Durch Molybdationen katalysierte Reaktionen bei Kohlenhydraten, V. Epimerisierung von L‐Rhamnose

Abstract

In einstufiger Synthese wird L-Chinovose durch Epimerisierung von L-Rhamnose in Gegenwart von Molybdansaure zu 60% d. Th. erhalten. Epimerisation Reactions of Carbohydrates Catalyzed by Molybdate Ions, V. -Epimerisation of L-RhamnoseA new synthesis of L-chinovose is achieved by epimerisation of L-rhamnose in presence of molybdic acid giving a yield of 60 %.

The kinetics of the molybdate-catalysed epimerization of D-glucose and D-mannose in aqueous solutions

“…This mmimization was achieved with a single-response Marquardt algorithm [ 13 1. The mathematical models leading to calculated values consisted of algebraic equations originating from equilibrium relations in the case of titrations or from the continuity equation (2) in the case of batch epimerization.…”

Comparison of Homogeneous and Heterogeneous Catalysts for Glucose‐to‐Fructose Isomerization in Aqueous Media

“…However, Ni 2+ complexes with diamine co-catalysts, [14] as well as various alkaline-metal and rare-earthmetal-ion-based [15] complexes, catalyze the glucose-to-mannose epimerization reaction through a different reaction pathway, which involves a 1,2-carbon shift (the bond to the C3 atom migrates from the C2 atom to the C1 atom), analogous to the Bilik reaction. [16] Several mechanistic studies of aldose-to-ketose isomerization reactions on various metal-based catalysts have been reported and many different reaction pathways have been suggested. In the enzymatic reaction (xylose isomerase), the function of the metal center of the enzyme is to stabilize the open-chain form and to catalyze the aldose-to-ketose isomerization reaction; however, the exact mechanism for the movement of the hydrogen atom from the C2 position to the C1 position is not yet understood.…”

Structure and Taste of Some Dihydrochalcone Glycosides

“…MeOH (12,167) was added dropwize under cooling with ice-water and stirring for 2 hr. After neutralization with dilute hydrochloric acid the solution was evaporated to a small volume and stored in a refrigerator.…”