Fenofibric acid

Unlike the related fenofibrate molecule [Henry, Zhang, Gao & Bruckner (2003). Acta Cryst. E 59 , o699–o700], fenofibric acid {systematic name: 2‐[4‐(4‐chlorobenzoyl)phenoxy]‐2‐methylpropanoic acid}, C₁₇H₁₅ClO₄, contains a carboxylic acid moiety instead of an ester moiety. This polar moiety plays an important role in the formation of a rare acid‐to‐ketone hydrogen‐bond‐type packing interaction. The lack of an isopropyl group in fenofibric acid aligns the carboxyl group on the same side as the ketone carbonyl group; this conformation may play an important role in discrimination between the acid and the fenofibrate mol­ecule in molecular recognition.     

Decomposition of oxalic acid with nitric acid

Oxalic acid or oxalate is widely used as a precipitant and a detergent in the field of nuclear energy. The present work aimed at developing a method of decomposing oxalic acid with HNO₃ in the presence of Mn²⁺ ion. The use of Mn²⁺ ion as low as 10^?3 mol/l facilitated the complete decomposition of oxalic acid, and the acidity of the resulting solution became as low as 0.1 eq/1 under the optimum conditions. The decomposition of oxalic acid is a first order reaction and proceeds at temperatures above 80°C; the activation energy of the reaction is 18.6 kcal/mol. This decomposition method is applicable to the dissolution of an oxalate precipitate.     

Determination of ascorbic acid, dehydroascorbic acid, and isoascorbic acid in blood

Summary High-performance liquid chromatography with UV-detection at 254 nm was used for determining ascorbic acid, dehydroascorbic acid, and isoascorbic acid in plasma and erythrocytes obtained from healthy volunteers and from patients with coronary infarct, acute lymphatic leukemia (ALL), and acute myeloic leukemia (AML). Deproteinisation was done by a simple ultrafiltration technique. Dehydroascorbic acid (DHA) was determined after reduction to ascorbic acid with dithiothreitol. The separation system chosen allows the search for the stereoisomer isoascorbic acid. To exclude interfering substances which could coelute with ascorbic or isoascorbic acid, several other compounds present in plasma were investigated including e.g. the aromatic amino acids, glutathione, cysteine, and uric acid. The results reveal a drastic decrease in total vitamin C concentration in plasma and erythrocytes with a concomitant increase in rel. DHA concentration in patients with AML. In ALL patients, both the total vitamin C and rel. DHA concentrations were increased.

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Bestimmung von Ascorbinsäure, Dehydroascorbinsäure und Isoascorbinsäure in Blut

Zusammenfassung High-performance-liquid-Chromatographie mit UV-Nachweis bei 254 nm wurde zur Bestimmung von Ascorbinsäure, Dehydroascorbinsäure und Isoascorbinsäure in Plasma und Erythrocyten von gesunden Probanden und von Patienten mit Herzinfarkt, akuter lymphatischer Leukämie (ALL) und akuter myeloischer Leukämie (AML) benutzt. Deproteinisierung erfolgte mittels einer einfachen Ultrafiltrationstechnik. Dehydroascorbinsäure wurde nach Reduktion mit Dithiothreitol als Ascorbinsäure bestimmt. Die benutzte Methode erlaubt auch die Bestimmung des Stereoisomers Isoascorbinsäure. Der mögliche Einfluß von im Plasma vorkommenden Substanzen auf die Bestimmung des Vitamin C wurde untersucht. Die Ergebnisse zeigen eine drastische Abnahme der Gesamt-Vitamin C-Konzentration in Plasma und Erythrocyten mit einer parallelen Zunahme der relativen DHA-Konzentration in AML-Patienten. In ALL-Patienten sind sowohl die Gesamt-Vitamin C- als auch die relative DHA-Konzentrationen erhöht.

     

Simultaneous kinetic determination of uric acid ascorbic acid mixtures

A kinetic stopped-flow method is described for the simultaneous determination of uric acid and ascorbic acid with tris (2,2'-bipyridine)iron(III). For the least favourable ratios of uric to ascorbic acid, in a total concentration of 10^-5 M, the error in the determination of uric acid is estimated at ±10%.     

Stereoselective synthesis of malyngic acid and fulgidic acid

A new stereoselective total synthesis of malyngic acid has been achieved from a known oxazolidinone derivative via eight steps involving the Evans asymmetric alkylation as the chirality-inducing step and chelation-controlled Zn(BH₄)₂ reduction of an α-hydroxy ketone intermediate for the installation of the 12,13-anti stereochemistry. Fulgidic acid, the C12-epimer of malyngic acid, has also been synthesized in eight steps from the same starting material by using syn-selective K-Selectride reduction of an α-alkoxy ketone intermediate.     

Degradation of uric acid and 3-ribosyluric acid during treatment with charcoal

Uric acid and 3-ribosyluric acid at a concentration of 1.5 × 10^?4M were quantitatively adsorbed to charcoal, but were not recovered when the charcoal was washed with ethanol:water:NH₄OH (60:36:4), a solvent which readily eluted a number of other bases and nucleosides. With [2-¹⁴C]uric acid it was shown that the radioactivity was adsorbed to the charcoal and that [¹⁴C]allantoin was the primary product recovered after elution. Incubation of uric acid or 3-ribosyluric acid in the ethanol:water:NH₄OH did not result in any degradation. The elution of uric acid from charcoal with other eluents such as 7% phenol, 0.1 M NaOH, or ethanol:water:pyridine (50:40:10) also resulted in the conversion of uric acid to allantoin. It was concluded that when uric acid and 3-ribosyluric acid are adsorbed to charcoal and then eluted, there is a substantial conversion of these compounds to the corresponding allantoin.     

Flow-injection spectrophotometric determination of ascorbic acid by reduction of vanadotungstophosphoric acid

Ascorbic acid may be determined spectrophotometrically at 360 nm based on reduction of vanadotungstophosphoric acid using flow-injection analysis. The carrier stream was distilled water and the reagent streams were buffer solution (pH 3.0), 1.735 × 10^?3 M dodecatungstophosphoric acid and 1.735 × 10^?3 M sodium vanadate. The injection rate was 80 h^?1. The calibration graph was linear up to 80 μg ml^?1 ascorbic acid and the relative standard deviation for the determination of 20 μg ml^?1 ascorbic acid was 1.5% (n=10). The detection limit was 1.0 μg ml^?1 ascorbic acid, based on an injection volume of 250 μl. The system was applied to the determination of ascorbic acid in vitamin C tablets.     

Trifluoromethyl sulphonic acid as a titrant in glacial acetic acid systems

Trifluoromethyl sulphonic acid in glacial acetic acid has been compared with perchloric acid in glacial acetic acid as a titrant in a limited number of cases. It does not appear that the reagent is likely to compete seriously with perchloric acid in non-aqueous titrimetry. Although comparable to perchloric acid in acid strength in acetic acid as well as in instrument response, it is unlikely that the considerably higher cost can be justified on the grounds of freedom from precipitate formation alone and no other advantageous feature has been observed which could justify this.

Abstract

Trifluoromethylsulfonsäure in Eisessig wurde mit Perchlorsäure in Eisessig als Titrationsmittel verglichen. Es scheint nicht wahrscheinlich, dass das Reagens ernsthaft mit Perchlorsäure als Titrationmittel in nichtwässrigem Medium konkurrieren kann. Das Reagens ist zwar mit Perchlorsäure vergleichbar, soweit es die Stärke (in Essigsäure) und das Ansprechen des Instrumentes betrifft; es ist aber unwahrscheinlich, dass sich die beträchtlich höheren Kosten lediglich wegen Nichtauftretens von Niederschlägen rechtfertigen lassen. Dies ist der einzige auffindbare Vorteil.     

The decarboxylation of methylmalonic acid and n-octadecylmalonic acid in normal alkanols

Rate constants and activation parameters are reported for the decarboxylation of methylmalonic acid and n-octadecylmalonic acid in three normal alkanols (hexanol-1, octanol-1, and decanol-1). Enthalpies of activation for both substrates in the various solvents are found to be a linear function of the number of carbon atoms or methylene groups in the hydrocarbon chain of the solvent. For both reaction series the isokinetic temperature is found to be equal to the melting point of the substrate. The free energy of activation at the isokinetic temperature in kcal/mole is 29.0 for n-octadecylmalonic acid and 29.4 for methylmalonic acid. Based on the results of the present investigation as well as on previously reported data in the case of malonic acid and n-butylmalonic acid, an empirical method of calculating the rate of reaction for the decarboxylation of malonic acid and its n-alkyl derivatives in normal alkanols is proposed. As a further test of the method of calculation the decarboxylation of n-dodecylmalonic acid in heptanol-1 at 110.30°C was studied. The calculated value of the pseudo-first-order specific reaction velocity constant of the reaction agreed with the experimental value to within about 0.1 percent.     

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.     

Raman spectra of glycolic acid,l-lactic acid and d,l-lactic acid oligomers

Polymerization of glycolic acid, l- and d,l-lactic acid was followed by Raman spectroscopy in aqueous solution at different concentrations, in viscous and solid states. The Raman spectra of some oligomers obtained by progressive polycondensation of α-hydroxycarboxylic acid aqueous solutions were investigated in the 200–18 cm⁻¹ region. Vibrational analysis revealed the characteristic peaks of ester groups that appeared in the repeat unit of the polymeric chain during the polymerization reaction, and those of the monomers which disappeared. In particular, the ν(CC) stretching vibrations occur in the 800–1000 cm⁻¹ range, which is easily accessible because of the weak diffusion of water. Moreover, spectral monitoring of the semicrystalline sample of poly(glycolic acid) oligomers showed Raman peaks associated with the vibrations of the polymer in the amorphous and semicrystalline states.     

Reaction of fluoronitroacetic acid with hydrochloric acid

Conclusions Fluoronitroacetic acid reacts with hydrochloric acid to form fluorochloronitrosome-thane which is capable of undergoing dimerization to give N,N'-azofluorochlormethane dioxide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1420–1422, June, 1985.     

Diastereoselective synthesis of (+)-nephrosterinic acid and (+)-protolichesterinic acid

A diastereoselective synthesis of (+)-nephrosterinic acid and (+)-protolichesterinic acid, common members of the paraconic acids is described. The synthesis is based on a diastereoselective orthoester Johnson–Claisen rearrangement of a (Z)-allyl alcohol with a vicinal dioxolane moiety as key steps. The synthesis is completed in 10 steps and with overall yields of 15.9% for (+)-nephrosterinic acid and 16.4% for (+)-protolichesterinic acid.     

A note on the distillation of permanganic acid from sulphuric acid solutions

1. If solutions which contain XXX periodic acid and sulphuric acid are boiled, permanganic acid is found in the XXX concentration of permanganate in the steam is negligibly small until the sulphuric acid concentration of the solution exceeds about 6 M. It is at a maximum when the sulphuric acid is to M and then rapidly decreases as the sulphuric acid concentration further increases. 2.The'distillation of permanganic acid from nitric acid solutions is inappreciable even from the concentrated acid. 3. A brief account is given of the analytical application of the distillation from IoM sulphuric acid.     

Alkyliminomalonic acid and 2-alkyloxaziridine-3, 3-dicarboxylic acid esters

2-Alkyloxaziridine-3, 3-dicarboxylic acid esters have been obtained by oxidizing alkylaminomalonic acid esters by monoperphthalic acid. The activation parameters for the inversion of the nitrogen atom have been obtained for a number of alkyliminomalonic acid and 2-alkyloxaziridine-3, 3-dicarboxylic acid ester.Report 46 from a series entitled Asymmetric Nonbridging Nitrogen. For report 45 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 525–532, April, 1986.     

Nature of the transformations of oleanolic acid in an acid medium

3-Trifluoroacetoxyoleanolic acid and 3-trifluoroacetoxyolean-13(18)-en-28-oic acid have been isolated from the mixture of the products of the transformation of oleanolic acid in a trifluoroacetic acid medium, and their structures have been established with the aid of IR, PMR and mass spectra. The formation of these products indicates an unambiguous route of the stabilization of the intermediate carbocation with the charge on the C-13 atom. The hydroxy group at C-3 is esterified by the trifluoroacetic acid.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 320–323, May–June, 1986.     

Convenient and chromatography-free partial syntheses of maslinic acid and augustic acid

A convenient and chromatography-free 4-step synthesis of analytically pure maslinic acid (1, 41.2%) from oleanolic acid has been developed. Slight variations in the final steps gave an excellent yield of isomeric augustic acid (7, 71.9%).     

Determination of uranium in wet phosphoric acid by extraction with octylphenylphosphoric acid

A method for quantitative determination of uranium in phosphoric acid and wet phosphoric acid has been developed. After reduction with Fe, uranium(IV) is extracted with a kerosene solution of octylphenylphosphoric acid. The uranium was stripped with 10M H₃PO₄, containing H₂O₂, and then determined spectrophotometrically with Arsenazo III and by direct uranium(IV)-phosphoric acid solution measurements.     

The separation of dimethylarsinic acid,methylarsonous acid,methylarsonic acid,arsenate and dimethylarsinous acid on the Hamilton PRP‐X100 anion‐exchange column

In order to separate the potential arsenite metabolites methylarsonous acid and dimethylarsinous acid from arsenite, arsenate, methylarsonic acid and dimethylarsinic acid, the pH‐dependent retention behaviour of all six arsenic compounds was studied on a Hamilton PRP‐X100 anion‐exchange column with 30 mM phosphate buffers (pH 5, 6, 7, 8 and 9) containing 20% (v/v) methanol as mobile phase and employing an inductively coupled plasma atomic emission spectrometer (ICP–AES) as the arsenic‐specific detector. Baseline separation of dimethylarsinic acid, methylarsonous acid, methylarsonic acid, arsenate and dimethylarsinous acid was achieved with a 30 mmol dm⁻³ phosphate buffer (pH 5)–methanol mixture (80:20, v/v) in 25 min. Arsenite is not baseline‐separated from dimethylarsinic acid under these conditions. Copyright © 1999 John Wiley & Sons, Ltd.     

Morphological silica-supported acid catalyst for esterification of aliphatic fatty acid

Abstract

Silica-supported acid catalysts were synthesized and characterized for composition, morphology, particle size distribution, and crystallinity. The catalysts are used for the esterification of long-chain aliphatic acids with alcohol to produce the corresponding ester. Process parameters such as time, temperature, and solvent ratio influence the conversion of fatty acid to ester. A supported catalyst was found to show higher catalytic activity as compared to the conventional sulfuric acid catalyst.