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The dissociation of tris-(2,2'-bipyridyl) iron(II) ([Fe(bipy)(3)](2+)) has been studied in the Triton X-100/hexanol/cyclohexane reverse micellar medium. The reaction obeys simple first-order kinetics with no evidence of autoinhibition. The first-order rate constant (k(1)) has been determined at different values of W ([H2O]/[Triton X-100]). The rate (k(1)) decreases with increasing value of W. k(1) also increases with increase in Triton X-100 concentration at constant values of W, showing that the reaction takes place at greater speed at the micellar interface. The kinetic results can be interpreted by the monomolecular pseudo-phase model. The effect of W on rate (k(1)) is more pronounced in the range of W from 1.55 to 4.2 but less pronounced at higher W. The reaction is further accelerated by Cl- and SCN- ions and the kinetic results provide evidence for the formation of ion pairs between the cation [Fe(bipy)(3)](2+) and each of these anions. The formation of such ion pairs has not been observed in aqueous medium but has been reported earlier in aqueous-alcohol mixtures. This result therefore provides evidence for the lower micropolarity of solubilized water compared to ordinary water. (c) 2005

Sodium methoxide is used as a reagent or a catalyst in many industrial processes such as, for example, pharmaceuticals and biodiesel syntheses. This work presents a new and selective quantitative analytical thermometric method for sodium methoxide determination in methanol solutions in the presence of hydroxide ions. For comparative purposes with the Karl-Fischer procedure, these two methods were applied to four different solutions of sodium methoxide in methanol, including in presence of sodium hydroxide, and the results were compared statistically showing total agreement. O metóxido de sódio é usado como reagente ou como catalisador em muitos processos industriais como, por exemplo, na síntese de fármacos e de biodiesel. O presente trabalho apresenta um novo e seletivo método analítico quantitativo termométrico para a determinação de metóxido de sódio em soluções de metanol na presença de íons hidróxido. Para fins de comparação com o método Karl-Fischer, os dois procedimentos foram aplicados a quatro diferentes soluções de metóxido de sódio em metanol, inclusive em presença de hidróxido de sódio, e os resultados foram comparados estatisticamente mostrando total concordância.