Solubilities of magnesium-l-ascorbate,calcium-l-ascorbate,magnesium-l-glutamate,magnesium-d-gluconate,calcium-d-gluconate,calcium-d-heptagluconate,l-aspartic acid,and 3-nitrobenzoic acid in water

The solubility in water of magnesium-l-ascorbate, calcium-l-ascorbate, magnesium-l-glutamate, magnesium-d-gluconate, calcium-d-gluconate, calcium-d-heptagluconate, l-aspartic acid, and 3-nitrobenzoic acid was determined in the 278.15 K to 343.15 K temperature range. The solubility of these compounds served to permit the evaluation of the apparent molar enthalpies of solution.     

Solubilities of terephthalaldehydic,p-toluic,benzoic, terephthalic and isophthalic acids in N,N-dimethylformamide from 294.75 to 370.45 K

Using a laser monitoring observation technique, solubilities of terephthalaldehydic, p-toluic, benzoic, terephthalic and isophthalic acids in N,N-dimethylformamide have been measured as a function of temperature in the temperature range 294.75–370.45 K. The experimental data are correlated with the λh equation. The calculated results show good agreement with the experimental solubilities. The molar mixing enthalpy of solution H^E is estimated from the h parameter to discuss the properties of solution. In the terephthalic acid-N,N-dimethylformamide system a repulsive interaction exists between solute and solvent, which leads to an endothermic effect during dissolution. The strongest attractive interaction exists in the p-toluic acid-N,N-dimethylformamide system, causing a significant exothermic effect.     

Synthesis of (S)-3-hydroxytetrahydropyran from l-glutamic acid

A concise synthesis of (S)-3-hydroxytetrahydropyran from natural l-glutamic acid has been developed. The intramolecular etherification starting from 1,5-diol was promoted by trifluoromethanesulfonic anhydride. The clinnamates of the alcohols were prepared for accurately determining the optical purity by HPLC method.     

Isoparametricity paradox in the pyridine-catalyzed reaction of phenyloxirane with 3-nitrobenzoic acid

The combined effect of structure and temperature on rate and activation energy of the X-substituted pyridine-catalyzed reaction between phenyloxirane and 3-nitrobenzoic acid in acetonitrile is studied. It is found that the intense interaction (nonadditivity) of effects of X substituents and temperature manifests itself in cross-reaction series; experimental evidence of isoparametricity in its enthalpy-entropy compensation aspect is obtained. It is determined that at the isoparametric temperature point (the isokinetic temperature), the rate (activation energy) of the catalytic process does not depend on structure of X substituents and a reversal of the order of effect of X on catalytic activity of pyridines is observed upon the transition of this isoparametric point (the isoparametricity paradox). It is shown that at the isoparametric point on the constant of the X substituent, temperature has almost no effect on the rate of the process since the value of the activation enthalpy is close to zero.     

Electrodialytic purification of calcium gluconate

Possibility of using the electrodialytic method for purification of calcium gluconate to remove sodium bromide was examined. The electrodialysis conditions were optimized.     

Multivariate analysis of homogeneous nucleation rate measurements. Nucleation in the p-toluic acid/sulfuric acid/water system

Recent kinetic extensions of the nucleation theorem suggest that the logarithm of the steady-state nucleation rate has strong multilinear dependence on the log concentrations of condensable species present in the vapor phase. A further remarkable result is that the coefficients of this linear dependency provide a direct determination of the molecular content of the critical nucleus itself. Building on these results, the powerful utility of multivariate statistical methods is demonstrated here for physically based parametrization and interpretation of nucleation rate measurements. The new approach is applied to recent measurements by Zhang et al. [Science 304, 1487 (2004)] on the p-toluic acid/sulfuric acid/water ternary vapor system. A linear minimum variance parametrization for nucleation rate dependence on vapor composition, accurate over the range of the measurements, is obtained. Estimates of critical nucleus molecular composition are also presented. These suggest that a single molecule of p-toluic acid present in the critical nucleus is sufficient to trigger a ternary nucleation event. Efforts under way to apply the new methods to analysis of new particle formation in the atmosphere are discussed.     

Solubilities of cinnamic acid,phenoxyacetic acid and 4-methoxyphenylacetic acid in supercritical carbon dioxide

The solid solubilities of cinnamic acid, phenoxyacetic acid and 4-methoxyphenylacetic acid in supercritical carbon dioxide were measured using a semi-flow apparatus. The experiments were taken at 308.2, 318.2 and 328.2 K. The pressure range was from 11 to 24 MPa. These data were confirmed as equilibrium solid solubilities based on a plug flow mass transfer model. The solid solubilities were further correlated using the equations of state or semi-empirical models. The correlation results are satisfactory with optimally fitted binary interaction parameters in the Peng–Robinson equation of state.     

Solvolysis of 4-acyloxy-3-nitrobenzoic acid substrates catalyzed by polyethylenimine derivatives

The solvolytic reactions of anionic activated esters (S_n^?) catalyzed by dodecane-block-poly[ethylenimine-graft-4(5)-methylimidazole] and related model compounds were investigated. Hydrolysis of 4-acetyl-3-nitrobenzoic acid (S₂^?) as a function of pH suggested that electrostatic interactions are operative only in the higher molecular weight polymers. Apolar interactions were evident from the greater catalytic rates observed for the hydrolysis of a series of 4-acetoxy-3-nitrobenzoic acid substrates (S_n^?). The largest rate enhancements were reflected by catalysts that make effective use of the electrostatic interaction and also provide an apolar binding site. Dodecane-block-poly[ethylenimine-graft-4(5)-methylimidazole], with a DP = 85, catalyzed hydrolysis of S_n^?(n = 2, 4, and 7), in excess substrate, exhibited saturation kinetics and followed a simple Michaelis-Menten-type mechanism. Inhibition of the catalyst in the hydrolysis of S₁₂^? was observed and can be rationalized by analogy to certain multisite enzymatic reactions.     

High pressure Raman spectra of l-glutamic acid hydrochloride crystal

Semiorganic nonlinear optical single crystal l-glutamic acid hydrochloride has been studied by Raman spectroscopy under high pressure conditions. Our results show that this amino acid crystal presents one structural phase transition at about 2.1 GPa and one molecular conformational change around 7.5 GPa. If we compare such behavior with that of the l-glutamic acid crystal in the same range of pressure we note a great stability for the hydrochloride samples. The chloride ion plays an important role increasing the number of the hydrogen bonds that hold the crystal together and thus, contributing to improve the structural stability of the crystal.     

Synthesis,crystal structure,and antimicrobial activity of silver(I) complexes derived from 3-nitrobenzoic acid and diamines

Russian Journal of Coordination Chemistry - Two new silver(I) complexes, [Ag2(NBA)2(DAC)] (I) and [Ag2(NBA)2(DAB)] (II), where NBA, DAC, and DAB are 3-nitrobenzoate, 1,2-diaminocyclohexane, and...     

Hydrogen-bonding network in the organic salts of 4-nitrobenzoic acid

The crystal structures of six novel salts of 4-nitrobenzoic acid — namely, 2-hydroxyethylammonium 4-nitrobenzoate (I), 2-hydroxypropylammonium 4-nitrobenzoate (II), 1-(hydroxymethyl)propylammonium 4-nitrobenzoate (III), 3-hydroxypropylammonium 4-nitrobenzoate (IV), bis-(2-hydroxyethylammonium) 4-nitrobenzoate (V), morpholinium 4-nitrobenzoate (VI) — containing the same anion but different cations have been studied. The ionic forms of I-VI serve as building blocks of the supramolecular architecture, and in crystals they are held together via ionic N-H···O and O-H···O hydrogen bonds. In the crystal packing the building blocks of I-III are self-assembled via N-H...O, O-H···O and C-H...O hydrogen bonds to form the chains which are further consolidated into two-dimensional layers by the same type of interactions. In IV-VI the chain-like structures have been generated by building blocks.     

Solubilities of lactic acid and 2-hydroxyhexanoic acid in supercritical CO2

Solubilities of lactic acid and 2-hydroxyhexanoic acid in supercritical CO₂ have been measured at T=(311 or 313, 318, 328 K) in the pressure range from 50 to 200 bar. The measurements have been performed using a flow-type apparatus. The solute solubility in compressed carbon dioxide increased with pressure at all investigated temperatures. At pressures below 130 bar, a solubility decrease on temperature increase was observed. An accurate correlation method for the solubility of low volatile substances in supercritical CO₂ has been applied for the interpolation of the experimental results.     

Solubilities of benzoin,propyl 4-hydroxybenzoate and mandelic acid in supercritical carbon dioxide

A semi-flow type apparatus was used to measure the equilibrium solubilities of benzoin , propyl 4-hydroxybenzoate, and mandelic acid in supercritical carbon dioxide at 308.15, 318.15, and 328.15 K over the pressure range from 9 to 24 MPa. New equilibrium data of solid solubility in supercritical carbon dioxide are presented. The approach to solid–fluid phase equilibrium is examined based on a plug flow fluid–solid mass transfer model. The Soave–Redlich–Kwong and the Peng–Robinson equations of state (EOS), with the van der Waals and the Huron–Vidal type mixing rules were used to correlate the experimental data. The solid solubility data were also correlated with density based semi-empirical equations of Chrastil, and Santiago–Teja. It is shown that these solid solubility data are correlated with reasonably good accuracy using optimally fitted parameters.     

Synthesis,crystal structure,and coordination properties of a helical peptide having β-(3-pyridyl)-l-alanine and l-glutamic acid residues

A novel helical peptide containing β-(3-pyirdyl)-l-alanine (Pal) and l-glutamic acid (Glu) residues has been designed and successfully prepared as a model ligand of metalloenzyme active sites. The helical peptide, Boc-Leu-Aib-Glu-Leu-Leu-Pal-Aib-Leu-OEt (1) (Boc = tert-butoxycarbonyl, Aib = 2-aminoisobutylic acid) yields fine crystals as an acetnitrile solvate. The metal ion binding affinities of 1 were tested for CoCl₂ using UV/vis, CD, Raman, and ¹H NMR spectroscopies. The non-linear fitting calculations have revealed the 1:1 complex for CoCl₂ with the binding constant 3.6 (±0.7) × 10² M⁻¹.     

Catalyst-free microwave-assisted amination of 2-chloro-5-nitrobenzoic acid

The synthesis of N-substituted 5-nitroanthranilic acid derivatives 3a-w was achieved by a new, mild, microwave-assisted, regioselective amination reaction of 5-nitro-2-chlorobenzoic acid (1a) with a diverse range of aliphatic and aromatic amines 2a-w without added solvent or catalyst. Up to >99% isolated yield was obtained within 5-30 min at 80-120 degrees C. The reaction, which is suitable for upscaling, yielded new compounds that are of considerable interest as useful building blocks and as potential drugs.     

Solution equilibria in l-glutamic acid and l-serine + iron(III) systems

Complex formation equilibria in l-glutamic acid (H2Glu) and l-serine (HSer) +iron(III) ion systems have been studied by a combination of glass electrode potentiometric and visible spectrophotometric measurements in 0.5 mol dm–3 (Na)NO3 ionic medium at 25°C. In the concentration range 1.0[Fe3+]5.0; 3.0[Glu2–]30.0 mmol dm–3 ([Glu]/[Fe]=3:1 to 30:1) and pH between 1.5 and 4.5, iron(III) and glutamic acid form the Fe(Glu)–2, Fe(Glu)+, Fe(HGlu)2+, Fe(OH)Glu, Fe2(OH)2Glu2+, Fe(OH)Glu22– complexes: and several pure hydrolytic products. Iron(III) and l-serine, beside pure hydrolytic complexes of iron(III), form the Fe(HSer)3+, Fe(Ser)2+, Fe(OH)Ser+, Fe(OH)2- Ser0, Fe(OH)Ser2 and Fe2(OH)2(Ser)2+2 complexes, over a broad concentration range of serine to iron ([Ser]/[Fe]=5:1 to 500:1), from pH 1.5 to 4.0. The stability constants of the complexes are given and their formation mechanism is suggested. The possible structure of the complexes, in solution, is discussed.     

3－氨基－4－硝基苯甲酸的合成

以苯甲酸为原料，经硝化、还原、乙酰化、再硝化、水解，制备了标题化合物，结果较好。