Formation of 1-(2-aminophenyl)-5-ethoxy-4-methyl-3-phenylpyrazole and 4-methyl-3-phenylpyrazolo-[5,1-b]benzimidazole via an unusual enzotriazole ring opening

Successive treatment of N-[(1-ethoxy)alken-2-yl]benzotriazoles VII with butyllithium and trimethylsilyl chloride in TH-Fat — 78°C followed by refluxing in acidic acetone generated ring-opened 1-(2-aminophenyl)-5-ethoxy-4-methyl-3 phenylpyrazole VIII and 4-methyl-3 phenylpyrazolo[5, 1-b]benzimidazole IX.Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 775–780, June, 1996. Original article submitted May 14, 1996.     

Simultaneous comparison of δ31P and 1JPN for the assignment of E/Z-stereochemistry of the phosphorus-nitrogen double bond in iminophosphines R-P=N-R′

 The analysis of ³¹P and ¹⁵N NMR data of a series of 40 iminophosphines R-P=N-R′ reveals that the E/Z-stereochemistry of the PN double bond can be predicted on the basis of a simultaneous comparison of the values of δ³¹P and ¹J_PN. Received: 31 May 1996/Revised: 2 July 1996/Accepted: 5 July 1996     

HPLC determination of collectors used for the flotation of heavy metal minerals

 A reversed-phase HPLC-method for the separation of mixtures of collectors for the flotation of heavy metal minerals is described. It is based on a Nucleosil 5C18 column, isocratic elution and UV-detection at 238 nm. The mobile phase is methanol-water-5% phosphoric acid (40:60:4, v/v). The method is applied to the determination of six collectors in aqueous solutions from flotation processes. The relative standard deviations are 1.6–3.2% in the concentration range 2–10 mg/L. The detection limits are 1 μg/L for 8-hydroxyquinoline, dimethylglyoxime and salicylic acid, 2 μg/L for salicylhydroxamic acid and 5 μg/L for benzenetriazol and salicylaldoxime, respectively. Received: 19 April 1996/Revised: 14 August 1996/Accepted: 23 August 1996     

Multinuclear (11B, 31P) MAS NMR spectroscopy of borophosphates

¹¹B and ³¹P MAS NMR spectroscopy of three borophosphates was used to monitor their phase composition via the isotropic chemical shifts. CaBPO₅ and BPO₄ represent nearly pure samples, SrBPO₅ contains β-Sr₂P₂O₇ as well as BPO₄ as impurities. The anisotropic chemical shift data provide additional information on the geometry and connectivity of the BO₄ and PO₄ building units. Received: 25 July 1996 / Revised: 19 August 1996 / Accepted: 23 August 1996     

Simultaneous comparison of δ31P and 1JPN for the assignment of E/Z-stereochemistry of the phosphorus-nitrogen double bond in iminophosphines R-P=N-R′

 The analysis of ³¹P and ¹⁵N NMR data of a series of 40 iminophosphines R-P=N-R′ reveals that the E/Z-stereochemistry of the PN double bond can be predicted on the basis of a simultaneous comparison of the values of δ³¹P and ¹J_PN. Received: 31 May 1996/Revised: 2 July 1996/Accepted: 5 July 1996     

Multinuclear (11B, 31P) MAS NMR spectroscopy of borophosphates

¹¹B and ³¹P MAS NMR spectroscopy of three borophosphates was used to monitor their phase composition via the isotropic chemical shifts. CaBPO₅ and BPO₄ represent nearly pure samples, SrBPO₅ contains β-Sr₂P₂O₇ as well as BPO₄ as impurities. The anisotropic chemical shift data provide additional information on the geometry and connectivity of the BO₄ and PO₄ building units. Received: 25 July 1996 / Revised: 19 August 1996 / Accepted: 23 August 1996     

Synthesis of 3,4-diamino-1H-pyrazolo[3,4-d]pyrimidines

The reaction of 4-(amino-substituted)-2-methylthio-6-chloropyrimidine-5-carbonitriles with hydrazine and methylhydrazine was used to synthesize 3, 4-diamino-6-methylthio-1H-pyrazolo[3, 4-d]pyrimidines. It was shown that the formation of pyrazolopyrimidines proceeds through intermediate 6-hydrazinopyrimidine-5-carbonitriles.Department of Organic Chemistry, Vil'nyus University, Vil'nyus 2006. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 831–836, June, 1996. Original article submitted February 9, 1996.     

PLS-UV spectrophotometric method for the simultaneous determination of paracetamol, acetylsalicylic acid and caffeine in pharmaceutical formulations

 A simple and fast analytical procedure is proposed for the simultaneous determination of paracetamol, acetylsalicylic acid and caffeine in pharmaceuticals by means the partial least square treatment of the spectrophotometric absorbance data between 216 and 300 nm, taken at 5 nm intervals. The method involves the use of 8 standard mixtures of the three compounds assayed, considered at two concentration levels, and the measurement of the absorbance of samples in a 20% (v/v) ethanol in water solution previously filtered. In the analysis of real and synthetic samples precise and accurate values were obtained by the aforementioned procedure, providing in all cases variation coefficients and accuracy errors lower than 5% which agree with the tolerance level established by the pharmacopoeia for this kind of samples which is ±10%. Received: 10 May 1996 / Revised: 8 July 1996 / Accepted: 12 July 1996     

Furan derivatives of group V elements (review)

Methods of synthesis, physical properties, chemical transformations, and biological activity data for the furan derivatives of phosphorus, arsenic, and antimony are reviewed.Latvian Institute of Organic Synthesis, Riga. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 579–632. May, 1996. Original article submitted February 21, 1996.     

Separation of nonionic surfactants of the polyoxyethylene type by capillary electrophoresis

 Nonionic surfactants are widely used in commercial formulations as complex mixtures requiring efficient and selective separation methods. Capillary electrophoretic separations were carried out in electrolytes containing high amounts of organic solvents and anionic surfactants based on the formation of association complexes between analytes and anionic surfactants without micelle formation. Octyl- and nonylphenol polyethoxylates were separated as their ethoxylate homologues. Influences of the electrophoretic conditions like electrolyte concentration and pH, type and content of anionic surfactant and organic solvents were investigated. Received: 12 February 1996/Revised: 21 May 1996/Accepted: 5 June 1996     

Synthesis of new heterocyclic compounds based on n-benzyl(heptyl)-3-benzyl(heiityl)amino-4hydroxybutanamide

New derivatives of 1, 3-oxazolidine, 1,3-oxazolidin-2-one, 1,2,3-oxathiazolidin-2-one, and morpholine-2,3-dione respectively, containing the CH₂CONHR group, have been prepared by Me reactions of N-benzyl(heptyl)-3benzyl(hepiyl amino-4-hydroxybutanamide with 5-iodofurfural, ethyl trichloroacetate, thionyl chloride, and diethyl oxalate. The biological activity of the new compounds has been studied.Kuban State Technical University, Krasnodar 350072. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 711–716, May, 1996. Original article submitted January 29, 1996.     

Rapid resolution of five polynuclear aromatic compounds in a mixture by derivative non-linear variable-angle synchronous fluorescence spectrometry

 A combination of non-linear variable-angle synchronous fluorescence spectrometry with the derivative technique has been developed. A rapid simultaneous identification and quantitative determination of acenaphthene, carbazole, anthracene, 9,10-dimethylanthracene and perylene were achieved from a single spectrum by non-linear variable-angle synchronous fluorescence and combined derivative non-linear variable-angle synchronous fluorescence. The latter approach offered a further improvement in spectral resolution and analytical sensitivity. The usefulness of the proposed method was confirmed by adding known amounts of these five polynuclear aromatic compounds to the extract of waste water samples. Received: 5 August 1996/Revised: 11 September 1996/Accepted: 14 September 1996     

Rapid resolution of five polynuclear aromatic compounds in a mixture by derivative non-linear variable-angle synchronous fluorescence spectrometry

 A combination of non-linear variable-angle synchronous fluorescence spectrometry with the derivative technique has been developed. A rapid simultaneous identification and quantitative determination of acenaphthene, carbazole, anthracene, 9,10-dimethylanthracene and perylene were achieved from a single spectrum by non-linear variable-angle synchronous fluorescence and combined derivative non-linear variable-angle synchronous fluorescence. The latter approach offered a further improvement in spectral resolution and analytical sensitivity. The usefulness of the proposed method was confirmed by adding known amounts of these five polynuclear aromatic compounds to the extract of waste water samples. Received: 5 August 1996/Revised: 11 September 1996/Accepted: 14 September 1996     

Preparation and characterization of chelating resins loaded with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol for preconcentration of rare earth elements

 Chelating resins prepared by sorption of 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol (5-BrPADAP) on macroporous resins (Amberlite XAD-4 and XAD-7) were characterized. The adsorption properties (amount of chelating agent adsorbed per gram of resin, sorption kinetics, retention capacity, etc.) and the thermodynamic quantities of each adsorption process were determined. The retention of some rare earth elements (e.g. Er, Yb and Lu) on these chelating resins was studied in order to preconcentrate them for their determination by X-Ray fluorescence spectrometry. Received: 7 September 1995/Revised: 2 January 1996/Accepted: 10 January 1996     

Structure of paniculadine

The new alkaloid paniculadine has been isolated from the epigeal parts of the cultivated plant Aconitum paniculatum Lam., and its structure has been established by spectral and chemical methods.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 576–579, July–August, 1996. Original article submitted February 5, 1996     

Determination of acetaldehyde in liquid, solid and semi-solid food after pervaporation-derivatization

 A spectrophotometric method for the determination of acetaldehyde in liquid, semi-solid and solid food samples, employing the coupling of a continuous flow configuration to a pervaporation unit, has been proposed. It is based on the reaction of the analyte with fuchsin in acidic medium and subsequent formation of a coloured product (alkylsulphonic acid chromophore) with sodium sulphite, which was monitored spectrophotometrically. Variable sensitivity was obtained by altering the pervaporation temperature and the thickness of the membrane. The detection limits went down to 4.2 μg/mL and the precision was between 1.2 and 3.6%. Received: 5 August 1996/Revised: 16 October 1996/Accepted: 18 October 1996     

Determination of acetaldehyde in liquid, solid and semi-solid food after pervaporation-derivatization

 A spectrophotometric method for the determination of acetaldehyde in liquid, semi-solid and solid food samples, employing the coupling of a continuous flow configuration to a pervaporation unit, has been proposed. It is based on the reaction of the analyte with fuchsin in acidic medium and subsequent formation of a coloured product (alkylsulphonic acid chromophore) with sodium sulphite, which was monitored spectrophotometrically. Variable sensitivity was obtained by altering the pervaporation temperature and the thickness of the membrane. The detection limits went down to 4.2 μg/mL and the precision was between 1.2 and 3.6%. Received: 5 August 1996/Revised: 16 October 1996/Accepted: 18 October 1996     

Isosteric heat of adsorption and isochoric heat of vaporization and sublimation

Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1316–1317, May, 1996.     

Alkaloids ofDelphinium retropilosum

Elasine, methyllycaconitine, lycoctonine, and the new alkaloid delretine have been isolated from the plantDelphinium retropilosum, and the structure of delretine has been determined.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 739–742, September–October, 1996. Original article submitted March 4, 1996.     

Determination of iron and lead by flame atomic absorption spectrometry after preconcentration with sepiolite

By using a new adsorbent (sepiolite) an adsorption-elution and atomic absorption spectrometric method has been developed for the preconcentration and determination of Fe and Pb. Recoveries of the analytes were 82 ± 3% for Fe and 91 ± 2% for Pb at 95% confidence level. For Cu it was only 5 ± 1%. The recovery of iron could be increased to about 97 ± 1% by complexing with EDTA, the recovery of copper only to 57 ± 2%. The optimised method was applied to the determination of lead in metal materials (e.g. brass). Received: 20 February 1996 / Revised: 7 May 1996 / Accepted: 11 May 1996