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Aromatic Acids (aromatic + acid)
Selected AbstractsSynthesis of Azo Aromatic Diacyl Chlorides from Nitro Aromatic Acids.CHEMINFORM, Issue 29 2006Chuan-Xi Xiong Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Hybrid silica monolithic column for capillary electrochromatography with enhanced cathodic electroosmotic flowELECTROPHORESIS, Issue 21 2006Jiwei Hu Abstract A hybrid silica monolithic stationary phase for RP CEC was prepared by in,situ co-condensation of (3-mercaptopropyl)-trimethoxysilane (MPTMS), phenyltriethoxysilane (PTES), and tetraethoxysilane (TEOS) via a sol,gel process. The thiol groups on the surface of the stationary phase were oxidized to sulfonic acids by peroxytrifluoroacetic acid. The introduced sulfonic acid moieties on the monoliths were characterized by a strong and relatively stable EOF in a broad pH range from 2.35 to 7.0 in CEC. Aromatic acids and neutral compounds can be simultaneously separated in this column under cathodic EOF. The CEC column exhibited a typical RP chromatographic mechanism for neutral compounds due to the introduced phenyl groups. [source] Sorption and leaching behaviour of polar aromatic acids in agricultural soils by batch and column leaching testsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2005R. Celis Summary Aromatic acids can reach the soil from direct anthropogenic activities or, indirectly, from the degradation of many aromatic compounds, such as pesticides or polycyclic aromatic hydrocarbons. Because of the anionic character of aromatic acids at the pH of most soil and sediment environments, they are expected to move rapidly through the soil profile and to pose a great risk of ground water contamination. We designed batch and column leaching tests to characterize the behaviour of three aromatic acids differing in their chemical structures, picloram (4-amino-3,5,6-trichloropicolinic acid), phthalic acid (2,2-benzenedicarboxylic acid), and salicylic acid (2-hydroxybenzoic acid), in four European soils with different physicochemical characteristics. Batch experiments revealed that the persistence of the three acids in soil:water suspensions decreased in the order: picloram , phthalic acid > salicylic acid, and their dissipation curves were relatively independent of soil type. Sorption by the soils, their clay-size fractions and model sorbents indicated much greater affinity of soil constituents for salicylic acid than for picloram or phthalic acid, most likely due to the ability of salicylic acid to form bidentate complexes with positively charged soil components. The extent of leaching of the aromatic acids in hand-packed soil columns decreased in the order: picloram (90,96%) > phthalic acid (25,90%) > salicylic acid (0,37%), which was consistent with the sorption and persistence results of the batch tests. The organic C content, the amount of small-size pores, and the initial concentration of aromatic acid in soil appeared to be important factors influencing the leaching patterns of phthalic acid and salicylic acid in the soils studied, but did not greatly influence the leaching pattern of picloram. Sorption and leaching of polar aromatic acids in soil can therefore vary considerably depending on the structural characteristics of the aromatic acid or soil type. [source] Crataegus tanacetifolia leaf extract prevents L-NAME-induced hypertension in rats: a morphological studyPHYTOTHERAPY RESEARCH, Issue 1 2006Z. Çelebi Koçyőldőz Abstract Crataegus (hawthorn) has long been used as a folk medicine all around the world. Most of the studies with Crataegus species focus on effects on heart failure and cardiovascular disease. The pharmacological effects of Crataegus have been attributed mainly to the content of flavonoids, procyanidin, aromatic acid and cardiotonic amines. The present study investigated the blood pressure and the structure of the coronary arterial wall of L-NAME-induced hypertensive rats given an aqueous leaf extract of C. tanacetifolia (100 mg/kg), for 4 weeks via gavage. It was observed that C. tanacetifolia, especially the hyperoside fraction, prevented L-NAME-induced hypertension in rats and had beneficial effects on the cardiovascular system. Copyright © 2006 John Wiley & Sons, Ltd. [source] Application of CE with novel dynamic coatings and field-amplified sample injection to the sensitive determination of isomeric benzoic acids in atmospheric aerosols and vehicular emissionELECTROPHORESIS, Issue 19 2007Ewa Dabek-Zlotorzynska Dr. Abstract A simple and reliable CE method with direct UV detection has been developed to separate eight isomeric benzoic acids in atmospheric aerosols and vehicular emission without complex sample pretreatment. Optimal electrophoretic conditions, with migration times under 5,min, were obtained by using a 50,mM acetate buffer (pH,4.7) containing a dynamic surface coating EOTrolÔ LN (0.005% w/v). The separations were carried out in a cathode to anode direction (,30,kV) allowing the low cathodal EOF (,1×10,9,m2V,1s,1) to extend the effective separation by slowing the movement of the studied aromatic acids. Moreover, the sensitivity of the method at 200,nm was enhanced by using a field-amplified sample injection (FASI) with electrokinetic (EK) sample injection (,2,kV, 60,s). Prior to sample injection, a short water plug (3,s at 0.5,psi) was introduced. Under these conditions, the method was capable of detecting the analytes in deionized water with LODs (S/N,=,3) as low as 0.1,,g/L for most of the studied acids. In the presence of 10,mg/L of sulphate (added to simulate a sample matrix), LODs ranged from 0.26 to 0.62,,g/L. The validation of the method has proven an excellent separation performance and accuracy for the determination of isomeric benzoic acids in the studied matrices. [source] Capillary electrochromatography with zwitterionic stationary phase on the lysine-bonded poly(glycidyl methacrylate- co -ethylene dimethacrylate) monolithic capillary columnELECTROPHORESIS, Issue 12 2006Xiaoli Dong Abstract A polymer-based neutral monolithic capillary column was prepared by radical polymerization of glycidyl methacrylate and ethylene dimethacrylate in a 100,,m id fused-silica capillary, and the prepared monolithic column was subsequently modified based on a ring opening reaction of epoxide groups with 1,M,lysine in solution (pH,8.0) at 75°C for 10,h to produce a lysine chemically bonded stationary phases in capillary column. The ring opening reaction conditions were optimized so that the column could generate substantial EOF. Due to the zwitterionic functional groups of the lysine covalently bonded on the polymer monolithic rod, the prepared column can generate cathodic and anodic EOF by varying the pH values of running buffer during CEC separation. EOF reached the maximum of ,2.0×10,8,m2v,1s,1 and 2.6×10,8,m2v,1s,1 with pH of the running buffer of 2.25 and 10, respectively. As a consequence, neutral compounds, ionic solutes such as phenols, aromatic acids, anilines, and basic pharmaceuticals were all successfully separated on the column by CEC. Hydrophobic interaction is responsible for separation of neutral analytes. In addition, the electrostatic and hydrophobic interaction and the electrophoretic migration play a significant role in separation of the ionic or ionizable analytes. [source] Sorption and leaching behaviour of polar aromatic acids in agricultural soils by batch and column leaching testsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2005R. Celis Summary Aromatic acids can reach the soil from direct anthropogenic activities or, indirectly, from the degradation of many aromatic compounds, such as pesticides or polycyclic aromatic hydrocarbons. Because of the anionic character of aromatic acids at the pH of most soil and sediment environments, they are expected to move rapidly through the soil profile and to pose a great risk of ground water contamination. We designed batch and column leaching tests to characterize the behaviour of three aromatic acids differing in their chemical structures, picloram (4-amino-3,5,6-trichloropicolinic acid), phthalic acid (2,2-benzenedicarboxylic acid), and salicylic acid (2-hydroxybenzoic acid), in four European soils with different physicochemical characteristics. Batch experiments revealed that the persistence of the three acids in soil:water suspensions decreased in the order: picloram , phthalic acid > salicylic acid, and their dissipation curves were relatively independent of soil type. Sorption by the soils, their clay-size fractions and model sorbents indicated much greater affinity of soil constituents for salicylic acid than for picloram or phthalic acid, most likely due to the ability of salicylic acid to form bidentate complexes with positively charged soil components. The extent of leaching of the aromatic acids in hand-packed soil columns decreased in the order: picloram (90,96%) > phthalic acid (25,90%) > salicylic acid (0,37%), which was consistent with the sorption and persistence results of the batch tests. The organic C content, the amount of small-size pores, and the initial concentration of aromatic acid in soil appeared to be important factors influencing the leaching patterns of phthalic acid and salicylic acid in the soils studied, but did not greatly influence the leaching pattern of picloram. Sorption and leaching of polar aromatic acids in soil can therefore vary considerably depending on the structural characteristics of the aromatic acid or soil type. [source] Utilization of oligo- and polysaccharides at microgram-per-litre levels in freshwater by Flavobacterium johnsoniaeJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2010E.L.W. Sack Abstract Aims:, To obtain a bacterial strain that can be used to quantify biodegradable polysaccharides at concentrations of a few micrograms per litre in freshwater. Methods and Results:,Flavobacterium johnsoniae strain A3 was isolated from tap water supplemented with laminarin, pectin or amylopectin at 100 ,g C l,1 and river Rhine water. The organism utilized 14 of 23 oligo- and polysaccharides, and 1 of 9 monosaccharides, but none of the sugar acids, sugar alcohols, carboxylic acids or aromatic acids tested at 10 ,g C l,1. Amino acids promoted growth of strain A3, but not in coculture with assimilable organic carbon (AOC) test strain Pseudomonas fluorescens P17, which utilized these compounds more rapidly than strain A3. Compounds released by strain P17 and AOC test strain Spirillum sp. NOX grown on acetate promoted the growth of strain A3 at Nmax values of , 2 × 105 CFU ml,1 of strain P17 and , 5 × 105 CFU ml,1 of strain NOX. Significant growth of strain A3 was observed in surface water and in tap water in the presence of strain P17 (Nmax P17 < 2 × 105 CFU ml,1). Conclusions:, Strain A3 utilizes oligo- and polysaccharides at microgram-per-litre levels. In surface water and in tap water, the organism was able to utilize compounds that were not utilized by strain P17. These compounds may include oligo- and/or polysaccharides. Significance and Impact of the Study:, Phytoplanktonic and bacterial polysaccharides can constitute an important biodegradable fraction of natural organic matter in water and may promote growth of heterotrophic bacteria during water treatment and drinking water distribution. Strain A3 can be used to quantify a group of compounds that includes oligo- and polysaccharides at microgram-per-litre levels in freshwater. [source] Capillary electrophoresis determinative and GC-MS confirmatory method for water-soluble organic acids in airborne particulate matter and vehicle emissionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2005Ewa Dabek-Zlotorzynska Abstract Urban fine airborne particulate matter (PM2.5) and vehicle emission samples were studied for water-soluble low-molecular-weight carboxylic acids using CE with indirect UV detection. Further identification of these acids was achieved using GC-MS as their butyl esters (after derivatization with BF3/butanol). Several dicarboxylic acids in the range C2,C10 including straight-chain, branched-chain, cis - and trans -unsaturated, and aromatic acids were confirmed by GC-MS. In addition, aromatic acids such as benzoate, phthalate, terephthalate, isophthalate, and 4-methylphtalate were present in such samples, but some of these were not well resolved by the used CE method. Oxocarboxylic acids (Cwn with n > 4) were also identified by GC-MS but not determined by CE due to lack of standards. The rapidity and simplicity of the CE method were clearly demonstrated, and the method was observed to be advantageous for routine monitoring of water-soluble organic acids in airborne PM2.5 and vehicle emission at low ,g/L levels. [source] Interaction of non-ionic hydrogels with weak aromatic acidsMACROMOLECULAR SYMPOSIA, Issue 1 2003Krisztina László Abstract Measurements are reported of the swelling behaviour at 20°C of poly (N isopropylacrylamide) (PNIPA) gels in aqueous solutions of two weak aromatic acids, phenol and resorcinol. For solute concentrations below 45 mmol/l the uptake of these solutions is similar. Due to selective solvation phenol exhibits an excess equilibrium concentration inside the gel of 5% over that in the surrounding bath, while for resorcinol, the excess is found to be 12%. At 50 mmol/l solute concentration, both systems display a volume transition accompanied by expulsion of the solvent. The solubility limits in water of these aromatic compounds, which are significantly different from each other (870 mmol/l and 9080 mmol/l respectively), are far above this critical concentration. In the collapsed condition the expelled liquid spreads on the surface of the phenol treated gel, while an ordered arrangement of separate droplets is generated in the case of resorcinol. In the latter case an acute contact angle was observed. It is also shown by acid-base titration that the PNIPA/water system may exhibit a slight ion exchanging character. [source] Fragmentation pathways of acylated flavonoid diglucuronides from leaves of Medicago truncatulaPHYTOCHEMICAL ANALYSIS, Issue 3 2010ukasz Marczak Abstract Introduction , Flavonoids are important plant compounds occurring in tissues mostly in the form of glycoconjugates. Most frequently the sugar moiety is comprised of mono- or oligosaccharides consisting of common sugars like glucose, rhamnose or galactose. In some plant species the glycosidic moiety contains glucuronic acid and may be acylated by phenylpropenoic acids. Methodology , Flavonoid glyconjugates were extracted from leaves of Medicago truncatula ecotype R108 and submitted to analysis using high-performance liquid chromatography combined with high-resolution tandem (quadrupole-time of flight, QToF) mass spectrometry. Results , The studied leaf extracts contained 26 different flavonoid glycosides among which 22 compounds were flavone (apigenin, luteolin, chrysoeriol and tricin) glucuronides and 13 were acylated with aromatic acids (p -coumaric, ferulic or sinapic). The fragmentation pathways observed in positive and negative ion mass spectra differed substantially between each other and from these of flavonoid glycosides which did not contain acidic sugars. The application of high-resolution MS techniques allowed unequivocal differentiation between ions with the same nominal m/z values containing different substituents (e.g. ferulic acid or glucuronic acid). Eleven of the identified flavonoids have not been reported previously in this species. Perspectives , The presented unique fragmentation pathways of flavonoid glucuronates enable detection of these compounds in tissue extracts from different plant species. Copyright © 2009 John Wiley & Sons, Ltd. [source] Torque-rheometry investigation of model transreactions involving condensation polymers.POLYMER ENGINEERING & SCIENCE, Issue 2 2006The chemical transformations taking place when poly(ethylene terephthalate) (PET) or poly(ethylene naphthalate) (PEN) are blended in the melt with different low molar mass substances containing hydroxyl, carboxyl, or amine functional groups have been investigated as models of the transreactions, undergone by the polyesters in reactive blending operations. The polyester molecular weight changes caused by the alcoholysis, acidolysis, aminolysis, and esterolysis reactions have been monitored by torque-rheometry, using a Brabender Plasticorder static mixer. The degradation of the polyesters by hydrolysis was also studied, under similar conditions, by the addition of a water-releasing substance (wet polyamide-6), and was shown to occur quite rapidly, although most of the added water was lost by flash vaporization caused by the high temperature of the polyester melt. It has been shown that the rate constants of the reactions leading to breakage of the inner ester bonds of the polyester macromolecules decrease in the following order: aminolysis (with aliphatic amines, either primary and secondary) > alcoholysis (with aliphatic alcohols) , hydrolysis > acidolysis (with aromatic acids) , acidolysis (with aliphatic acids) , aminolysis (with aromatic amines) > alcoholysis (with phenols) , esterolysis. POLYM. ENG. SCI. 46:139,152, 2006. © 2005 Society of Plastics Engineers [source] Analysis of urinary aromatic acids by liquid chromatography tandem mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 12 2008Brian Crow Abstract The separation and detection of 11 urinary aromatic acids was developed using HPLC-MS/MS. The method features a simple sample preparation involving a single-step dilution with internal standard and a rapid 8 min chromatographic separation. The accuracy was evaluated by the recovery of known spikes between 87 and 110%. Inter- and intra-assay precision (CV) was below 11% in all cases and the analytes were observed to be stable for up to 8 weeks when stored at ,20°C. The method was validated based upon linearity, accuracy, precision and stability and was used to establish reference intervals for children and adults. Copyright © 2008 John Wiley & Sons, Ltd. [source] Phenolic Antioxidants from the Whole Plant of Phyllanthus urinariaCHEMISTRY & BIODIVERSITY, Issue 9 2007Min Xu Abstract The 1,1-diphenyl-2-picrydydrazyl (DPPH) assay on the extract of Phyllanthus urinaria L. (Euphorbiaceae) displayed considerable radical-scavenging activity (SC50=14.3,,g/ml). Further bioassay-guided purification of the extract led to the isolation of a series of 15 phenolic compounds, including the ellagitannins 1,7, the flavonoids 8,10, and the simple hydroxylated (or glycosylated) aromatic acids 11,15. Their structures were identified by spectroscopic analyses and comparison with authentic samples or literature data. The structure of repandinin B (1) was for the first time fully assigned by 1D- and 2D-NMR experiments. The phenolic compounds 1, 3, 4, 6, 9, 11, and 15 have not been isolated before from the title plant. The antioxidant activities and mushroom-tyrosinase-inhibitory activities of all compounds were determined by DPPH-radical-scavenging and mushroom-tyrosinase-inhibitory assays (Table,2). [source] | ||||||||||||||||