Proton conductivity in phenolsulfonic acids and their salts

The geometric parameters and energies of crystal hydrates of aromatic sulfonic acids and their salts, as well as the pathways of proton transport in them, were calculated by the DFT (B3LYP) method with the 6-31G** basis set. For aromatic sulfonic acids, the proton relay mechanism was shown to be energetically more favorable than rotation of the HSO group or direct proton transfer. Calculations show that an increase in the number of water molecules located near the HSO₃ group from one to four decreases the barrier from 6 to 0.3 kcal/mol. Hence, a moderate increase in humidity should enhance the conductivity, which is fully consistent with experimental data. Calculations predict that the salts where all protons are substituted by metal atoms are unlikely to show good conductivity. Conversely, mixed salts, for example, H₃C₆(OH)(NaSO₃)(HSO₃) and H₃C₆(OH)(RbSO₃)(HSO₃), are expected to be thermally stable and resistant to deliquescence with an increase in the humidity of a medium and to have good conductivity.     

Proton conductivity of calix[4]arene-para-sulfonic acids

The proton conductivity of hydrates of calix[4]arene-para-sulfonic acids is studied. The high proton conductivity is observed at ambient temperatures in the wide ranges of environmental humidity and, correspondingly, water content in the hydrate. For the air humidity of 10 rel. %, the conductivity of compounds is 10^?4-10^?3 S cm^?1 and approaches 10^?2-10^?1 S cm^?1 as the humidity increases up to 70 rel. %.     

o-Phosphorus-substituted benzoic acids

Russian Chemical Bulletin -     

Electrical conductivity and IR spectra of molten benzoic acid

Impedance method was used to measure the electrical conductivity of benzoic acid melts, and the concentration of free protons in these melts was estimated. IR spectroscopic data are presented and the existence of benzoic acid in melts in the form of molecules is suggested.     

Crystal structures of monohalogenated benzoic acids

Crystal structures resulting from a combination of different types of specific intermolecular interactions have been analysed using examples of 12 monohalogenated benzoic acids (HBA). These have been compared with structures known for corresponding monofunctional compounds, namely benzoic acid, fluorobenzene, chlorobenzene and iodobenzene. It is found that common for carboxylic acids centrosymmetric hydrogen-bonded dimers exist in all HBA, and at the same time a degree of halogen atoms aggregation is rather high in the most part of HBA, similarly to chlorobenzene and iodobenzene crystals. Previously reported tendency to increasing degree of Hal-aggregation in the sequence F < Cl ≤ Br ≤ I is confirmed. It is remarkable that a stacking motif of benzene rings is realised in all HBA crystals though it is absent in all considered monofunctional substances.     

One-pot synthesis of 2-（1-acyloxypentyl） benzoic acids

A one-pot synthesis of 2-（1-acyloxypcntyl） benzoic acids by trapping the carboxylatc/alkoxide dianion with acylating reagents following Grignard addition with n-BuMgBr to 2-formylbcnzoic acid was described. Compared with routine synthetic method, this novel procedure has the advantage of convenient operation and higher yields.     

Cotton-Mouton constants for benzoic and phthalic acids

The Cotton-Mouton effect was used to investigate benzoic, phthalic, isophthalic, and terephthalic acids. The additive tensor characteristics of the magnetic susceptibility ellipsoid were obtained for the C_ar-COOH fragment. Magnetic and electric double refraction, dipole moment, and quantum chemistry methods were used to study the spatial structure of phthalic acid in solution.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1568–1571, September, 1993.     

Proton conductivity of calix[n]arene-para-sulfonic acids (n = 4, 8)

High proton conductivity in calix[n]arene-para-sulfonic acid hydrates (n = 4, 8) reaching a value of 10^?1 Ohm^?1 cm^?1 at a relative humidity of 80% was revealed for the first time. This value is close to the record conductivity of solid proton conductors and acid water solutions. The dependence of proton transfer parameters and water quantity in the title compounds dependent on the relative humidity of air was investigated.     

Protodecarboxylation of benzoic acids under radical conditions

A new approach to protodecarboxylation is described that enhances the substrate scope for benzoic acids. The reaction uses oxidative radical conditions to decarboxylate a variety of acids in acetonitrile.     

Online preconcentration in capillary electrophoresis with contactless conductivity detection for sensitive determination of sorbic and benzoic acids in soy sauce

A sensitive method of online preconcentration followed by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C⁴D) is evaluated as a novel approach for the determination of benzoic acid and sorbic acid in soy sauce. The online preconcentration technique, namely field-enhanced sample injection, coupled with CE-C⁴D were successfully developed and optimized. In order to reduce the complex matrix interference resulting from the constituents of soy sauce, a suitable sample clean-up procedure was also investigated for real sample pretreatment. Under optimized conditions, sorbic acid and benzoic acid were well separated within 10 min, and the detection limits were 0.05 μM (5.6 μg L⁻¹) and 0.08 μM (9.8 μg L⁻¹), respectively. The accuracy was tested by spiking 10.0 mg L⁻¹ and 100.0 mg L⁻¹ of standards in the soy sauce samples, and the recoveries were 95-99%, respectively. Results of this study show a great potential for the proposed method as a tool for the fast screening of benzoic acid and sorbic acid in a complex matrix.     

Proton conductivity of potassium doped barium zirconates

Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10%. Introducing extra potassium leads to the formation of second phase or YSZ impurities. The water uptake of barium zirconates was increased even with 5% doping of potassium at the A-site. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. The maximum solubility for yttrium at B-sites is around 15 at% after introducing 1 wt% zinc. The conductivity of Ba_0.95K_0.05Zr_0.85Y_0.11Zn_0.04O_3−δ at 600 °C is 2.2×10⁻³ S/cm in wet 5% H₂. The activation energies for bulk and grain boundary are 0.29(2), 0.79(2) eV in wet 5% H₂ and 0.31(1), 0.74(3) eV in dry 5% H₂. A power density of 7.7 mW/cm² at 718 °C was observed when a 1 mm thick Ba_0.95K_0.05Zr_0.85Y_0.11Zn_0.04O_3−δ pellet was used as electrolyte and platinum electrodes.     

Proton conductivity and interphase interaction in CsH2PO4-SrZrO3 composites

Microstructure, transport, and thermal properties of the composites of (1 ? x)CsH₂PO₄/xSrZrO₃ (x = 0.01–0.2) are studied. Introduction of highly dispersed strontium zirconate results in an increase in low-temperature conductivity by 1–3 orders of magnitude as depedent on the composition, leveling, and disappearance of a superionic phase transition in CsH₂PO₄. The methods of differential scanning calorimetry and thermogravimetry were used to show that a significant change in thermodynamic properties of CsH₂PO₄ in composites at x = 0.1–0.2 is observed due to salt amorphization. According to the data of X-ray phase analysis, there is no chemical interaction between the components and no new compounds are formed. An increase in conductivity is caused by salt disordering due to the interphase surface interaction.     

Active-sodium-promoted reductive cleavage of halogenated benzoic acids

The outcome of the reaction between 1,2-diaryl-1,2-disodioethanes and halogenated benzoic acids strongly depends on the nature of both reaction partners. Indeed, whilst chloro-, bromo- and iodobenzoic acids are easily dehalogenated, the reductive cleavage of fluorobenzoic acids proceeds to a high extent only in the presence of the dianions endowed with more powerful reducing properties. Moreover, it was observed that ortho-substituted benzoic acids are more easily dehalogenated than the corresponding para or meta isomers. These observations allowed the development of reaction conditions for the exhaustive or regioselective cleavage of selected polyhalogenated benzoic acids.     

肌肉醇取代苯甲酸盐的合成及生物活性

本文以硫脲和硫酸二甲酯为原料反应生成S-甲基异硫脲硫酸盐,再与2-甲基氨基乙醇反应生成肌肉醇硫酸盐,分离出肌肉醇碱,最后与具有生物活性的取代苯甲酸反应生成了7种肌肉醇取代苯甲酸盐。化合物结构经IR,1H NMR和元素分析进行表征,初步室内生测结果表明该类化合物具有一定的抑菌活性。     

Substituent effects on the acidity of weak acids. 2. Calculated gas-phase acidities of substituted benzoic acids

To investigate the origin of substituent effects on the acidity of benzoic acids, the structures of a series of substituted benzoic acids and benzoates have been calculated at the B3LYP/6-311+G* and MP2/6-311+G* theoretical levels. The vibrational frequencies were calculated using B3LYP/6-311+G* and allowed corrections for the change in zero-point energies on ionization, and the change in energy on going from 0 K (corresponding to the calculations) to 298 K. A more satisfactory agreement with the experimental values was obtained by energy calculations at the MP2/ 6-311++G* level using the above structures. The resulting Delta H(acid) values agree very well with the experimental gas-phase acidities. The energies of compounds with pi-electron-accepting or -releasing substituents, rotated to give the transition state geometries, provided rotational barriers that could be compared with those found for the corresponding substituted benzenes. Isodesmic reactions allowed the separate examination of the substituent effects on the energies of the acids and on the anions. Electron-withdrawing groups stabilize the benzoate anions more than they destabilize the benzoic acids. Electron-donating groups stabilize the acids and destabilize the anions by approximately equal amounts. The gas-phase acidities of meta- and para-substituted benzoic acids are linearly related. This is also found for the acidities of substituted phenylacetic acids and benzoic acids. Since direct pi-electron interactions are not possible with the phenylacetic acids, this indicates that the acidities are mainly controlled by a field effect interaction between the charge distribution in the substituted benzene ring and the negative charge of the carboxylate group. The Hammett sigma(M) and sigma(P) values are also linearly related for many small substituents from NO(2) through the halogens and to OH and NH(2). Most of the other substituents fall on a line with a different slope     

Two methods for direct ortho-arylation of benzoic acids

Two new palladium-catalyzed methods for the direct ortho-arylation of free benzoic acids have been developed. The first method employs stoichiometric silver acetate for iodide removal, aryl iodide as the coupling partner, and acetic acid solvent. This method is applicable to the arylation of electron-rich to moderately electron-poor benzoic acids and tolerates chloride and bromide substituents on both coupling partners. The second method involves the use of aryl chloride, cesium carbonate base, n-butyl-di-1-adamantylphosphine ligand, and DMF solvent and is suitable for both electron-rich and electron-poor benzoic acids. Mechanistic studies of the second method point to the heterolytic C-H bond cleavage as the rate-determining step.