The relative reactivities of tert-butyl hydroperoxide (TBHP) and pinane hydroperoxide (PHP) in metal (Cr, Mo, Ru, Se, V, and Zr)-catalyzed oxidations were compared. When these oxidations involve rate-limiting oxygen transfer from a peroxometal species to the substrate huge differences between TBHP and PHP were observed, e.g., molybdenum-catalyzed epoxidation of cyclohexene with TBHP gave a 98% yield while PHP gave 0%. When the reaction involves reaction of an oxometal species with the substrate as the rate-limiting step, little or no difference is observed, e.g., the selenium-catalyzed allylic oxidation of β-pinene gave a 96% and 99% yield with TBHP and PHP, respectively. Small but significant differences are observed when reoxidation of the catalyst by the hydroperoxide to the active oxometal species is the rate-limiting step; e.g., the chromium-catalyzed oxidation of carveol gave carvone in 89% and 24% yield with TBHP and PHP, respectively. Hence, the effect of RO2H structure on rate is dependent on the rate-limiting step.

Biodegradable segmented polyurethanes were prepared with poly(caprolactone) diol as a soft segment, 4,4'-methylene bis(cyclohexyl isocyanate) (HMDI) and either butanediol or dithioerythritol as chain extenders. Platelet adhesion was similar in all segmented polyurethanes studied and not different from Tecoflex® although an early stage of activation was observed on biodegradable segmented polyurethane prepared with dithioerythritol. Relative viability was higher than 80% on human umbilical vein endothelial cells in contact with biodegradable segmented polyurethane extracts after 1, 2 and 7 days. Furthermore, both biodegradable segmented polyurethane materials supported human umbilical vein endothelial cell adhesion, spreading, and viability similar to Tecoflex® medical-grade polyurethane. These biodegradable segmented polyurethanes represent promising materials for cardiovascular applications.

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