Mechanismus der autokatalytischen Primärreaktion bei der Formose-Reaktion / Mechanism of the Autocatalytic Primary Reaction Step in the Formose Reaction

Abstract

Abstract New insights into the autocatalytic primary reaction step of the formose reaction are obtained by using soluble calcium hydroxide bismethylene glycolate complexes for kinetic investigations in homogeneous phase. The reaction kinetics follows between 20% and 80% formaldehyde consumption a nonlinear rate equation. Specific co-catalytic activities are determined for the most important intermediates and end products of the formose reaction. By correlation of the kinetic results with solubility experiments, ultraviolet, 13C NMR spectroscopic measurements and rates of oxidation and acid formation, a mechanism for the autocatalytic primary reaction is given. The main catalytic effects for the formaldehyde activation are caused by calcium enediolate complexes in an autocatalytic cycle and competition with the Cannizzaro and oligomerisation reaction. Further, but less probable mechanisms are also discussed.