Über den Verlauf der Umsetzung von Epichlorhydrin mit zweiwertigen Phenolen (Kinetik der Epoxyharzherstellung)

V. Mitteilung über Chemie der Epoxyharze

Abstract

A reaction sequence is proposed for the reaction of epichlorohydrin with bivalent phenols in an alkaline medimu, leading to the formation of epoxy resins. Experiments have shown that at a reaction temperature of about 100 °C phenol is converted quantitatively into resin, whereas the conversion of the epichlorohydrin is incomplete. In a slower side reaction the unreacted epichlorohydrin is transformed into polyglycerol, which explains the previously unsatisfactory epichlorohydrin balance.
From critical assessment of the various reaction rates which could be considered for the proposed reaction sequence, it follows that the rate determining reactions are pure addition reactions. A kinetic expression is derived for the polyaddition, depending on the molar ratio of the employed starting materials and on the ratio of two rate constants. During the reaction four variable concentrations can be calculated. At complete conversion of the component present in a deficient amount, the expression gives the residual amounts of the other component, and the average molecular weight of the polyaddition product.