Results 31 to 40 of about 1,354 (166)
Low Temperature Chemoselective Hydrogenation of Aldehydes over a Magnetic Pd Catalyst
Applied Sciences, 2019 Chemoselective hydrogenation of aldehydes with heterogeneous catalysts under mild conditions is of great importance but remains a major challenge. Herein, an efficient strategy was developed for low temperature chemoselective hydrogenation of aldehydes ...
Anqiu Liu +6 more
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A Special Case of the Hammett Equation
Transactions of the Kansas Academy of Science (1903-), 1954 k=rate constant for a reaction of a substituted compound ko=rate constant for the reaction of the unsubstituted compound =--constant specific for the substituent p=constant specific for the reaction Hammett has shown that it is necessary to restrict the use of this equation to series of reactions in which the entrophy of activation is constant if the ...
Gilkerson, W.R. +2 more
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Molecules, 2020 The chloride-chloride exchange reaction in arenesulfonyl chlorides was investigated experimentally and theoretically by density functional theory (DFT) calculations. The second order rate constants and activation parameters of this identity reaction were
Marian Mikołajczyk +4 more
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Advanced Science, EarlyView.An exogenous reagent‐free dual‐substrate strategy harnesses phenol as an intrinsic electron donor to drive synchronous phenol degradation and Cr(VI) reduction over modified carbon nitride. π–π stacking and hydrogen bonding direct electron transfer to the catalyst, enriching photogenerated electrons and accelerating Cr(VI) reduction 6.4‐fold. This waste‐
Xiaoman Zhang +9 more
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Advanced Science, EarlyView.Cross‐disciplinary endeavors are blossoming across the broad chemical sciences. This perspective provides a glimpse into the rewarding interdisciplinary journey taken by the Charles Loh research group in pioneering the σ‐hole based catalytic glycosylation strategy.
Charles C. J. Loh
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Advanced Science, EarlyView.A nickel‐catalyzed three‐component reductive fluoroalkylation‐amination strategy of N‐vinylamides for the direct access to the α‐amidyl‐β‐difluoroalkyl amines was reported here. The synthetic method features with broad substrate scope, mild conditions, high functional group tolerance, and convenience to handle.
Chang Xu +8 more
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A Theoretical Formulation of the Hammett Equation
Transactions of the Kansas Academy of Science (1903-), 1952 the rates of over two hundred reactions with the structure of the reactants. The equation as it stands now is applicable only to reactions of aromatic compounds and their derivatives. The Hammett equation is usually written, k 0, k p iog,'-- = po" k0 is the specific reaction rate constant for a given reaction with an unsubstituted reactant, k is the ...
Gallup, Gordon A +2 more
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Solvent Effects on ρ Values of the Hammett Equation [PDF]
Bulletin of the Chemical Society of Japan, 1969 Abstract The effects of selvents on ρ values have been systematically treated as a two-variable problem within a linear free-energy relationship framework. It is assumed that the standard activation free energy is a continuous function of σ, a substituent variable, and ξ, a solvent variable.
Yasuhiko Kondo +2 more
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Application of the Hammett Equation to Substituted Pyridines
Nippon kagaku zassi, 1967 5-置換ニコチン酸エチルの85%エタノール中のアルカリ性加水分解速度に対しては, Hammettのメタ置換基定数を用いるとよくHammett式が成立し, その反応定数ρHは反応温度25℃のとき2. 26であって, 同条件下の置換安息香酸エチルエステルの反応定数ρBとの比は,ρH/ρB=0. 89であった。 また, 5-置換ニコチン酸の50%エタノール水中におけるρKaについてもよくHammett式が成立し, その反応定数は1. 73で, 同条件下の置換安息香酸のρBに対して, ρH/ρB=1. 08であった。すなわち, 置換基,反応基およびヘテロ原子の三者の問に交叉共役が存在しない場合はρH/ρBが1に近くなる。
Yoshio UENO, Eiji IMOTO
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, 2014 Citation: 'Hammett equation' in the IUPAC Compendium of Chemical Terminology, 3rd ed.; International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1, 2019. 10.1351/goldbook.H02732 • License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International for individual terms.
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