CHROMOGENIC REAGENTS FOR IRON(II) - STUDIES IN THE 1,2,4-TRIAZINE SERIES

Sixteen as-triazines with different substituents at the 3- and 5-/6-po sitions have been prepared as the first part of a comprehensive study ultimately to develop an improved means to determine whether an indivi dual has handled a firearm. Their reaction with iron(II) in solution w as studied spectrophotometrically, and sensitivity to iron(II) was com pared with that of 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDT). Ei ght of the new compounds exhibited higher sensitivity than PDT. The su bstituents which brought about the greatest increase in sensitivity wh ere 4-phenyl-2-pyridyl (at position 3) and 3,4-dimethoxyphenyl (at pos itions 5 and 6). Quite surprisingly, as-triazines containing the 2-qui nolyl group at position 3 did not exhibit any visible reaction with ir on(II) even after 12 h. idyl)-5,6-bis-(3,4-dimethoxyphenyl)-1,2,4-tria zine was found to be the most sensitive ferroin-type chromogen reporte d to date (molar absorptivity = 3.81 x 10(4) l mol(-1) cm(-1) at 571 n m).