Hydrochloric acid was added to bring the pH to 5.5. The mixture was shaken on a rotary shaker for 16 hr., at which time the p H was adjusted to 3.0 with HCl, and the mixture was agitated for an additional 48 hr. The product accumulated as a precipitate in the aqueous phase; and was filtered without phase separation. The tetracycline-urea compound waa dried in vacuo at 50°, weight 7.80 g. (90% from organic extract), assay 938 pg./mg. as tetracycline hydrochloride.Anal. Calcd. for C Z~H~~N~~~~: C, 52.80; H, 5.75; N, 10.72. Found: C, 52.85; H, 5.68; N, 10.70.Determination of solubilities. An unweighed portion of the tetracycline derivative was suspended in the solvent and placed on a rotary shaker for two hours at room temperature, the undissolved material filtered, and the filtrate assayed spectrophotometrically.Determination of distribution coefiients. Samples were dissolved in pH 2.5/0.25M sodium dihydrogen phosphate buffer (previously equilibrated against the organic phase) a t a final concentration of 50 pg./ml. and equilibrated with a mixture of 80% chloroform-20% butanol (10 ml. of each phase). Each phase was assayed spectrophotometrically after thirty inversions. The distribution coefficient for tetracycline urea compound was 0.14 (organic phasejaqueous phase), for tetracycline base, 0.13.Fractionation of mixtures of tetracycline and 7-chlorotetracycline. Mixtures containing 7-chlorotetracycline neutral and tetracycline neutral were prepared, and 5.0 g. of the crystal mixture was slurried in 100 ml. of saturated aqueous urea solution. after one hour of shaking the undissolved material was filtered and analyzed.Lactonitrile, a typical cyanohydrin, was not stable in an attempted base-catalyzed condensation with dicyandiamide to an a-hydroxyguanamine. The acid-catalyzed condensation of cyanohydrins with vinyl ethers gave a-cyanoacetals, I, which were stable in this condensation. Acid-catalyzed hydrolysis of the resulting diaminotriazines, 11, gave the desired a-hydroxyguanamines, I11 (2,4-diamino-s-triazine-6-alkanols). A homologous formal, 2,Pdiamino-6-ethoxymethoxymethyls-triazine, was either recovered quantitatively or converted to resins under comparable conditions.