75670-24-5Relevant academic research and scientific papers
RELATIONSHIPS OF TRANSAMINATION OF SUBSTITUTED UREAS. V. THERMODYNAMICS OF TRANSAMINATION OF DIARYLUREAS BY DIALKYLAMINES
Chimishkyan, A. L.,Gulyaev, N. D.,Leonova, T. V.
, p. 20 - 24 (2007/10/02)
The equilibrium constant of the transamination of N,N'-diarylureas by dialkylamines in o-dichlorobenzene in the range of 120-158 deg C depends significantly on the nature of both reagents.The enthalpy of activation and the entropy of dissociation of diarylureas are proportional to the thermal effect of the transamination of these ureas by diisobutylamine.The same relationships is observed between the enthalpy of activation of the bimolecular reaction of N,N'-diphenylurea with dialkylamines and the enthalpy of the process.The established relationships between the enthalpies of activation and the enthalpy of equilibrium are explained satisfactorily in terms of the Hammond-Thornton model.
RELATIONSHIPS IN THE TRANSAMINATION OF SUBSTITUTED UREAS. IV. TRANSAMINATION OF SYMMETRICAL DIARYLUREAS BY DIISOBUTYLAMINE
Chimishkyan, A. L.,Gulyaev, N. D.,Leonova, T. V.
, p. 1845 - 1848 (2007/10/02)
The effect of substituents in N,N'-diarylureas on the kinetics of transamination by diisobutylamine differs for each of the reaction paths.For the dissociation of ureas ρ1 = -0.34, and for their bimolecular reaction with diisobutylamine ρ3 = 1.05 (o-dichlorobenzene, 142 deg C).At the same time both reactions obey an isokinetic law: β1 441 deg K, β2 357 deg K.The controlling stage of each of the paths takes place through a four-center concerted transition state.
RELATIONSHIP IN THE TRANSAMINATION OF SUBSTITUTED UREAS. III. CONFIRMATION OF THE MECHANISM OF TRANSAMINATION OF SUBSTITUTED UREAS BY VARIOUS KINETIC METHODS
Chimishkyan, A. L.,Snagovskii, Yu. S.,Gulyaev, N. D.,Leonova, T. V.,Kusakin, M. S.
, p. 1955 - 1961 (2007/10/02)
The suitability of the model involving two parallel mechanisms of transamination, i.e., through the intermediate formation of the corresponding isocyanate and by a bimolecular mechanism of nucleophilic substitution, was confirmed for the case of the reaction of N,N'-diphenylurea with diisobutylamine in o-dichlorobenzene by various chemical methods and by mathematical modeling.At the same time the rate constants for all the micro stages of the processes were determined.
RELATIONSHIPS IN THE TRANSAMINATION OF SUBSTITUTED UREAS. TRANSAMINATION OF N,N'-DIPHENYLUREA WITH DIALKYLAMINES
Chimishkyan, A. L.,Leonova, T. V.,Gulyaev, N. D.,Kusakin, M. S.
, p. 2197 - 2203 (2007/10/02)
The kinetics of the transamination of N,N'-diphenylurea by secondary alkylamines (dimethyl-, diethyl-, dibutyl-, diisobutyl-, dihexyl-, and dibenzylamine) and hexamethyleneimine in o-dichlorobenzene were studied in the range of 128 - 148 deg C.The mechanism of the process was confirmed and involves reaction in two parallel directions: 1) Bimolecular reaction of the N,N'-diphenylurea with the dialkylamine; 2) its dissociation into aniline and phenyl isocyanate followed by reaction of the latter with the dialkylamine.The relation between the obtained rate constants and the nature of the dialkylamine is closely described by the twoparameter modified Taft equation.The reaction obeys an isokinetic law; the isokinetic temperature was determined.
RELATIONSHIPS IN THE TRANSAMINATION OF SUBSTITUTED UREAS. TRANSAMINATION OF N,N'-DIPHENYLUREA WITH DIISOBUTYLAMINE
Gulyaev, N. D.,Leonova, T. V.,Chimishkyan, A. L.
, p. 1909 - 1912 (2007/10/02)
The kinetics of the reaction of N,N'-diphenylurea with diisobutylamine in o-dichlorobenzene at 128 - 148 deg C were investigated.It is suggested that the reaction takes place in two directions at the same time, i.e., through dissociation of the N,N'-diphenylurea with the intermediate formation of phenyl isocyanate and by direct reaction of the initial urea with the diisobutylamine.The rate constants and activation parameters were determined for the controlling stages of the process.
