THE ULTRAVIOLET ABSORPTION OF VITAMINS IG, Kz, AND SOME RELATED COMPOUNDS

The ultraviolet absorption spectra of vitamins K1 from alfalfa and Kz from putrefied fish meal, both of which were isolated by Dr. E. A. Doisy and his associates at St. Louis University School of Medicine (McKee, Binkley, MacCorquodale, Thayer, and Doisy, 1939), have been determined. Absorption curves of the reduction products of these two vitamins have been evaluated in the ultraviolet region as well as those of the corresponding diacetates and the hydrolyzed diacetate of dihydro vitamin K,. In addition, ultraviolet absorption curves are presented for certain substituted 1,4-naphthoquinones. The close analogy between the naphthoquinone curves and those of vitamins II1 and Kz clearly indicated the 1,4-naphthoquinoid structure of the vitamins. The compounds used throughout this investigation were prepared by Doisy and his associates in the course of their work on the isolation of vitamins K1 and KS and the establishment of the chemical structures of the two vitamins. Spectrophotometric examinations were made, concurrently, of various preparations as obtained by Doisy in his vitamin K investigations. The work was begun in January, 1939, after the isolation of the two pure vitamins to aid in the elucidation of the structure of the compounds.