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81.
Charagondla Krishnaiah Marisetti Vishnu Murthy Komanduri S. V. D. Raghavacharyulu Bhavanipurapu J. Durga Prasad Rongali Bangaru Babu Khagga Mukkanti Ramesh Kumar 《Chromatographia》2009,69(9-10):1119-1122
A simple, sensitive and selective gradient reversed phase LC method has been developed for separation and determination of 2,3-dichlorobenzoyl cyanide and its regio isomers which is an intermediate of lamotrigine pure form. The separation was achieved on a reversed phase C-18 column using 0.01 M ammonium acetate buffer at pH 5.5 and methanol (50:50 v/v) mixture as solution A and methanol, water mixture (90:10 v/v) as solution B in a gradient elution at a flow rate of 1.5 mL min?1 with UV detection at 215 nm. The method is found to be selective, precise, linear, accurate and also robust. It was not only used for quality assurance, but also monitoring the synthetic reactions involved in the process development of Lamotrigine. The LC method is found to be simple, rapid, specific and reliable for the determination of unreacted levels of raw materials and isomers in reaction mixtures and finished product Lamotrigine. The method was fully validated as per ICH guidelines and results from validation confirm that the method is highly suitable for its intended purpose. 相似文献
82.
Biswanath Das Keetha Laxminarayana Martha Krishnaiah Duddukuri Nandan Kumar 《Helvetica chimica acta》2009,92(9):1840-1844
A stereoselective total synthesis of verbalactone has been achieved starting from commercially available hexanal. The sequence involves Maruoka allylation, diastereoselective iodine‐induced electrophillic cyclization, ring opening of epoxide, and Yamaguchi macrolactonization as the key steps. 相似文献
83.
G. Sankara Reddy A. Subba Reddy M. Venkata Subbaiah A. Krishnaiah 《Journal of solution chemistry》2010,39(3):399-408
The data on excess volume (V
E), density (ρ), viscosity (η) and speeds of sound (u) for the binary mixtures of tert-butylamine (TBA) + methyl acetate (MA), + ethyl acetate (EA), + butyl acetate (BA) and + isoamyl acetate (IAA) at 303.15 K
were measured experimentally over the entire range of composition. Speeds of sound were evaluated using Jacobson’s free length
theory (FLT) and Schaaffs’ collision factor theory (CFT). The viscosity data were analyzed on the basis of the corresponding
states approach and the Grunberg and Nissan treatment. The experimental results for excess volume, deviation in isentropic
compressibility and deviation in viscosity were discussed in terms of molecular interactions between unlike molecules. A Redlich-Kister
type equation was used to fit the experimental data on excess volume, deviation in compressibility and deviation in viscosity. 相似文献
84.
Synthesis of 6‐(5‐Methylisoxazol‐3yl)‐3‐alkyl Sulfanyl‐[1,2,4]triazolo‐[3,4‐b][1,3,4]thiadiazoles 下载免费PDF全文
A new series of isoxazole substituted fused triazolo‐thiadiazoles have been synthesized by the cyclocondensation of 5‐methylisoxazole‐3‐craboxylic acid and 4‐amino 1,2‐4‐triazole‐ 3,5‐dithiol using phosphorous oxychloride. The cyclised intermediate 6‐(5‐methylisoxazol‐3‐yl)‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazole‐3‐thiol later on S‐alkylated with different alkyl halides in ethanol to give the title products in good to excellent yields. 相似文献
85.
A novel series of bis (phenylimino dihydro thiazolyl-2H-chromene) derivatives have been synthesized through an efficient one-pot multicomponent approach involving different substituted of 3-(2-bromoacetyl)-2H-chromen-2-ones, phenyl isothiocyanates and para-phenylenediamine in presence of dimethylformamide solvent. The target compounds were obtained in a shorter reaction time through simple reaction work up with good yields. All the synthesized products were characterized by their spectral and analytical data like IR, 1H NMR, 13C NMR, Roesy, and mass spectral data. 相似文献
86.
87.
The authors consider various procedures for testing the hypotheses of independence of two sets of variables and certain regression coefficients are zero under multivariate regression model. Various properties of these procedures and the asymptotic distributions associated with these procedures are also considered. 相似文献
88.
Charagondla Krishnaiah Anumula Raghupathi Reddy Ramesh Kumar Khagga Mukkanti 《中国化学会会志》2010,57(1):68-74
A simple, rapid, selective and sensitive high performance liquid chromatographic method was developed for the separation and quantification of o‐Toluene Sulphonamide and its positional isomers which is an intermediate of Zafirlukast drug substance using a chiral column. Elution time was below 10 min in normal phase mode and ultra violet detection was carried out at 220 nm. Efficient separation was achieved on a Chiralcel OD‐H column using of n‐Hexane and 2‐Propanol mixture (50:50 v/v) as isocratic at 1.0 mL min−1 flow rate. Resolutions between m‐Toluene Sulphonamide and p‐Toluene Sulphonamide isomers of o‐Toluene Sulphonamide were found to be >; 2.5. The calibration graphs for m‐Toluene Sulphonamide and p‐Toluene Sulphonamide isomers of o‐Toluene Sulphonamide were linear (R2 > 0.999) when ranging from the limit of quantitation to 0.5%. The method is found to be selective, precise, linear, accurate and also robust. It was used for not only Quality assurance but also monitoring the synthetic reactions involved in the process development of Zafirlukast. The liquid chromatographic method is found to be specific and reliable for the determination of unreacted levels of positional isomers in reaction mass. This method was successfully validated according to the International Conference Harmonization (ICH) guidelines (Validation of Analytical Procedures: Test and Methodology Q2). 相似文献
89.
B. Munirathinam M. Krishnaiah M. Manivel Raja 《Journal of Physics and Chemistry of Solids》2010,71(12):1763-1767
Lanthanum based mixed valence manganite system La1−xCax−0.08Sr0.04Ba0.04MnO3 (LCSBMO; x=0.15, 0.24 and 0.33) synthesized through the sol-gel route is systematically investigated in this paper. The electronic transport and magnetic susceptibility properties are analyzed and compared, apart from the study of unit cell structure, microstructure and composition. Second order phase transition is observed in all the samples and significant difference is observed between the insulator to metal transition temperature (TMI) and paramagnetic (PM) to ferromagnetic (FM) transition temperature (TC). In contrast to the insulating FM behaviour usually observed in La1−xCaxMnO3 (LCMO) for x=0.15, a clear insulator to metal transition is observed for LCSBMO for the same percentage of lanthanum. The temperature dependent resistivity of polycrystalline pellets, when obeying the well studied law ρ=ρo+ρ2T2 for T<TMI, is observed to differ significantly in the values of ρo and ρ2, with the electrical conductivity increasing with x. The variable range hopping model has been found to fit resistivity data better than the small polaron model for T>TMI. AC magnetic susceptibility study of the polycrystalline powders of the manganite system shows the highest PM to FM transition of 285 K for x=0.33. 相似文献
90.
Emmadi Narender Reddy Atmakur Krishnaiah Tadikamalla Prabhakar Rao 《Tetrahedron: Asymmetry》2013,24(12):724-728
The stereoselective total synthesis of Ieodomycin A and B, bioactive secondary metabolites from marine sources with potent anti-microbial activity was achieved starting from commercially available geranial. The key steps involved in the synthetic sequence of Ieodomycin A and B are the Sharpless asymmetric epoxidation, the formation of a β-ketoester, and the 1,3-anti reduction. The synthesis of C-3 epimer of Ieodomycin A and B was also accomplished in good yields. 相似文献