MCM-41 Supported Phosphotungstic Acid for the Hydroxyalkylation of Phenol to Phenolphthalein

Abstract

A novel application of phosphotungstic acid, H3PW12O40 (PWA) supported on MCM-41 molecular sieve as a solid acid catalyst has been demonstrated for the synthesis of phenolphthalein by hydroxyalkylation of phenol and phthalic anhydride. PWA/MCM-41 (20%) showed the highest activity as compared to that of parent PWA and MCM-41 individually, due to the excellent dispersion of PWA on MCM-41 leading to the redistribution of Bronsted and Lewis acid sites on MCM-41. The effect of PWA loading on phthalic anhydride conversion and phenolphthalein selectivity was also studied. All these prepared catalysts were characterized by XRD, N2 adsorption–desorption isotherm, pyridine-FTIR, and NH3-TPD. The effect of various reaction parameters, namely, mole ratios, catalyst concentration, temperature, reaction time, and percentage of PWA present in the catalysts on conversion and selectivity of products has been also investigated. The utility of 20% PWA/MCM-41 catalyst was established by its efficient activity for hydroxyalkylation of phenol and p-cresol with formaldehyde to the corresponding dihydroxydiarylmethane products.

Heteropoly Acid/Nitrogen Functionalized Onion‐like Carbon Hybrid Catalyst for Ester Hydrolysis Reactions

“…For NOLC supports, the peaks below 400 8Co riginate from the desorption of the weakly chemisorbed NH 3 .T he peak centered above 500 8C is ar esult of the decomposition of nitrogen speciesi nt he form of NH 3 ,w hich has been also reportedi naprevious work. This phenomenoni sa lso observed in the case of PWAs supported on mesoporous molecular sieves, [19] which may be due to the interactions between PWAc lusters and NOLC supports. The integrated peak area below 400 8Ci ncreases by 173 %( NOLC:0 .60 10 À7 vs. PWA/NOLC:1 .65 10 À7 ), while some strong acid sites (desorption of NH 3 above 500 8C) for PWAs are lost after immobilization.…”

“…The integrated peak area below 400 °C increases by 173 % (NOLC: 0.60×10 −7 vs. PWA/NOLC: 1.65×10 −7 ), while some strong acid sites (desorption of NH 3 above 500 °C) for PWAs are lost after immobilization. This phenomenon is also observed in the case of PWAs supported on mesoporous molecular sieves, which may be due to the interactions between PWA clusters and NOLC supports. The average number of available protons on each PWA cluster was determined to 1.9 protons per PWA through careful comparison of the NH 3 desorption peak areas of PWA, NOLC and PWA/NOLC.…”

Efficient and controllable ultrasound-assisted depolymerization of organosolv lignin catalyzed to liquid fuels by MCM-41 supported phosphotungstic acid

“…Phosphotungstic acid (PTA) has been used widely in catalysis and homogeneous catalysis due to its good solubility in polar solvents, high proton mobility, strong acidity, and thermal and oxidation stability besides its capability to activate oxidants. 27,28 However, owing to the good solubility of PTA in the reaction system, the separation and recovery of PTA will be more difficult. So, the heterogeneity of this catalyst with a solid support will be very important for facile catalyst/product separation as well as for improving the apportionment of the active sites for high catalytic activity.…”

Highly Efficient Povidone–Phosphotungstic Acid Catalyst for the Tandem Acetalization of Aldehydes to Bis‐ and Tris(indolyl)methanes

“…In continuation of our prior results on supported HPAs for the synthesis of bisphenol and phenolphthalein,9a,b herein we report the synthesis of new hybrid HPA salts with nonhazardous polyvinylpyrrolidone (PVP or povidone) as a counter cation. This unique combination was found to be truly heterogeneous, with Brønsted acid sites, was easily reusable, and was highly active for the Friedel–Crafts alkylation of indole to synthesize BIMs and TIMs.…”