Preparation of palladium-containing mesoporous bioactive glass catalyst and evaluation of its catalytic effect on oxidation of benzyl alcohol
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Abstract:
Benzaldehyde is widely used in food, pharmaceutical, paint and spices, and it is also an important organic reaction intermediate. At present, benzaldehyde is generally obtained by selective oxidation of benzyl alcohol in the industry. It is the most green by using oxygen as the oxidant to oxidise the benzyl alcohol into benzaldehyde. Pd/mesoporous bioactive glass (MBG) catalysts were prepared by ions exchanging between Pd2+ ions and Ca2+ ions of MBG. As the Ca2+ ions content was limited in MBG, ion exchange saturation would occur and Pd particles would aggregate and grow up in case of high Pd2+ concentration. The Pd/MBG catalysts were demonstrated to have highly catalytic activity in the reaction of catalytic oxidation of benzyl alcohol with oxygen as the green oxidant. However, Pd concentration must be controlled in a small range. When the Pd concentration was higher than 0·96%, Pd particles would form, resulting in the decreasing of the catalytic activity of catalysts.Keywords:
Benzyl alcohol
Alcohol Oxidation
Bioactive Glass
A simple palladium-catalysed oxidative cross-coupling between two different alcohols was developed. Various benzylic alcohols could couple with aliphatic alcohols in excellent yields. The use of benzyl chloride as the oxidant and the amount of aliphatic alcohol were both important for achieving the reaction selectivity.
Benzyl alcohol
Alcohol Oxidation
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Benzaldehyde is widely used in food, pharmaceutical, paint and spices, and it is also an important organic reaction intermediate. At present, benzaldehyde is generally obtained by selective oxidation of benzyl alcohol in the industry. It is the most green by using oxygen as the oxidant to oxidise the benzyl alcohol into benzaldehyde. Pd/mesoporous bioactive glass (MBG) catalysts were prepared by ions exchanging between Pd2+ ions and Ca2+ ions of MBG. As the Ca2+ ions content was limited in MBG, ion exchange saturation would occur and Pd particles would aggregate and grow up in case of high Pd2+ concentration. The Pd/MBG catalysts were demonstrated to have highly catalytic activity in the reaction of catalytic oxidation of benzyl alcohol with oxygen as the green oxidant. However, Pd concentration must be controlled in a small range. When the Pd concentration was higher than 0·96%, Pd particles would form, resulting in the decreasing of the catalytic activity of catalysts.
Benzyl alcohol
Alcohol Oxidation
Bioactive Glass
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Benzyl alcohols were oxidized with oxygen to aldehydes in excellent yields with high selectivities at room temperature. Dual catalysis was operative with HNO 3 as the oxidant and precursor of the nitrogen oxides and with the use of 1,1,1,3,3,3‐hexafluoro‐2‐propanol as a template catalyst and solvent. Fluorinated alcohols also increased the selectivity by inhibiting further oxidation to benzoic acids. Activation of nitric acid catalyzed aerobic oxidation by the fluorinated solvent made the use of 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (TEMPO) or a metal catalyst superfluous.
Benzyl alcohol
Nitric acid
Alcohol Oxidation
Benzoic acid
Dual role
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Cell suspensions of Methylosinus trichosporium oxidized the aromatic alcohols benzyl alcohol, vanillyl alcohol, and veratryl alcohol to the corresponding aldehydes, and with the exception of vanillyl alcohol, the aldehydes were further oxidized to the corresponding aromatic acids. No other transformation was observed, and the methoxyl moieties attached to the aromatic nucleus remained intact. More than 70% of the alcohol oxidized could be accounted for by aldehyde and/or acid. Investigation of the inhibitor kinetics of EDTA or p -nitrophenylhydrazine (specific for NAD + -independent methanol dehydrogenase in methylotrophs) on aromatic alcohol oxidation revealed noncompetitive inhibition in which the V max was decreased but the K m remained unchanged. The pattern of inhibition of aromatic alcohol oxidation matched that of methanol oxidation, and the K m values for all of the substrates were similar (12 to 16 mM). The results indicate that the initial step in the oxidation of aromatic alcohols was similar to that for methanol, and because oxidation was incomplete (i.e., only the corresponding aldehyde or acid was produced), there may be some biotechnological advantages in using whole cells of methylotrophs to facilitate aromatic biotransformations.
Alcohol Oxidation
Biotransformation
Benzyl alcohol
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When treated with tert-butyl hypochlorite, in the presence of pyridine and methyl alcohol, saturated aliphatic primary alcohols are oxidized to methyl esters in very high yields. Oxidation of benzylic alcohols, under the same conditions, yields a mixture of aldehydes and methyl esters. It appears that this reaction is a three-step process with an aldehyde and acyl chloride as the intermediates. Investigation of the relative rates of reaction reveals that benzyl alcohols are, as expected, oxidized faster than aliphatic alcohols, while the corresponding aldehydes show an opposite trend in reactivity. The reaction mechanism is proposed and the difference in the reactivity for aliphatic and benzylic aldehydes attributed to the stereoelectronic factors.
Hypochlorite
Reactivity
Alcohol Oxidation
Primary (astronomy)
Sodium hypochlorite
Benzyl alcohol
Primary alcohol
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Gold nanoparticles have shown excellent activity for selective oxidation of alcohols; such catalytic systems are highly dependent on the initial activation of the substrates, which must occur on the catalyst surface in heterogeneous catalysts. In many cases, an extra base addition is required, although the basicity of the support may also be of significant importance. Here, we explored the intrinsic basicity of magnesium-based enrichments on CoFe2O4 magnetic nanoparticles for the oxidation of benzyl alcohol using molecular oxygen as oxidant. The MgO and Mg(OH)2 enrichments enabled gold impregnation, which was not possible on the bare CoFe2O4 nanoparticles. The Au/MgO/CoFe2O4 and Au/Mg(OH)2/CoFe2O4 catalysts reached 42% and 18% conversion, respectively without base promotion, in 2.5 hour and 2 bar of O2. When the catalysts were tested with sub-stoichiometric amounts of base, they became more active (>70% of conversion) and stable in successive recycling experiments without metal leaching, under the same reaction conditions. We also showed the oxide phases of the enrichments performed using Rietveld refinements and how the Mg(OH)2 phase interferes with the activity of MgO-based materials.
Benzyl alcohol
Alcohol Oxidation
Base (topology)
Stoichiometry
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Abstract Using a type of tetra‐substituted metal phthalocyanine carbon nanotubes composite material [ 4 a (OPh‐ p ‐CF 3 )CuPc]‐MWCNTs as a catalyst, a method to synthesize benzamides through the oxidative amidation of benzyl alcohol was developed. Synthesize copper phthalocyanine by simple DBU liquid phase catalytic method, and then load phthalocyanine on carbon nanotubes by ultrasound to form four‐substituted metal phthalocyanine carbon nanotubes composite material [ 4 a (OPh‐ p ‐CF 3 )CuPc]‐MWCNTs. The composite materials were detected by ultraviolet visible spectroscopy (UV‐Vis), Fourier transforms infrared spectroscopy (FT‐IR), X‐ray diffraction spectroscopy (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). To achieve high‐efficiency and optional catalyze, studied solvent type, oxidant type and dosage, catalyst dosage, time and temperature. In the screening experiment, [ 4 a (OPh‐ p ‐CF 3 )CuPc]‐MWCNTs composite material has high catalytic ability in the oxidation of benzyl alcohol. At the greatest of times, the highest conversion ratio of benzyl alcohol (100 %), selectivity of benzamide (89 %) was obtained. The oxidant was TBHP and the amount was 3 mL, 60 °C for 24 h in DMF. Different kinds of amides were set up by various substituted benzyl alcohols, and good results were obtained.
Benzyl alcohol
Amide
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Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Hypochlorite
Alcohol Oxidation
Primary (astronomy)
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Catalytic combustion
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Benzyl alcohol
Benzaldehyde
Alcohol Oxidation
Coupling reaction
Suzuki reaction
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