Calcined Mg–Al hydrotalcite as an efficient catalyst for the synthesis of guaiacol

Talawar, M. B.; Jyothi, T. M.; Sawant, Prashant D.; Raja, Thirumalaiswamy; Rao, B.S.

doi:10.1039/b006077l

Cited by 36 publications

(14 citation statements)

References 12 publications

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“…[1][2][3][4] In particular, dialkylcarbonates are products of great interest since they find a large use in industry. [5][6][7][8][9][10][11] The main benefits of such reagents are their low toxicity and their complete biodegradability. For this reason they find a wide application in the chemical industry as monomers for polymers [12] and in transesterification reactions for the production of carbonates such as diphenylcarbonate [13] and others.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Use of Nb^V/Ce^IV‐Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal

Dibenedetto

Aresta

Angelini

et al. 2012

Chemistry A European J

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New catalytic systems based on ceria have been used in the direct carboxylation of ethanol. The catalytic behavior of Al(2)O(3) and Nb(2)O(5) loaded ceria is compared, the latter showing a better performance. A morphological and structural study has been carried out on Nb(2)O(5)/CeO(2) catalysts in order to explain their behavior in catalysis. Pervaporation membranes have been used for water separation. The synthesis of diethylcarbonate (DEC) has been carried out either in a liquid phase (ethanol) pressurized with CO(2) or in supercritical conditions. A set-up has been developed that allows the production of quite pure DEC (>90%) with recycling of CO(2) and ethanol.

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Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Use of Nb^V/Ce^IV‐Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal

Dibenedetto

Aresta

Angelini

et al. 2012

Chemistry A European J

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“…At high temperatures (T > 120 °C, usually 160 °C) and in the presence of a nucleophile (ArOH, ArSH), the electrophilic methyl group of DMC was attacked producing and the corresponding methylated compound was isolated [15]; the only by-products were methanol and CO 2 (Scheme 1). In consideration of the high temperatures required, the reaction was generally performed under gas liquid phase-transfer catalysis (GL-PTC) conditions or in autoclave over alkali ion-exchanged zeolites, alumina, alumina-silica, CrPO 4 , AlPO 4 , CrPO 4 -AlPO 4 , AlPO 4 -Al 2 O 3 , cesium carbonate [16,17,18,19,20,21]. The search for milder and more practical conditions to carry out the methylation reactions with DMC is an interesting topic.…”

Section: Introductionmentioning

confidence: 99%

A Convenient and Safe O-Methylation of Flavonoids with Dimethyl Carbonate (DMC)

2011

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Dietary flavonoids exhibit beneficial health effects. Several epidemiological studies have focused on their biological activities, including antioxidant, antibacterial, antiviral, anti-inflammatory and cardiovascular properties. More recently, these compounds have shown to be promising cancer chemopreventive agents in cell culture studies. In particular, O-methylated flavonoids exhibited a superior anticancer activity than the corresponding hydroxylated derivatives being more resistant to the hepatic metabolism and showing a higher intestinal absorption. In this communication we describe a convenient and efficient procedure in order to prepare a large panel of mono-and dimethylated flavonoids by using dimethyl carbonate (DMC), an ecofriendly and non toxic chemical, which plays the role of both solvent and reagent. In order to promote the methylation reaction under mild and practical conditions, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was added in the solution; methylated flavonoids were isolated in high yields and with a high degree of purity. This methylation protocol avoids the use of hazardous and high toxic reagents (diazomethane, dimethyl sulfate, methyl iodide).

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“…Notably, O-methylation of guaiacol, catechol, and phenol by DMC has been reported by Jyothi and coworkers to be catalyzed by calcined Mg-Al hydrotalcite. 34,35 The present study applies this methodology to stabilize or trap reactive phenolic intermediates generated during the reductive disassembly of lignin and of several relevant models. We describe studies with several lignin model compounds including 2-phenoxy-1-phenylethan-1-ol, which is a model for the β-O-4 linkage that comprises 40-60 % of lignin's linkages, 8 and with organosolv poplar lignin (OPL), which is a much more complex model for lignins.…”

Section: Introductionmentioning

confidence: 99%

Enhancing Aromatic Production from Reductive Lignin Disassembly: in Situ O-Methylation of Phenolic Intermediates

Barrett

Gao

Bernt

et al. 2016

ACS Sustainable Chem. Eng.

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ABSTRACT:The selective conversion of lignin into aromatic compounds has the potential to serve as a "green" alternative to the production of petrochemical aromatics. Herein, we evaluate the addition of dimethyl carbonate (DMC) to a biomass conversion system that uses a Cu-doped porous metal oxide (Cu 20 PMO) catalyst in supercritical methanol (sc-MeOH) to disassemble lignin with little to no char formation. While Cu 20 PMO catalyzes C-O hydrogenolysis of aryl-ether bonds linking lignin monomers, it also catalyzes arene methylation and hydrogenation, leading to product proliferation. The MeOH/DMC co-solvent system significantly suppresses arene hydrogenation of the phenolic intermediates responsible for much of the undesirable product diversity via Omethylation of phenolic -OH groups to form more stable aryl-OCH 3 species. Consequently, product proliferation was greatly reduced and aromatic yields greatly enhanced with lignin models, 2-methoxy-4-propylphenol, benzyl phenyl ether, and 2-phenoxy-1-phenylethan-1-ol. In addition, organosolv poplar lignin (OPL) was examined as a substrate in the MeOH/DMC co-solvent system. The products were characterized by nuclear magnetic resonance spectroscopy ( 31 P, 13 C, and 2D 1 H-13 C NMR) and gas chromatography-mass spectrometry techniques. The co-solvent system demonstrated enhanced yields of aromatic products. INTRODUCTION.

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Calcined Mg–Al hydrotalcite as an efficient catalyst for the synthesis of guaiacol

Cited by 36 publications

References 12 publications

Synthesis, Characterization, and Use of Nb^V/Ce^IV‐Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal

Synthesis, Characterization, and Use of Nb^V/Ce^IV‐Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal

A Convenient and Safe O-Methylation of Flavonoids with Dimethyl Carbonate (DMC)

Enhancing Aromatic Production from Reductive Lignin Disassembly: in Situ O-Methylation of Phenolic Intermediates

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Calcined Mg–Al hydrotalcite as an efficient catalyst for the synthesis of guaiacol

Cited by 36 publications

References 12 publications

Synthesis, Characterization, and Use of NbV/CeIV‐Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal

Synthesis, Characterization, and Use of NbV/CeIV‐Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal

A Convenient and Safe O-Methylation of Flavonoids with Dimethyl Carbonate (DMC)

Enhancing Aromatic Production from Reductive Lignin Disassembly: in Situ O-Methylation of Phenolic Intermediates

Contact Info

Product

Resources

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Synthesis, Characterization, and Use of Nb^V/Ce^IV‐Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal

Synthesis, Characterization, and Use of Nb^V/Ce^IV‐Mixed Oxides in the Direct Carboxylation of Ethanol by using Pervaporation Membranes for Water Removal