THE PREPARATION AND CHARACTERIZATION OF THE DIAQUOCOBINIC FORMS OF SEVERAL INCOMPLETE CORRINOIDS - COBYRIC ACID, COBINAMIDE, AND 3 ISOMERIC COBINIC ACID PENTAAMIDES

The preparation of the diaquo- forms of the incomplete corrinoids, cobyric acid, cobinamide, and three isomeric cobinic acid pentaamides, from the corresponding aquocyanocorrinoids has been accomplished. The compounds were characterized by electronic absorption spectra, pk(a) values, and HPLC/TLC behavior. Upon titration, the acids exhibited three pK(a) values, but only the pK(a) corresponding to the carboxylic acid involved the transfer of a full equivalent of protons. In addition, the progress of diaquo- to dihydroxo-titration, and the spectrum of the final products indicated a complex process. These diaquocorrinoids appear to be unstable, and should be stored in solution, frozen, under an inert atmosphere.