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51.
The thermal decomposition of alkaline earth formates has been studied. Experiments with single crystals, compacts and powders of strontium formate demonstrate that the method of sample presentation can affect the rate of decomposition.For anhydrous calcuim, strontium and barium formates, isothermal kinetic runs show that the decompositions follow the Erofeev law, In(l-α) = ktn; the measured activation energies were 199.4, 228 and 270 kJ/mol respectively. 相似文献
52.
Thomas F.O. Lim Jerry K. Myers Greg. T. Rogers Paul Ronald Jones 《Journal of organometallic chemistry》1977,135(2):249-259
The regioselectivity of the hydroboration of the methylchlorovinylsilanes, ClnMe3?nSiCHCH2 (n= 0 ? 3), has been investigated using BH3←THF, 9-BBN, disiamyl- and dicyclohexylborane. Methylation of the adducts with methylmagnesium bromide is complicated by formation of tetraalkylboronates. Alkaline hydrogen peroxide oxidation of the boronates gives reasonable yields of the corresponding α- and β-trimethylsilylethanols forn= 0 and 1. Forn= 2 and 3, conversion of the adducts to the corresponding α- and β- deuteroethylsilanes by treatment with excess sodium methoxide in methanol-0-d provides a more effective means of derivatization. Addition of the alkenes,n= 2 or 3, to excess BH3←THF givesca. 90% of the α-boro-organo-chlorosilanes. For all of the alkenes, the dialkylboranes giveca. 80% of the β-boron adducts. 相似文献
53.
Webster Hughes 《Journal of statistical physics》1985,41(5-6):975-1013
In this paper I combine techniques recently developed by Charles Fefferman with the well-known methods of Joel Lebowitz and Elliott Lieb to resolve some technical problems left unsettled by Lebowitz and Lieb's fundamental 1972 paper The constitution of matter: Existence of thermodynamics for systems composed of electrons and nuclei. 相似文献
54.
Guldi DM Zilbermann I Anderson G Kotov NA Tagmatarchis N Prato M 《Journal of the American Chemical Society》2004,126(44):14340-14341
Novel organic (positively charged fullerene)-inorganic (negatively charged CdTe nanoparticle) nanoensembles were devised through electrostatic interactions and probed as versatile donor-acceptor hybrids. Photoirradiation of their homogeneous solutions, containing the electrostatically packed components, let to very long-lived (1.3 ms) charge separated states. 相似文献
55.
Synthetic approaches to, and the chemistry of, phospholes, benzophospholes and dibenzophospholes are reviewed and particular attention is paid to the possible aromatic character of the phosphole ring. Systems containing the 2H- and 3H-phosph(V)ole nucleus are surveyed as are phosphole derivatives containing pentacovalent and six-coordinate phosphorus. Stereochemical considerations in the more complex phosphole derivatives are discussed. 相似文献
56.
It is shown from SCF-MO studies using localised orbitals that the angles between the lone-pairs in H2O and H2S are 115° and 127°, in agreement with the qualitative predictions of the Sidgwick-Powell theory. 相似文献
57.
Gupta HK Stradiotto M Hughes DW McGlinchey MJ 《The Journal of organic chemistry》2000,65(12):3652-3658
Tetracyclone, 2a, reacts with C(6)F(5)Li to yield 2-pentafluorophenyl-2,3,4,5-tetraphenylcyclopent-3-en-1-one, 7, and 5-hydroxy-5-pentafluorophenyl-1,2,3,4-tetraphenylcyclopentadiene, 8, as the result of 1,6 and 1,2 additions, respectively. In contrast, treatment of 3-ferrocenyl-2,4,5-triphenylcyclopentadienone, 2b, with lithiopentafluorobenzene leads to 4-ferrocenyl-4-pentafluorophenyl-2, 3,5-triphenylcyclopent-2-en-1-one, 9, and 5-hydroxy-5-pentafluorophenyl-2-ferrocenyl-1,3, 4-triphenylcyclopentadiene, 10, the products of 1,4 and 1,2 addition, respectively. The structures of 7-9 have been established by X-ray crystallography, and the barriers to rotation (19-21 kcal mol(-)(1)) of the pentafluorophenyl groups in 8-10 have been studied by variable-temperature (19)F NMR. Nucleophilic attack at the ferrocenyl-bearing carbon in 2b is rationalized in terms of a zwitterionic structure in which the positive charge of the "cyclopentadienyl cation" is delocalized onto the iron atom in the organometallic substituent. 相似文献
58.
A scheme is outlined for the separation of Li, K, Rb, Cs, Sr, Ba, Ce, Nd, Sm and Eu from silicate materials. The elements are separated by cation-exchange to provide groups suitable for mass spectrometric analysis, and are then further purified by anion-exchange. Results obtained by isotopic dilution analysis are reported for G-1, W-1, and the Harwell meteorite-in these measurements the alkali metals were determined separately from the other elements. Requirements are discussed for combining the procedures to form a more comprehensive method for use with a single sample. 相似文献
59.
Croley TR Hughes RJ Metcalfe CD March RE 《Rapid communications in mass spectrometry : RCM》2000,14(16):1494-1498
The ubiquity and favorable medicinal properties of flavonoids make essential the determination of flavonoid levels in various matrices. While developing a liquid chromatography/tandem mass spectrometry method for the analysis of the flavonoid, apigenin, anionic oligomers and nitrate- and chloride-bound clusters of this compound were observed. Tandem mass spectrometry of these oligomers and cluster ions showed the cleavage of apigenin molecules from the precursor. The observation of these cluster ions shows the possibility of post-column derivatization techniques to enhance specificity in analysis. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
60.