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51.
The need for accurate (< 0.06%) isotopic blends of 6Liand 7Li is explained and their preparation is discussed. It is shown that lithium must be determined at an accuracy level better than 0.035%. Four methods — acid-base titration with hydrochloric acid or benzoic acid, and weighing as sulphate or carbonate — were tested and improved for the precise and accurate analysis of lithium hydroxide solutions. The results of these four methods for a 0.1 M solution agreed within ± 0.02%. The preparation of pure isotopically enriched lithium hydroxide solutions, with specially purified cation- and anion-exchangers, is described. The prepared products contain as little as 100 μg of other alkali metals and 50 μg of alkaline-earth metals per gram of lithium, and are sufficiently free of anions to permit accurate chemical assay of lithium. No changes in the isotopic compositions of 99% 6Li or 99.99% 7Li were detected during the treatment. 相似文献
52.
S. V. Volkov S. V. Kutyakov A. N. Levov E. I. Polyakova Le Tuan An S. A. Soldatova P. B. Terentiev A. T. Soldatenkov 《Chemistry of Heterocyclic Compounds》2007,43(10):1260-1268
It has been established that on heating, 3-benzoyl-4-hydroxy-1-methyl-4-phenylpiperidine is ring-opened in the presence of
arylamines by a type of retroaldol reaction, with subsequent transamination of the intermediate Mannich base and the formation
of 3-arylamino-1-oxo-1-phenylpropanes. When using arylhydrazines this γ-piperidol is recyclized with the formation of 1,3-diarylpyrazoles
and their 4,5-dihydro derivatives. The mass spectral behavior of a series of 3-arylamino-substituted 1-phenylpropanones has
been studied.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1486–1495, October, 2007. 相似文献
53.
The σ-bonded organochromium (III) complexes resulting from the reduction of
-O-acyl benzylic bromides
with CrCl2., undergo an 1,5-transposition of the ester acyl functional group which allows, through selected experimental conditions either a selective access to the unmasked
-hydroxybenl ketones
or a new preparation of the 2-substituted benzo¦b¦furans
. The scope and limitations of the method are presented. 相似文献
54.
55.
Piasecki E Bresson S Lott B Bougault R Colin J Crema E Galin J Gatty B Genoux-Lubain A Guerreau D Horn D Jacquet D Jahnke U Jastrzebski J Kordyasz A Le Brun C Lecolley JF Louvel M Morjean M Paulot C Pienkowski L Pouthas J Quednau B Schröder WU Schwinn E Skulski W Töke J 《Physical review letters》1991,66(10):1291-1294
56.
57.
58.
Wei QH Zhang LY Yin GQ Shi LX Chen ZN 《Journal of the American Chemical Society》2004,126(32):9940-9941
Unusual AuI-AgI heterometallic complexes [Au5Ag8(mu-dppm)4{1,2,3-C6(C6H4R-4)3}(CCC6H4R-4)7]3+ (R = H 1, CH3 2, But 3) were isolated by reactions of polymeric silver arylacetylides (AgCCC6H4R-4)n with binuclear gold component [Au2(mu-dppm)2(MeCN)2]2+ (dppm = bis(diphenylphosphino)methane), in which cyclotrimerization of arylacetylide -CCC6H4R-4 affords trianion {1,2,3-C6(C6H4R-4)3}3- with an unprecedented mu5-bonding mode. Compounds 1(SbF6)3-3(SbF6)3 exhibit intense photoluminescence derived from an MLCT (Au5Ag8 --> CCC6H4R-4) transition, mixed with a metal cluster-centered excited states. 相似文献
59.
A M Le Roux C A Wium J R Joubert P P Van Jaarsveld 《Journal of chromatography. A》1992,581(2):306-309
Salbutamol concentrations were determined by high-performance thin-layer chromatography in the sera of two sets of ten volunteers at hourly intervals for 6 h after taking one 8-mg slow-release tablet. The influence of time lapse in processing of serum samples, i.e. centrifugation, extraction and chromatography, was studied. A statistical significant instability of salbutamol in the sera of patients was found which was not present in standard drug-free serum samples spiked with salbutamol and used for construction of standard curves. 相似文献
60.
Arylvinylidenecyclopropanes undergo a novel reaction upon heating at 150 °C with diaryl diselenide to give the corresponding 1,2-diarylselenocyclopentene derivatives in good to high yields within 1.5 h. The further transformation of 1,2-diarylselenocyclopentene derivatives has been disclosed. 相似文献