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431.
P. Chandrasekhar Reddy B. Polaiah B. Rangamannar 《Journal of Radioanalytical and Nuclear Chemistry》1989,137(1):51-56
A substoichiometric radiochemical method has been developed for the determination of selenium with potassium ethyl xanthate. The selenium ethyl xanthate complex formed was extracted into chloroform from borate buffer at pH 5. The effect of foreign ions on the extraction was studied. Microgram quantities of selenium could be conveniently determined with a fair degree of accuracy. The method has been successfully applied for the determination of selenium content in food stuffs such as Jaggery and Wheat powder. 相似文献
432.
P. Chandrasekhar Reddy B. Rangamannar 《Journal of Radioanalytical and Nuclear Chemistry》1996,213(1):9-19
The relative extent of extraction of mercury with potassium salts of ethyl, propyl, butyl, pentyl and benzyl xanthates has been studied employing a sensitive and rapid substoichiometric radiochemical method. The effect of pH on the extractability of mercury xanthate complexes into chloroform was investigated. Buffer solutions of pH 12, 11, 10, 9 and 5.5 were found to be suitable media for the maximum extraction of mercury as ethyl, propyl, butyl, pentyl and benzyl xanthate complexes, respectively. The procedures developed were utilized for the determination of mercury content in standard solutions and geological water samples collected in eight parts of Chittoor district of Andhra Pradesh. 相似文献
433.
434.
Chandrasekhar V Nagarajan L Gopal K Baskar V Kögerler P 《Dalton transactions (Cambridge, England : 2003)》2005,(19):3143-3145
The synthesis and structure of a novel decanuclear copper(II) cage is reported. The assembly of the cage is facilitated by the cumulative coordinative interaction of tert-butyl phosphonate, 2-pyridylpyrazole and hydroxide ligands with copper(II) ions. Magnetic studies of this decanuclear copper(II) cage indicate complex antiferromagnetic behaviour. 相似文献
435.
Chandrasekhar V Athimoolam A Reddy ND Nagendran S Steiner A Zacchini S Butcher R 《Inorganic chemistry》2003,42(1):51-59
The reaction of the dicarbaphosphazene, [NC(NMe(2))](2)[NPCl(2)] (2), with the sodium salt of 4-hydroxy-4'-vinylbiphenyl afforded the vinyl group containing monomer [NC(NMe(2))](2)[NP(Cl)(O-C(6)H(4)-p-C(6)H(4)-p-CH=CH(2))] (3). Replacement of the lone chlorine atom of 3 by oxygen nucleophiles gave [NC(NMe(2))](2)[NP(OR)(O-C(6)H(4)-p-C(6)H(4)-p-CH=CH(2))] [R = CH(2)CF(3) (4); C(6)H(5) (5); C(6)H(4)-m-CH(3) (6); C(6)H(4)-p-Br(7)]. The X-ray crystal structures of 3-7 reveal that all the cyclodicarbaphosphazenes have a planar N(3)PC(2) ring; the ring carbons are completely planar, while the geometry around phosphorus is pseudotetrahedral. The presence of weak intermolecular hydrogen bonding [C-H---X(Cl or Br), C-H---N, or C-H---pi] interactions in 3-7 leads to the formation of polymeric architectures in the solid-state. The monomers 4-7 can be polymerized by a free-radical initiator to afford the corresponding air-stable homopolymers 8-11. These have moderate molecular weights with polydispersity indices ranging from 1.33 to 1.58. All of these polymers have high glass transition temperatures and have excellent thermal stability. 相似文献
436.
P. Chandrasekhar Reddy B. Rangamannar 《Journal of Radioanalytical and Nuclear Chemistry》1994,187(2):107-112
A rapid and sensitive substoichiometric radiochemical method has been developed for the determination of microgram amounts of antimony employing potassium ethylxanthate as a reagent and chloroform as an extractant from sulfuric acid medium. The effect of associated ions on the extraction was studied. The method developed was successfully applied to determine the antimony content in standard solutions and synthetic mixture with an average error ±2.07% 相似文献
437.
438.
N. Chandrasekhar R. N. Bhave B. S. M. Rao 《Journal of Radioanalytical and Nuclear Chemistry》1985,93(2):73-80
Reactions of recoil38Cl atoms with CCl4 and C6H5Cl have been studied in presence of various high electron density scavengers. Relative reactivities of recoil38Cl towards the two components of these mixtures are determined using the model proposed by Urch. 相似文献
439.
B. Parthasarathi Chandrasekhar Ursula Schmid Rudolf Schmid Heinz Heimgartner Hans Schmid 《Helvetica chimica acta》1975,58(4):1191-1200
2,2-Dimethyl-3-dimethylamino-2H-azirine ( 1 ) reacts with the formyl-cycloalkanones 4 – 8 in boiling benzene to give the 1:1 adducts 13 – 17 in 60–99% yield (Table). These adducts are N′-[(2-oxo-cycloalkylidene)-methyl] derivatives of 2-amino-N, N-dimethylisobutyramide. The reaction mechanism (Scheme 6) is analogous to the mechanism of the reaction of 1 with carboxylic acids and cyclic enolisable 1,3-diketones [1]. Sulfinic acids and 1 undergo a similar reaction at ?15° to yield 2-sulfinamido-N, N-dimethylisobutyramides (Schemes 4 and 7), while sulfonic acids and the azirine 1 lead to a dimeric salt of type 20 , which with sodium hydroxide gives the dihydropyrazine 21 (Scheme 5). 相似文献
440.