Kinetic studies and thermodynamic treatments of substituent effect of the alkaline hydrolysis of acetoxybenzenes and acetoxynaphthalenes

The kinetics of the alkaline hydrolysis of acetoxybenzene, 1,4-diacetoxybenzene, l-acetoxynaphthalene, 1,4-diacetoxynaphthalene and 1,5-diacetoxynaphthalene have been studied in 50% [v/v] dioxane-water. Analysis of the data showed that an increase in the rate was found to be dependent on the position of the acetoxy group. Also, the presence of oxo-group caused an inhibition in the rate to a great extent either in the naphthalene or benzene compounds. The various thermodynamic parameters were deduced. A linear free energy relationship was observed for such substituted acetoxynaphthalene where a good correlation between log k vs. deltaij was observed. Also, the effect of bromo-substitution on the rate of hydrolysis of 2-acetoxynanphthalene has been studied

Spectral studies on some pyrimidine derivatives

The electronic absorption spectra of 2-[2'-Thiopyrimidine]-5-nitro-pyridine [I], 1[2'-Thiopyrimidine]-2, 4-dinitrobenzene [II] 2-[2'-Thiopyrimidine]-1, 3, 5-trinitrobenzene [III] and 3-[[2'-Thiopyrimidine] methyl] benzoic acid [IV] were measured in a series of fifteen different solvents. The solvent effects induced spectral shifts in the different peak locations have been analyzed as a function of different solute-solvent interaction mechanisms. Ground state properties of optimum molecular geometries, singlet-singlet electronic transitions have been calculated using the AM1, PM3, ZINDO/S and ab initio/3-21G methods

Electronic spectral properties of quinoxalinones and thioquinoxalinones in different solvents

The electronic absorption spectra of 3-benzyl-1H- quinoxalin-2- one and 3-benzyl-1H-quinoxalin-2-thione in solvents of different polarity were analyzed by the multiple regression technique using the equation psi = a[0] + a[1]x[1] + a[2]x[2] + a[3]x[3] +.... The constants a[1], a[2], a[3], ' are the different regression coefficients and the constant a[0] is the regression intercept. The x[1], x[2], x[3], ' are different solvent polarity parameters. The multiple regression coefficients [MRC] were also calculated. The values of the acid dissociation constants of both compounds were determined

Kinetics of the reaction of 2-chloro-3,5-dinitro-pyridine with aniline in hydroxylic solvents

The rates of aromatic nucleophilic substitution [ANS] reactions are notably affected by the solvent polarity such as substrate or intermediate[s] solvent interactions[1-3], the non-specific coulombic, inductive and dispersion interactions, specific hydrogen bond, electron pair donor [EPD], electron pair acceptor [EPA] and solvophobic interactions[4]. It has been found that the reaction of nitroaryl halides with amines in hydroxylic solvents was inversely proportional to the hydrogen bond donating [HBD] ability of the solvent[5]. Moreover, the reaction rate in these hydroxylic solvents was found to be smaller than that in aprotic solvents, which suggests that inter-and intramolecular bond interactions, in the pure solvent and between the solvent and the amine, are relevant in determining the reaction rates[6]. The object of this work was to supplement a systematic study of the hydroxylic solvents influence on the reaction rate of 2-chloro-3,5-dinitropyridine with aniline as a simple model in heterocyclic rings of the ANS [Aromatic nucleophulic substitution] reaction. Also, it is of interest to correlate the kinetic data with E[T[30]] values on rates the preferential solvation in order to evaluate its influence