Showing papers on "Benzoic acid published in 2012"
TL;DR: A new layered MOF material has been synthesized and used as a highly recyclable heterogeneous catalyst for olefin epoxidation reactions and both high conversion and high selectivity of epoxide products are achieved.
147 citations
TL;DR: The Fe-TiO2 photocatalysts synthesized by a sol-gel method have the mesoporous structure with a narrow pore size distribution, large pore volume and high surface area.
144 citations
TL;DR: Spheres-like coordination polymer architectures in submicro regimes have been synthesized from the hydrothermal reaction of transition metal ions and 3,5-bis(pyridin-3-ylmethylamino)benzoic acid.
Abstract: Spheres-like coordination polymer architectures in submicro regimes have been synthesized from the hydrothermal reaction of transition metal ions and 3,5-bis(pyridin-3-ylmethylamino)benzoic acid (L...
142 citations
TL;DR: Surprisingly, the proposed anion export pump Pdr12p was shown to play an important role in the ability of yeast cells to restore the pHi upon lipophilic (sorbic and benzoic) acid stress, probably through a charge interaction of anion and proton transport.
Abstract: Weak organic acids are naturally occurring compounds that are commercially used as preservatives in the food and beverage industries. They extend the shelf life of food products by inhibiting microbial growth. There are a number of theories that explain the antifungal properties of these weak acids, but the exact mechanism is still unknown. We set out to quantitatively determine the contributions of various mechanisms of antifungal activity of these weak acids, as well as the mechanisms that yeast uses to counteract their effects. We analyzed the effects of four weak organic acids differing in lipophilicity (sorbic, benzoic, propionic, and acetic acids) on growth and intracellular pH (pH(i)) in Saccharomyces cerevisiae. Although lipophilicity of the acids correlated with the rate of acidification of the cytosol, our data confirmed that not initial acidification, but rather the cell's ability to restore pH(i), was a determinant for growth inhibition. This pH(i) recovery in turn depended on the nature of the organic anion. We identified long-term acidification as the major cause of growth inhibition under acetic acid stress. Restoration of pH(i), and consequently growth rate, in the presence of this weak acid required the full activity of the plasma membrane ATPase Pma1p. Surprisingly, the proposed anion export pump Pdr12p was shown to play an important role in the ability of yeast cells to restore the pH(i) upon lipophilic (sorbic and benzoic) acid stress, probably through a charge interaction of anion and proton transport.
138 citations
TL;DR: Here it is reported on a metal-free reduction of CO2 by trialkylsilanes, R3SiH (R = Et, iPr), using stoichiometric amounts of trityl borate [Ph3C][B(C6F5)4].
Abstract: The use of CO2 as a renewable and environmentally friendly C1 source for the synthesis of carboxylic acids and fuels such as methanol and methane is a topic of current interest. The high thermodynamic stability of CO2 clearly calls for highly efficient activation which must be combined with a strong thermodynamic driving force to ensure irreversible fixation. While in the past transition-metal chemistry played a dominant role in CO2 conversion chemistry, [5] recent years have seen the emergence of organocatalytic methods for CO2 reduction. For example N-heterocyclic carbenes have been applied for the nucleophilic activation of CO2, and subsequent reduction of the resulting imidazolium carboxylates by silanes yielded methanol. In addition stoichiometric and catalytic reductions of CO2 have been reported which utilize frustrated Lewis pairs (FLPs) for the activation, and dihydrogen, silanes, or ammonia borane as the hydrogen source. In view of the high electrophilic activity of silyl cations and their complexes with solvents and counteranions, we were intrigued by the possibility of exploiting this extreme reactivity in CO2 activation. Silanes then would be the logical hydrogen source for the reduction and would provide the desired thermodynamic driving force through the formation of siloxanes. Here we report on a metal-free reduction of CO2 by trialkylsilanes, R3SiH (R = Et, iPr), using stoichiometric amounts of trityl borate [Ph3C][B(C6F5)4]. The reduction is fast under ambient conditions, but different products— depending on the applied solvent—are formed. In chlorobenzene (PhCl) either disilylated formic acid 1 or the disilylmethyl oxonium ion 2 is formed, depending on the substituent R at the silane. Simple hydrolysis of these compounds yields formic acid and methanol (Scheme 1). In benzene (PhH), the reaction of CO2 with the preformed silylbenzenium salt [Et3Si(C6H6)][B(C6F5)4] (3[B(C6F5)4]) leads to further functionalization of CO2. [8b] In this case the benzylic cation 4 is formed, which can be easily transformed either by hydrolysis into benzoic acid (PhCO2H, 6), or, by careful deprotonation, into the silylester 5 (Scheme 1). Reaction of triethylsilane with one equivalent of the trityl borate [Ph3C][B(C6F5)4] in benzene yields benzenium ion 3, identified by its characteristic Si NMR resonance at d(Si) = 97.4 ppm (Table 1). Also when PhCl is used as the solvent, cationic complexes [R3Si(PhCl)] + (7) are formed, as indicated by the strongly deshielded Si NMR resonances at d(Si) = 99.9 (R = Et, 7a) and 103.3 ppm (R = iPr, 7b ; Table 1). Based on the results of our quantum mechanical calculations, however, we assign to these complexes the chloronium ion structure 7 rather than the chloroarenium ion structure 8. Scheme 1. Reduction of CO2 by [Ph3C][B(C6F5)4]/R3SiH in different solvents (the B(C6F5)4 anion is omitted, 1a : R = Et, 1b : R = iPr). Conditions: a) 0.1013 MPa CO2, 1 equiv Ph3C , 2 equiv R3SiH, PhCl, room temperature; b) 2 equiv Et3SiH, RT; c) H2O; d) 0.1013 MPa CO2,1 equiv Ph3C , 1 equiv Et3SiH, PhH, room temperature; e) symcollidine, PhH, temperature.
123 citations
TL;DR: In this paper, the antioxidant properties of 14 different benzoic acid derivatives against superoxide radical were determined by Beauchamp and Fridovich methods, and the relationship between structure and antioxidant activity of the compounds was studied.
106 citations
TL;DR: Results of the investigation on the effect of substitution at the azomethine carbon of coordinated hydrazone in these ruthenium chelates on the potential binding with DNA/BSA, free radical scavenging and cytotoxicity is presented.
81 citations
TL;DR: The metabolism of Lu AA21004 was investigated using human liver microsomes, human liver S9 fraction, and recombinant enzymes, and revealed that the rate-limiting step in the formation of the benzoic acid from Lu AA 21004 is theformation of the corresponding alcohol.
Abstract: 1-[2-(2,4-Dimethyl-phenylsulfanyl)-phenyl]-piperazine (Lu AA21004) is a novel antidepressant that is currently in late-stage clinical development for major depressive disorder. In the present study, the metabolism of Lu AA21004 was investigated using human liver microsomes (HLM), human liver S9 fraction, and recombinant enzymes. Lu AA21004 was found in vitro to be oxidized to a 4-hydroxy-phenyl metabolite, a sulfoxide, an N-hydroxylated piperazine, and a benzylic alcohol, which was further oxidized to the corresponding benzoic acid [3-methyl-4-(2-piperazin-1-yl-phenysulfanyl)-benzoic acid (Lu AA34443)]. The formation of the 4-hydroxy-phenyl metabolite was catalyzed by CYP2D6 with some contribution from CYP2C9, whereas the formation of the sulfoxide was mediated by CYP3A4/5 and CYP2A6. CYP2C9 and CYP2C19 were the primary enzymes responsible for formation of the N-hydroxylated metabolite. The benzylic alcohol was formed by CYP2D6 only. The oxidation of the benzylic alcohol to the corresponding benzoic acid of Lu AA21004 was catalyzed by alcohol dehydrogenase and aldehyde dehydrogenase, with some contribution from aldehyde oxidase. CYP2D6 was also capable of catalyzing the formation of the benzoic acid of Lu AA21004; however, its overall contribution to this pathway was negligible. Enzyme kinetic parameters revealed that the rate-limiting step in the formation of the benzoic acid from Lu AA21004 is the formation of the corresponding alcohol. Thus, the intrinsic clearance (V(max)/K(m)) in HLM for metabolism of Lu AA21004 to the benzylic alcohol was 1.13 × 10(-6) l · min(-1) · mg(-1), whereas the subsequent metabolism of the benzylic alcohol to the benzoic acid of Lu AA21004 is characterized by an intrinsic clearance (V(max)/K(m)) in S9 fraction of 922 × 10(-6) l · min(-1) · mg(-1).
76 citations
TL;DR: In this paper, the authors compared the composition and performance of various lignocellulosic biomass hydrolysates as fermentation media, and found that most of the potential inhibitory compounds exhibit little effect at the concentrations detected in hydrolysate.
Abstract: To compare the composition and performance of various lignocellulosic biomass hydrolysates as fermentation media, 8 hydrolysates were generated from a grass-like and a wood biomass. The hydrolysate preparation methods used were 1) dilute acid, 2) mild alkaline, 3) alkaline/peracetic acid, and 4) concentrated acid. These hydrolysates were fermented at 30°C, pH 5.0 using Saccharomyces cerevisiae CEN.PK113-7D as model strain. The growth in different hydrolysates varied in the aspects of lag-phase, growth rate, glucose consumption rate and ethanol production rate. Subsequently, 11 potential inhibitory compounds as described in literature were selected for further analysis. The concentrations of these compounds were determined in the time-samples of the 8 fermentations, using a novel analytical method, ethyl-chloroformate derivatization-GC-MS. Some of these compounds, e.g. furfural, decreased during the fermentation process, while others, such as formic and benzoic acid, remained almost constant. Inhibitory effect analysis of individual compound revealed that most of these compounds exhibit little effect at the concentrations detected in hydrolysates. Only furfural and benzoic acid clearly affected the growth of the model yeast: furfural elongated the lag-phase, while benzoic acid reduced the growth rate and biomass yield.
73 citations
TL;DR: The enzymatic carboxylation of phenol and styrene derivatives using (de)carboxylases in carbonate buffer proceeded in a highly regioselective fashion.
72 citations
TL;DR: In this article, chitosan grafted β-cyclodextrin (CGC) was synthesized using glutaraldehyde as cross-linker in acidic aqueous solution.
TL;DR: In this article, the concept of reactive extraction and effect of various parameters were discussed, which is very useful in the view of complete design of a reactive extraction process for the carboxylic acid production.
Abstract: Since last few decades, there has been a revitalization of attention towards new energy-efficient fermentation technology for large production of fermentation chemicals due to sharp increase in petroleum costs. Carboxylic acid has wide applications in various chemical, food, and pharmaceutical industries. A growing demand for biodegradable polymers, substitutes for both conventional plastic materials and new materials of specific uses such as controlled drug delivery or artificial prostheses, draws attention the need for improvement of conventional processes for carboxylic acids production. Reactive extraction is a multifunctional reactor having reaction and extraction in a single unit. This intensified approach has the closed loop process with sustainability. In present paper, the concept of reactive extraction and effect of various parameters were discussed. These studies are very useful in the view of complete design of a reactive extraction process for the carboxylic acid production. (14),(15), phenyl acetic acid (16), propionic acid (17)-(35), benzoic acid (36), pyridine-3-carboxylic acid (36), levulinic (37), butyric acid (27), (38), glycolic acid (40), itaconic acid (40), gluconic acid (41), etc. Also few reviews are available (42)-(45). In present paper various aspects for the development of reactive extraction process for the recovery of carboxylic acids has been discussed. Physical equilibrium, chemical equilibrium, extraction kinetics, effect of temperature, effect of substrate, effect of salts, effect of pH, back extraction equilibrium and kinetics, regeneration, toxicity, water co-extraction, economical has been analyzed and presented. This paper will be very useful in the context of design of intensifying process for the recovery of carboxylic acid by reactive extraction. The design window of the reactive extraction is shown in Fig. 1.
TL;DR: In this paper, a series of TV-GC-MS experiments on powdered basalt containing known organic compounds (benzoic acid or mellitic acid) at different concentrations (500 and 0.5 ) were described.
TL;DR: In this paper, a cocrystal strategy for the precipitation of liquid 2,3-dimethyl pyrazine (2.3-DMP) with the hydroxyl substituted benzoic acids: salicylic acid (SA), m-hydroxybenzoic acid (MHBA), and p-hydroxylbenzoilic acid (PHBA) under identical conditions, and obtained three cocrystals (cocrystal 1-3), respectively.
Abstract: We here report the cocrystal strategy for the precipitation of liquid 2,3-dimethyl pyrazine (2,3-DMP) with the hydroxyl substituted benzoic acids: salicylic acid (SA), m-hydroxybenzoic acid (MHBA) and p-hydroxybenzoic acid (PHBA) under identical conditions, and obtained three cocrystals (cocrystal 1–3), respectively. Their crystal structures were characterized by single-crystal X-ray diffraction, IR spectra, differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), hot stage microscopy (HSM) and X-ray powder diffraction (XRPD). Wherein, 1 forms a 1 : 2 2,3-DMP : SA cocrystal; 2 forms a 1 : 1 2,3-DMP : MPHA cocrystal and 3 forms a 1 : 1 : 1 2,3-DMP : PHBA : H2O cocrystal. The structure determination shows that the three cocrystals are all primarily stabilized by a strong O–H⋯N hydrogen bonding interaction between 2,3-DMP and the hydroxyl substituted benzoic acid. We also prepared and analysed Hirshfeld surfaces and fingerprint plots of the reported cocrystals and reveal that the structures are stabilized by H⋯H, O–H⋯N, O–H⋯N, C–H⋯π, π⋯π and lone-pair⋯π intermolecular interactions. Additionally, what is interesting is that cocrystal 2 sublimes half the 2,3-DMP at about 110 °C during the heating procedure, while the other half sublimes at about 226 °C, which was confirmed by the XRPD measurement. This may be developed for the controlled release of 2,3-DMP.
TL;DR: Key to high enantioselection is the finding that ortho-iodo benzoic acid salts of the chiral copper(II) bis(oxazoline) catalyst deliver both diastereomers of the Henry adduct with highEnantiomeric excess, homochiral at the oxygen-bearing carbon.
Abstract: α-Oxy amides are prepared through enantioselective synthesis using a sequence beginning with a Henry addition of bromonitromethane to aldehydes and finishing with Umpolung Amide Synthesis (UmAS). Key to high enantioselection is the finding that ortho-iodo benzoic acid salts of the chiral copper(II) bis(oxazoline) catalyst deliver both diastereomers of the Henry adduct with high enantiomeric excess, homochiral at the oxygen-bearing carbon. Overall, this approach to α-oxy amides provides an innovative complement to alternatives that focus almost entirely on the enantioselective synthesis of α-oxy carboxylic acids.
SIDI1
TL;DR: The degradation of 100mL of solution with salicylic acid in the pH range 3.0-10.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a stainless steel cathode by applying a current of 100, 300 and 450 mA at 25°C.
TL;DR: A series of CAPE analogues was synthesized and their antiradical/antioxidant effects analyzed to evaluate the effect of the presence of the double bond and of the conjugated system on the antioxidant effect.
Abstract: Caffeic acid phenethyl ester (CAPE) is a bioactive component isolated from propolis. A series of CAPE analogues was synthesized and their antiradical/antioxidant effects analyzed. The effect of the presence of the double bond and of the conjugated system on the antioxidant effect is evaluated with the analogues obtained from 3-(3,4-dihydroxyphenyl) propanoic acid. Those obtained from 2-(3,4-dihydroxyphenyl) acetic acid and 3,4-dihydroxybenzoic acid allow the evaluation of the effect of the presence of two carbons between the carbonyl and aromatic system.
TL;DR: Experiments show that the main O(2)-incorporation pathway involves the reduction of O( 2) by e(cb)(-) and the subsequent formation of free (⋅)OH via H(2)O(2), which was usually overlooked in the past photocatalytic studies.
Abstract: The hydroxylation process is the primary, and even the rate-determining step of the photocatalytic degradation of aromatic compounds. To make clear the hydroxylation pathway of aromatics, the TiO2 photocatalytic hydroxylation of several model substrates, such as benzoic acid, benzene, nitrobenzene, and benzonitrile, has been studied by an oxygen-isotope-labeling method, which can definitively assign the origin of the O atoms (from oxidant O2 or solvent H2O) in the hydroxyl groups of the hydroxylated products. It is found that the oxygen source of the hydroxylated products depends markedly on the reaction conditions. The percentage of the products with O2-derived hydroxyl O atoms increases with the irradiation time, while it decreases with the increase of substrate concentration. More intriguingly, when photogenerated valence-band holes (hvb+) are removed, nearly all the O atoms (>97 %) in the hydroxyl groups of the hydroxylated products of benzoic acid come from O2, whereas the scavenging of conduction-band electrons (ecb−) makes almost all the hydroxyl O atoms (>95 %) originate from solvent H2O. In the photocatalytic oxidation system with benzoic acid and benzene coexisting in the same dispersion, the percentage of O2-derived hydroxyl O atoms in the hydroxylated products of strongly adsorbed benzoic acid (ca. 30 %) is much less than in that of weakly adsorbed benzene (phenol) (>60 %). Such dependences provide unique clues to uncover the photocatalytic hydroxylation pathway. Our experiments show that the main O2-incorporation pathway involves the reduction of O2 by ecb− and the subsequent formation of free .OH via H2O2, which was usually overlooked in the past photocatalytic studies. Moreover, in the hydroxylation initiated by hvb+, unlike the conventional mechanism, the O atom in O2 cannot incorporate into the product through the direct coupling between molecular O2 and the substrate-based radicals.
TL;DR: A series of hydroxybenzoic acid derivatives have shown inhibitory activity against carbonic anhydrase, and the binding mode observed for these molecules is distinct when compared to other non-metal-binding CA inhibitors.
TL;DR: Tunneling effects have been measured in the pulsed jet Fourier transform microwave spectra of two isotopologues of the benzoic acid-formic acid bimolecule and it has been possible to model/size the barrier to the concerted double proton transfer.
Abstract: Tunneling effects have been measured in the pulsed jet Fourier transform microwave spectra of two isotopologues of the benzoic acid–formic acid bimolecule. The tunneling splittings are originated by the concerted proton transfer of the two carboxylic hydrogens. From the values of these splittings for the OH–OH and OD–OD species, it has been possible to model/size the barrier to the concerted double proton transfer.
TL;DR: Experimental crystal structures of mono and polyfluorinated benzoic acids correspond to high energy computed crystal structure of benzosic acid itself, thereby permitting access to its structural landscape.
TL;DR: The results indicated that the proposed method was effective for the separation of mixtures of organic acids in the three traditional Chinese medicine samples.
TL;DR: In this paper, the mechanisms of benzyl alcohol oxidation on a gold surface covered with atomic oxygen are elucidated; the results show direct correspondence to the reaction on gold-based catalysts.
TL;DR: In this article, the effect of three alkali metal dopants on the photocatalytic properties of zinc oxide (ZnO) was investigated, and the results showed that doping ZnO with lithium, sodium and potassium increases the crystallinity of powders and reduces band gap energy.
09 Apr 2012
TL;DR: New 4-(2-cyanoacetamido)benzoic acid (1) was utilized as key intermediate for the synthesis of some new thiazole, pyrazole, oxazole, pyrimidine, 1,3-dithiolane, thiophene, coumarin, oxazine and pyridazine derivatives as mentioned in this paper.
Abstract: New 4-(2-cyanoacetamido)benzoic acid (1) was utilized as key intermediate for the synthesis of some new thiazole, pyrazole, oxazole, pyrimidine, 1,3-dithiolane, thiophene, coumarin, oxazine and pyridazine derivatives. Newly synthesized compounds were characterized by elemental analyses and spectral data (IR, 1 H NMR and mass spectra).
TL;DR: In this paper, tridentate chelating hydrazone Schiff bases benzoic acid (2-hydroxyl-benzylidene)-hydrazide (H2L) (1) obtained from salicylaldehyde and benzhydrazides with [NiCl2(PPh3)2] and [CoCl 2(Pph3)3) 2] afforded respective metal hyrazone complexes of the composition.
Abstract: Reactions of tridentate chelating hydrazone Schiff bases benzoic acid (2-hydroxyl-benzylidene)-hydrazide (H2L) (1) obtained from salicylaldehyde and benzhydrazide with [NiCl2(PPh3)2] and [CoCl2(PPh3)2] afforded respective metal hydrazone complexes of the composition [Ni(L)(PPh3)] (2) and [Co1(L)2]2[Co2(H2O)4(OPPh3)2] (3). The molecular structure of both complexes 2 and 3 determined by single crystal X-ray diffraction revealed that complex 2 is neutral in charge with distorted square planar geometry. However, complex 3 was found to have distorted octahedral geometry. All of the synthesised compounds 1–3 were studied by interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA). In addition in vitro free radical scavenging and cytotoxic potential of all the synthesised compounds were also investigated.
TL;DR: The anatase TiO 2 nanorods capped by oleic acid with the length of 30-50nm and diameter of approximately 4-5nm were prepared by a facile two-phase hydrothermal method as discussed by the authors.
TL;DR: The extent of acyl glucuronidation was reduced through structural optimization of both the carboxylic acid and amide substituents, coupled with a reduction in lipophilicity leading to an overall increase in metabolic stability.
Abstract: Inhibition of 11β-HSD1 is viewed as a potential target for the treatment of obesity and other elements of the metabolic syndrome. We report here the optimization of a carboxylic acid class of inhibitors from AZD4017 (1) to the development candidate AZD8329 (27). A structural change from pyridine to pyrazole together with structural optimization led to an improved technical profile in terms of both solubility and pharmacokinetics. The extent of acyl glucuronidation was reduced through structural optimization of both the carboxylic acid and amide substituents, coupled with a reduction in lipophilicity leading to an overall increase in metabolic stability.
TL;DR: The structure of a mechanochemically synthesized cocrystal containing theophylline (TP) and benzoic acid (BA) has been determined from powder X-ray diffraction data as discussed by the authors.
Abstract: The structure of a mechanochemically synthesised cocrystal containing theophylline (TP) and benzoic acid (BA) has been determined from powder X-ray diffraction data
TL;DR: In this paper, the distribution of hydroxylation products when different photocatalysts were used and to correlate the selectivity to some physico-chemical features of the powders.
Abstract: The hydroxylation of phenol (a substrate containing an electron donor group) and of benzoic acid (a substrate containing an electron withdrawing group) has been carried out by the photocatalytic method in aqueous suspensions containing commercial or home prepared TiO2 samples. The aim of the work was to study the distribution of hydroxylation products when different photocatalysts were used and to correlate the selectivity to some physico-chemical features of the powders. The samples were characterized by X-ray diffraction, thermogravimetry, determination of crystalline phase percentage, specific surface area and zero charge point. The photoreactivity results indicate that the products of the primary oxidation of phenol are the ortho- and para-mono-hydroxy derivatives while those of benzoic acid are all the mono-hydroxy derivatives independently of the catalyst. The selectivity toward mono-hydroxy derivatives shows a strong dependence on catalyst hydroxylation and crystallinity degrees: the highest selectivity values were obtained by using the commercial samples that resulted the least hydroxylated and the most crystalline ones. A kinetic model, taking into account the mineralization and the partial oxidation reaction routes, is proposed by using the Langmuir–Hinshelwood model.