Preparation of N,N'-dibenzylethylenediamine tetracyclines
Addn. of 0.1-0.4 g. of N,N'-dibenzylethylenediamine (I)/l. as a sol. salt to fermentations of tetracycline or its homologs results in formation of complexes (II) of I with the tetracyclines. As a result, fermentation liquors show greater activities, and isolation of the antibiotics is facilitated. I is maintained at a level of 20-33% by wt. of that of the antibiotic in the mixt. throughout the fermentation. II are extd. with H2SO4 or (COOH)2, pptd. at pH 8-10, and crystd., either as the base or as a salt. These II consist of I and a tetracycline in ratios of 1:1 or 1:2 or of these and an alk. earth metal in a ratio of 1:4:3. Extn. yields are 65-80%.