Synthesis, spectral studies and C-S bond fission of some alkyl- [[substituted benzylidene] disulfonic] diacetates

Some methyl and ethyl [[substituted benzylidene] disultonyl] diacetates have been synthesized and their structures were identified. A correlation was found between 6-values of benzylidene protons and o-Hammett values. The internal chemical shift of the methylene proton was found to be structural and applied field dependent. The carbon-sulfur bond fission by the action of sodium hydroxide solution in 50 percent aqueous dioxane medium, in addition to the alkaline ester hydrolysis was studied. 2-or 4-Nitro compounds gave dicarboxyazoxybenzenes. This led to the suggestion that the reaction might proceed through two intermediates namely [[a-hydroxynitrosobenzylidene] disultonyl 1] diacetic acid and nitrosobenzoic acid. However, the C-S bond fission of other compounds gave aldehydes, supporting that, no a-proton abstraction took place for these compounds

Solvent and substituent effect on the absorption spectra of some ethyl [[substituted benzylidene] dithio] diacetates

The UV and visible electronic spectral behavior of some ethyl [[substituted benzylidene] dithio] diacetates is measured using solvents of different polarities. The spectral bands due to pi-pi* transition and the intermolecular charge transfer are assigned. The contribution of the dielectric constant and the refractive index affecting the electronic spectral bands was studied using a multiple regression technique, where peak locations were visually determined and the coefficients K1, K2 describing the quantitative contribution of dielectric constant and the refractive index of the given solvent and the wave number of maximum absorption in the vapor phase gamma vap were calculated. The hydrogen bonding association constants Kass between the investigated compounds and acetic acid indioxane were calculated. A relationship between Kass and Hammett sigma-values was found

Dissociation constants of some ethyl [[substituted benzylidene] dithio] diacetates in water organic solvent mixtures

The pKa values of some ethyl[[substituted benzylidene]dithio] diacetates in water-organic solvent mixtures are determined potentiometrically. The results obtained are discussed in terms of medium and structure effects. It has been found that the hydrogen bonding interactions, as well as solvent basicity, play important roles on the pKa values. Also, the calculated standard Gibbs transfer energies provided an evidence that solute-solvent interactions are of considerably greater importance of the solvent effect on the dissociation weak carbon acids. The structure effect is discussed in terms of Hammett correlations and the resulted alpha-values indicate that, for the present system, the negative charge on the benzylidene carbon is extensively delocalized into the two adjacent sulfur atoms