Взаимодействие гидрата 1-герматранола со щавелевой кислотой

Abstract

Polycarboxylic acids are involved in many life processes, along with germatranes exhibiting high biological activity. At the same time, the studies on the reactions of 1-substituted germatranes with polycarboxylic acids appear to be insufficient. On the one hand, compounds of germatranes with substances containing a car boxyl group were reported to be stable in the presence of water. On the other hand, the germatranic cycle of 1-germatranol hydrate in an aqueous medium is acknowledged to be decomposed by D-tartaric acid to bis(µ-tartrato)di(hydroxy)germanate(IV) triethanolammonium form. In this work, the interaction of 1-germatranol hydrate (H 2 O·НОGe(OCH 2 CH 2 ) 3 N) with oxalic acid (HOC(O)COOH) in water, dimethyl sulphoxide and acetonitrile alcohol was studied. The reaction in an aqueous medium at 20–25 °С quickly leads to the cleavage of the germatrane skeleton followed by the formation of [(C 2 O 4 )2Ge(OH) 2 ] 2- ·H + ·[(HOCH 2 CH 2 ) 3 NH] + bis(oxalate-O,O') dihydroxygermanate triethanolammonium. As a result of the topochemical reaction, exposing the reaction residue following evaporation of water at 50 °С in a vacuum of 2 mm Hg for 2 h subsequently leads to the formation of (ROC(O)COOGe(OCH 2 CH 2 ) 3 N(R=H) and N(CH 2 CH 2 O) 3 Ge mono- and bis(germatran-1-yl)oxalate), as well as to the reduction of 1-germatranol. Under additional exposure of the reaction mixture in a 2 mm Hg vacuum at 100 °C for 40 min, O[Ge(OCH 2 CH2) 3 N] 2 bis(germatran-1-yl)oxide and (germatran-1-yl)formate is formed. Following the water dissolution of the reaction mixtures, the resulting compounds undergo another conversion to bis(oxalate-O,O')dihydroxygermanate triethanolammonium and 1-germatranol. Heating a mixture of 1-germatranol hydrate with oxalic acid in a dimethyl sulphoxide and acetonitrile medium along with 1-germatranyl oxalates leads to the formation of a hydrolytic cleavage product of the germatrane skeleton, bis(oxalate-O,O')dihydroxygermanate triethanolammonium, while the boiling of isoamyl alcohol mainly provides for the esterification reaction with a 1-isoamyloxygermatrane yield exceeding 90 %.