猪去氧胆酸化学 III: 猪去氧胆酸转变成鹅去氧胆酸和熊去氧胆酸

在从猪去氧胆酸合成熊去氧胆酸和鹅去氧胆酸时, 其关键是在羟基移位的一系列反应中保留5β构型. 本文报导了应用1,2-酮基移位反应, 实现上述转化的过程.     

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.     

Synthesis of orotic acid from maleuric acid

Summary The bromination of maleuric acid or its methyl ester, with subsequent alkaline treatment of the intermediate bromides, leads to the formation of orotic acid.The authors wish to thank B. V. Lopatin, I. S. Runge, and V. A. Shyapochnikov for making the spectral studies.     

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.     

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.

     

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 dibenzylphosphinous acid with formic acid esters

Summary The reaction of dibenzylphosphinous acid with formic acid esters was studied in the presence of sodium. Here we obtained dibenzylmethylolphosphine oxide and the enol form of the phenylalkoxybenzylphosphorylacetaldehyde.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1085–1088, June, 1965     

Aminophosphonic and aminophosphinic acid analogues of aspartic acid

4-Oxoazetidin-2-ylphosphonates and phosphinates, obtained from Arbusov reactions of 4-acetoxyazetidin-2-one and 4α-acetoxy-3β-phthalimido-2-one with a variety of phosphites and phosphonites, were hyrdolysed to β-phosphono- and β-phosphino β-alanine (phosphono- and phosphinoaspartic acid) derivatives. In model studies for their incorporation in peptides, conditions for the selective removal of protecting groups for carboxylic acids, phosphonic and phosphinic acids, and amines, in derived di- and tri-peptides were investigated. Alanyl and alanyl alanyl peptide incorporation into bacteria was studied.     

Protonation study of peroxynitric acid and peroxynitrous acid

The equilibrium structures and harmonic vibrational frequencies of peroxynitric acid (HOONO(2)) and seven structures of protonated peroxynitric acid, along with peroxynitrous acid (HOONO) and its 12 protonated peroxynitrous acid structures, have been investigated using several ab initio and density functional methods. The ab initio methods include second-order Moller-Plesset perturbation theory, quadratic configuration interaction, including single and double excitations theory (QCISD), and the QCISD(T) methods, which incorporate a perturbational estimate of the effects of connected triple excitation. The Becke three-parameter hybrid functional combined with Lee, Yang, and Parr correlation function is the density functional method used. The lowest energy form of protonated peroxynitric acid is a complex between H(2)O(2) and NO(+) rather than between H(2)O and NO(2) (+). For peroxynitrous acid, a complex between H(2)O(2) and NO(2) (+) is found to be the lowest energy structure. The ab initio proton affinity (PA) of HOONO and HOONO(2) is predicted to be 182.1 and 175.1 kcal mol(-1), respectively, at the QCISD(T)/6-311++G(3df,3pd) level of theory. The results are contrasted with an earlier study on nitrous acid, and is shown that peroxynitric acid and peroxynitrous acid have a smaller PA than nitrous acid.     

Uranium leaching using citric acid and oxalic acid

Journal of Radioanalytical and Nuclear Chemistry - Citric acid and oxalic acid, the main metabolites of fungi, have different leaching effects on uranium ore. Herein, uranium leaching from a...