The Mixed Complex of Tetracycline-Metal Chelates. IV. Chlorotetracycline-Copper (II) Chelate with 4, 4'-Bis (dimethylamino)-thiobenzophenone (Thio-Michler's Ketone)

Abstract

The mixed complex of CT-Cu (II) chelate with thio-Michler's ketone (TMK) and its copper complex were studied concerning the properties and molar ratios in acid medium. Molar ratios of the complexes were measured by the continuous variation method. TMK formed a complex with copper (II) nitrate in a 2 : 1 ratio of TMK to copper, and the mixed complex had a 1 : 1 ratio of CT-Cu(II) to TMK, that is 1 : 1 : 1 (CT : Cu : TMK) ratio. TMK is oxidized to an indigo blue substance by halogen. TMK was not changed to the indigo blue substance by chloride ion, but it was changed to the indigo blue substance by copper (II) ion in the presence of chloride ion. This phenomenon was caused by the reaction of TMK with chlorine which is produced from the reduction of copper(II) chloride by the formation of a complex. The indigo blue complex was isolated by reaction of TMK with copper (II) chloride. The complex of TMK with copper(II) nitrate was a reddish brown powder. The mixed complex was prepared by the addition of ether to the solution of CT-Cu (II) chelate and TMK in acetone-methanol. The mixed complex prepared in the presence of chloride ion was an indigo blue substance. Color of the mixed complex was similar to that of TMK-Cu complex. The formation of the mixed complex was identified by paper chromatography using benzene-butanol as a developer.