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Showing papers on "Benzaldehyde published in 2009"


Journal ArticleDOI
TL;DR: In this paper, the photocatalytic oxidation of benzyl alcohol and its derivatives, such as 4-methoxybenzyl alcohol, 4-chlorobenzyl alcohol (CB), 4-nitrobenzinzyl al alcohol (NB), 4-(trifluoromethyl) benzyl (TRB) alcohol, and 4-tertiary-butyl-benzymethyl alcohol (TBBA), into corresponding aldehydes was investigated under both UV and visible light irradiation.

252 citations


Journal ArticleDOI
TL;DR: In this paper, a range of activated carbon-supported Au-Pd bimetallic catalysts were investigated for the oxidation of different alcohols with molecular oxygen in water, and a synergistic effect was observed in a large range of the Au-pd ratio.
Abstract: The oxidation of different alcohols with molecular oxygen in water has been investigated using a range of activated carbon-supported Au-Pd bimetallic catalysts. The effect of the Au-Pd ratio on the conversion and selectivity was observed and a synergistic effect is present in a large range of the Au-Pd ratio, being maximized for Au80-Pd20 composition instead of Au90-Pd10 shown in glycerol oxidation (1). Moreover the en- hancement of conversion observed by adding a base resulted greater for gold-rich catalysts rather than for palladium-rich ones. The effect of the alcohol concentration and the metal/substrate ratio in the presence or the absence of the base was also studied revealing substan- tial differences in terms of both activity and selectivity. At 1 M concentration under biphasic conditions benzyl alcohol has been selectively oxi- dized to benzaldehyde (S90=98%) even in the presence of NaOH with a TOF of 18000h -1 using Au60-Pd40/AC as the catalyst.

149 citations


Journal ArticleDOI
TL;DR: In this paper, the performance of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical was studied for both synthesized and in situ made complexes in alkaline water solutions, revealing high efficiency and selectivity.
Abstract: Novel copper(II) 2-N-arylpyrrolecarbaldimine-based catalysts for the aerobic oxidation of benzylic alcohols mediated by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical are reported. The catalytic activity for both synthesized and in situ made complexes in alkaline water solutions was studied revealing high efficiency and selectivity (according to GC selectivity always >99%) for both of these catalytic systems. For example, quantitative conversion of benzyl alcohol to benzaldehyde can be achieved with the in situ prepared bis[2-N-(4-fluorophenyl)-pyrrolylcarbaldimide]copper(II) catalysts in 2 h with atmospheric pressure of O2 at 80 °C. Interestingly, these catalysts can utilize dioxygen as well as air or hydrogen peroxide as the end oxidants, producing water as the only by-product.

142 citations


Journal ArticleDOI
TL;DR: In this article, the authors reported the synthesis of Au/SBA-15 and Au-Pd/Sba-15 materials by impregnation and grafting methods.
Abstract: In this paper, we report the synthesis of Au/SBA-15 and Au-Pd/SBA-15 materials by impregnation and grafting methods It was found that the Au-Pd/SBA-15 sample prepared by the grafting method could highly disperse metal nanoparticles in mesoporous channels of SBA-15 and exhibit excellent catalytic performances for the selective oxidation of benzyl alcohol to benzaldehyde at mild reaction conditions (air atmosphere, 80 degrees C) The prevention of agglomeration and leaching of gold nanoparticles by restricting them inside the mesopores of SBA-15 leads to a high stability of Au-Pd/SBA-15 In both approaches the addition of Pd to Au/SBA-15 catalysts can decrease the size of gold nanoparticles, which attributes to higher activity for the selective aerobic oxidation of benzyl alcohol (C) 2009 Elsevier BV All rights reserved

140 citations


Journal ArticleDOI
TL;DR: It is proposed that toluene and benzaldehyde are formed by competing parallel reactions of the initial benzyl intermediate via an adsorbed benzylidene species that can either be hydrogenated or oxidised, Hence, conditions that maximise the availability of oxygen on the catalyst surface favour the synthesis of benzaldehyde.
Abstract: We report the preparation of Au–Pd nanocrystalline catalysts supported on TiO2 and carbon prepared via a sol-immobilisation technique using three different preparation strategies; namely, simultaneous formation of the sols for both metals or initial formation of a seed sol of one of the metals followed by a separate step in which a coating sol of the second metal is added. The catalysts have been structurally characterised using a combination of transmission electron microscopy and X-ray photoelectron spectroscopy. The catalysts have been evaluated for the oxidation of benzyl alcohol under solvent-free conditions. The catalysts prepared using the sol immobilisation technique show higher activity when compared with catalysts prepared by impregnation, particularly as lower metal concentrations can be used. The Au–Pd catalysts were all more active than the corresponding monometallic supported Au or Pdcatalysts. For 1 wt% Au–Pd/TiO2 the order of metal addition in the preparation was not observed to be significant with respect to selectivity or activity. However, the 1 wt% Au–Pd/carboncatalysts are more active but less selective to benzaldehyde than the TiO2-supported catalysts when compared at iso-conversion. Furthermore, for the carbon-supported catalyst the order of metal addition has a very marked affect on activity. The carbon-supported catalysts are also more significantly affected by heat treatment, e.g.calcination at 400 °C leads to the activity being decreased by an order of magnitude, whereas the TiO2-supported catalysts show a 50% decrease in activity. Toluene is observed as a by-product of the reaction and conditions have been identified that minimise its formation. It is proposed that toluene and benzaldehyde are formed by competing parallel reactions of the initial benzyl intermediate via an adsorbed benzylidene species that can either be hydrogenated or oxidised. Hence, conditions that maximise the availability of oxygen on the catalyst surface favour the synthesis of benzaldehyde.

135 citations


Journal ArticleDOI
TL;DR: It was found that title compounds 8g, 8e, 8k, and 8m had the same curative effects of TMV as the commercial product Ningnanmycin and would appear to be the first report of the synthesis and antiviral activity of chiral thiourea derivatives containing an alpha-aminophosphonate moiety.
Abstract: Starting from benzaldehyde 1, the title compounds 8 were synthesized in six steps Benzaldehyde 1 was reacted with ammonium hydroxide, and the resulting imine was then treated with dialkyl phosphite 3 to give dialkyl N-(arylmethylene)-1-amino-1-aryl methylphosphonates 4 Phosphonates 4 were then easily hydrolyzed to give dialkyl 1-amino-1-aryl-methylphosphonates 6, which on treatment with triethylamine, carbon disulfide, and phosphorus oxychloride provided 7 Target compounds 8 were then prepared by the reaction of 7 with substituted chiral amine The structures were clearly verified by spectroscopic data (IR, (1)H, (13)C, and (31)P NMR, and elemental analysis) The bioassay of these compounds revealed them as antivirally active It was found that title compounds 8g, 8e, 8k, and 8m had the same curative effects of TMV (inhibitory rate = 548, 505, 504, and 504%, respectively) as the commercial product Ningnanmycin (562%) This would appear to be the first report of the synthesis and antiviral activity of chiral thiourea derivatives containing an alpha-aminophosphonate moiety

131 citations


Journal ArticleDOI
TL;DR: Dinuclear copper peroxo complexes obtained from mononuclear copper(I) complexes showed extremely high stabilities under ambient conditions in the solid state and could be heated above 100 degrees C without decomposition.
Abstract: Dinuclear copper peroxo complexes obtained from mononuclear copper(I) complexes showed extremely high stabilities under ambient conditions in the solid state and could be heated above 100 °C without decomposition. The increased stability could be explained with regard to their molecular structures. Furthermore, the four complexes investigated showed a high potential for aliphatic C−H bond oxidations: for example, technical-grade toluene was oxidized to benzaldehyde in yields of up to 20%.

123 citations


Journal ArticleDOI
Jianglei Hu1, Kexin Li1, Wei Li1, Fengyan Ma1, Yihang Guo1 
TL;DR: A series of Schiff base-modified ordered mesoporous silica materials impregnated with the transition metal-monosubstituted Keggin-type polyoxometalates (mono-TMSPs), K 10− n X n + MW 11 O 39 -Schiff-SBA-15, (X = P/Si, M = Co/Ni/Cu/Mn), was prepared using successive grafting procedures of SBA15 silica with 3-aminopropyl-trimethoxysilane, benzaldehyde, and
Abstract: A series of Schiff base-modified ordered mesoporous silica materials impregnated with the transition metal-monosubstituted Keggin-type polyoxometalates (mono-TMSPs), K 10− n X n + MW 11 O 39 -Schiff-SBA-15, (X = P/Si, M = Co/Ni/Cu/Mn), was prepared using successive grafting procedures of SBA-15 silica with 3-aminopropyl-trimethoxysilane, benzaldehyde, and mono-TMSP. The composite materials were well-characterized by spectroscopy methods, X-ray diffraction analysis, transmission electron microscopy, and nitrogen sorption analysis to confirm the structure integrities of the Keggin unit and Schiff base ligand after the incorporation, to evidence formation of the coordination binding between the starting Keggin units and the Schiff base-modified silica matrix, and to investigate the morphology and surface textural properties of the composite catalysts. These materials were subsequently utilized as efficient and selective catalysts in the reaction of oxidation of styrene to benzaldehyde using H 2 O 2 as an oxidant. For comparison, an amine-modified SBA-15 silica material impregnated with mono-TMSP (K 10− n X n + MW 11 O 39 -NH 2 -SBA-15) and the neat Keggin unit (K 10− n [X n + M(H 2 O)W 11 O 39 ]) was also tested. The influences of key reaction parameters, including the molar ratios of H 2 O 2 to styrene, compositions and loadings of the neat mono-TMSPs, solvents, the catalyst amount, and reaction temperatures on the reactivity and selectivity, were also studied. Finally, the reusability of the catalysts was evaluated.

104 citations


Journal ArticleDOI
Aizhong Jia1, Lan-Lan Lou1, Cui Zhang1, Yin-Qing Zhang1, Shuangxi Liu1 
TL;DR: In this article, a stable, economic and high active catalyst for selective oxidation of benzyl alcohol (BzOH) was developed by treating ZSM-5 zeolite with sodium hydroxide solution.
Abstract: A stable, economic and high active catalyst for selective oxidation of benzyl alcohol (BzOH) was developed by treating ZSM-5 zeolite with sodium hydroxide solution. The changes resulted by alkali-treatment in crystallinity, composition, structure parameters and acidities of alkali-treated ZSM-5 zeolites were examined by XRD, ICP, N2 adsorption-desorption, scanning electron micrographs (SEM), temperature program desorption (TPD) and Fourier transform infrared spectroscopic (FT-IR). The results showed that the specific MFI structure was preserved and the intrinsic micropores were kept without obvious change, the amount of Lewis acid sites and the external surface area were evidently increased after alkali-treatment. Without any organic solvent, the catalytic performance of alkali-treated ZSM-5 zeolite was investigated in selective oxidation of BzOH with hydrogen peroxide (H2O2), and the effects of reaction temperature, reaction time, dosage of catalyst, dosage of H2O2 and SiO2/Al2O3 ratio of as-received zeolites on catalytic selective-oxidation of BzOH were investigated. The results showed that the conversion of BzOH and the selectivity to benzaldehyde (BzH) were about 53% and about 86% respectively under reflux for 4 h in water. At the same time, the catalyst was very stable and could be reused for more than six times.

103 citations


Journal ArticleDOI
TL;DR: The novel catechol-BODIPY dyad, 8-(3,4-dihydroxyphenyl)-2,6-bis(ethoxycarbonyl)-1,3,5,7-tetramethyl-4, 4-difluoro-4-bora-3a,4a-diaza-s-indacene (FerriBRIGHT) was rationally designed with the aid of computational methods and suggests
Abstract: The novel catechol−BODIPY dyad, 8-(3,4-dihydroxyphenyl)-2,6-bis(ethoxycarbonyl)-1,3,5,7-tetramethyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (FerriBRIGHT) was rationally designed with the aid of computational methods. FerriBRIGHT could be prepared by standard one-pot synthesis of BODIPY fluorophores from 3,4-bis(benzyloxy)benzaldehyde (1) and 3,5-dimethyl-4-(ethoxycarbonyl)pyrrole (3); however, isolating the dipyrrin intermediate 8-[3,4-bis(benzyloxy)phenyl]-2,6-bis(ethoxycarbonyl)-1,3,5,7-tetramethyl-4,4-diaza-s-indacene (7) prior to reaction with excess BF3·OEt2 led to marked improvements in the isolated overall yield of the desired compound. In addition to these improvements in fluorophore synthesis, microwave-assisted palladium-catalyzed hydrogenolysis of benzyl ethers was used to reduce reaction times and catalyst loading in preparation of the desired compound. When FerriBRIGHT is exposed to excess FeCl3, CuCl2, [Co(NH3)5Cl]Cl2, 2,3-dichloro-5,6-dicyanobenzoquinone, or ceric ammonium nitrate in met...

103 citations


Journal ArticleDOI
TL;DR: In the absence of H2, toluene can only be observed in transient experiments when the Ga/HZSM-5 catalysts are reduced as mentioned in this paper, and it is suggested that the GaH2+ species generated under H2 play an important role in the hydrogenation/hydrogenolysis.

Journal ArticleDOI
TL;DR: A thin and well-defined film of covalently attached benzaldehyde with an estimated coverage of 4 x 10(-10) mol cm(-2) was formed and the electrochemical responses of benzaldehyde were highly reproducible and largely independent of grafting medium and along with that also the thickness of the initially grafted film.
Abstract: A methodology is described for introducing a thin layer of covalently attached benzaldehyde on glassy carbon surfaces using aryl diazonium chemistry. Usually the electroreduction of aryl diazonium salts leads to the formation of an ill-defined multilayer because of the involvement of highly reactive aryl radicals that can add to already-grafted aryl groups. However, in this study we used a two-step “formation-degradation” procedure to solve this problem with the first step consisting of an electrografting of an aryl diazonium salt of a long-chain and bulky alkyl hydrazone onto a glassy carbon surface. The design of the hydrazone group serves to minimize multilayer formation by greatly diminishing the grafting rate after the first-layer formation and at the same time preventing radical additions from taking place at the inner aryl ring. Another valuable property of the hydrazone group is that it easily can be deprotected to the corresponding aldehyde by acid hydrolysis (i.e., the degradation step). In this...

Journal ArticleDOI
TL;DR: In this paper, a reinvestigation of the reaction of benzaldehyde and salicylaldehyde with aniline revealed two important factors which explain the putative contradiction: (i) NMR only reveals the fraction of products which is soluble in water, and (ii) imines 3 form during or after workup.

Journal ArticleDOI
TL;DR: The aqua-soluble multinuclear copper(II) compounds have been applied as efficient catalysts for the mild, selective and clean oxidation of benzyl alcohols to benzaldehydes, which proceeds in sole water as solvent at 50°C, under atmospheric pressure of air (or O 2 ) as oxidant, and is mediated by TEMPO radical as discussed by the authors.
Abstract: The aqua-soluble multinuclear copper(II) compounds [Cu 2 ( μ -H 2 tea) 2 { μ 3 -Na 2 (H 2 O) 4 }( μ 6 -pma)] n ·10 n H 2 O (1) and [O ⊂ Cu 4 (tea) 4 (BOH) 4 ][BF 4 ] 2 ( 2 ) (H 3 tea = triethanolamine, H 4 pma = pyromellitic acid) have been applied as efficient catalysts for the mild, selective and clean oxidation of benzyl alcohols to benzaldehydes, which proceeds in sole water as solvent at 50 °C, under atmospheric pressure of air (or O 2 ) as oxidant, and is mediated by TEMPO radical. Molar yields of benzaldehydes (based on alcohol) up to 99% have been achieved (with a high selectivity). Attractive features of these catalytic systems include the use of organic-solvent-free reaction medium, air or dioxygen as oxidant, and aqua-soluble copper catalysts that are readily available by self-assembly.

Journal ArticleDOI
TL;DR: The treatment of the textile dye solution using laccase and 2,2'-azino-di-(-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was demonstrated in an enzyme membrane reactor with nearly 95% decolorization, 10% reduction in flux and 70% recovery of active ABTS.

Journal ArticleDOI
TL;DR: The synthesis of a Mo(VI) Schiff base complex, cis-[MoO2{(4,6-bis(tert-butyl)-2-{(benzyl)iminomethyl}phenolate)2}], was reported in this article.

Journal ArticleDOI
TL;DR: To elucidate the reaction mechanism and the origin of the high enantioselectivity, DFT calculation (BHandHLYP/6-31G*) was carried out and found that when using the aldimine derived from benzaldehyde, the re-facial attacking TS is destabilized to decrease the enantiOSElectivity.
Abstract: Asymmetric hydrophosphonylation reaction of aldimines with dialkyl phosphites proceeds catalytically by means of a phosphoric acid diester, derived from (R)-BINOL, as a chiral Bronsted acid to afford α-amino phosphonates with good to high enantioselectivities (up to 90% ee). The use of the aldimines derived from cinnamaldehyde derivatives and sterically demanding dialkyl phosphites was essential for achieving high enantioselectivity as well as high yield. To elucidate the reaction mechanism and the origin of the high enantioselectivity, DFT calculation (BHandHLYP/6-31G*) was carried out. The reaction proceeds via the nine-membered zwitterionic transition state (TS) with the chiral phosphoric acid, where aldimine and phosphite could be activated by the Bronsted acidic site and Lewis basic site, respectively. The si-facial attacking TS could be less favored by the steric repulsion of 3,3′-aryl groups on the chiral phosphoric acid with the bulky phosphite. When using the aldimine derived from benzaldehyde, t...

Journal ArticleDOI
TL;DR: In this article, the authors investigated the catalytic performance of the ZrO2-supported nanogold catalysts in liquid-phase oxidation of benzyl alcohol to benzaldehyde by tertiary butyl hydroperoxide.
Abstract: Liquid-phase oxidation of benzyl alcohol to benzaldehyde by tertiary butyl hydroperoxide (at 95 °C) over nanogold supported on TiO2 and other transition-metal oxides (viz, MnO2, Fe2O3, CoOx, NiO, CuO, ZnO, and ZrO2) or rare-earth oxides (viz, La2O3, Sm2O3, Eu2O3, and Yb2O3) by the homogeneous deposition−precipitation (HDP) method has been investigated. The Au/TiO2 catalyst, prepared using the HDP method, showed high activity and selectivity in the reaction. The ZrO2-supported nanogold catalyst (HDP) also showed very good performance. The Au/TiO2 catalyst that was prepared using the deposition−precipitation (DP) method, however, showed poor catalytic activity, mostly because of its much-lower gold loading and/or lower Au3+/Au0 ratio. Irrespective of the catalyst preparation method, the catalytic activity increased as the gold loading increased. The gold deposition method strongly influenced the amount of gold that was deposited on TiO2, the gold particle size distribution, and also the surface Au3+/Au0 rat...

Journal ArticleDOI
TL;DR: In this article, a vanadium containing molybdophosphoric acid supported on niobia catalysts using t-butyl hydrogen peroxide (TBHP) as oxidant was used for selective oxidation of toluene.
Abstract: Selective oxidation of toluene at room temperature was carried on vanadium containing molybdophosphoric acid supported on niobia catalysts using t-butyl hydrogen peroxide (TBHP) as oxidant. The catalysts were characterized by FT-IR, X-ray diffraction (XRD), 31P MAS NMR, Laser Raman spectroscopy and N2 adsorption. The characterization data reveals the incorporation of vanadium and retention of intact Keggin ion on the support. The catalyst activity is related to the presence of vanadium in Keggin ion. The effect of TBHP–toluene concentration on the conversion and selectivity during toluene oxidation was also studied. A plausible reaction mechanism for the selective formation of benzaldehyde was proposed. The present catalyst is highly active, selective towards benzaldehyde and reusable with out any appreciable loss in activity and selectivity.

Journal ArticleDOI
24 Mar 2009-ACS Nano
TL;DR: In vitro studies found these labeled nanostructures to undergo cell association in polymer vesicles constructed through self-assembly of an amphiphilic block copolymer PEO(45)-b-PVBA(26) in water.
Abstract: Polymer vesicles with diameters of ca. 100-600 nm and bearing benzaldehyde functionalities within the vesicular walls were constructed through self-assembly of an amphiphilic block copolymer PEO(45)-b-PVBA(26) in water. The reactivity of the benzaldehyde functionalities was verified by cross-linking the polymersomes and also by a one-pot cross-linking and functionalization approach to further render the vesicles fluorescent, each via reductive amination. In vitro studies found these labeled nanostructures to undergo cell association.

Journal ArticleDOI
TL;DR: In this article, the influence of the catalyst support (MgO, CaO, BaO, SrO, Al2O3, Ga2O 3, GaO 3 and In2O23), method of gold deposition, Au loading and catalyst calcination temperature and reaction conditions (viz. reaction time and temperature) on the benzyl alcohol to benzaldehyde oxidation have been thoroughly investigated.

Journal ArticleDOI
TL;DR: The role of the support nature in the Knoevenagel condensation activity is considered in this article, where the condensation of benzaldehyde and other substituted benzaldehydes with ethyl acetoacetate using these catalysts and in absence of any solvent, is also proposed as a "green method" in the preparation of pharmaceuticals in the line of calcium channel blockers and antihypertensives.

Journal ArticleDOI
TL;DR: An analysis of the differential effect of ortho- versus para-substitution shows that the iminium ion to salicylaldehyde is stabilized by an intramolecular hydrogen bond in aqueous solution, with an estimated energy ca.
Abstract: Equilibrium constants for addition of glycine to substituted benzaldehydes to form the corresponding imines and pKa’s for ionization of the iminium ions were determined by 1H NMR analysis in D2O. The introduction of a phenoxide anion substituent into the aromatic ring of benzaldehyde leads to a substantial increase in the pKa of the iminium ion from 6.3 to 10.2 for p-hydroxybenzaldehyde and to 12.1 for salicylaldehyde. An analysis of the differential effect of ortho- versus para-substitution shows that the iminium ion to salicylaldehyde is stabilized by an intramolecular hydrogen bond in aqueous solution, with an estimated energy ca. 3 kcal/mol larger than can be accounted for by a simple electrostatic interaction. A comparison of the o-O− substituent effect on the acidity of the iminium ions of glycine to benzaldehyde and 4-pyridine-carboxaldehyde provides evidence for the existence of an internal hydrogen bond of similar strength in pyridoxal 5′-phosphate (PLP) iminium ions in water. The effects of othe...

Journal ArticleDOI
Xueqin Wang1, Junping Wu1, Mingwei Zhao1, Yufen Lv1, Guiying Li1, Changwei Hu1 
TL;DR: In this article, the partial oxidation of toluene by hydrogen peroxide with catalytic amount of bis (acetylacetonato) oxovanadium (VO(acac)2) in acetic acid is studied in detail.
Abstract: The partial oxidation of toluene by hydrogen peroxide with catalytic amount of bis (acetylacetonato) oxovanadium (VO(acac)2) in acetic acid is studied in detail. Benzaldehyde is found to be the main product in the reaction, and V51NMR and ESI-MS are used to detect the possible intermediate species. The effect of reaction parameters, such as the amounts of catalyst and hydrogen peroxide used, the reaction temperature, and reaction time on the reaction are investigated. The mechanism of toluene partial oxidation is also studied, and the hydroxyl radical is found to be the key active species. The solvent acetic acid coordinates with vanadium atom, and the toluene partial oxidation passes through cage reaction to form the C6H5CH·(OOH) radical, which promptly decomposes to benzaldehyde and hydroxyl radical. C6H6CH2OOCH2C6H6 is also found to be one possible intermediate.

Journal ArticleDOI
TL;DR: In this paper, the photocatalytic activity of both commercial and homemade N-doped TiO2 samples, prepared at different pH from TiCl3 solutions, was tested for the degradation of toluene in the gas phase by using a solar irradiation source.

Journal ArticleDOI
TL;DR: In this paper, the influence of substituting groups in the aromatic ring of styrene on the reactivity was discussed, and it was shown that the hydrophilic dipyridyl-based ligand (L) with Pd(OAc)2 formed a water-soluble palladium(II) complex.

Journal ArticleDOI
TL;DR: In this article, an efficient oxidative cleavage of cinnamaldehyde to benzaldehyde catalyzed by metalloporphyrins in the presence of dioxygen has been developed.

Journal ArticleDOI
TL;DR: The reliance of the benzaldehyde coupling on subsurface defects, and not surface vacancies, over reduced TiO(2)(110), may be general for other reductive processes induced by reducible oxides, and has broad significance in modeling oxide-based catalysis with reduced crystals.
Abstract: Selective reductive coupling of benzaldehyde to stilbene is driven by subsurface Ti interstitials on vacuum-reduced TiO2(110). A combination of temperature-programmed reaction spectroscopy and scan...

Journal ArticleDOI
TL;DR: Chiral phosphine oxide successfully catalyzed the direct aldol-type reactions of cyclohexanone derivatives and benzaldehyde derivatives in high stereoselectivities as mentioned in this paper.

Journal ArticleDOI
TL;DR: Asymmetric synthesis of an unnatural amino acid was demonstrated by ω-transaminase from Vibrio fluvialis JS17 and severe product inhibition by benzaldehyde was overcome by employing a biphasic reaction system.
Abstract: Asymmetric synthesis of an unnatural amino acid was demonstrated by ω-transaminase from Vibrio fluvialis JS17 l-2-Aminobutyric acid was synthesized from 2-oxobutyric acid and benzylamine with an enantiomeric excess higher than 99% The reaction showed severe product inhibition by benzaldehyde, which was overcome by employing a biphasic reaction system to remove the inhibitory product from the aqueous phase In a typical biphasic reaction (50 mM 2-oxobutyric acid, 70 mM benzylamine and 264 U/ml purified enzyme) using hexane as an extractant, conversion of 2-oxobutyric acid reached 96% in 5 h whereas only 39% conversion was obtained without the product extraction