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Showing papers on "Benzaldehyde published in 2008"


Journal ArticleDOI
TL;DR: In this article, the authors focused on the smooth oxidation of benzyl alcohol by air in a vapor phase process affording benzaldehyde with high selectivity and yield, using mono-and bimetallic gold-copper on silica catalyst.

252 citations


Journal ArticleDOI
TL;DR: The theoretical kinetic isotope effects based on this mechanism were in excellent agreement with the experimental values for both substrates, but only when migratory extrusion of CO was selected as the rate-determining step.
Abstract: The mechanism for the rhodium-catalyzed decarbonylation of aldehydes was investigated by experimental techniques (Hammett studies and kinetic isotope effects) and extended by a computational study (DFT calculations). For both benzaldehyde and phenyl acetaldehyde derivatives, linear Hammett plots were obtained with positive slopes of +0.79 and +0.43, respectively, which indicate a buildup of negative charge in the selectivity-determining step. The kinetic isotope effects were similar for these substrates (1.73 and 1.77 for benzaldehyde and phenyl acetaldehyde, respectively), indicating that similar mechanisms are operating. A DFT (B3LYP) study of the catalytic cycle indicated a rapid oxidative addition into the C(O)−H bond followed by a rate-limiting extrusion of CO and reductive elimination. The theoretical kinetic isotope effects based on this mechanism were in excellent agreement with the experimental values for both substrates, but only when migratory extrusion of CO was selected as the rate-determinin...

170 citations


Journal ArticleDOI
TL;DR: In this paper, the authors explored the influence of RH on the PCO of toluene and the roles of water vapor in the process: PCO reaction paths and the accumulation of intermediates on the activated carbon fibers (ACFs)-supported TiO2 photocatalyst.
Abstract: Photocatalytic oxidation (PCO) tests were carried out for toluene adsorbed on the activated carbon fibers (ACFs)-supported TiO2 photocatalyst in an environmental condition controlled chamber. TiO2/ACF catalyst was made and characterized by N2 adsorption isotherm for pore structure and scanning electron microscopy (SEM) for morphology, respectively. Through exploring the remnant of toluene and the accumulation of intermediates on the TiO2/ACF catalyst including species, amount and their change processes under different relative humidity (RH), this study aimed to explore the influence of RH on the PCO of toluene and the roles of water vapor in the PCO process: PCO reaction paths and the accumulation of intermediates on the TiO2/ACF catalyst. Results showed that (1) with the increase of RH in the chamber (15%, 30%, 45% and 60%) the PCO conversion rate of toluene was positive correlated and no catalyst deactivation was observed under all RH levels; (2) during the gas–solid PCO process of toluene, byproducts of aromatic ring oxidation including 2-methyl, p-benzoquinone and o(m, p)-cresol were observed on the TiO2/ACF catalyst which had not been reported, together with the intermediates of side chain oxidation including benzyl alcohol, benzaldehyde and benzoic acid which had been reported; (3) although benzaldehyde was the primary intermediate under all RH level, amounts of the byproducts of aromatic ring oxidation were increased with the increase of RH; and (4) elevated RH increased the accumulation of benzyl alcohol but assuredly decreased the accumulation of benzaldehyde. These results suggested that (1) RH affects both the PCO rate and the PCO reaction path of toluene; (2) although methyl group oxidation is the major path, aromatic ring oxidation, which is not the expected path for the PCO of toluene, is enhanced when the RH increases; (3) apart from the role of hydroxyl radical (OH) produced from water by TiO2, water molecule also directly takes part in the PCO process. A hypothesis has been suggested: transition species comprised of benzaldehyde, hydroxyl and water molecule exists in the PCO conversion process from benzaldehyde to benzoic acid, though the hypothesis has not been confirmed.

156 citations


Journal ArticleDOI
TL;DR: A green protocol for producing simple esters by selectively oxidizing an aldehyde dissolved in a primary alcohol has been established, utilising air as the oxidant and supported gold nanoparticles as catalyst.

147 citations


Journal ArticleDOI
TL;DR: A good agreement between the theoretically predicted enantioselectivities for 1a and 1h and the experimental data allowed to understand the specific aspects of the reaction mechanism, and it is suggested that attractive aromatic interactions between the catalyst 9 and the aldehyde 1 contribute to the enantiodifferentiation.
Abstract: Allylation of aromatic aldehydes 1a−m with allyl- and crotyl-trichlorosilanes 2–4, catalyzed by the chiral N-oxide QUINOX (9), has been found to exhibit a significant dependence on the electronics of the aldehyde, with p-(trifluoromethyl)benzaldehyde 1g and its p-methoxy counterpart 1h affording the corresponding homoallylic alcohols 6g,h in 96 and 16% ee, respectively, at −40 °C. The kinetic and computational data indicate that the reaction is likely to proceed via an associative pathway involving neutral, octahedral silicon complex 22 with only one molecule of the catalyst involved in the rate- and selectivity-determining step. The crotylation with (E) and (Z)-crotyltrichlorosilanes 3 and 4 is highly diastereoselective, suggesting the chairlike transition state 5, which is supported by computational data. High-level quantum chemical calculations further suggest that attractive aromatic interactions between the catalyst 9 and the aldehyde 1 contribute to the enantiodifferentiation and that the dramatic d...

113 citations


Journal ArticleDOI
TL;DR: In this paper, water has dual promotional functions in the reaction system: to help form unique microdroplets in a multiphase reaction system and to assist the oxygen adsorption and activation.

93 citations


Journal ArticleDOI
TL;DR: A full kinetic model of the hydrogenation based on rate constants for individual steps in the catalysis was developed and simulates the rate of carbonyl compound hydrogenation and of the amounts of ruthenium species 1 and 2 present during hydrogenations.
Abstract: The catalytic hydrogenation of benzaldehyde and acetophenone with the Shvo hydrogenation catalysts were monitored by in situ IR spectroscopy in both toluene and THF. The disappearance of organic carbonyl compound and the concentrations of the ruthenium species present throughout the hydrogenation reaction were observed. The dependence of the hydrogenation rate on substrate, H2 pressure, total ruthenium concentration, and solvent were measured. In toluene, bridging diruthenium hydride 1 was the only observable ruthenium species until nearly all of the substrate was consumed. In THF, both 1 and some monoruthenium hydride 2 were observed during the course of the hydrogenation. A full kinetic model of the hydrogenation based on rate constants for individual steps in the catalysis was developed. This kinetic model simulates the rate of carbonyl compound hydrogenation and of the amounts of ruthenium species 1 and 2 present during hydrogenations.

84 citations


Journal ArticleDOI
TL;DR: Analysis of the data indicated that phenylacetaldehyde, the Strecker aldehyde of phenylalanine, is the most effective precursor and that both air and water significantly enhanced the rate of benzaldehyde formation from phenyl acetaldehyde.
Abstract: Benzaldehyde, a potent aroma chemical of bitter almond, can also be formed thermally from phenylalanine and may contribute to the formation of off-aroma. To identify the precursors involved in its generation during Maillard reaction, various model systems containing phenylalanine, phenylpyruvic acid, phenethylamine, or phenylacetaldehyde were studied in the presence and absence of moisture using oxidative and nonoxidative Py-GC-MS. Analysis of the data indicated that phenylacetaldehyde, the Strecker aldehyde of phenylalanine, is the most effective precursor and that both air and water significantly enhanced the rate of benzaldehyde formation from phenylacetaldehyde. Phenylpyruvic acid was the most efficient precursor under nonoxidative conditions. Phenethylamine, on the other hand, needed the presence of a carbonyl compound to generate benzaldehyde only under oxidative conditions. On the basis of the results obtained, a free radical initiated oxidative cleavage of the carbon-carbon double bond of the enolized phenylacetaldehyde was proposed as a possible major mechanism for benzaldehyde formation, and supporting evidence was provided through monitoring of the evolution of the benzaldehyde band from heated phenylacetaldehyde in the presence and absence of 1,1'-azobis(cyclohexanecarbonitrile) on the ATR crystal of an FTIR spectrophotometer. In the presence of the free radical initiator, the enol band of the phenylacetaldehyde centered at 1684 cm(-1) formed and increased over time, and after 18 min of heating time the benzaldehyde band centered at 1697 cm(-1) formed and increased at the expense of the enol band of phenylacetaldehyde, indicating a precursor product relationship.

81 citations


Journal ArticleDOI
TL;DR: In this paper, the trityl chloride (triphenylmeth-yl chloride, TrCl) was used as an efficient organic catalyst for the synthesis of bis(indol-3-yl)methanes.
Abstract: A simple, clean, and highly efficient solvent-free proce- dure for the preparation of bis(1H-indol-3-yl)methanes is described from the reaction of carbonyl compounds (aldehydes and ketones) with 1H-indole in the presence of trityl chloride as a catalyst. The reaction proceeds rapidly in high yields at room temperature in a neutral medium. A proposed mechanism is suggested based upon former reactions and calculated results. Indole and its derivatives are known as an important class of heterocyclic compounds in the pharmaceutical chemis- try. 1 Bis(indol-3-yl)methanes have abundant pharmaco- logical and biological properties, 2 therefore, there is great interest in the synthesis of these compounds. 3-5 Syntheti- cally the reaction of 1H-indole with aldehydes or ketones produces azafulvenium salts that react further with a sec- ond 1H-indole molecule to form bis(indol-3-yl)meth- anes. 6 Previously, the use of various Lewis acids or protic acids has been reported in the literature for the synthesis of bis(indol-3-yl)methanes, 7-27 however, there are only a few reports using neutral organic catalysts for this aim. 4,11,28 The use of organic catalysts instead of inorganic Lewis acids has some advantages including (i) the possibility of using acid-sensitive substrates and (ii) substrates bearing basic functional groups or electron-donating substituents that are prone to capture the acidic catalysts do not affect the reaction results. From another viewpoint, it is always interesting to develop new catalysts with desirable fea- tures such as efficiency, recyclability, and ecofriendliness for organic transformations. In the present investigation, for the first time, we report trityl chloride (triphenylmeth- yl chloride, TrCl) as an efficient organic catalyst for the preparation of bis(indol-3-yl)methanes. The trityl group is a bulky protective group for the selective protection of primary hydroxy functions in the presence of secondary and tertiary hydroxy groups. Trityl chloride can be ob- tained commercially or easily prepared by a known proce- dure. 29 The application of solvent-free reaction conditions in or- ganic chemistry has been explored extensively within the last decade. Solvent-free reactions have been demonstrat- ed to be an efficient technique for various organic reac- tions instead of using harmful organic solvents. Solvent- free conditions often lead to a remarkable decrease in re- action time, increased yields, easier workup, matching with green chemistry protocols and they may enhance the regio- and stereoselectivity of reactions. 30 Following from our previous work on the application of solvent-free tech- niques in organic transformations, 31 we report here the use of trityl chloride as an excellent organic catalyst in the re- action of 1H-indole with aromatic/aliphatic aldehydes and ketones at room temperature or 35 °C under solvent-free conditions (Scheme 1). We first examined the synthesis of bis(indol-3-yl)meth- anes using trityl chloride (2 mmol), 1H-indole (1, 20 mmol), and benzaldehyde (10 mmol) in the absence of solvent as a model reaction. The reaction was achieved at room temperature and the corresponding product 3a was obtained in 90% yield in approximately 20 minutes.

69 citations


Journal ArticleDOI
TL;DR: In this paper, the intrinsic electronic properties of home prepared (HP) TiO2 catalysts were investigated by diffuse reflectance spectroscopy and quasi-Fermi level measurements.
Abstract: In this paper some intrinsic electronic properties of home prepared (HP) TiO2 catalysts were investigated by diffuse reflectance spectroscopy and quasi-Fermi level measurements These powders were used for carrying out the photocatalytic oxidation of benzyl alcohol to benzaldehyde and CO2 in water; the selectivity for aldehyde formation was enhanced by the addition of small amounts of ethanol, a typical hole trap The values of band gap, valence band and conduction band edges are almost identical for all the HP samples in which anatase phase is predominant, whereas appreciable differences can be noticed for an HP sample containing high amount of rutile phase A comparative ATR-FTIR study of the HP catalyst showing the highest selectivity and the commercial titania showing the highest activity towards benzyl alcohol oxidation (Degussa P25 TiO2) was carried out The ATR-FTIR results indicate that HP and Degussa P25 surfaces show a very dissimilar hydrophilicity and different ability for adsorbing the organic compounds deriving from benzyl alcohol photocatalytic oxidation Results show moreover that the improved selectivity to aldehyde by adding ethanol is due to competition between the substrate and the hole trap for adsorption on reactive sites

66 citations


Journal ArticleDOI
Gongde Wu1, Xiaoli Wang1, Junping Li1, Ning Zhao1, Wei Wei1, Yuhan Sun1 
TL;DR: In this paper, the Mg-Al layered-double hydroxides (LDHs) intercalated by three kinds of sulphonato-salen-chromium(III) complexes were prepared and characterized by FTIR, UV-vis, XRD and elemental analysis.

Journal ArticleDOI
TL;DR: In this paper, the selective catalytic oxidation of styrene with hydrogen peroxide was studied over Co-ZSM-5 catalysts which differ in the preparation methods, such as wetness impregnation and ion exchange.
Abstract: The selective catalytic oxidation of styrene with hydrogen peroxide was studied over Co–ZSM-5 catalysts which differ in the preparation methods. The catalysts were obtained from NH 4 + –ZSM-5 by wetness impregnation and ion-exchange techniques followed by different post-thermal treatments: oxidation and reduction. The characterization of acidic properties by FTIR of adsorbed pyridine revealed that new and strong Lewis sites (1452 cm −1 ), different from those characteristics of aluminum in the matrix (1456 cm −1 ) were generated by cobalt introduction. Styrene conversion shows an important increment over the exchanged samples as compared to the impregnated ones. This behavior may be explained by the high Lewis acid sites concentration. Benzaldehyde was the main product in all the samples under study. The samples’ magnetic properties were improved with the cobalt incorporation and the applied thermal treatments. The catalytic and magnetic properties of Co–ZSM-5 samples are discussed.

Journal ArticleDOI
TL;DR: In this article, a phase-transfer catalyst was used to achieve 95.8% conversion of BzOH and over 99% selectivity of benzaldehyde in 0.5h.

Journal ArticleDOI
TL;DR: A series of substituted pyridine derivatives were prepared from 2-chloro-6-ethoxy-4-acetylpyridine, which was prepared from the corresponding citrazinic acid as starting material as discussed by the authors.
Abstract: A series of substituted pyridine derivatives were prepared from 2-chloro-6-ethoxy-4-acetylpyridine, which was prepared from the corresponding citrazinic acid as starting material. Reaction of acetylpyridine with thiophene-2-carboxaldehyde afforded the 2-chloro-6-ethoxy-4-β-(2-thienyl)acryloylpyridine, which was reacted with malononitrile in refluxing ethanol in the presence of piperidine as a catalyst to afford the cyanoaminopyrane derivative. Acryloylpyridine was treated with urea or guanidine hydrochloride in refluxing ethanolic potassium hydroxide to give the corresponding pyrimidinone and aminopyrimidine derivatives. The latter was condensed with hydrazine hydrate or phenyl hydrazine to give pyrazoline and N-phenylpyrazoline derivatives. Finally, cycloaddition reaction of acryloylpyridine with thiourea yielded thioxopyrimidine, which was treated with 2-bromopropionic acid, 3-bromopropionic acid, or bromoacetic acid to yield methylthiazolo-, thiazino-, and thiazolopyrimidine derivatives. The arylmethylene derivative was prepared by reacting thiazolopyrimidine with benzaldehyde or by reacting thioxopyrimidine with benzaldehyde and bromoacetic acid in one step. The pharmacological screening showed that many of these compounds have good analgesic and antiparkinsonian activities comparable to Valdecoxib® and Benzatropine® as reference drugs.

Journal Article
TL;DR: In this article, four new azo dyes were prepared by linking benzaldehyde p-aminobenzoylhydrazone (3) and p-hydroxybenzaldehyede (4) to barbituric acid and 1,3-dimethylbarbiturric acid through diazo-coupling reactions.
Abstract: Four new azo dyes, L, L, L, and L, were prepared by linking benzaldehyde p-aminobenzoylhydrazone (3) and p-hydroxybenzaldehyede p–aminobenzoylhydrazone (4) to barbituric acid and 1,3-dimethylbarbituric acid through diazo-coupling reactions. Reactions of the azo-dyes with copper chloride and bidentate ligand, 1,10-phenanthroline, produced mixed-ligand dinuclear complexes with general stoichiometry [Cu2L(phen)2 ]Cl2 (7, 8, 9, and 10). The structures of both azo dyes and their complexes were identified by elemental analyses, FT-IR, H-NMR, UV-VIS, magnetic susceptibility, and mass spectral data.

Journal ArticleDOI
TL;DR: In this paper, the performance of nano Au catalysts for the selective oxidation of benzyl alcohol to benzaldehyde in supercritical carbon dioxide (scCO 2 ) medium has been investigated.
Abstract: Selective oxidation of alcohols to aldehydes or ketones has been investigated over nano Au catalysts using molecular oxygen in supercritical carbon dioxide (scCO 2 ). TiO 2 -supported nano Au catalysts prepared by a deposition–precipitation method show unprecedented catalytic performance for selective oxidation of alcohols compared to the other Au catalysts reported so far. The results show that the selective oxidation of benzyl alcohol to benzaldehyde in scCO 2 could be accomplished with a high conversion of 97% and a selectivity of 95% at 70 °C in the presence of TiO 2 -supported nano Au catalyst. Carbon dioxide (CO 2 ) medium enhances the oxidation of benzyl alcohol to benzaldehyde, and inhibits the ester formation and the over-oxidation of aldehyde to the corresponding acid. The oxidation of various alcohols has also been examined and related aldehydes were obtained with good yields and selectivities.

Journal ArticleDOI
TL;DR: In this paper, a simple and efficient one-pot method for the synthesis of new 2,4-diaryl-1,2,3,4tetrahydroquinolines using a three-component imino Diels-Alder cycloaddition between trans-isoeugenol or trans-anethole, anilines, and benzaldehyde in the presence of BF3·OEt2 in PEG-400, a green and reusable solvent, has been developed.

Journal ArticleDOI
TL;DR: In this paper, the applicability of amine/diamine functionalized synthetic talc as catalysts for the synthesis of jasminaldehyde or α-pentylcinnamaldehyde by condensation of 1-heptanal with benzaldehyde was studied.
Abstract: Synthetic talc (magnesium organo silicates; MOS) was synthesized by sol–gel method under non-hydrothermal conditions and modified by introducing amine/diamine functionalities in the interlayer space. The applicability of amine/diamine functionalized MOS was studied as catalysts for the synthesis of jasminaldehyde or α-pentylcinnamaldehyde by condensation of 1-heptanal with benzaldehyde. The effect of amine/diamine functionality, amount of catalyst, benzaldehyde to 1-heptanal molar ratio and temperature on the selectivity of jasminaldehyde was studied in detail. The highest conversion of 1-heptanal (99%) with 82% selectivity of jasminaldehyde was achieved using MOS3 as a catalyst. The rate constant for condensation of 1-heptanal with benzaldehyde was calculated under optimized reaction conditions. This is the first report on application of MOS as a solid base catalyst for the condensation of 1-heptanal with benzaldehyde.

Journal ArticleDOI
TL;DR: The reaction rate enhancement in the reaction of allylboronate with benzaldehyde in the presence of AlCl3 has been studied theoretically and an analysis of electron populations and orbitals taking part in bond formation indicates that the AlCl2 molecule attached to the boronate oxygen atom strengthens the electrophilicity of theboron center, while it weakens the nucleophilicityof the C(gamma)-C(beta) bond.
Abstract: The reaction rate enhancement in the reaction of allylboronate with benzaldehyde in the presence of AlCl3 has been studied theoretically. B3LYP calculations find a relatively high activation barrier for the reaction of pinacol allylboronate with benzaldehyde in the absence of the Lewis acid. The reaction paths that go through the transition states coordinated by an AlCl3 molecule at one of the two oxygen atoms in the boronate give significantly lower values of activation energy. An analysis of electron populations and orbitals taking part in bond formation indicates that the AlCl3 molecule attached to the boronate oxygen atom strengthens the electrophilicity of the boron center, while it weakens the nucleophilicity of the Cγ−Cβ bond. The result supports the electrophilic boronate activation mechanism proposed by Rauniyar and Hall on the basis of experiments and kinetic studies. In contrast, the reaction path in which AlCl3 is coordinated to the carbonyl oxygen of benzaldehyde shows a higher activation bar...

Journal ArticleDOI
TL;DR: Gold nanoparticles supported on polymorphs of gallia (α-, β-, and γ-Ga2O3) were evaluated for the solvent-free liquid phase oxidation of benzyl alcohol by molecular oxygen as discussed by the authors.

Journal ArticleDOI
Guan Huang1, Jin Luo1, Cao Cheng Deng, Yong An Guo1, Shu Kai Zhao1, Hong Zhou1, Shan Wei1 
TL;DR: In this paper, a simple manganese tetraphenylporphyrin (Mn TPP) supported on chitosan [CTS] for liquid phase aerobic oxidation of toluene has been investigated.
Abstract: Catalysis by simple manganese tetraphenylporphyrin [Mn TPP] supported on chitosan [CTS] for liquid phase aerobic oxidation of toluene has been investigated. The toluene conversion depends on the reaction temperature, the air pressure and the amount of catalyst, but the selectivity for aldehyde and alcohol is little affected by these three parameters. Using the Mn TPP/CTS containing 2 mg of Mn TPP as a catalyst, the aerobic oxidation of toluene under the optimum conditions of 195 °C and 0.6 MPa produced benzaldehyde and benzyl alcohol at 96% selectivity with 5.9% conversion of toluene. The catalyst can be reused once. Chitosan played an important role in the catalytic oxidation of toluene.

Journal ArticleDOI
TL;DR: In this article, a mesoporous Al-MCMcm-41 (Si/Al ratio 36, 57, 81 and 108) was synthesized by a hydrothermal method using X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm (BET), thermo gravimetric-differential thermal analysis (TGA-DTA) and TEM techniques.
Abstract: The reaction of benzaldehyde with aliphatic glycols was performed over Al-MCM-41 with various Si/Al ratios. The effects of various parameters like temperature, mole ratio, reaction time and catalyst amount on the formation of acetals were optimized. The mesoporous Al-MCM-41 (Si/Al ratio 36, 57, 81 and 108) were synthesized by hydrothermal method. The synthesized catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption isotherm (BET), thermo gravimetric-differential thermal analysis (TGA-DTA) and TEM techniques. The acidity of the catalysts was measured by pyridine adsorption followed by FT-IR analysis. TEM analysis showed that the honeycomb-like regular arrangement of hexagonal pores on the molecular sieves. The highly hydrophobic Al-MCM-41 (108) showed higher activity than the other Si/Al ratios. The activity of the catalysts showed the following order Al-MCM-41 (108) > Al-MCM-41 (81) > Al-MCM-41 (57) > Al-MCM-41 (36). The hydrophobicity and nucleophilicity of the glycols highly influences the conversion of benzaldehyde, it followed the order; hexylene glycol (HG) > propylene glycol (PG) > ethylene glycol (EG). The results showed that mole ratio of 1:3 (aldehyde:glycol) gave higher yield than the other mole ratios.

Journal ArticleDOI
TL;DR: The catalytic activity of hydrotalcite was evaluated for the synthesis of jasminaldehyde by solvent free condensation of 1-heptanal with benzaldehyde as discussed by the authors.
Abstract: The catalytic activity of hydrotalcite ([M(II)1−xM(III)x(OH2)]x+(CO32−)x/n·mH2O; where M(II) = Mg, Ni, Zn and M(III) = Al) was evaluated for the synthesis of jasminaldehyde by solvent free condensation of 1-heptanal with benzaldehyde The effect of activation of as-synthesized Mg-Al hydrotalcite samples of varied Mg/Al molar ratio on its catalytic activity was studied and correlated with their basicity as determined from the model test reaction The effect of reaction parameters such as, amount of catalyst, benzaldehyde to 1-heptanal molar ratio and reaction temperature on conversion of 1-heptanal and selectivity of jasminaldehyde was studied in detail Maximum selectivity of jasminaldehyde (86%) with 98% conversion of 1-heptanal was observed using as-synthesized Mg-Al hydrotalcite of Mg/Al molar ratio of 35 as a catalyst The kinetics of the reaction was measured and reaction rate and order of reaction were determined under optimum reaction conditions The catalyst was re-used upto three cycles without significant loss in its activity The base catalyzed reaction mechanism for condensation of 1-heptanal with benzaldehyde is proposed

Journal ArticleDOI
TL;DR: The reactivity of the dihydride−acetone complex [OsH2(η5-C5H5)(κ1-OCMe2)(PiPr3)]BF4 (1) toward cinnamaldehyde, isovaleraldehyde, and benzaldehyde has been investigated as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, a one-pot procedure for tetraphenylporphyrin synthesis using iodine-catalysis and microwave activation was described, and commercial pyrrole, benzaldehyde and dichloromethane were being used as such, without prior distillation.

Journal ArticleDOI
TL;DR: Both spectroscopic and X-ray structural studies are consistent with inhibition resulting from the binding of MBP to the thiamin diphosphate in the active centers, and the role of His29 and Trp163 are delineated in cofactor activation and catalysis by benzaldehyde lyase.
Abstract: Benzaldehyde lyase (BAL) catalyzes the reversible cleavage of (R)-benzoin to benzaldehyde utilizing thiamin diphosphate and Mg2+ as cofactors. The enzyme is important for the chemoenzymatic synthesis of a wide range of compounds via its carboligation reaction mechanism. In addition to its principal functions, BAL can slowly decarboxylate aromatic amino acids such as benzoylformic acid. It is also intriguing mechanistically due to the paucity of acid−base residues at the active center that can participate in proton transfer steps thought to be necessary for these types of reactions. Here methyl benzoylphosphonate, an excellent electrostatic analogue of benzoylformic acid, is used to probe the mechanism of benzaldehyde lyase. The structure of benzaldehyde lyase in its covalent complex with methyl benzoylphosphonate was determined to 2.49 A (Protein Data Bank entry 3D7K) and represents the first structure of this enzyme with a compound bound in the active site. No large structural reorganization was detected...

Journal ArticleDOI
TL;DR: In this article, an efficient selective oxidation of ketones to lactones by molecular oxygen with benzaldehyde as an oxygen acceptor, in the presence of metalloporphyrins, has been reported.
Abstract: Efficient selective oxidation of ketones to lactones by molecular oxygen with benzaldehyde as an oxygen acceptor, in the presence of metalloporphyrins, has been reported. Iron(III) meso-tetraphenylporphyrin chloride (Fe(TPP)Cl) showed excellent activity and selectivity for oxidation of cyclohexanones under mild conditions. Moreover, different factors influencing ketones oxidation, e.g. catalyst, solvent, temperature and additive, have been investigated. The turnover number (TON) of the Fe(TPP)Cl catalyst could reach up to 71000 in a large scale oxidation of cyclohexanone. A plausible mechanism of ketone oxidation by molecular oxygen in the presence of metalloporphyrins and benzaldehyde was proposed.

Journal ArticleDOI
TL;DR: Calix[4]resorcinarenes were prepared by the condensation of resorcinol and aldehydes (acetaldehyde, benzaldehyde, and 4-isopropylbenzaldehyde), and two isomers, C4v (ccc) and C2v (ctt), were separa...
Abstract: Calix[4]resorcinarenes were prepared by the condensation of resorcinol and aldehydes (acetaldehyde, benzaldehyde, and 4-isopropylbenzaldehyde), and two isomers, C4v (ccc) and C2v (ctt), were separa...

Journal ArticleDOI
TL;DR: In this article, primary, secondary and tertiary aminodiols were synthetized regio-and stereoselectively from (−)-α-pinene 1 via αpinene oxide 2, (−)- trans-pinocarveol 3 and key intermediate epoxy alcohol 4.

Journal ArticleDOI
TL;DR: In this paper, X-ray photoelectron spectroscopy (XPS) was used to characterize the CeO2 catalysts for hydrogenation of benzoic acid to benzaldehyde.
Abstract: The CeO2 catalysts for hydrogenation of benzoic acid to benzaldehyde were characterized by X-ray photoelectron spectroscopy (XPS). The results indicate the catalyst deactivation is due to the coke formation and the valence changes of Ce over the catalyst.