I 1655 (OTTO) Isophthalaldehyde, 99% Cas 626-19-7 - used in the synthesis of binuclear ruthenium complex. I 1655 (OTTO) Isophthalaldehyde, 99% Cas 626-19-7 - used as a reagent in the synthesis of 2-chlorobenzoic acid derivatives which display antimicrobial activity.