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91.
A series of 6,7-Benzobicyclo[3.2.1]octadienes (10–13) have been prepared. Direct and sensitized irradiation of the dienes gave di-π-methane rearrangement products (14–17). Quantum yields for the direct and sensitized rearrangements were recorded and compared. Substituent effect and structure-multiplicity relationships are discussed. 相似文献
92.
The kinetics of the reaction between CH3 and HCl was studied in a tubular reactor coupled to a photoionization mass spectrometer. Rate constants were measured as a function of temperature (296–495 K) and were fitted to an Arrhenius expression: k1 = 5.0(±0.7) × 10?13 exp{?1.4(±0.3) kcal mol?1/RT} cm3 molecule?1 s?1. This information was combined with known kinetic parameters of the reverse reaction to obtain Second Law determinations of the methyl radical heat of formation {34.7(±0.6) kcal mol?1} and entropy {46(±2) cal mol?1 K?1} at 298 K. Using the known entropy of CH3, a more accurate Third Law determination of the CH3 heat of formation at this temperature was also obtained {34.8(±0.3) kcal mol?1}. The values of k1 obtained in this study are between those reported in prior investigations. The results were also used to test the accuracy of the thermochemical information which can be obtained from kinetic studies of R + HX (X = Cl, Br, I) reactions of the type described here. 相似文献
93.
Ivan Gutman 《Chemical physics letters》1984,103(6):475-478
A generalization of the perturbation graph theory of Herndon and Párkányi is developed, enabling the calculation of resonance energies of conjugated heterocyclic and inorganic systems possessing any number of π-electrons. 相似文献
94.
The concepts of weakly Ω-invariant sets and strictly weakly Ω-invariant sets in control systems with bounded controls are defined and analyzed. Computable conditions for weak Ω-invariance are derived, and the question of existence of rest points and stationary points in weakly Ω-invariant sets is considered. For linear dynamics, properties of weakly Ω-invariant sets are studied, and questions of constrained reachability are investigated. 相似文献
95.
96.
O-alkylations of indoxylie acid (2b) to produce 3-indolyl-alkyl ethers and a synthesis of 5-melhoxy-2-earboxyindol-3-oxyaeetic acid (25) are described. 相似文献
97.
98.
The room temperature reactions between oxygen atoms and methanethiol, ethanethiol, and methylsulfide have been studied in crossed jets to directly detect and identify the free-radical and stable products they produce. Knowledge of the products was used to assign reactive routes. The overall rate constants for all three O-atom reactions were also measured at 300 ± 2°K using a fast-flow reactor. They are 1.9 (CH3SH), 2.8 (C2H5SH), and 63 (CH3SCH3) × 10?12cm3/mol · sec. The identity of the detected products and the trend in rate constants in these reactions support an electrophilic addition mechanism followed by decomposition of the excited adduct by S-R bond cleavage (R = H, CH3, or C2H5). 相似文献
99.
The paper applies Jacobi's fundamental result on minors of the adjoint matrix to obtain properties on determinants of unimodular matrices. 相似文献
100.