O-Acetyl-Substituted Phenol Ester Synthesis via Direct Oxidative Esterification Utilizing Ethers as an Acylating Source with Cu₂(dhtp) Metal–Organic Framework as a Recyclable Catalyst

Abstract

A metal−organic framework (MOF) Cu 2 (dhtp) was prepared and used as a recyclable catalyst for the direct C−O coupling of ethers with 2-acylphenols to generate phenol esters. The Cu 2 (dhtp) displayed better efficiency in the production of phenol esters than several MOFs, as well as traditional homogeneous catalysts. The oxidant played an important role for the conversion, and aqueous tert-butyl hydroperoxide was the best choice. Heterogeneous catalysis was confirmed for the transformation, and no phenol ester generated by leached species, if any, was recorded. It was possible to reuse the Cu 2 (dhtp) catalyst numerous times in the conversion of 2-acylphenols and ethers to phenol esters without a noticeable deterioration in catalytic efficiency. To our best understanding, the direct esterification to produce phenol esters utilizing ethers as an acylating source assisted by solid catalysts has not been previously reported in the literature.

Alternative and Uncommon Acylating Agents – An Alive and Kicking Methodology

“…[106] In 2016, Phan group applied Cu 2 (dhtp) MOF as a catalyst in the presence of TBHP for the synthesis of O-acetyl substituted phenol esters 200 using dibenzyl ether 195 as an acyl surrogate in heterogeneous platform (Scheme 50c). [107] 4. Miscellaneous Acylating Agents…”

Unravelling the catalytic potential of a magnetic CoFe2O4/Cu–ABDC MOF composite in the sustainable synthesis of 2H-indazole motifs

“…To date, various MOFs possessing high metal binding sites have been reported as solid catalysts for catalyzing a wide array of organic transformations. [15][16][17][18][19] Certainly, the synergistic combination of MOFs and magnetic nanoparticles has opened a promising gateway towards an ecological as well as economical chemistry in which the resulting material is endowed with immense chemical and thermal stability and prudent durability. [20][21][22][23][24] Indeed, material chemists have eventually moved towards a smarter engineered chemistry design, wherein an external magnetic field is employed for separating the catalyst post reaction from the reaction mixture as compared to the tedious and cumbersome filtration and centrifugation techniques.…”

Questionable Recyclable Catalyst: Comment on “O-Acetyl-Substituted Phenol Ester Synthesis via Direct Oxidative Esterification Utilizing Ethers as an Acylating Source with Cu2(dhtp) Metal–Organic Framework as a Recyclable Catalyst”

“…It has become fashionable and standard practice to add the term “ recyclable catalyst ” in the title, abstract, content, or conclusion of a research manuscript and get it published in a reputed journal without any explanation of the greenness of the recovery process of the so-called solid catalyst. Recently, a paper has been published in Industrial & Engineering Chemistry Research , titled “O-Acetyl-Substituted Phenol Ester Synthesis via Direct Oxidative Esterification Utilizing Ethers as an Acylating Source with Cu 2 (dhtp) Metal–Organic Framework as a Recyclable Catalyst” (DOI: 10.1021/acs.iecr.6b02733) …”

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1 This work described the use of Cu 2 (2,5-dihydroxyterephthalate) Metal−Organic Framework Cu 2 (dhtp) to catalyze the oxidative coupling of dibenzyl ether with o-hydroxyacetophenone to provide o-(benzoyloxy)acetophenone. This catalyst was also applied to other analogues.

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