The formation constants of the species formed in the systems fr + glycine + dioxovanadium(V) + and H+ + glycine have been determined in aqueous solutions of methanol at 25 °C and constant ionicstrength, using spectrophotometric and potentiometric techniques. It was shown thatdioxovanadium(V) forms two mononuclear 1 : land 1:2 complexes with glycine. The formationconstants in various media were ...

Catalyst S. Al-Khattaf* Chemical Engineering Department, King Fahd University of Petroleum & Minerals Dhahran 31261, Saudi Arabia Abstract Catalytic transformation of toluene has been investigated over Y-zeolite based catalysts in a novel riser simulator at different operating conditions. A number of experiments were carried out in the temperature range of 400-500C to understand the transformat...

Benzo[b]cyclohexa-2,4-dien-1-one (4) and benzo[b]cyclohexa-2,5-dien-1-one (5), the two most stable keto tautomers of 1-naphthol (1), were generated in aqueous solution by Norrish Type II fission of 4- and 2-phenacyl-1-tetralone, respectively, and the pH-rate profiles of their enolization were measured by flash photolysis. Several isotopic exchange rates of 1 were measured in aqueous acid to det...

Countercurrent chromatography (CCC) is a liquid chromatography technique in which the stationary phase is also a liquid. The solute separation is based on partitioning between the two immiscible liquid phases: the mobile phase and the support-free liquid stationary phase. Octanol-water partition coefficients (Po/w) of 17 βblockers and 17 sulphonamides were determined by CCC. Some of the Po/w co...

The acidity constants of eight macrolides (erythromycin, roxithromycin, oleandomycin, azithromycin, josamycin, tylosin tartrate, tilmicosin and spiramycin) have been determined in acetonitrile-water binary mixtures (30%, 40% and 50% (v/v)) by spectrophotometric method. The pKa's available in literature determined by various methods are compiled in comparison with the value of this work. These r...

Dissociation constants (pK, 20°C) of D-galacturonic acid, D-glucuronic acid, their O-methyl derivatives, as well as of the corresponding 4,5-unsaturated substance have been determined by means of discontinuous Potentiometrie titration. The found pK values have been interpreted from the point of view of inductive and mesomeric effects, and nonbonding interactions. It is demonstrated that the eff...