New heterogeneous catalysts for greener routes in the synthesis of fine chemicals

Coman, Simona M.; Pop, Georgeta; Stere, Cristina; Pârvulescu, Vasile I.; Haskouri, Jamal El; Beltrán, Daniel; Amorós, Pedro

doi:10.1016/j.jcat.2007.08.001

Cited by 22 publications

(16 citation statements)

References 34 publications

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“…This methodology usually leads to chemical homogeneous materials avoiding or limiting in a large extent phase segregation phenomena. In this case, the hydrolysis retarding effect provided by atrane ligands is not sufficient to completely hinders the formation of a certain proportion of Sn(O,OH)x oxidic nanodomains, according to previous works [25,26]. Then, different tin sites in the form of Snisolated centers or oxidic nanodomains will be dispersed along the rich silica walls.…”

Section: Catalysts Characterizationmentioning

confidence: 89%

“…All catalysts showing unimodal porous system (denoted as SnTf-MCM-41) or bimodal porosity (denoted as SnTf-UVM-7) were prepared in a two-step synthesis as described in detail elsewhere [25,26]. The triflic acid was incorporated into previously synthesized Sn-containing porous silicas (Sn-MCM-41 or Sn-UVM-7 materials).…”

Section: Catalyst Preparationmentioning

confidence: 99%

“…We have already suggested that such kind of catalysts exhibit a high activity in various reactions requiring strong acidity like acylation or alkylation of various substrates [25,26]. These catalysts combine the advantages of a mesoporous texture with the strong acidity exhibited by well dispersed triflate anchored tin species.…”

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confidence: 99%

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Mesoporous Tin-Triflate Based Catalysts for Transesterification of Sunflower Oil

et al. 2010

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Unimodal porous system (denoted as SnTf-MCM-41) and bimodal porosity (denoted as SnTf-UVM-7) were prepared in a two-step synthesis. The triflic acid was incorporated into previously synthesized Sn-containing porous silicas. Chemical analysis was carried out by electron probe microanalysis (EPMA), textural properties were determined by transmission electron microscopy (TEM) and from nitrogen adsorption-desorption isotherms (77 K), while structural characterization by X-ray absorption near-edge structure (XANES), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) measurements. The structural characterization provided evidences on the direct interaction of triflate with incorporated tin species. The acidity of these catalysts was determined from the ammonia chemisorption measurements. The catalysts have been tested for transesterification of sunflower oil under both microwave and ultrasound activation. These experiments showed a direct reaction between the acidity of the catalysts and catalytic performances. No leaching of the triflate species or catalyst deactivation have been detected over several runs.

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Section: Catalysts Characterizationmentioning

confidence: 89%

Section: Catalyst Preparationmentioning

confidence: 99%

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Mesoporous Tin-Triflate Based Catalysts for Transesterification of Sunflower Oil

et al. 2010

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“…Following these procedures, catalysts with different Si/Sn ratios: 21. . Detailed preparation procedures are described elsewhere [37].…”

Section: Catalyst Preparation and Characterizationmentioning

confidence: 99%

“…The system architecture has been built up taking into account the described activity of metal triflate complexes and the compatibility of Sn(IV) and Si(IV) centers in silica networks. The described catalysts were already successfully applied into the acylation of aromatic sulfonamides with acetic acid as acylating agent and the synthesis of (dl)-[a]-tocopherol [37].…”

Section: Introductionmentioning

confidence: 99%

Metal Triflates Incorporated in Mesoporous Catalysts for Green Synthesis of Fine Chemicals

et al. 2009

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Strong Lewis acid SnTf-MCM-41 and SnTf-UVM-7 catalysts with unimodal and bimodal pore systems were prepared in a two-step synthesis in which the triflic acid (Tf) was incorporated into previously synthesized mesoporous tin-containing silicas. The Sn incorporation inside the pore walls was carried out through the Atrane method. The SnTf-UVM-7 catalysts were prepared by aggregating nanometric mesoporous particles defining a hierarchic textural-type additional pore system. Catalysts with different Si/Sn ratios in the range 21.8-50.8 for SnTf-MCM-41 and 18.4 for SnTf-UVM-7 were found to be efficient catalysts for the acylation of aromatics and heteroaromatics. Under microwave irradiation the reaction was possible even with acetic acid. The selectivity to the desired product (o-hydroxyacetophenone for phenol) or the unfavored three-substituted five ring heterocycles was dramatically increased under these conditions. The process is green, environmentally safe, and heterogeneous.

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Catalytic Performance of Nanoscopic, Aluminium Trifluoride‐Based Catalysts in the Synthesis of (all‐rac)‐α‐Tocopherol

et al. 2008

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A novel nanoscopic, partly hydroxylated aluminium fluoride was prepared in a sol-gel fluorination synthesis and characterised by IR probe molecules. It was shown that this material has, in contrast to high surface area aluminium fluoride (HSAlF 3 ) which is one of the strongest Lewis acids, a low amount of strong Lewis acid sites combined with weak and medium strength Brønsted sites. Both materials were tested in the synthesis of (allrac)-a-tocopherol through the condensation of 2,3,6-trimethylhydroquinone (TMHQ) with isophytol (IP). The activity data indicate the partly hydroxylated aluminium fluoride to be a very efficient and highly selective catalyst for (all-rac)-a-tocopherol (> 99.9%, for an IP conversion of 100%) whereas high surface area aluminium fluoride is a poor catalyst for this reaction.

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New heterogeneous catalysts for greener routes in the synthesis of fine chemicals

Cited by 22 publications

References 34 publications

Mesoporous Tin-Triflate Based Catalysts for Transesterification of Sunflower Oil

Mesoporous Tin-Triflate Based Catalysts for Transesterification of Sunflower Oil

Metal Triflates Incorporated in Mesoporous Catalysts for Green Synthesis of Fine Chemicals

Catalytic Performance of Nanoscopic, Aluminium Trifluoride‐Based Catalysts in the Synthesis of (all‐rac)‐α‐Tocopherol

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