Showing papers on "Benzaldehyde published in 1998"
TL;DR: In this article, photocatalytic oxidations of toluene and benzene in air were carried out over water (TiO 2 /H 2 O) and HCl pretreated TiO 2.
Abstract: Photocatalytic oxidations of toluene and benzene in air were carried out over water (TiO 2 /H 2 O) and HCl (TiO 2 /HCl) pretreated TiO 2 as this latter pretreatment enhances the toluene removal rate. The main purpose was to identify intermediate products. No gas-phase by-products were detected by direct GC/FID analysis under our conditions despite the high aromatic concentration (50 mg m −3 ) and the short contact time (ms); this result illustrates an attractive capability of this air purification method. Adsorbed intermediate products recovered by extraction from the used photocatalysts were the same over TiO 2 /H 2 O and TiO 2 /HCl; i.e. no chlorinated products were found in this latter case. Benzoic acid, benzaldehyde, and benzyl alcohol were three major toluene intermediate products identified; trace derivatives of these products and of toluene that were monohydroxylated on the ring were also detected in catalyst extract samples. The benzene major by-product was phenol which was accompanied by hydroquinone and 1,4-benzoquinone. Acetic and formic acids were also formed from both benzene and toluene. For both aromatics, a water extraction of the used photocatalysts permitted separation of a yellow viscous material that settled between water and TiO 2 after centrifugation. We have not identified the products contained in this material but believe them to be polymeric products which may be at the origin of the decreased photocatalytic activity of used TiO 2 with respect to fresh TiO 2 . Finally, we discuss the photocatalytic oxidation pathways.
312 citations
TL;DR: In this article, an 8% SiO2-TiO2 binary catalyst was used for the photocatalytic oxidation of gas-phase toluene and the presence of benzaldehyde and benzoic acid was identified on the surface of the deactivated photocatalyst.
246 citations
TL;DR: At -40°C aryl iodides that contain other functional groups can be selectively converted into Grignard reagents, which react with electrophiles such as benzaldehyde in the usual manner.
Abstract: At -40°C aryl iodides that contain other functional groups can be selectively converted into Grignard reagents, which react with electrophiles such as benzaldehyde in the usual manner [Eq. (a)]. Aryl bromides and iodides that are immobilized as esters on a Wang resin behave analogously.
219 citations
TL;DR: In this article, the reaction of the highly electrophilic borane B(C6F5)3 with the carbonyl Lewis bases benzaldehyde, acetophenone, ethyl benzoate, and N,N-diisopropylbenzamide led to isolation of the crystalline adducts 1-H, 1-Me, 1OEt, and 1-NPr, respectively, in good to excellent yields.
157 citations
TL;DR: In this article, the authors described benzaldehyde formation from phenylalanine by using a cell extract of Lactobacillus plantarum and found that several cations could replace the extract in the conversion of phenylpyruvic acid to benzaldehyde.
Abstract: The production of benzaldehyde from phenylalanine has been studied in various microorganisms, and several metabolic pathways have been proposed in the literature for the formation of this aromatic flavor compound. In this study, we describe benzaldehyde formation from phenylalanine by using a cell extract of Lactobacillus plantarum. Phenylalanine was initially converted to phenylpyruvic acid by an aminotransferase in the cell extract, and the keto acid was further transformed to benzaldehyde. However, control experiments with boiled cell extract revealed that the subsequent conversion of phenylpyruvic acid was a chemical oxidation step. It was observed that several cations could replace the extract in the conversion of phenylpyruvic acid to benzaldehyde. Addition of Cu(II) ions to phenylpyruvic acid resulted not only in the formation of benzaldehyde, but also in the generation of phenylacetic acid, mandelic acid, and phenylglyoxylic acid. These compounds have been considered intermediates in the biological conversion of phenylalanine. The chemical conversion step of phenylpyruvic acid was dependent on temperature, pH, the availability of cations, and the presence of oxygen.
135 citations
126 citations
TL;DR: In this article, a semi-empirical transition state (TS) model was developed for enantioselective chiral β-amino alcohol catalyzed additions of organozinc reagents to benzaldehyde.
Abstract: PM3 transition state (TS) models were developed for enantioselective chiral β-amino alcohol catalyzed additions of organozinc reagents to benzaldehyde. These semiempirical TS models are consistent with earlier ab initio computations on smaller model systems and with experimental data for a variety of stereoselective examples. General trends for varying chiral β-amino alcohol ligands (e.g., camphor, 1,2-diphenylethane, and proline derivatives) and alkylating agent (ZnMe2, ZnEt2) are reproduced by these models.
99 citations
TL;DR: In this paper, the partial oxidation of toluene to benzaldehyde on potassium-promoted vanadium pentoxide catalysts was investigated and the surface acidity of these solids was inferred from the 2-propanol decomposition reaction, which gives an indication of the acid strength.
Abstract: Catalytic activity was measured for the partial oxidation of toluene to benzaldehyde on potassium-promoted vanadium pentoxide catalysts. In addition, the surface acidity of these solids was inferred from the 2-propanol decomposition reaction, which gives an indication of the acid strength. The results of this work showed that both toluene conversion and selectivity to benzaldehyde are related to the presence of acidic sites in the catalyst.
78 citations
TL;DR: In this paper, a series of benzaldehyde and benzoic acid derivatives can be obtained from benzylic alcohols by tungsten-catalyzed oxidation with aqueous hydrogen peroxide under halide-free/organic biphasic conditions.
78 citations
TL;DR: An operationally simple method based on [Cn*RuIII(CF3CO2)3·H2O] (Cn * = N,N,N‘,N ‘‘-trimethyl-1,4,7-triazacyclononane) catalyst and 1−1.2 equiv of tert-butyl hydroperoxide as terminal oxidant is effective for selective transformation of alcohols to aldehydes and ketones in methylene chloride as mentioned in this paper.
Abstract: An operationally simple method based on [Cn*RuIII(CF3CO2)3·H2O] (Cn* = N,N‘,N‘‘-trimethyl-1,4,7-triazacyclononane) catalyst and 1−1.2 equiv of tert-butyl hydroperoxide as terminal oxidant is effective for selective transformation of alcohols to aldehydes and ketones in methylene chloride. The reaction proceeds in high yield and selectivity. Preparation of benzaldehyde (98% yield) from benzyl alcohol on a 200 mmol scale can be performed without modification of the procedure such as slow addition of the oxidant or cooling to 0 °C, and catalyst turnovers of 700 are achieved. Oxidation of geraniol which contains an isolated trisubstituted CC bond leads to geranial selectively without oxidation of the CC bond. Results from Hammett correlation studies (ρ = −0.47) and primary kinetic isotope effect (kH/kD = 4.8) for the catalytic benzyl alcohol oxidations are inconsistent with an oxoruthenium (ORu) based mechanism. A mechanism involving reactive tBuO•/tBuOO• radicals is also excluded based on results from previo...
78 citations
TL;DR: In this paper, the reaction between isoprene and Cl atoms yields mainly HCl, formyl chloride, formic acid, methylglyoxal (pyruvic aldehyde), CO and CO2.
Abstract: The reactions of isoprene, MBO (2-methyl-3-buten-2-ol) and toluene with chlorine atoms have been studied at 298 ± 5 K and 740 ± 5 Torr with the use of FTIR spectroscopy. Major products of the isoprene-Cl reaction and of the MBO-Cl reaction have been identified and quantified, and reaction mechanisms have been tentatively proposed in order to explain the products formed. The reaction between isoprene and Cl atoms yields mainly HCl, formyl chloride, formic acid, methylglyoxal (pyruvic aldehyde), CO and CO2, while the MBO-Cl reaction forms acetone, HCl, formyl chloride, formic acid, CO, CO2. As products from the reaction between toluene and Cl we identified and quantified HCl and benzaldehyde. The rate constants for the reactions of isoprene and toluene with Cl atoms have also been determined using a relative rate method. The measured values are: kisoprene = (5.5 ± 1.0) × 10−10 cm3 molecule−1 s−1 and ktoluene = (5.6 ± 1.3) × 10−11 cm3 molecule−1 s−1. Atmospheric lifetimes have been estimated from these values.
TL;DR: In this article, the catalytic behavior of CeO2 in the reduction of benzoic acid has been studied in the temperature range 523-723 K. Two types of catalytic behaviour are observed in the whole temperature range.
Abstract: Catalytic behaviour of CeO2 in the reduction of benzoic acid has been studied in the temperature range 523–723 K. Two types of catalytic behaviour are observed in the whole temperature range. One type is observed from 523 up to 723 K. In this range, the selectivity to benzaldehyde can be higher than 95% and the reaction proceeds by the redox (Mars and van Krevelen) mechanism, with the oxygen vacancy as the active site. The activity is controlled by the steady-state concentration of oxygen vacancies under reaction conditions. The second type behaviour is observed above 648 K. Under these conditions the conversion of benzoic acid achieves nearly 100%, but the selectivity to benzaldehyde decreases, while that to toluene and benzene increases. In this range of temperatures, the reaction proceeds too far, due to a very high concentration of vacancies. Besides the redox mechanism decar☐ylation (hydrogenolysis) of the relative stable adsorbed benzoic acid takes place. The results observed with the reaction of adsorbed benzoic acid, under a flow of H2 reflects the two types of reaction. The potential promotion effects by Al, Cr, Mn, Fe, Ga, Zr, In and Pb oxides added to CeO2 were investigated. The catalytic behaviour of CeO2 changes by the addition of the metal oxides, positive effects are observed after adding Mn, Zr, In and Pb oxides.
TL;DR: In the presence of small amounts (0.002−0.3 M) of protic additives (alcohols, phenol, carboxylic acids), the sulfoxide becomes the main product in benzene also as discussed by the authors.
Abstract: Singlet oxygen adds to benzyl ethyl sulfide (5, total quenching rate ca. 1 × 107 M-1 s-1, little dependent on the solvent) to ultimately give benzaldehyde (6) and a small amount of the sulfone (8) in aprotic media (rate of the chemical reaction in benzene 5.5 × 106 M-1 s-1) and mainly the sulfoxide (7) in protic media (1.1 × 107 M-1 s-1 in methanol). In the presence of small amounts (0.002−0.3 M) of protic additives (alcohols, phenol, carboxylic acids), the sulfoxide becomes the main product in benzene also. Various evidence support the formation of two intermediates in aprotic solvents. The first one is an exciplex or a syn persulfoxide. It undergoes intramolecular hydrogen abstraction to give a ylide and finally benzaldehyde. Such rearrangement is either a concerted or a radicalic process and not a proton transfer (as indicated by the deuterium effect observed with the α-d benzyl sulfide and the occurrence of the process with the p-nitro and p-methoxy derivatives, 5‘ and 5‘ ‘). This intermediate is not ...
TL;DR: New chiral monoaza-15-crown-5 derivatives and lariat ethers anellated to phenyl β-D-glucoside have been synthesized which show significant asymmetric induction as phase transfer catalysts as discussed by the authors.
TL;DR: A number of new chiral monoaza-15-crown-5 derivatives (4, 9 ) and lariat ethers ( 10, 15 ) anellated to phenyl-β-D-glucopyranoside have been synthesized.
TL;DR: The trichlorosilyl enolates of cyclopentanone and cycloheptanone were prepared by a mercury(II)-catalyzed metathesis from their TMS enol ethers in good yield as mentioned in this paper.
TL;DR: In this article, the effects of pulse peak power, pulse on time, duty cycle, and monomer pressure on film composition, especially aldehyde functional groups, and surface polarity are examined.
Abstract: Pulsed plasma polymerization of benzaldehyde is used to produce thin films containing aldehyde functional groups. The effects of pulse peak power, pulse-on time, duty cycle, and monomer pressure on film composition, especially aldehyde functional groups, and surface polarity are examined. Film properties are determined using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurements, and scanning electron microscopy (SEM). Analysis using these techniques shows retention of the aromatic structure occurs with the longest off times and smallest duty cycles while retention of the aldehyde group occurs only under plasma conditions that result in fragmentation of the aromatic ring, higher peak pulse power, and a relatively large duty cycle (20%).
TL;DR: In the case of benzyl chloride, triphase conditions resulted in the ring hydroxylation forming p-hydroxyl and o-hydroxy benzyl derivatives (75%) (para:ortho ratio 85:15) along with side-chain oxyfunctionalization followed by HCl removal directly forming benzaldehyde as mentioned in this paper.
TL;DR: In this paper, two solid support (SS) versions of tetrahydroquinoline synthesis based on the three component condensation reaction of aldehydes, anilines, and electron-rich olefins catalyzed by trifluoroacetic acid were described.
TL;DR: In this paper, N -Boc-4,4-dimethyl-1,3-oxazolidine with s -BuLi and the following reaction with benzaldehyde was carried out in the presence of (−)-sparteine.
Abstract: Lithiation of N -Boc-4,4-dimethyl-1,3-oxazolidine with s -BuLi and the following reaction with benzaldehyde was carried out in the presence of (−)-sparteine. The reaction was not diastereoselective ( syn : anti =46:54), but each isomer of the adducts was obtained enantioselectively ( syn : 90% ee, anti : 88% ee). Addition of MgBr 2 to the reaction mixture increased the diastereoselectivity to syn : anti =90:10.
TL;DR: In this article, the authors studied the kinetics of the reaction of the lithium enolate of p-(phenylsulfonyl)isobutyrophenone and benzaldehyde in THF by monitoring the disappearance of LiSIBP.
Abstract: The lithium enolate of isobutyrophenone reacts with two molecules of benzaldehyde at room temperature in THF to yield after protonation a 1,3-diol monoester. The kinetics of this process was studied for the reaction of the lithium enolate of p-(phenylsulfonyl)isobutyrophenone (LiSIBP) and benzaldehyde in THF by monitoring the disappearance of LiSIBP. The observed rates obey the rate law −d[{LiSIBP}]/dt = kob[{LiSIBP}]0.83[benzaldehyde]2.0 (braces denote initial formal concentration of LiSIBP) and exhibit a kinetic isotope effect kH/kD = 2.0 (determined from independent experiments using benzaldehyde-d). These results and competitive isotope effect experiments are consistent with formation of an initial lithium aldolate (P1), followed by reaction with a second aldehyde to form a ketal (P2), and finally a rate-limiting intramolecular hydride transfer (Tishchenko reaction). These reactions are modeled with ab initio molecular orbital calculations. Corresponding theoretical kinetic and equilibrium isotope eff...
TL;DR: In this paper, pyridyl-and biparidyl alcohols were obtained and their catalytic role in the reaction of diethylzinc with benzaldehyde to give 1-phenyl-1-propanol was studied.
Abstract: New chiral ligands, pyridyl- and bipyridylalcohols, were prepared and their catalytic role in the reaction of diethylzinc with benzaldehyde to give 1-phenyl-1-propanol was studied. In several cases, the yields approach 100%, and ee-values of up to 86% are observed.
TL;DR: In this article, a combined study of the product distribution present in the liquid phase (di- and triarylmethanes together with N-benzylated byproducts in the case of dimethylaniline) as well as the organic material entrapped inside the zeolite micropores (triphenylmethane or trityl ions) has established that there is a direct relationship between the reactivity of the arene and the conversion of benzaldehyde, percentage of diaryl methanes in liquid phase and population of trityls c
Abstract: Condensation of benzene, anisole and N,N-dimethylaniline with benzaldehyde has been carried out in the presence of a USY zeolite (Si/Al 17.5). A combined study of the product distribution present in the liquid phase (di- and triarylmethanes together with N-benzylated byproducts in the case of dimethylaniline) as well as the organic material entrapped inside the zeolite micropores (triphenylmethane or trityl ions) has established that there is a direct relationship between the reactivity of the arene and the conversion of benzaldehyde, percentage of diarylmethanes in the liquid phase and population of trityl cations. A hydride transfer from triarylmethanes to diarylmethyl cation intermediates has been proposed as a key step for the simultaneous presence of trityl cations adsorbed in the solid and diarylmethanes in the liquid phase.
TL;DR: In this paper, the self-condensation of benzaldehyde to benzyl benzoate was carried out over KF-loaded alumina, and the catalytic activity strongly depends on the loading amount of KF.
Abstract: The self-condensation of benzaldehyde to benzyl benzoate was carried out over KF-loaded alumina. The catalytic activity strongly depends on the loading amount of KF. The pretreatment of the catalyst at high temperature under vacuum is essential for the high catalytic activity. When KF (5 mmol/g-alumina) loaded alumina was evacuated at 673 K, the catalyst gave selectively benzyl benzoate, whose yield was 94.2% in 3 h at 323 K.
TL;DR: The perhalogenated porphyrin ruthenium complex (TFPPCl 8 )Ru(CO) as discussed by the authors catalyzes aerobic oxidation of olefins at room temperature.
TL;DR: Palladium-catalyzed allylation of carbonyls (1.1 − 1.5 mmol) with allylic esters 3a-d (1 mmol) in the presence of Pd(PPh 3 ) 4 (0.05 mmol) and Et 2 Zn (2.4 mmol) at room temperature shows marked carbonyl-dependent regioselectivity.
TL;DR: α,β,γ-disubstituted allylzincs with alkoxycarbonyl as the β-substituent, generated via an umpolung of in situ generated π-allylpalladium by transmetallation with diethylzINC, react with benzaldehyde at the most substituted allylic terminus to provide syn-γ-butyrolactones 4 exclusively, while those with electron-donating Me, i-Pr, or OMOM as βsubstitituents react at both allylic
TL;DR: In this article, a cycloaddition of 2- o -methoxyphenyl-5-methoxyoxazole with benzaldehyde, m - and p - substituted benzaldehydes in the presence of 30 mol% of (R )-methylaluminum β-binaphthoxide, which was prepared from ( R )-2,2′-dihydroxy-1,1′-dinaphthyl and 1.1 -1.05 equiv.
TL;DR: In this paper, a trimethylsilylcyanated benzaldehyde has been used with a catalyst prepared in situ from titanium tetraisopropoxide and chiral Schiff bases.
Abstract: Benzaldehyde has been trimethylsilylcyanated with a catalyst prepared in situ from titanium tetraisopropoxide and chiral Schiff bases. Cyanohydrin is obtained in high optical yield (up to 67.5%).
TL;DR: Chiral ferrocenyl amino alcohols possessing either OH or NR 2 functionality α to the ring were prepared and exhibit modest enantioselectivities for the addition of diethylzinc to benzaldehyde.
Abstract: Chiral ferrocenyl aminoalcohols possessing either OH or NR 2 functionality α to the ferrocenyl ring were prepared and exhibit modest enantioselectivities for the addition of diethylzinc to benzaldehyde. Chiral ferrocenyl aminonitriles exhibit a facile inversion process in protonic solvents.