A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 766-96-1, Name is 1-Bromo-4-ethynylbenzene, molecular formula is C8H5Br. In an article, author is Silva, Samuel L.,once mentioned of 766-96-1, Product Details of 766-96-1.
Micro-solvation and counter ion effects on ionic reactions: Activation of potassium fluoride with 18-crown-6 and tert-butanol in aprotic solvents
Ionic reactions have an important solvent effect and the first solvation shell makes the most important contribution for determining the reactivity. In the case of nucleophilic fluorination with potassium fluoride, the solubilization of the salt is another aspect which needs be considered. In the present work, the effect of adding stoichiometric quantity of 18-crown-6 and the bulky alcohol tert-butanol to the reaction of potassium fluoride with alkyl bromide in toluene and acetonitrile solvents was investigated by theoretical methods as molecular dynamics and electronic structure calculations, as well as by experiments. The calculations indicate that the fluoride ion in the IT (18-crown-6) complex interacts with tern-butanol molecules forming aggregates with one (acetonitrite solvent) and three (toluene solvent) tert-butanol molecules. The calculations predict that formation of these aggregates increase the solubilization of KF and produces and important rate acceleration effect in both acetonitrile and toluene solvents, which is experimentally observed. In the concentration around 0.75 mol L-1 of the tert-butanol, the reaction rate is proportional to the alcohol concentration and the rate of alkyl halide decay becomes 10 times higher than the rate without this alcohol. The present results point out that both the interactions of KF with crown ether and tert-butanol molecules have a synergic effect, increasing its reactivity towards S(N)2 reactions. (C) 2020 Elsevier B.V. All rights reserved.
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