NOPR Collection:

Preparation of fine sized boehmite

Tue, 01 Jul 1997 00:00:00 GMT

Title: Preparation of fine sized boehmite Authors: Sidheswaran, P; Bhat, A N Abstract: Preparation of boehmite of fine particle size (< 6 μ) was attempted by three different routes. Flash calcinations of gibbsite at about 325°C for 2 h gave the desired material. However, the other two methods, dehydration of pseudoboehmite (at 110°C) and hydrothermal neutralization of aluminate with acid gave boehmite of larger particle size (11 and 17 μ, D₅₀). Page(s): 206-209

Improved synthesis of trifluoromethyl substituted 3-spiro indolines and 3-indolyimines under microwaves irradiation

Tue, 01 Jul 1997 00:00:00 GMT

Title: Improved synthesis of trifluoromethyl substituted 3-spiro indolines and 3-indolyimines under microwaves irradiation Authors: Dandia, Anshu; Saha, Mitali; Shivpuri, Asha Abstract: The trifluoromethyl substituted 3' - phenyl spiro [3 H -indole-3-2' -thiazolidine]- 2,4' -(1H)-diones(VI) and 4,5-dihydro-3-phenyl spiro [2H-1,3-benzothiazine-2:3-[3H]-indole]-2',4 (1'H, 3H)-diones (VII) have been synthesized by the cyclo condensation of 3-indolylimines (III) with thioacids viz. Mercaptoacetic acid (IV a)/2-mercapto propionic acid (IV b) and O mercapto benzoic acid (V), under microwave in open borosil glass vessels using either ethanol as energy transfer medium or silica gel as mineral solid support. The former compound, (III) have been synthesized by the condensation reaction of indole-2,3- diones (I)and trifluoromethyl substituted anilines (II) under microwave irradiation. The comparison of synthetic procedure under microwave and classical thermal method indicates tremendous reduction in time, higher selectivity, yield and purity compared to traditional methods. Characterization of the products has been done on the basis of elemental analyses; IR ¹HNMR and ¹⁹FNMR spectral data Representative compounds have been 'Screened in vitro for antifungal activity against Rhizoctonia solani, Fusarium oxysporum and Colletotrichum capsici. Page(s): 201-205

Spectrophotometric determination of Isoproturon and Metoxuron in technical and formulation grade samples using citric acid-acetic anhydride reagent

Tue, 01 Jul 1997 00:00:00 GMT

Title: Spectrophotometric determination of Isoproturon and Metoxuron in technical and formulation grade samples using citric acid-acetic anhydride reagent Authors: Raju, K Ramakrishnam; Akella, S R K M; Lingaiah, N; Reddy, A Rama Krishna; Bhalerao, U T Abstract: A spectrophotometric method for the determination of Isoproturon and Metoxuron in technical and formulation grade samples based on the reaction with citric acid-acetic anhydride reagent has been developed. The absorption maxima of the coloured compounds so formed are 408 and 409 nm and the molar absorptivities are 1.69 x 10² and 1.13 x 10² L mol^-1 cm^-1 respectively. The reaction variables have been optimized and the reaction mechanism is discussed. The method is simple, convenient and successfully applied for the determination of Isoproturon and Metoxuron in technical and formulation grade samples. The percent relative standard deviation is found to be in the range 0.6-1.55 for Isoproturon and 1.24-1.90 for Metoxuron. Page(s): 196-200

Spectrofluorimetric determinations of chromium, selenium and manganese in their mixtures and their application to environmental and biological samples

Tue, 01 Jul 1997 00:00:00 GMT

Title: Spectrofluorimetric determinations of chromium, selenium and manganese in their mixtures and their application to environmental and biological samples Authors: Pal, B K; Ahmed, M J U; Chakrabarti, A K; Chakraborty, D Abstract: Highly sensitive and selective fluorimetric methods have been developed for sequential determination of ultratrace amounts of toxic metals, Cr, Se, Mn present in mixtures and in biological samples. These are based on a novel oxidative action of Cr(VI), Se(IV) and Mn(Vll) on nonfluorescent 2-(α-pyridyl) thioquinaldinamide, PTQA, in different acidic media, Le., 0.9-0.54 M H₂SO₄ (for Cr), 0.05-0.15 M H₂SO₄ (for Se) and 0.033-0.833 M H₃PO₄ (for Mn) to produce intensely fluorescent oxidized product of the reagent, having excitation and emission wavelength maximum at 360 and 500 nm respectively. Sequential determination of Cr, Se and Mn in their mixtures at different mass ratios has been achieved with high accuracies. The method has been applied to the environmental analysis of biological materials, e.g., aquatic fish samples after destruction of organic matter with HNO₃HCIO₄-H₂SO₄. The standard deviation for analysis is ±0.003 for Cr; ±0.004 for Se and ±0.0014 for Mn in mixture while their corresponding values are ±0.3, ±0.3 and ±0.5 in fish samples. The methods are simple, rapid and highly reproducible and do not require any cleanup or enrichment step. Page(s): 191-195