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591.
Four simple and sensitive visible spectrophotometric methods (A–D) have been described for the assay of azathioprine (ATP) either in pure form or in pharmaceutical formulations. Methods A and B are based on the oxidation of ATP with excess N-bromosuccinimide (NBS) or chloramine-T (CAT) and determining the consumed NBS or CAT with a decrease in colour intensity of celestine blue (CB) (method A) or gallocyanine (GC) (method B), respectively. Methods C and D are based on the diazotisation of reduced azathioprine (RATP) with excess nitrous acid and estimating either the consumed nitrous acid (HNO2) with cresyl fast violet acetate (CFVA) (method C) or by coupling reaction of the diazonium salt formed with N-1-naphthyl ethylene diamine dihydrochloride (NED) (method D). All of the variables have been optimized and the reactions presented. The concentration measurements are reproducible within a relative standard deviation of 1.0%. Recoveries are 99.2–100.3%. 相似文献
592.
Reddy NC Fayazyddin SM Reddy RR Reddy GS Reddy SL Rao PS Reddy BJ 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(1-3):71-75
A sample of prehnite from Rayalaseema zone of Andhra Pradesh, India containing about 2.565 wt.% Fe(2)O(3) is used in the present work. The mineral has been characterized by EPMA, optical absorption, EPR, NIR and M?ssbauer techniques. M?ssbauer studies confirm the presence of iron as an impurity in two sites. An EPR study on powder sample confirm the presence of Fe(III) impurity in the mineral. Optical absorption spectrum also indicates that Fe(III) impurity is present in two sites with octahedral structure. NIR results are due to water fundamentals. 相似文献
593.
K. N. Murty P. V. S. Anand V. Lakshmi Prasannam 《Proceedings of the American Mathematical Society》1997,125(12):3533-3539
In this paper, the general solution of the homogeneous matrix difference system is constructed in terms of two fundamental matrix solutions. The general solution of the inhomogeneous matrix difference system is established by the variation of parameters formula. A unique solution of the two-point boundary value problem associated with the matrix difference system is constructed by applying the QR-algorithm and the Bartels-Stewart algorithm.
594.
M. Lakshmi Kantam V. Balasubrahmanyam K.B. Shiva Kumar G.T. Venkanna 《Tetrahedron letters》2007,48(41):7332-7334
The one-pot synthesis of propargylamines is achieved efficiently via a three component coupling of various aldehydes, alkynes and amines using zinc dust under mild reaction conditions and in the absence of a co-catalyst. Zinc dust was recovered quantitatively by simple centrifugation and reused. 相似文献
595.
Lal Dhar S. Yadav Rajesh Patel Vijai K. Rai Vishnu P. Srivastava 《Tetrahedron letters》2007,48(44):7793-7795
A new and efficient method of conjugate hydrothiocyanation of chalcones along with the preparation of a probe for demonstrating the utility of the resulting β-thiocyanato ketones in heterocyclic synthesis is reported. Chalcones undergo an efficient conjugate hydrothiocyanation with the task-specific ionic liquid (TSIL), 1-n-butyl-3-methylimidazolium thiocyanate ([bmim]SCN) followed by reaction with AcONH4 or an amine to afford chemically and pharmaceutically interesting 2-amino-1,3-thiazines at room temperature in a one-pot procedure. After isolation of the product, the ionic liquid [bmim]OH could be used for the synthesis of [bmim]SCN, thus allowing recycling of the TSIL for further use. 相似文献
596.
597.
Goud TV Srinivasulu M Reddy VL Reddy AV Rao TP Kumar DS Murty US Venkateswarlu Y 《Chemical & pharmaceutical bulletin》2003,51(8):990-993
Two new bromotyrosine-derived metabolites (1, 2) have been isolated along with the known compounds 3,5-dibromo-4-methoxyphenylacetonitrile, 3-bromo-4-methoxyphenylacetonitrile, 3-bromo-4-hydroxyphenylacetonitrile, 1-hydroxyuracil, 1-methoxyhemibastadin 2, purpuramine H and a steroid 5alpha,8alpha-epidioxycholest-6-en-3beta-ol from the sponge Psammaplysilla purpurea. Compounds 1 and 2 were characterized by interpretation of their spectral data. The antibacterial activity of these compounds is summarized. 相似文献
598.
Vijai N. Pandey 《Transition Metal Chemistry》1977,2(1):48-50
Summary [(-C5H5)Fe(NO)(CO)]2 and (-C5H5)Fe(NO)(CO)I are formed when a slow stream of NO is passed through a benzene solution of [(-C5H5)Fe(CO)2]2 and (-C5H5)Fe(CO)2 I respectively. Similarly NO reacts with (-C5H5)Fe(CO)(Ph3E)I and [(-C5H5)Fe(CO)2(Ph3E)]I, where E = P, As and Sb, to give (-C5H5)Fe(NO)(Ph3E)I and [(-C5H5)Fe(NO)2(Ph3E)]I respectively. The complexes were characterized by elemental analyses and i.r. spectra.Reprints of this article are not available. 相似文献
599.
M. Chandrasekharam Ch. Srinivasa Rao M. Lakshmi Kantam P. Yella Reddy 《Tetrahedron letters》2007,48(14):2627-2630
The synthesis of metalloporphyrazines with enhanced yields directly from substituted maleonitriles is described. The one-step procedure involves tetramerization using hexamethyldisilazane, p-toluenesulfonic acid and DMF in a sealed tube under microwave irradiation. The reaction time has been drastically reduced from 24 h by classical oil-bath heating to just 15 min. 相似文献
600.
Suvarapu Lakshmi Narayana Koduru Janardhan Reddy Somala Adi Narayana Reddy Jyothi Rajesh Kumar Ammireddy Varada Reddy 《中国化学会会志》2007,54(5):1233-1241
A new reagent, benzyloxybenzaldehydethiosemicarbazone (BBTSC) was synthesized and a new method was developed for the simple, highly selective and extractive spectrophotometric determination of palladium(II) with BBTSC at wave length 365 nm. The metal ion formed a yellow colored complex with BBTSC in acetate buffer of pH 5.0, which was easily extractable into cyclohexanol with 1:1 (Metal: Ligand) composition. The method obeys Beer's law in the range of 5–60 ppm. The molar absorptivity and Sandell's sensitivity were found to be 0.4 × 104 Lt. mol?1 cm?1 and 0.02661 μg cm?2, respectively. The correlation co‐efficient of the Pd(II)‐BBTSC complex was 0.9657, which indicated an excellent linearity between the two variables. The repeatability of the method was checked by finding the relative standard deviation (RSD) (n = 10), which was 0.321% and its detection limit 0.016875 μg.mL?1. The instability constant of the method was calculated by Asmus' method as 3.5714 × 10?4. The interfering effect of various cations and anions were also studied. The proposed method was successfully applied for the determination of palladium(II) in synthetic and water samples. The results were compared with those obtained using an atomic absorption spectrophotometer, testing the validity of the method. 相似文献