Durchführung von chemischen Reaktionen im Mikrowellenfeld

Feasibility of Chemical Reactions in Microwave Field The article presents a view on the present knowledge of the influence of microwaves on reactions, material‐, and heat transfer. The heating behavior of representative test reactions and material systems in a microwave field is compared to that under thermal energy. Common features and differences between the convective and dielectrical irradiation methods are discussed using the yield, selectivity, and optical purity of the products as main criteria. The energy absorption of substances and substance mixtures in dependence of the input energy and substance quantity is discussed in view of recent problems with the scaling‐up of microwave‐supported reactions.     

Oxydation mehrfach ungesättigter polymerer mit organischen hydroperoxiden

A series of results is known about oxidation of low molecular weight olefins with alkyl hydroperoxides in the presence of derivates of transition metals. Depending on the catalyst the reaction products mainly have epoxide or alkenyl alkyl peroxide groups. The reactions of polymers with a high degree of unsaturation - mainly performed with tertiary butyl hydroperoxide - gave on catalysis with molybdenum compounds almost exclusively polymers containing epoxide groups. With vanadium derivates polymers having mainly epoxide groups were obtained. Application of derivates of manganese, cobalt, and copper resulted in a selective formation of polyfunctional peroxides. The reaction is inhibited by water. No cross-linking was observed when the reaction was performed in solution. Explanations are given for the formation of epoxides or peroxides in the presence of transition metal compounds as catalysts. Reaction mechanisms for the epoxidation or peroxidation are proposed. On epoxidation of liquid polybutadienes with tertiary butyl hydroperoxide the presence of molybdenyl bisacetylacetonate curable liquid epoxidized poly-butadienes are obtained. In the presence of acetylacetonates of copper, manganese, and cobalt polyfunctional polybutadienyl tertiary butyl peroxides with a “critical temperature” of about 120°C are obtained which are useful for the initiation the polymerization of styrene.     

Neutralisation von Säuren mit Basen im Aerosol

Neutralization of Acids with Bases in Aerosol In the neutralization of strong acids with strong bases, the dilution with water can be avoided by working in aerosol, whereby air is employed as the diluting agent. This can be carried out by using a three-component jet, with which the concentrated acids and bases can be sprayed together. It is shown that the above process can be applied in spray-drying as well as in spray-mixing. Elimination of one processing step and low energy costs are the advantages.