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851.
Quinolizidines containing an exocyclic double bond at C-2 (1,2) give on mild oxidation the amino dienes (3,4), as mixtures of geometric isomers with respect to the exocyclic double bond. The free enthalpy of activation for the rotation about the double bond has been estimated by NMR. 相似文献
852.
Jack G. Calvert 《Chemical physics letters》1973,20(5):484-488
New and previously published SO2 fluorescence emission data related to non-radiative decay processes are considered in light of the recent observations of Brus and McDonald. All the present data are consistent with the previous conclusion of Mettee that non-radiative processes in SO2 singlet photochemistry are unimportant. It appears that any small inefficiency in the emission of light quanta for SO2 excited at short wavelengths (2650 A) is largely due to the population of a second very short-lived state which is quenched effectively even at pressures down to 1 μ. The very low efficiency of quanta production which we observed at long wavelengths (3020 Å) appears to have its origin not only in the second easily quenched state, but more importantly, in the diffusional loss of the long-lived singlet which for these conditions has a 20-fold greated lifetime than was expected previously. 相似文献
853.
An universal function for non-bonded interactions, which takes into account the relative orientation of the bonds is considered in calculating the conformational energies of cycloalkenes and cycloalkadienes. A comparison is made with previous results obtained by using usual 6-exp functions for non-bonded interactions. 相似文献
854.
Chalcogenolates and their Derivatives. I. Syntheses and Properties of Ionic Chalcogenophenolates The syntheses and properties of ionic chalcogenophenolates are described. Using liquid ammonia as solvent the alkali chalcogenophenolates M[EPh] (M = Na, K; E = Se, Te; Ph = C6H5) have been synthesized via reduction of the diphenyl dichalcogenides with alkali metals. Similarly, the tetraphenylphosphonium chalcogenophenolates [Ph4P][EPh] (E = S, Se, Te) have been obtained by reacting alkali chalcogenophenolates with tetraphenylphosphonium chloride. 相似文献
855.
A rapid, sensitive and selective method for the determination of carbamazepine and its major metabolite in plasma has been developed. Other commonly used anticonvulsants can be determined in the same procedure without interference. After extraction with dichloromethane, the components are separated by high-pressure liquid chromatography without further clean-up or concentration on a column packed with small-particle silica gel. The mean recovery from plasma is 98.6% with a relative standard deviation of 1.6%. The detection limit for carbamazepine is approximately 2 ng/ml, requiring 1 ml of plasma. 相似文献
856.
V. G. Kharchenko S. N. Chalaya T. M. Konovalova 《Chemistry of Heterocyclic Compounds》1975,11(2):125-136
The literature data touching upon the synthesis of thiapyrylium salts and the stability of the thiapyrylium cation as compared with its isoelectronic analogs, as well as the nucleophilic, oxidation, anion-exchange, and other reactions of the salts with substituted and unsubstituted thiapyrylium cations are examined in this review. 相似文献
857.
858.
The C2H4 was investigated ab initio for the equilibrium distance of the centers, taking all 16 electrons into account, using the Allgemeines Programmsystem/SCF ? MO ? LC (LCGO ) Methode. A total energy of ?76.77 a.u. and an ionization energy of 10.55 eV were found. 相似文献
859.
Non-destructive neutron-activation analysis is used for determining chlorine in paper-pulp. Numerical data have been obtained for bleached and unbleached paper-pulps of different types and origins. The sensitivity of this method is 100 ppm for an irradiation time of 30 min and a neutron flux of 6 x 10(10) neutrons.cm(-2).sec(-1) and 10 ppm for an irradiation time of 1 min and a neutron flux of 2 x 10(12) neutrons.cm(-2).sec(-1). In both cases the amount of chlorine that can be determined depends on the presence of the interfering elements manganese and sodium in the paper-pulp. The time required for a complete analysis, after irradiation, is 5 min. 相似文献
860.
Z. Popova R. Dimitrova Chr Dimitrova G. Wendt 《Reaction Kinetics and Catalysis Letters》1989,39(1):27-32
Temperature programmed reduction (TPR) has been used to study the redox behavior of Ni(II) ions in nickel sodium mordenite (NiNaM) and decationated nickel mordenite (NiHM). The TPR profiles suggest that Ni(II) ions occupy nonequivalent sites with different cooridination states in the mordenite. The reducibility of Ni(II) depends strongly on the zeolite acidity.
() NiII NiNaM NiHM. . .相似文献