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Reaction mechanism
About: Reaction mechanism is a research topic. Over the lifetime, 26264 publications have been published within this topic receiving 668528 citations.
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01 Jul 2005
TL;DR: In this paper, the authors introduce the structure and models of bonding and structural properties of organic materials, and propose a model of non-covalent binding forces and non-convex binding forces.
Abstract: 1: Introduction to Structure and Models of Bonding 2: Strain and Stability 3: Solutions and Noncovalent Binding Forces 4: Molecular Recognition and Supramolecular Chemistry 5: Acid-Base Chemistry 6: Stereochemistry 7: Energy Surfaces and Kinetic Analyses 8: Experiments Related to Thermodynamics and Kinetics 9: Catalysis 10: Organic Reaction Mechanisms Part 1: Reactions Involving Additions and/or Eliminations 11: Organic Reaction Mechanisms Part II: Substitutions at Aliphatic Centers and Thermal Isomerizations/Rearrangements 12: Organotransition Metal Reaction Mechanisms and Catalysis 13. Organic Polymer and Materials Chemistry 14. Advanced Concepts in Electronic Structure Theory 15: Thermal Pericyclic Reactions 16: Photochemistry 17: Electronic Organic Materials
1,209 citations
TL;DR: This work has reported several recently reported Cu-catalyzed C-H oxidation reactions that feature substrates that are electron-deficient or appear unlikely to undergo single-electron transfer to copper(II), and evidence has been obtained for the involvement of organocopper(III) intermediates in the reaction mechanism.
Abstract: The selective oxidation of C-H bonds and the use of O(2) as a stoichiometric oxidant represent two prominent challenges in organic chemistry. Copper(II) is a versatile oxidant, capable of promoting a wide range of oxidative coupling reactions initiated by single-electron transfer (SET) from electron-rich organic molecules. Many of these reactions can be rendered catalytic in Cu by employing molecular oxygen as a stoichiometric oxidant to regenerate the active copper(II) catalyst. Meanwhile, numerous other recently reported Cu-catalyzed C-H oxidation reactions feature substrates that are electron-deficient or appear unlikely to undergo single-electron transfer to copper(II). In some of these cases, evidence has been obtained for the involvement of organocopper(III) intermediates in the reaction mechanism. Organometallic C-H oxidation reactions of this type represent important new opportunities for the field of Cu-catalyzed aerobic oxidations.
1,129 citations
TL;DR: In this paper, the reaction mechanisms of three antioxidants are proposed in order to explain experimental results obtained from a kinetic study using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, previously adapted in our laboratory.
Abstract: The reaction mechanisms of three antioxidants are proposed in order to explain experimental results obtained from a kinetic study using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH . ) method, previously adapted in our laboratory. In its radical form, DPPH . shows an absorbance maximum at 515 nm which disappears upon reduction by an antiradical compound. BHT, a synthetic antioxidant, slowly reacts with DPPH . reaching a steady state within 5 h. This 2.8-stoichiometric complete reaction follows a 1.5-order with respect to DPPH . and 0.5 to BHT. The kinetic rate constant, k, is estimated to be 5.0 L/(mol·s) at 20 °C and the energy of activation, Ea , is equal to 35 kJ/mol in methanol. Eugenol reacts with DPPH . reaching a steady state within 2 h. This 1.9-stoichiometric reaction follows a 2-order with respect to both DPPH . and eugenol, k and Ea are estimated to be 5.4 × 10 10 L 3 /(mol 3 ·s) at 20 °C and 30 kJ/mol, respectively. The eugenol mechanism may involve a dimerization between two phenoxyl radicals. The reaction with isoeugenol is rapid and reversible, with a stoichiometry of 1.1. It is first order with respect to isoeugenol with k (direct reaction) equal to 8.9 × 10 −2 s −1 at 10 °C. This reaction is consistent with a pseudo-monomolecular mechanism.
1,126 citations
1,104 citations
TL;DR: A reaction in which primary amines are directly acylated by equimolar amounts of alcohols to produce amides and molecular hydrogen in high yields and high turnover numbers is reported.
Abstract: Given the widespread importance of amides in biochemical and chemical systems, an efficient synthesis that avoids wasteful use of stoichiometric coupling reagents or corrosive acidic and basic media is highly desirable. We report a reaction in which primary amines are directly acylated by equimolar amounts of alcohols to produce amides and molecular hydrogen (the only products) in high yields and high turnover numbers. This reaction is catalyzed by a ruthenium complex based on a dearomatized PNN-type ligand [where PNN is 2-(di-tert-butylphosphinomethyl)-6-(diethylaminomethyl)pyridine], and no base or acid promoters are required. Use of primary diamines in the reaction leads to bis-amides, whereas with a mixed primary-secondary amine substrate, chemoselective acylation of the primary amine group takes place. The proposed mechanism involves dehydrogenation of hemiaminal intermediates formed by the reaction of an aldehyde intermediate with the amine.
1,098 citations