Thalliumverbindungen als Katalysatoren für Umesterungen mit Glycidol und für Esteraustauschreaktionen mit Glycidylacetat

Thallium compounds as catalysts for transesterifications and ester exchange reactions The transesterification of di-, tri- and tetracarboxylic alkyl esters with 2,3-epoxy-propanol was investigated in the presence of various metal compounds as catalysts. It was found that only thallium compounds catalyse the reactions under mild conditions without decomposition of 2,3-epoxypropanol. Many thallium compounds also proved to be very good catalysts for the reactions of 2,3-epoxypropanol with alkoxysilanes and the ester exchange reactions of di-, tri- and tetracarboxylic alkyl esters with 2,3-epoxypropyl-acetate.     

Zur Reaktion von Dihydroxybiphenylen mit Phosphorpentachlorid ‐ Phosphepine mit Phosphonium‐ und Phosphoranstruktur

The 2, 2'‐dihydroxybiphenyl derivatives 1d‐f react with phosphorus pentachloride to give the dioxaphosphepinium hexachlorophosphates 3a, 3b , and 17 . The trichloro‐dioxaphosphepins 8a, 8b , and 21 were discussed as intermediates, which were obtained by chlorination of the 6‐chloro‐dioxaphosphepins 7a, 7b , and 20 . The hydrolysis of the dioxaphosphepins leads to the stable, cyclic phosphates 4a, 4b, 9a, 9b, 11a, 11b, 19a, and 19b . The crystal struc‐ture of 4a was determined; two different molecules was observed in the asymmetric unit.