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81.
Summary New complexes of chromium(III), manganese(II) and nickel(II) with methylhydrazinecarboxylate (MeCz) and of manganese(II) and
nickel(II) with 1,1-dimethylhydra-zinecarboxylate (Me2Cz) were prepared by reacting salts of the metals with CO2-saturated solutions of the hydrazines in EtOH. The compounds [Cr(MeCz)3]·2H2O, Ni(MeCz)2(H2O)3·MMH, Mn(MeCz)2(H2O)2(MMH = monomethylhydrazine) and M(Me2Cz)2(H2O)2 (M = Mn or Ni) were investigated using d.t.a., t.g.a., electronic and i.r. spectroscopy and by magnetic susceptibility measurements. 相似文献
82.
Hassan Sheibani 《Tetrahedron》2004,60(28):5931-5934
2-Pyrone derivatives were prepared in a one step procedure from readily available (chlorocarbonyl)phenyl ketene and 1,3-diketones such as 2,4-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-1,3-butanedione, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dimethyl-pyrimidine-2,4,6-trione and ethyl 2,4-dioxopentanoate. A mechanism is presented to account for the formation of the products. This method provides an easy route to prepare 3,4,5,6-tetrasubstituted 2-pyrones in good to excellent yields and in a short experimental time. 相似文献
83.
M. S. K. Youssef Kh. M. Hassan F. M. Atta M. S. Abbady 《Journal of heterocyclic chemistry》1984,21(5):1565-1568
3-Hydrazino-7-methyl-5-phenyl-5H-pyrazolo[3,4-c]-as-triazine 1 underwent ring closure and/or condensation reaction with formic acid, acetic acid, acetic anhydride and benzoyl chloride to afford 1H-pyrazolo-[3,4-d]-s-triazolo[3,4-c]-as-triazines 2, 5 and 7a and/or N-acyl derivatives 3, 4 and 6 . N-Acyl derivatives 3 and 6 underwent cyclisation reaction on treatment with phosphoryl chloride to give 5 and 7a . 3-Methyl-1-phenyl-8-aryl-1H-pyrazolo[3,4-e]-s-triazolo[34,-c]-as-triazines 7 were also prepared by the reaction of the hydrazono derivatives 8 wit thionyl chloride. On treatment of 1 with nitrous acid gave the 8H-pyrazolo[3,4-e]tetrazolo-[5,1-c]-as-triazine 9 . Compound 1 underwent ring closure with carbon disulphide or ethyl chloroformate to 1,7-dihydro-8H-pyrazolo[3,4-e]-s-triazolo[3,4-c]-as-triazine derivatives 10 and 12 . Reaction of 1 with ethyl acetoacetate or acetylacetone gave 3-pyrazolo derivatives 13 and 14 . 相似文献
84.
A simple, rapid and sensitive spectrophotometric method is described for the quantitative determination ofN-substituted phenothiazines. The method depends on the formation of a stable phenothiazine free radical cation by the use ofN-bromophthalimide as oxidising agent in a strong acid medium (methanol/ sulphuric acid 1 1 v/v). The produced red or violet color possesses absorption maximum range from 500 to 530 nm. A linear relationship exists between the absorbance at (max) and concentration in the range 5 to 40 g ml–1 with apparent molar absorptivities range from 6 × 103 to 12 × 1031 mol–1 cm–1. The color is developed instantaneously for all the studied phenothiazines except for thioproperazine mesylate, trifluoperazine dihydrochloride and prochlorperazine mesylate that require 25, 15 and 25 min, respectively, for complete reaction. The developed colors are stable over 24 h. The average % recovery is 99.85±0.61 to 100.28±0.95. The method was applied successfully to the microdetermination of chlorpromazine HCl, promethazine HCl, pericyazine, thioproperazine mesylate, perphenazine, prochlorperazine mesylate, trimeprazine tartrate and trifluoperazine 2HCl either in pure form or incorporated in their pharmaceutical preparations. The results of analysis are in good agreement with those of the official B.P. 1988 and USP XXII. 相似文献
85.
M. Amin H. H. Hassan E. M. Abdel-Bary 《Journal of polymer science. Part A, Polymer chemistry》1974,12(11):2651-2657
Styrene–butadiene rubber (SBR) charged with 50 phr of HAF carbon black has been found to show a positive temperature coefficient of resistivity close to 0.07/°C at 27°C. Beyond a point (75°C) of minimum conductivity, however, it behaves as a normal noncrystalline semiconductor with a resistivity which decreases with rise of temperature with an activation energy of 0.56 eV. Blending the composition with poly(vinyl chloride) (PVC) shifts the minimum towards lower temperatures. The descending branch of the conductivity versus reciprocal absolute temperature characteristic is probably associated with thermal expansion of tunnelling paths separating the conducting carbon particles. 相似文献
86.
Refat M. Hassan 《Journal of polymer science. Part A, Polymer chemistry》1993,31(5):1147-1151
The kinetics of decomposition of [Alg · Mn VIO42?] intermediate complex have been investigated spectrophotometrically at a constant ionic strength of 0.5 mol dm?3. The decomposition reaction was found to be first-order in the intermediate concentration. The results showed that the rate of reaction was base-catalyzed. The kinetic parameters have been evaluated and found to be ΔS? = ?103.88±6.18 J mol?1 K?1, ΔH? = 51.61 ± 1.02 kJ mol?1, and ΔG? = 82.57 ± 2.86 kJ mol?1, respectively. A reaction mechanism consistent with the results is discussed. © 1993 John Wiley & Sons, Inc. 相似文献
87.
Ali Tavassoli 《Tetrahedron letters》2005,46(12):2093-2096
Trimethyl (2S,3R)- and (2R,3R)-[2-2H1]-homocitrates, 10b and 10c respectively, and dimethyl (2S,3R)- and (2R,3R)-[2-2H1]-homocitric lactones, 11b and 11c respectively, have been synthesised from shikimic acid and [2-2H]-shikimic acid by a route which defines the stereochemistry of the two chiral centres in each compound. The NMR spectra of these products will enable the stereochemistry of the biological reaction catalysed by homocitrate synthase and by the protein from the nifV gene to be elucidated. 相似文献
88.
H. A. Azab A. M. El-Nady A. Hassan R. S. A. Azkal 《Monatshefte für Chemie / Chemical Monthly》1994,125(10):1059-1066
Summary Potentiometric equilibrium measurements have been made for the interaction of adenosine-5-mono-,-di-, and -triphosphate, and Co(II) with biologically important secondary ligands (malic, maleic, succinic, tartaric, citric, and oxalic acid). The formation of various 1:1:1 mixed ligand complexes inferred from the potentiometric titration curves. Initial estimates of the formation constants of the resulting species and the acid dissociation constants ofAMP,ADP,ATP and the secondary ligand acids have been refined with a computer program. In some systems, the ternary complexes are found to be more stable than the corresponding binary ones. In some ternary systems studied, interligand interactions or some cooperativity between the coordinate ligands, possibly H bond formation, have been found to be most effective in deciding the stability of the complexes formed in solution. Stabilities of mixed ligand complexes increase in the orderAMP <ADP <ATP. With respect to the secondary ligands, the formation constants of the mixed ligand complexes decrease in the following order: succinic > maleic > tartaric > malic > citric > oxalic acid.
Potentiometrische Untersuchung der Bildungsgleichgewichte von binären und ternären Komplexen von Kobalt(II) mit Adenosin-5-mono-, -di- und -triphosphat und einigen biologisch bedeutenden polybasischen Sauerstoffsäuren
Zusammenfassung Die Wechselwirkung vonAMP,ADP undATP mit Co(II) und einigen biologisch interessanten Sekundärliganden (Bernsteinsäure, Hydroxybernsteinsäure, Maleinsäure, Weinsäure, Zitronensäure und Oxalsäure) wurde bei 25°C und einer lonenstärke von 0.1M KNO3 potentiometrisch untersucht. Die Titrationskurven zeigen das Vorliegen von Species der Zusammensetzung 1:1:1 an. Die geschätzten Bildungskonstanten der Komplexe und die Dissoziationskonstanten der Liganden wurden mittels eines Computerprogramms optimiert. In einigen der untersuchten Systeme sind die ternären Komplexe stabiler als die sekundären. Die Stabilität der Verbindungen hängt im wesentlichen von Interligandwechselwirkungen — möglicherweise der Ausbildung von Wasserstoffbrückenbindungen — ab. Die Stabilität der Komplexe mit gemischten Liganden steigt in der ReihenfolgeAMP <ADP <ATP und fällt entsprechend der Serie Bernsteinsäure > Maleinsäure > Weinsäure > Hydroxybernsteinsäure > Zitronensäure > Oxalsäure.相似文献
89.
Mohamed Hilmy Elnagdi Mohamed Riffaat Hamza Elmoghayer Hassan Attia Elfaham Mohamed Mohamed Sallam Hikmat Hussein Alnima 《Journal of heterocyclic chemistry》1980,17(2):209-212
The 4-bromo-3-phenylpyrazol-5-ylhydrazonyl chlorides (Ia,b) and 1,2,4-triazol-5-ylhydrazonyl chlorides (IIa,b) were prepared via coupling of diazotized 4-bromo-3-phenyl-5-aminopyrazole (III) and 5-amino-1,2,4-triazole (IV) with α-chloro derivatives of acetylacetone and of ethyl aceto-acetate. Compounds Ia and IIa,b were utilised for the synthesis of several new heterocyclic derivatives. 相似文献
90.
Three‐center nuclear attraction integrals over exponential‐type functions are required for ab initio molecular structure calculations and density functional theory (DFT). These integrals occur in many millions of terms, even for small molecules, and they require rapid and accurate numerical evaluation. The use of a basis set of B functions to represent atomic orbitals, combined with the Fourier transform method, led to the development of analytic expressions for these molecular integrals. Unfortunately, the numerical evaluation of the analytic expressions obtained turned out to be extremely difficult due to the presence of two‐dimensional integral representations, involving spherical Bessel integral functions. % The present work concerns the development of an extremely accurate and rapid algorithm for the numerical evaluation of these spherical Bessel integrals. This algorithm, which is based on the nonlinear D transformation and the W algorithm of Sidi, can be computed recursively, allowing the control of the degree of accuracy. Numerical analysis tests were performed to further improve the efficiency of our algorithm. The numerical results section demonstrates the efficiency of this new algorithm for the numerical evaluation of three‐center nuclear attraction integrals. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献