Topic
Substituent
About: Substituent is a research topic. Over the lifetime, 42877 publications have been published within this topic receiving 516716 citations. The topic is also known as: side chain & side group.
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132 citations
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132 citations
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TL;DR: In this article, the activated complex for the Diels-alder reactions of 5-substituted 1,4-naphthoquinones with cyclopentadiene is more polar in water than in other solvents.
Abstract: In order to check whether the activated complex for the Diels-Alder reactions of 5-substituted 1,4-naphthoquinones with cyclopentadiene is more polar in water than in other solvents, we have determined the substituent effects in seven different solvents. The substituent effects gradually decrease with increasing rate of the reaction in a specific solvent, indicating that the charge separation in the activated complex in water is not much different from that in the other solvents. We also compared solvent effects on the Diels-Alder reaction of methyl vinyl ketone with cyclopentadiene with effects on the corresponding reaction of methyl vinyl sulfone. The medium effects were separated into effects on initial state and activated complex. The destabilization of the initial state by water and the stabilization of the activated complex by 2,2,2-trifluoroethanol were less pronounced for the sulfone than for the ketone. These results further underline the importance of enforced hydrophobic interactions and changes in hydrogen bonding during the activation process in explaining the acceleration of Diels-Alder reactions in water.
132 citations
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TL;DR: In this article, a ladder of relative Na+ affinities of amino acids (AA) was derived using the Cooks kinetic method, and the relative values to the Na+ affinity of Ala (167kJ−1), measured by the same approach using Na+-bound dimers of Ala and a series of acetamide derivatives.
132 citations
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28 Jan 1976TL;DR: In this paper, combinations of amino phenols, wherein said phenols contain a substantially saturated hydrocarbon substituent of at least 10 aliphatic carbon atoms, and one or more detergent/dispersants selected from the group consisting of (I) neutral or basic metal salts of an organic sulfur acid, phenol or carboxylic acid; (II) hydrocarbylsubstituted amines wherein the hydrocar-byl substituents is substantially alophatic and contains at least 12 carbon atoms; (III) acylated nitrogen-containing
Abstract: Disclosed are combinations of amino phenols, wherein said phenols contain a substantially saturated hydrocarbon substituent of at least 10 aliphatic carbon atoms, and one or more detergent/dispersants selected from the group consisting of (I) neutral or basic metal salts of an organic sulfur acid, phenol or carboxylic acid; (II) hydrocarbylsubstituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 12 carbon atoms; (III) acylated nitrogen-containing compounds having a substituent of at least 10 aliphatic carbon atoms; and (IV) nitrogen-containing condensates of a phenol, aldehyde and amino compound. Fuels and lubricants containing such combinations as additives are particularly useful in two-cycle (two-stroke) engines.
132 citations