Efficient catalysis of alcohol/phenol esterification by HBeta zeolite
The self-made HBeta was used to catalyze the esterification of 4-methylbenzyl alcohol with acetic anhydride.Under the optimal conditions of catalyst acid HBeta zeolite 10 mg,4-methylbenzyl alcohol 0.5 mmol,acetic anhydride 0.5 mmol,cyclohexane 1.0 mL,reaction time 1 h in nitrogen atmosphere at room temperature,the yield of 4-methylbenzyl acetate reached>99%.The universality of substrates was explored and 32 kinds of aromatic esterification products were synthesized with a wide range of substrates.The zeolite was mixed with different mass fractions of phosphorus(0.2%～1.0%),and the texture parameters and acidity characteristics of the catalysts were characterized by XRD,N2 adsorption-desorption,NH3-TPD and Py-IR.The results showed that the esterification rate of aryl alcohol and phenol gradually decreased from>99%to 57%as the acid content of strong Brӧnsted acid sites(SBAS)in HBeta zeolite decreased,indicating that the SBAS were the active sites for converting aryl alcohols and phenols.Moreover,the catalyst exhibited excellent structural stability with no significant activity loss observed after being recycled 4 times.The proposed reaction mechanism was that 4-methybenzyl alcohol first underwent transformation into the corresponding carbocation intermediates on the SBAS of HBeta zeolite,followed by a nucleophilic addition reaction with acetic anhydride to yield the target product.
HBeta zeoliteesterification reactionaryl alcohols/phenolscarbocationfine chemical intermediates
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