Alkylation of Guaiacol with Alcohols on Porous Aromatic Frameworks Modified with Sulfo Groups

This paper reports on an investigation of the alkylation of guaiacol with isopropanol and cyclohexanol over sulfonated porous aromatic frameworks, designated as PAF-20–SO3H and PAF-30–SO3H. The catalyst structures were characterized by infrared spectroscopy and low-temperature nitrogen adsorption; the elemental composition and acidity were measured by CHNS analysis and potentiometric titration. The alkylate composition was found to be sensitive to the reaction conditions and catalyst structure. PAF-30–SO3H was demonstrated to achieve 58% guaiacol conversion over 2 h of alkylation with cyclohexanol at 250°C and 3 MPa, with the reaction products mostly consisting of benzene ring monoalkylation products. In guaiacol alkylation with isopropanol, the product composition depends on the catalyst structure: after 6 h of reaction, the benzene ring monoalkylation products prevailed (accounting for up to 23% of the total product) in the case of PAF-20–SO3H, whereas PAF-30–SO3H promoted the yield of a mixture of monoalkylates (up to 34%) and dialkylates (up to 35%).