REACTION OF GLYOXAL WITH BORIC ACID AND BORATE ION

Like many cis-dihydroxy compounds, glyoxal promotes the ionization of boric acid, apparently by withdrawing borate ions from solution. The association constant of glyoxal with borate ion is 2·8 × 105. The conductivity increment, 1032 μ-mhos m 0·500M glyoxal plus 0·500M boric acid at 25°, is unusually high. The data give an independent confirmation of the polycyclic structure of aqueous glyoxal. Salts of the new acid have not been isolated. Two different methods used to determine the ionization constants" gave different results which could be partially reconciled by assuming that glyoxal reacts with borate ion in preference to boric acid. The constants correspond to molar ratios of glyoxal to borate ion of 3·2 and 2·7 at 25°. The latter number is probably the average degree of polymerization of glyoxal in solution. © 1969."