Papers by Keyword: Benzoic Acid

Abstract: The process of oxidation of hydrocarbon with oxygen proceeds with formation of the corresponding hydroperoxide as the primary product [1,2]. A catalyst is the most important factor that influences on the direction of flow of the oxidation reaction. Catalysts based on metals of variable valency, and their derivatives are the most active in reactions of oxidation of hydrocarbon [3].

Abstract: Benzoic acid analysis in curry paste samples were carried out by using high performance liquid chromatography using ultrasonic extraction. Methanol-0.05 M ammonium acetate buffer pH 4.40 in the ratio of 55:45 (%v/v) at a flow rate of 1.00 mL/min was used as the mobile phase and benzoic acid detection was performed at 226 nm using an UV-Visible detector. Under the optimum conditions, linearity of spiked samples ranged from 50 to 3,000 mg/kg. Matrix matched calibrations had determined that benzoic acid contents in southern sour, red, and green curry paste samples were 67.59, 78.62 and 72.33 mg/kg, respectively. Recoveries were obtained from 89.34 to 101.70%, 83.37 to 130.30% and 92.75 to 113.56% with R.S.D. ranged from 2.71 to 6.53%, 4.02 to 11.58% and 5.81 to 6.35%, for southern sour, red, and green curry paste samples, respectively.

Abstract: The main factors affecting ultrasonic extraction, such as extraction solvent, extraction temperature and extraction time were optimized for benzoic acid determination by using UV-Visible spectrophotometer at a wavelength of 230 nm. Under the optimum conditions of ultrasonic extraction, linearity between the concentration of benzoic acid in spiked curry paste samples and the absorbance was obtained in the concentration range from 100 to 2,000 mg/kg. Recoveries for benzoic acid determination were obtained range from 74.67 to 95.33%, 71.78 to 97.56% and 88.00 to 106.45% with R.S.D. were 1.05 to 5.47%, 0.92 to 4.27% and 0.71 to 4.22%, when spiked red curry paste, southern red curry paste and southern sour curry paste samples were analyzed, respectively.

Abstract: Analysis of organic acids in natural water samples using by the distillation followed by the SPE procedure at Strata-X and GC-MS of trimethylsilane derivatives. Influence of distillation and elution, as well as a cartridge housing material, on the compounds recovery was discussed. Data on organic acids in some natural samples are provided.

Abstract: Dodecatungstophosphoric acid was synthesized and used as catalyst for oxidation of benzaldehyde to benzoic acid with aqueous hydrogen peroxide. The effect of various catalytic reaction parameters including time, temperatures, and the amount of catalyst on the yield of benzoic acid was investigated in details. The results indicated that the as-prepared sample was in the keggin-type structure and the optimal parameters under the reaction conditions were as follows: 0.5 g of catalyst, reacted at 80 C for 5 h.

Abstract: In this study, porous Si₃N₄ ceramics with interconnected pores were prepared by cold isostatic pressing using benzoic acid as a pore-foring agent. The pore-forming agent of green bodies was sublimation rapidly below 200°C without carbon remained. Mechanical Properties were tested by universal testing machine, and the microstructures of the specimen were observed by scanning electron microscopy (FEI Sirion 200). The resulting shows, many fibrous β-Si₃N₄ grains grown from the internal wall of the round pores, and the porous distribution uniform in the matrix. By changing the content of benzoic acid, the silicon nitride ceramics with different porosity was fabricated. As the acid content decreased from 15wt% to zero, the porosities decreased from 57.6% to 48.0%, flexural strength increased from 36.8MPa to 141.2MPa. Both the grains and suitable interfacial bonding strength contributes to the high fracture strength.

Abstract: Using a synthetic method designed and installed with laser monitor on line, the solubility values of benzoic acid in ethanol, benzene, acetic acid and ethyl acetate were determined over the temperature range of 291.69-356.27 K. The solubility of benzoic acid in all cases investigated was found to increase with temperature. The two-parameters empirical and λh equations were used successfully to correlate experimental data of benzoic acid solubilities in organic solvents. The mean absolute error σ of 65 data points correlating by two-parameters empirical equation and λh equation was less than 1%. Finally, molar dissolution enthalpy ΔsolH of benzoic acid in organic solvents was determined with the newly obtained empirical equation parameters.

Abstract: The organic–inorganic hybrid catalyst [(CH2)5NH2]4SiW12O40 was prepared by matrix acid and piperidine. The matrix acid was synthesized by sodium molybdate and sodium silicate, and the piperidine was organic ligand. The proposed composition and structure of the catalyst were evidenced by XPS, FT-IR, XRD, TG-DTA and elemental analysis. The results indicated that the heteropoly anions still reserved their Keggin structure in the compound. Its catalytic performance was evaluated in the oxidation of benzaldehyde to benzoic acid. Various reaction parameters were changed to attain the optimal conditions. The optimal reaction conditions were found to be: n(catalyst): n(benzaldehyde)=3.1×10-3:1; n(H2O2)： n(benzaldehyde)=4.5：1; reaction temperature was 80°C; reaction time was 4h. The yield of benzoic acid achieved above 85%.

Abstract: A type of benzoic acid end-capped ploy(ester-imide-ether) (PEIE) block copolymers was synthesized by melt polycondensation from polytetrahydrofuran diol (PTMG), 1,4-butanediol (BD), benzoic acid (BA) and a diacid monomer which was synthesized of trimellitic anhydride (TMA) with para aminobenzoic acid (PABA). The structures and properties of the copolymers were investigated by FT-IR spectroscopy and Ubbelohde viscometer, DSC and TGA. Some properties of the copolymer fibers such as breaking strength, breaking elongation and elasticity were also measured. The result demonstrated that the adding of BA can effectively reduce the inherent viscosities of PEIE. Especially the breaking strength, elastic recovery and heat stability of the fibers are improved obviously when adding 1 % (of the multiblock copolymer weight percentage) BA end capping agent.

Abstract: Sulfur-doped titanium dioxide powders (SxTi1-xO2) was prepared by calcinations, that is, the hydrolysis of acidic tetra-butyl tianate using thiourea in ethanol, followed by calcinations at temperatures about 500°C. Based on the characterizations of XRD, BET, surface photovoltage spectroscopy (SPS), electric-field-induced surface photovoltage spectroscopy (EFISPS) and XPS, it was found that the sulfur could restrain the crystallization transformation of TiO2 from anatase to rutile, although the calcinations temperature has attained 500°C, the crystallization still were anatase entirely. The catalysts exhibited photocatalytic activity in the visible light region owing to S-doping. The light absorption onset of SxTi1-xO2 was shifted to the visible region at 550nm compared to 329nm of pure TiO2. In the crystal, the S atoms occupied some of the lattice titanium atoms for form S-O bonds. Photocatalytic decomposition of benzoic acid solutions was carried out under simulated sun light, and the SxTi1-xO2 catalyst showed higher activity than pure TiO2.