Application of Non‐Stop‐Flow Differential Pulse Voltammetry at a Tubular Detector of Silver Solid Amalgam for Electrochemical Determination of Lomustine (CCNU)

An application of the flow differential pulse voltammetry with tubular detector based on silver solid amalgam for determination of antineoplastic drug lomustine in pharmaceutical preparations is presented. The highest sensitivity was obtained in [0.10 mol dm^?3 MES; 2.00 mol dm^?3 NaCl; pH 6.0]:EtOH (9 : 1) with flow rate 0.50 mL min^?1, and the magnitude of the modulation amplitude ?0.070 V. The calibration dependence was linear in the range 1×10^?6–1 × 10^?4 mol dm^?3 (R²=0.999). The limit of detection was 1.5×10^?7 mol dm^?3. This method was successfully used for determination of lomustine in real samples of chemotherapy drug CeeNU Lomustine 40 mg.     

Electrochemical Biosensors Based on Enzymatic Reactor of Silver Solid Amalgam Powder for Measurements in Flow Systems

An enzymatic reactor based on silver solid amalgam powder was suggested as the main part of biosensors in flow systems for the first time. Biosensors were tested with following enzymes: ascorbate oxidase, glucose oxidase, catalase, tyrosinase and laccase. The current response of each biosensor was optimized with respect to the detection potential, flow rate, the injection and reactor volume. Relative standard deviation for detection with the studied enzymes was found to be in the range of 0.81–2.1 %. The biosensor with the ascorbate oxidase reactor was used for determination of ascorbic acid in the vitamin tablets Celaskon.     

Synthesis of new-type 1,3,6-triazocine via intramolecular reactions of iodocyclization and [3+2] azido cycloaddition

Selective iodocyclization of 6-(alkenylamino)-1-allylpyrazolo[3,4-d]pyrimidines provided hydrogenated derivatives of 1-allyl-8(9)-iodomethylimidazo(pyrimido)[1,2-a]pyrazolo[4,3-e]pyrimidines which were further reacted with NaN₃ at 75°С to 80°С to give a series of new-type 1,3,6-triazocines annulated with the pyrazole, pyrimidine, imidazole (or pyrimidine), and 1,2,3-triazole rings. The compounds synthesized were structurally characterized by analytical, spectral (IR, ¹H and ¹³C NMR, HPLC-mass), and X-ray diffraction data.     

One‐Step Ring Opening Metathesis Block‐Like Copolymers and their Compositional Analysis by a Novel Retardation Technique

Using a one‐step synthetic route for block copolymers avoids the repeated addition of monomers to the polymerization mixture, which can easily lead to contamination and, therefore, to the unwanted termination of chain growth. For this purpose, monomers ( M1 – M5 ) with different steric hindrances and different propagation rates are explored. Copolymerization of M1 (propagating rapidly) with M2 (propagating slowly), M1 with M3 (propagating extremely slowly) and M4 (propagating rapidly) with M5 (propagating slowly) yielded diblock‐like copolymers using Grubbs’ first ( G1 ) or third generation catalyst ( G3 ). The monomer consumption was followed by ¹H NMR spectroscopy, which revealed vastly different reactivity ratios for M1 and M2 . In the case of M1 and M3 , we observed the highest difference in reactivity ratios (r₁=324 and r₂=0.003) ever reported for a copolymerization method. A triblock‐like copolymer was also synthesized using G3 by first allowing the consumption of the mixture of M1 and M2 and then adding M1 again. In addition, in order to measure the fast reaction rates of the G3 catalyst with M1 , we report a novel retardation technique based on an unusual reversible G3 Fischer‐carbene to G3 benzylidene/alkylidene transformation.     

Two-dimensional four-line models of the Ising model type

We briefly describe the theory of root transfer matrices for four-line models with the field in the new indexless form. We use theoretical and numerical methods to reveal new effects in the theory of singular points and phase transitions. A substantial part of the results is obtained using a numerical algorithm that drastically (at least exponentially) reduces the computational complexity of Ising-type models by using the extremely sparse root transfer matrix. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 149, No. 2, pp. 281–298, November, 2006.     

Synthesis and Crystal Structures of Two Schiff Bases of 2-(Methylthio)aniline with Halogenated Salicylaldehydes

Abstract  

The crystal structures of the new compounds 5-bromo-N-[2-(methylthio)-phenyl]salicylaldimine (1), and 3,5-dichloro-N-[2-(methylthio)phenyl]salicylaldimine (2) were obtained by single crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space group P2₁/c with a = 14.1479(14) ?, b = 5.3058(3) ?, c = 19.104(3) ?; β = 106.218(10)°; and Z = 4. Compound 2 crystallizes in the triclinic space group $ P\bar{1} $ P\bar{1} with a = 11.2249(10) ?, b = 13.863(2) ?, c = 13.9055(9) ?; and α = 99.378(15)°, β = 102.866(7)°, γ = 91.375(11)°; and Z = 6. Details of the synthesis, structures, and spectroscopic properties of the new compounds are discussed.     

Thiapyrylium trifluoroacetates and thiacyclohexanes from 1, 5-diketones

1,5-Diketones react with hydrogen sulfide and trifluoroacetic acid to give a mixture of thiapyrylium trifluoroacetates or sym-octahydrothiaxanthylium trifluoroacetates with thiacyclohexanes or perhydrothiaxanthenes, respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 916–919, July, 1972.