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41.
An amperometric method for the determination of thiocarbamyl sulphonamides has been developed, based on the cleavage of the S-N bond by hydriodic acid. The method can also be applied for the cleavage of the S-S bond in thiuram disulphides and dibenzothiazyl disulphide, and thus provides a useful means for the estimation of these compounds as well. 相似文献
42.
Krishna C. Joshi Vijai N. Pathak Raj Pal Singh 《Monatshefte für Chemie / Chemical Monthly》1980,111(6):1343-1350
Several new 2-(fluoroaryl)-3-dialkylaminomethylindoles, 3-acetyl-2-(fluoroaryl)-indoles, 2-(fluoroaryl)-3-indolylglyoxamides and corresponding tryptamines have been prepared as possible psychopharmacological agents. 2-(Fluoroaryl)-indoles have been synthesized by theFischer indole synthesis. 2-(Fluoroaryl)-indoles on treatment with oxalyl chloride and subsequent reaction with amines, gave 2-(fluoroaryl)-3-indolylglyoxamides. Some of these indolylglyoxamides were reducted with lithium aluminium hydride, to the corresponding tryptamines. 2-(Fluoroaryl)-indoles when subjected toMannich reaction afforded 3-dialkylaminomethyl-2-(fluoroaryl)-indoles. All these new compounds have been characterized by IR spectral studies.Possible Psychopharmacological Agents, Part XII, Part XI, J. Indian. Chem. Soc.57, 423 (1980). 相似文献
43.
Molecular mechanism of physical gelation of hydrocarbons by fatty acid amides of natural amino acids
Asish Pal 《Tetrahedron》2007,63(31):7334-7348
A variety of fatty acid amides of different naturally occurring l-amino acids have been synthesized and they are found to form gels with various hydrocarbons. The gelation properties of these compounds were studied by a number of physical methods including FTIR spectroscopy, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, rheology, and it was found that gelation depended critically on the fatty acid chain length and the nature of the amino acid. Among them l-alanine based gelators were found to be the most efficient and versatile gelators as they self-assemble into a layered structure to form the gel network. Mechanisms for the assembly and formation of gels from these molecules are discussed. 相似文献
44.
A very simple, highly-sensitive and selective quenchofluorimetric method for the rapid determination of molybdenum(VI) in aqueous media is described. The method is based on the instantaneous quenching action by the metal-ion upon the native fluorescence of bathophenanthrolinedisulphonate (4,7-diphenyl-1,10-phenanthrolinedisulphonate) solution [lambda(ex) (max) 288 nm; lambda(em) (max) 444.8 nm] in the optimum pH-range of 3.0-3.7 at room temperature (25 +/- 5 degrees ). The fluorescence quenching is co-linear in the range of 0.01-1.0 ppm molybdenum. Large excesses of over 50 cations, anions and some common complexing agents were found to have no interference. Cu, Ni, Co, Fe and V can be tolerated only up to the corresponding amount of molybdenum. Interference from greater amounts can however be removed by a one-step ion-exchange separation process. The developed method was successfully tested over several standard alloys, synthetic mixtures of various compositions, factory effluents and in spiked environmental waters. 相似文献
45.
Ionic discotic liquid crystals: synthesis and characterization of pyridinium bromides containing a triphenylene core 总被引:1,自引:0,他引:1
Five novel pyridinium salts tethered with hexaalkoxytriphenylene molecules were synthesized by the quaternization of pyridine with ω-bromo-substituted triphenylene derivatives. Their chemical structures were determined by 1H NMR, 13C NMR, IR, UV spectroscopy and elemental analysis. The thermotropic liquid crystalline properties of these salts were investigated by polarizing optical microscopy and differential scanning calorimetry. These triphenylene-based pyridinium salts with bromide as counterion were found to be mesomorphic over a wide temperature range. 相似文献
46.
B. S. Randhawa Anand Pal Singh R. P. Sharma P. S. Bassi 《Journal of Radioanalytical and Nuclear Chemistry》1988,128(3):165-179
The solid state reactions between ferrous oxalate dihydrate i.e. FeC2O4.2H2O and unsubstituted/ substituted aniline hydrochlorides have been studied. The products [FeCl/oxH/. AN-Cl] have been characterized by elemental analysis, infrared and Mössbauer spectroscopic techniques. The kinetic studies for the reactions have been performed at various temperatures for fixed particle sizes at constant compaction. The following order of reactivity has been observed: unsubstituted > p-substituted > m-substituted o-substituted. 相似文献
47.
Photocatalytic reactions occurring at semiconductor particles/solution interfaces can be applied to organic syntheses. In this review article, examples of photocatalytic syntheses of cyclic amino acids by suspended semiconductor particles, e.g., titanium(IV) oxide or cadmium(II) sulfide are introduced and interpreted. Different from the photocatalytic decomposition of pollutants under aerobic conditions, selective conversion of organic compounds can be driven by the photocatalytic reactions under deaerated conditions. 相似文献
48.
Reaction of hexaamminecobalt(III) chloride with the silver salt of methanesulphonic acid in aqueous medium (1:3 molar ratio) forms hexaamminecobalt(III) methanesulphonate, [Co(NH3)6](CH3SO3)3, in high yield. This cobalt(III) complex has been characterized by spectroscopic techniques (UV/visible, IR and NMR) and its solubility product determined. The X-ray crystal structure shows that the [Co(NH3)6]3+ cations interact at the second sphere by sharing edges with the anions, via N–H O hydrogen bonds. The structure is related to that of [Co(NH3)6]Cl(CH3SO3)2, but is modified to accommodate additional anions in place of Cl−. 相似文献
49.
Anuradha Mishra Malvika Bajpai Sunita Pal Monika Agrawal Sushant Pandey 《Colloid and polymer science》2006,285(2):161-168
The application of Tamarindus
indica seed mucilage (Tam), a food grade polysaccharide, and its acrylamide grafted copolymer as flocculants was assessed for the first time for removal of various types of dyes from model textile wastewater containing azo, basic, and reactive dyes. Acrylamide grafted T. indica mucilage (Tam-g-PAM) was obtained by ceric ion initiated polymerization technique. A series of contact time experiments were conducted to assess the system variables such as concentrations of mucilage and dyes and pH. These flocculants reduce the dye concentration by flocculation and settling. The grafted copolymer, Tam-g-PAM showed better results for dye removal. The optimal flocculant concentration, which was required to effect flocculation, was independent of dye concentration within the range examined. Both the flocculants performed better for removal of azo dyes than for reactive and basic dyes. 相似文献
50.
Sadasivam Senthilkumar Sukhendu Nath Haridas Pal 《Photochemistry and photobiology》2004,80(1):104-111
Experimental results on various photophysical properties of coumarin‐30 (C30) dye, namely, Stokes' shift (Δv), fluorescence quantum yield (τf), fluorescence lifetime (τf), radiative rate constant (kf) and nonradiative rate constant (knr), as obtained using absorption and fluorescence measurements have been reported. Though in most of the solvents the properties of C30 show more or less linear correlation with the solvent polarity function, Δf= [(ε ‐ 1)/(2ε+ 1) ‐ (n2 ‐ 1)/ (2n2+ l)], they show unusual deviations in nonpolar solvents at one end and in high‐polarity protic solvents at the other end. From the solvent polarity and temperature effect on the photophysical properties of the dye, following inferences have been drawn: ( 1 ) in nonpolar solvents, the dye exists in a nonpolar structure, where its 7‐NEt2 substituent adopts a pyramidal configuration and the amino lone pair is out of resonance with the benzopyrone π cloud; ( 2 ) in medium to higher polarity solvents, the dye exists in a polar intra‐molecular charge transfer structure, where the 7‐NEt2 group and the 1,2‐benzopyrone moiety are in the same plane and the amino lone pair is in resonance with the benzopyrone π cloud; ( 3 ) in protic solvents, the dye‐solvent intermolecular hydrogen bonding influences the photophysical properties of the dye; and ( 4 ) in high‐polarity protic solvents, the excited C30 undergoes a new activation‐controlled nonradiative deexcitation process because of the involvement of a twisted intra‐molecular charge transfer (TICT) state. Contrary to most other TICT molecules, the activation barrier for this deexcitation process in C30 is observed to increase with solvent polarity. A rational for this unusual behavior has been given on the basis of the solvent polarity‐dependent stabilization and crossing of relevant electronic states and the relative propensity of interconversion among these states. 相似文献