2-Methoxynaphthalene acylation using aluminum or copper salts of tungstophosphoric and tungstosilicic acids as catalysts

Méndez, Leticia; Torviso, Rosario; Pizzio, Luis R.; Blanco, Mirta N.

doi:10.1016/j.cattod.2011.03.028

Cited by 25 publications

(16 citation statements)

References 34 publications

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“…The diffractogram of lacunar salt Cs 8 SiW 11 O 39 displayed a lower crystallinity, with peaks of lower intensity and greater enlargement. The profile of this diffractogram showed characteristic peaks at angles near to 10 and 28° range 2θ, confirming the formation of a typical crystalline phase . The same was observed for the Cs 7 PW 11 O 39 and Cs 7 PMo 11 O 39 salts, whose XRD profiles have peaks similar those reported in the literature …”

Section: Resultssupporting

confidence: 87%

Cesium‐Exchanged Lacunar Keggin Heteropolyacid Salts: Efficient Solid Catalysts for the Green Oxidation of Terpenic Alcohols with Hydrogen Peroxide

2020

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In this work, an innovative and green oxidative process to convert renewable and abundant raw material to more value‐added fine chemicals was developed. Hydrogen peroxide, an environmentally benign oxidant, was used in Cs–exchanged lacunar Keggin heteropolyacid salts‐catalyzed oxidation reactions of the terpenic alcohols (i. e., nerol was the model molecule). The activity of most outstanding catalyst (Cs8SiW11O39) was compared with various catalysts. Epoxides and aldehydes, which are an attractive feedstock for fragrance and pharmaceutical industries were selectively obtained. Lacunar Keggin heteropolyacid salts containing cesium as the counter ion (i. e., Cs7PW11O39, Cs7PMo11O39 and Cs8SiW11O39) were easily synthesized and characterized by infrared spectroscopy, powdered X‐rays diffraction, X‐rays dispersive spectroscopy, scanning electronic microscopy, thermal analysis, porosimetry analyses, diameter and pores distribution. The influences of the main reaction variables such as catalyst concentration, the stoichiometry of the reactants and reaction temperature were evaluated. The reaction scope was successfully extended to the other terpenic alcohols. The Cs8SiW11O39 was the most active and selective lacunar salt. After five cycles of successive reuse, no loss of catalytic activity or selectivity was observed.

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Section: Resultssupporting

confidence: 87%

Cesium‐Exchanged Lacunar Keggin Heteropolyacid Salts: Efficient Solid Catalysts for the Green Oxidation of Terpenic Alcohols with Hydrogen Peroxide

2020

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“…These bands appear at the same wavenumbers in the FT‐IR spectrum of both phosphotungstic acid and aluminium salt, indicating that the structure of the Keggin anion was preserved after the exchange of protons. These data agree with the literature . It is noteworthy that no splitting occurred on the band attributed to the vibration of P−O bond ( ca .…”

Section: Resultsmentioning

confidence: 99%

“…The curves showed a similar profile; endothermic peak at low temperatures corresponds to the loss of physisorbed and crystal waters, while the exothermic peaks were noticed at high temperatures (ca. > 673 K), which were originated by the decomposition of Keggin anion …”

Section: Resultsmentioning

confidence: 99%

“…Literature has proposed that, for the neutral salts of Keggin HPAs, the Brønsted acidity is due to hydrolysis undergone by the aluminum cations coordinated to the water molecules, which result in releasing of H + cations . After the titration of sample of aluminum nitrate, it was confirmed that the hydrate aluminum salt can itself consume n ‐butylamine.…”

Section: Resultsmentioning

confidence: 99%

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A Rare Carbon Skeletal Oxidative Rearrangement of Camphene Catalyzed by Al‐Exchanged Keggin Heteropolyacid Salts

et al. 2019

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In this work, aluminum-exchanged Keggin heteropolyacid salts (i. e., AlPW 12 O 40 , AlPMo 12 O 40 , and Al 4/3 SiW 12 O 40 ) were synthesized and evaluated as catalysts on the camphene oxidation with hydrogen peroxide. The aluminum silicotungstate salt (i. e., Al 4/ 3 SiW 12 O 40 ) was the most active and selective toward formation of borneol and two novel products; 1-(3-(2-hydroxypropan-2-yl) cyclopentyl) ethan-1-one, and 3-(3-hydroxycyclopentyl)-3methylbutan-2-one), which were spectroscopically character-ized (FT-IR, 13 C and 1 H NMR analyses). All the catalysts were characterized by FT-IR/ ATR spectroscopy, BET, XRD, EDS/SEM, and TG/DSC analyses. After the characterization of the HPA salts, it was possible to link their structural properties to their catalytic activity. The effects of the main reaction variables were assessed. The aluminum cation as well as the silicotungstic anion showed to be essential to formation of three goalproducts.

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“…7 -13 Our research group has applied Keggin heteropolyacids in diverse clean processes. 14 -20 Particularly, transition metal-modified lacunary heteropoly compounds of the general formula [XW 11 O 39 M] n− , where X = P or Si and M = first row transition metal, have recently attracted considerable attention. 21 ,22 This is because of their thermal and chemical stability and the range of possibilities for their modification without affecting the Keggin-type primary structure.…”

Section: Introductionmentioning

confidence: 99%

Transition metal-modified polyoxometalates supported on carbon as catalyst in 2-(methylthio)-benzothiazole sulfoxidation

et al. 2015

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Polyoxometalates with lacunary Keggin structure modified with transition metal ions [PW 11 O 39 M(H 2 O)] 5− , where M= Ni 2+ , Co 2+ , Cu 2+ or Zn 2+ , were synthesized and supported on activated carbon to obtain the PW11MC catalysts. Using FT-IR and DTA-TGA it was concluded that the [PW 11 O 39 M(H 2 O)] 5− species are interacting with the functional groups of the support, and that thermal treatment leads to the loss of the coordinatively bonded water molecules without any noticeable anion degradation. The activity and selectivity of the catalysts in the sulfoxidation reaction of 2-(methylthio)-benzothiazole, an emerging environmental pollutant, were evaluated. The reaction was carried out in acetonitrile as solvent using H 2 O 2 35% p/v as a clean oxidant. The conversion values decreased in the following order: PW11NiC > PW11CuC > PW11CoC > PW11ZnC, with selectivity to sulfoxide higher than 69%. The catalyst could be reused without appreciable loss of the catalytic activity at least three times. The materials were found to be efficient and recyclable catalysts for 2-(methylthio)-benzothiazole sulfoxidation in order to obtain a more biodegradable product than the corresponding substrate.

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2-Methoxynaphthalene acylation using aluminum or copper salts of tungstophosphoric and tungstosilicic acids as catalysts

Cited by 25 publications

References 34 publications

Cesium‐Exchanged Lacunar Keggin Heteropolyacid Salts: Efficient Solid Catalysts for the Green Oxidation of Terpenic Alcohols with Hydrogen Peroxide

Cesium‐Exchanged Lacunar Keggin Heteropolyacid Salts: Efficient Solid Catalysts for the Green Oxidation of Terpenic Alcohols with Hydrogen Peroxide

A Rare Carbon Skeletal Oxidative Rearrangement of Camphene Catalyzed by Al‐Exchanged Keggin Heteropolyacid Salts

Transition metal-modified polyoxometalates supported on carbon as catalyst in 2-(methylthio)-benzothiazole sulfoxidation

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