Search results for "Benzaldehyde"
showing 10 items of 112 documents
A Colorimetric Probe for the Selective Detection of Norepinephrine Based on a Double Molecular Recognition with Functionalized Gold Nanoparticles
2019
[EN] A simple colorimetric probe for the selective and sensitive detection of neurotransmitter norepinephrine (NE), an important biomarker in the detection of tumors such as pheochromocytoma and paraganglioma, is described. The sensing strategy is based on the use of spherical gold nanoparticles functionalized with benzaldehyde and boronic acid-terminated moieties. A double molecular recognition involving on one hand the aromatic aldehyde and the aminoalcohol group of NE, and on the other hand the boronic acid and the catechol moiety of the neurotransmitter, results in analyte triggered aggregation of the gold nanoparticles, leading to a bathochromic shift of the SPR band in the UV-vis spec…
Gas-phase selective oxidation of chloro- and methoxy-substituted toluenes on TiO2–Sepiolite supported vanadium oxides
2009
Abstract Catalytic behaviour of vanadium oxide systems (5–20 wt.% V2O5) supported on TiO2–Sepiolite (with titania loading around the theoretical monolayer, 12 wt.%, 12Ti–Sep) and, as reference, on Sepiolite calcined (Sepc) in the p-substituted toluene derivatives selective oxidation was studied. In all the catalysts studied p-chloro (p-ClBA) and p-methoxybenzaldehyde (p-MeOBA) were the main products. The yields to benzaldehydes obtained with %V/12Ti–Sep are comparable with some of those reported in the literature under similar kinetically controlled experimental conditions (Sp-ClBA = 70% and X = 19% were obtained at 653 K on 20 V/12Ti–Sep). The activity for benzaldehyde derivatives formatio…
Synthesis of large-pore ordered mesoporous silicas containing aminopropyl groups
2005
Ordered mesoporous silicas with large-pore diameters incorporating aminopropyl groups in variable quantity have been synthesized via the co-condensation of tetraethyl orthosilicate (TEOS) and 3-tert-butyloxycarbonylaminopropyltriethoxysilane templated with nonionic surfactant P123 under acidic conditions. The deprotection of amino groups was then quantitatively achieved either by thermal treatment or acid hydrolysis followed by Et3N treatment, both routes leading to exactly the same materials. We showed that the free amino centers are fully accessible, by using the condensation of the amine function with benzaldehyde.
A statistical study of the additivity of substituent effects on the5J(HH) long-range coupling constant of the formyl proton in substituted benzaldehy…
1982
The additivity of chloro and hydroxy substituent effects on the formyl proton spin-spin coupling constants with the meta ring proton, 5J(HH), has been tested with 15 chlorinated benzaldehydes and hydroxybenzaldehydes by multiple linear regression analysis. No general additivity rule was detected with whole data. Using benzaldehyde as the reference substance, a good correlation was achieved for p-hydroxybenzaldehydes. The same reference compound was not suitable for o-hydroxy derivatives; a much better correlation was observed using o-hydroxybenzaldehyde as a reference compound in the latter case.
Azolium and acetate ions in DMF: Formation of free N-heterocyclic carbene. A voltammetric analysis
2016
In order to reveal the possible formation of free N-heterocyclic carbene (NHC) in DMF-azolium and acetate solutions, the proton exchange equilibrium between azolium cations and CH3COO− was investigated (by cyclic voltammetry) by adding CH3COOH or tetrabutylammonium acetate to DMF solutions of imidazolium or thiazolium salts of different acidity.The voltammetric analysis confirms that the deprotonation of the azolium cation by CH3COO− (with the formation of free NHC) is significant in the case of the more acidic thiazolium cations, while it is not effective with the less acidic imidazolium ones.Accordingly, the NHC-catalyzed benzoin condensation was carried out in DMF solutions of azolium sa…
Determination of atranol and chloroatranol in perfumes using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas…
2013
Abstract A new analytical method based on simultaneous derivatization and dispersive liquid–liquid microextraction (DLLME) followed by gas chromatography–mass spectrometry (GC–MS), for the determination of the allergenic compounds atranol and chloroatranol in perfumes, is presented. Derivatization of the target analytes by means of acetylation with anhydride acetic in carbonate buffer was carried out. Thereby volatility and detectability were increased for improved GC–MS sensitivity. In addition, extractability by DLLME was also enhanced due to a less polar character of the solutes. A liquid–liquid extraction was performed before DLLME to clean up the sample and to obtain an aqueous sample …
The catalytic effects of a thiazolium salt in the oxa-Diels–Alder reaction between benzaldehyde and Danishefsky's diene: a molecular electron density…
2021
The oxa-Diels–Alder (ODA) reaction of benzaldehyde with Danishefsky's diene in the presence of a [thiazolium][Cl] salt, as a model of an ionic liquid, has been studied within Molecular Electron Density Theory (MEDT) at the M06-2X/6-311G(d,p) computational level. The formation of two hydrogen bonds (HBs) between the thiazolium cation and the carbonyl oxygen of benzaldehyde modifies neither the electrophilic character of benzaldehyde nor its electronic structure substantially but accelerates the reaction considerably. This ODA reaction presents an activation energy of 4.5 kcal mol−1; the formation of the only observed dihydropyranone is strongly exothermic by −28.8 kcal mol−1. The presence of…
Preparation of fouling resistant and highly perm-selective novel PSf/GO-vanillin nanofiltration membrane for efficient water purification
2022
International audience; To meet the rising global demand for water, it is necessary to develop membranes capable of efficiently purifying contaminated water sources. Herein, we report a series of novel polysulfone (PSf)/GO-vanillin nanofiltration membranes highly permeable, selective, and fouling resistant. The membranes are composed of two-dimensional (2D) graphite oxide (GO) layers embedded with vanillin as porogen and PSf as the base polymer. There is a growing interest in addressing the synergistic effect of GO and vanillin on improving the permeability and antifouling characteristics of membranes. Various spectroscopic and microscopic techniques were used to perform detailed physicoche…
Degradation of dimeric lignin model compounds by aerobic bacteria isolated from the hindgut of xylophagous termites.
1997
The capability of the intestinal flora from the gut of xylophagous termites of degrading lignin model compounds was investigated. Different dimeric lignin model compounds-degrading bacteria were obtained from the hindgut flora of Mastotermes darwiniensis FROGGATT, Reticulitermes santonensis FEYTAUD, Nasutitermes nigriceps HALDEMAN and Zootermopsis angusticollis HAGEN. In the presence of oxygen dimeric model compounds were degraded by all isolates. This indicates that the hindgut flora of termites is basically able to produce substrate for their host from aromatic extractives of wood.
Green and Direct Synthesis of Benzaldehyde and Benzyl Benzoate in One Pot
2018
High yields of valued benzaldehyde and benzyl benzoate are obtained in one pot starting from benzyl alcohol using oxygen as only oxidant under mild conditions (2 bar O2, 100 °C) along with an ultralow amount (0.02 mol %) of Au nanoparticles heterogenized over a spherical ORMOSIL mesoporous support. The process is remarkably selective and the catalyst is stable.