The corresponding o-aminobenzophenones are usually reported as the main degradation products in the hydrolysis of 1,4-benzodiazepinones. Nevertheless, in previous studies of diazepam (DZ) in acidic aqueous medium we isolated and characterized seven unexpected degradation products. Kinetic measurements under several reaction conditions shed some light on the mechanisms of the complex reactions that are taking place, and photochemical studies give hints on the mechanisms of chlorination and annelation processes. Alprazolam (AL) seems to exhibit an unusually high stability against hydrolysis under several conditions; nevertheless, the structure is sensitive to photolytic cleavage. The photodegradation of AL was studied in aqueous and methanolic solutions. Characterization of the isolated products by 1 H and 13 C NMR and mass spectrometry revealed that electron transfer, oxidation and rearrangement reactions take place. The influence of several variables such as pH, solvent composition and light irradiation were examined and mechanisms for the formation of three photoproducts are proposed. A specific method for the determination of AL in the presence of photoproducts was developed, which allowed kinetic determinations of the photostability of AL. The photosensitivity observed in some patients treated with AL seems to be due to one of the characterized photoproducts.

Cases of imposex have been reported for some organisms living in areas of the Argentine Atlantic coast. Since this is one of the known effects of the anti-fouling agent tributyltin (TBT), quantitative determinations of organotins in samples of water and sediments collected from sites along the Argentine coast were carried out. Severe cases of imposex were first reported for two gastropod species living in the Mar del Plata area, and determinations of TBT in samples collected from this site gave extremely high values and showed a close correlation between the degree of imposex and TBT concentration. Recent investigations in the area have shown a significant decrease. Surveys were also conducted in sites that exhibit highly irregular coastal profiles to examine the relevance of physical environments. Alarming concentrations of TBT were determined in most of the sites where heavy boat traffic and/or marine activities occur, demonstrating the urgent need for regulations to avoid further input of TBT. Reports from other sites in South America reveal that this should be a subject of regional concern in order to avoid severe damage to the biodiversity of regional marine organisms.

Introduction Functionalized Chains Carbocyclic Compounds Heterocycles Conclusions Acknowledgments