicals, fungicides, heat stabilizers for polymers, dye intermediates, resins, and so on. − According to reports, both homogeneous and heterogeneous catalysts were reported in the alkylation of PhOH and TBA, including Lewis acids (such as AlCl 3 and BF 3 ), Bronsted acids (such as HF, H 2 SO 4 , and H 3 PO 4 ), mesoporous materials, ,− cation-exchange resins, , heteropoly acids, and ionic liquids. − However, the homogeneous catalysts, such as liquid acids, are unfriendly to environment and difficult to separate from the reaction system. Additionally, the corrosivity of homogeneous catalysts is also a difficult problem to solve.…”

“…In addition, Li et al reported a long-chain double SO 3 H-functionalized Brønsted acidic ionic liquid. A temperature of 70 °C was needed for the alkylation of PhOH with TBA in this report. Subsequently, a response surface methodology was employed to optimize the reaction conditions and the kinetic study was performed.…”