41845-95-8Relevant academic research and scientific papers
INVESTIGATION OF N-ACYLIMIDAZOLIUM SALTS IN LOW-POLARITY MEDIA BY PMR
Lapshin, S. A.,Chervinskii, A. Yu.,Litvinenko, L. M.,Dadali, V. A.,Kapkan, L. M.,Vdovichenko, A. N.
, p. 321 - 326 (2007/10/02)
A new model system is proposed for the investigation of the intermediate products from nucleophilic catalysis on the basis of 1-dimethylcarbamoyl-3-methylimidazolium chloride in low-polarity proton-inert media by the NMR method.It was shown that the structural parameter most sensitive to change in the nature of the acyl part, the anion of the salt, and the formation of an H bond is the chemical shift of the hydrogen atom at position 2 of the imidazolium ion.
EFFECT OF STRUCTURAL FACTORS ON THE KINETICS OF FORMATION AND REACTIVITY OF THE INTERMEDIATE PRODUCT IN ACYL TRANSFER REACTIONS CATALYZED BY IMIDAZOLES
Dadali, V. A.,Zubareva, T. M.,Litvinenko, L. M.,Simanenko, Yu. S.
, p. 1543 - 1551 (2007/10/02)
During the stage-by-stage investigation of the aminolysis of benzoyl halides catalyzed by N-substituted imidazoles in low-polarity media the effects of the structure of the reagents and of the intermediate product on the rate constants for the forward and reverse reactions and on the equilibrium constant of the first reversible stage were studied.The rate (k2) of the reaction of the intermediate product with the arylamines at the second rate-determining stage was also investigated.Compared with the noncatalytic reaction the first stage of the catalytic reaction is characterized by the formation of an earlier transition state, similar to a tetrahedral intermediate product.The equilibrium constants for the formation of the intermediate product do not depend on the effect of the substituent in the benzoyl fragment (which is due to the identical sensitivity of the forward and reverse reactions to this effect) but varies in relation to the basicity of the imidazole and the character of solvation of the anion in the intermediate product.The transition state of the k2 reaction is reagent-like with a small degree of formation and cleavage of bonds.A theory is formulated in with the reactivity of the acyl-ammonium halides in low-polarity media is determined by two factors: a) The "dipositive" character of the C-N bond, due to its "destabilization;" b) the additional stabilization of the transition state through general-base assistance from the anion.
KINETIC METHOD FOR DETERMINATION OF THE EQUILIBRIUM CONSTANTS FOR THE FORMATION OF ACYLIMIDAZOLIUM HALIDES IN AN APROTIC MEDIUM
Simanenko, Yu. S.,Dadali, V. A.,Litvinenko, L. M.,Zubareva, T. M.
, p. 1477 - 1485 (2007/10/02)
Two methods are proposed for determining the equilibrium constants for the formation of the intermediate product (I) in reactions with a nucleophilic mechanism of catalysis occuring in an aprotic low-polarity medium with accumulation of this product.The first method is based on investigation of the reactivity of compound (I) and its reaction rate at concentrations corresponding to the equilibrium state in the reaction with the corresponding nucleophile.The second is based on study of the kinetics of the reversible reaction of the substrate and the catalyst.The main conditions are formulated, and the regions for application of each of the methods are determined.
