Paste general requirements

Electron-deficient alkenes generally require the use of some other epoxidation procedure, owing to their low reactivity under electrophilic addition conditions. Within this categoiy, o,P-unsaturated ketones tend to be the substrates of interest, and basic oxygen transfer reagents are fiequently encountered, such as HjOj/NaOH, t-BuOOH/NaOH, and NaOCl. Much activity has centered around the modification of these traditional conditions to accommodate asymmetric induction. In this regard, variously substituted Cinchona alkaloids (e.g., 39 - 41) have received a fair amount of attention over the past year. 

From the position of drug development, the general requirement that scientific results have to be repeatable has been interpreted in the past by the Food and Drug Administration (the regulatory agency in the USA) to mean that two well-controlled studies are required to support a claim. But this requirement is itself controversial and its relation to a meta-analysis in the context of drug development is unclear. 

Though rarely used in current practice, this solvent was an important cause of hepatotoxicity in the past. Its hepatotoxic potential was first identified during its use in the first World War. Animal hepatotoxicity with fatty degeneration of the fiver has been documented in multiple species. Human inhalational exposures manifest in fiver enlargement, jaundice, steatosis with subsequent fiver failure in severe poisonings. Subacute exposure periods of weeks to months is generally required for hepatic injiuy. Liver regeneration oc-... 

The second means of transforming a liquid adhesive entirely into a solid without the loss of a solvent or dispersion medium is to produce solidification by a chemical change rather than a physical one. Such reactive adhesives may be single-part materials that generally require heating or exposure to electron beam or UV or visible radiation (see Radiation-cured adhesives) to perform the reaction, and which may be solids (that must be melted before application), liquids or pastes. The alternative two-part systems require the reactants to be stored separately and mixed only shortly before application. The former class is exemplified by the fusible, but ultimately reactive, epoxide film adhesives and the latter by the two-pack Epoxide adhesives and Polyurethane adhesives and by the Toughened acrylic adhesives that cure by a free-radical Chain polymerization mechanism. 

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