Characteristics of the oxidation process in the oleic acid-propionic acid system by means of dielectric constant measurements

The influence of the hydrogen-bond association on the course of autoxidation of oleic acid in the binary system oleic acid-propionic acid was discussed. The association was characterized with the help of dielectric constant measurements.     

Characteristics of the oxidation process in the methyl oleate-propionic acid system by means of dielectric constant measurements

In our paper the influence of association in the methyl oleate-propionic acid system on the course of autoxidation of this system was discussed. The course of autoxidation of the a/m system was characterized with the help of peroxide number and dielectric constant measurements.     

Spectroscopic and dielectric examination of the oleyl alcohol-oleic acid system

The comparison of association was made for the oleyl alcohol-oleic acid systems composed in several molar ratios. The ir spectroscopy and dielectric constant measurements were applied as analytical techniques. It was stated that oleyl alcohol and oleic acid interact in a number of molar ratios giving the hydrogen-bonded associates. In the range of temparatures 30–60 °C the most stable hydrogen-bonded associate is formed in a ratio of alcohol to acid of 9:1.     

Mechanism of the hydroperoxide destruction in the oxidized methyl oleate,oleyl alcohol,and oleic acid

The differentiated mechanism of destruction of hydroperoxides derived from methyl oleate, oleyl alcohol and oleic acid was explained with the influence of the hydrogen-bond interactions. The evidence for the proposed models was given through the quantitative yields of the five classes of the secondary products of autoxidation: monohydroxy-, dihydroxy-, keto-, ketohydroxyderivatives and monofunctional products of degradation of the oxidized molecules.     

The influence of hydrogen-bond association on the destruction of hydroperoxides in the autoxidation process of oleyl alcohol, oleic acid, and methyl oleate

The autoxidation process of oleyl alcohol, oleic acid, and methyl oleate at 40, 50, and 60 °C was considered with the special stress laid upon the mechanism of cumulating and destruction of peroxidic products. Interpretation of the observed differences was based on the hydrogen-bond association patterns.     

The oxidation of oleic acid by permanganate in oil in water emulsion

The oxidation of oleic acid and the cleavage of the carbon—carbon double bond was achieved using potassium permanganate added to oil in water emulsion.The best emulsifier to enable the oxidation and cleavage of the double bond was polyoxyethylene lauryl ether (HLD 16.9) which formed the best emulsion with the smaller droplets.The oxidation is controlled by parameters affecting emulsion stability. Increasing the concentrations of emulsifier or oxidizing agent improves the oleic acid conversion and azelaic acid formation. Poor stirring low HLB's, high oil phase content and poor emulsion preparation decrease the yields.     

Investigation of thermal decomposition reactions by means of thermal analysis and dielectric constant measurement

Dielectric constant measurements as a function of temperature and thermal analysis were performed in copper sulphate pentahydrate and sodium nitrite to study the nature of the decomposition reactions. The application of these combined techniques to the study of several possible mechanisms of thermal decomposition is advanced.     

Computer simulation and the dielectric constant of polarizable polar systems

A theory presented recently, allowing the static and frequency-dependent dielectric constant of polar systems to be calculated in computer simulations with arbitrary boundary conditions, is extended to the polarizable case. For modified dipolar interactions not explicitly depending upon time, the resulting equations are found to be of the generalized Fröhlich-Glarum type.     

Chromatographic and spectroscopic investigations of the oxidation process in methyl oleate and methyl elaidate

In our paper the studies on the initial stage of autoxidation of cis- and trans-9-octadecenoic acid methyl esters were reported. The applied analytical methods were: (1) high-resolution NMR spectroscopy; (2) absorption iR spectroscopy; (3) adsorption TLC. The complementary methods were: determination of peroxide number, acid number and iodine number in the course of autoxidation. Our results pointed to the fact that the oxidation of trans-isomer showed the more restrained character. We tried to suggest the influence of structure of the examined compounds and of the peroxides formed in the initial stage of autoxidation on the course of this process.     

Estimation of the zeta potential and the dielectric constant using velocity measurements in the electroosmotic flows

In this paper we develop a method for the determination of the zeta potential zeta and the dielectric constant epsilon by exploiting velocity measurements of the electroosmotic flow in microchannels. The inverse problem is solved through the minimization of a performance function utilizing the conjugate gradient method. The present method is found to estimate zeta and epsilon with reasonable accuracy even with noisy velocity measurements.     

Acid soap formation of oleic acid and catanionic complex formation in the alkyldimethylamine oxide/sodium oleate equimolar mixtures

The influence of adding alkyldimethylamine oxide (CnDMAO) with varying alkyl chain lengths (n_c) on the acid soap formation of oleic acid was investigated. The solutions of equimolar mixtures of CnDMAO and sodium oleate (Na⁺Ol^–), each 25 mmol kg^–1, became turbid at a certain critical pH (pH_c) on decreasing pH. Values of the pH_c depended on n_c and showed the minimum at C10DMAO/NaOl mixture. The presence of the minimum was interpreted in terms of two different kinds of the complex formed in the micelles depending on n_c: the catanionic complex (CnDMAOH⁺/Ol^–) in the mixed micelles of n_c=16, 14, 12 and 10, and the acid soap of oleic acid for C6DMAO/NaOl and C8DMAO/NaOl mixtures. At pH_c where the amounts of these complexes of double-chain nature reached certain critical values in the mixed micelles, a phase separation (most probably lamella formation) took place. It was expected that the critical amount of the catanionic complex was smaller for the mixtures of higher n_c values and hence pH_c increased with n_c for the mixtures n_c10. For the mixtures of n_c<10, it was expected that the amount of the acid soap in the mixed micelles increased with decreasing n_c at a given pH and the pH_c increased with decreasing n_c. Micelle compositions at cmc were evaluated on the basis of the regular solution theory coupled with the pseudo phase approximation. The micelle compositions at 100 mmol kg^–1 were examined with ¹³C-NMR. The results showed the mixed micelle formation for n_c=16–10, while the micelles mostly consisting of oleic acid for the mixtures of n_c=8 and 6. The assumption of two different complexes for the two groups of the mixture was thus supported. The cmc range of mixed micelles was evaluated and it was well correlated with the observed concentration range of pyrene fluorescence change.     

Synthesis of 8-heptadecene by decarboxylation of oleic acid in various catalyst systems

Decarboxylation of oleic acid in the presence of various catalysts synthesized in a flow system was performed to produce 8-heptadecene, which is an important product of the petrochemical and other industries. An effect of reaction temperature on the product yield was demonstrated.     

An estimation of the surface ionization constant of oleic acid in aqueous sodium chloride solution

The zeta potential () measurements and the site binding theory were utilized for calculations of the parameters of the electrical double layer (edl), ionization, and complexation constants for oleic acid-aqueous sodium chloride solution interface. Assuming that is equal to the diffuse layer potential ( _d ) of the edl, the charge of the diffuse part of the edl was calculated from the Gouy-Chapman equation. The intrinsic ionizaiton constant was then determined by an extrapolation method to be . Subsequently, the surface potential ( ₀) was calculated, and it was found that ₀ changes by 50 mV per pH unit (50 mV/pH) or 42.5 mV/pH for 10^–3 and 10^–2 M NaCl, respectively. For further calculations, the integral capacity of the outer zone of the compact part of the edl was assumed to be for both ionic strengths. It was established that the intrinsic complexation constant for the binding of Na⁺ ions with the surface of oleic acid ispK _Na ^int = 2.9±0.5 if the integral capacity of the inner zone of the compact edl (K ₁) is 80 for 10^–3 M NaCl, but 280 for 10^–2 M NaCl. The use of the sameK ₁ value for both ionic strengths gives a differentpK _Na ^int for different NaCl concentrations, and also provides unrealistic surface charge ( _o ) values greaterfor 10^–3 M NaCl than for 10^–2 M NaCl, at the same pH of the solution.     

The dielectric constant effect upon the acid hydrolysis of ethyl acetate

The dielectric constant effect upon the rate of acid hydroly.sis of ethyl acetate is presented from the standpoint of electrostatics and the results compared to like effects upon the acid hydrolysis of methyl propionate.     

The effect of dielectric constant on the electrical conductivity in double liquid systems

The effect of dielectric constant on the electrical conductivity of double systems containing chemically noninteracting components is considered. An equation has been obtained by means of which it is possible to evaluate the isotherm for electrical conductivity of such systems, the equation being confirmed by all available experimental material.     

Studies on the phase properties of lyotropic liquid crystals of Brij35/sodium oleate/oleic acid/water system:By means of polarizing microscope,SAXS,~2H-NMR and rheological methods

The pseudo-quaternary phase diagram of Brij35/sodium oleate/oleic acid/water systems has been investigated, and the liquid crystal area has been identified, which covers about two thirds of the whole phase diagram. The liquid crystal structure and behavior have been also studied by using polarizing texture, small angle X-ray scattering, 2H-NMR and rheometer etc. The result shows that when the composition of the system changes along the line of AA′ in this large liquid crystal region, the structural change is cubic→cubic/lamellar→lamellar→lamellar/hexagonal→hexagonal. Meanwhile, we made the first attempt of systematic study of the rheological properties of the above system. The lattice constants of cubic and hexagonal liquid crystals are 10.53 and 5.68 nm, respectively.     

The dielectric constant and salt effects upon the acid hydrolysis of ethyl formate

The hydrolysis of ethyl formate catalysed by hydrochloric acid was studied at three temperatures in water-acetone media and in water media containing different concentrations of sodium nitrate. The effect of various ionic strengths and dielectric constants upon the rate of acid hydrolysis of ethyl formate is presented from the point of electrostatics and the results were compared to like effects upon the acid hydrolysis of ethyl acetate and methyl propionate. Neither the dielectric constant effect nor the salt effect lends itself readily to theoretical interpretation. It was assumed that a partial explanation of these anomalous results might be in the extrapolation of the acid radical to the simplest carboxylic acid. This suggestion was supported somewhat by the trends towards less adherance to the electrostatic theory at certain temperatures in the series methyl propionate, ethyl acetate and ethyl formate.