Pinacyanol is a cyanine dye. It is an organic cation, typically isolated as the chloride or iodide salts. The blue dye is prepared from 2-methylquinoline by quaternization with ethyl chloride or ethyl iodide. Condensation with formaldehyde results in coupling. Subsequent oxidation of the leuco intermediate gives the dye. Pinacyanol is a prototypical cyanine dye that was widely used as a sensitizer in electrophotography. Its biological properties have also been investigated widely. References