Abstract
Schiff base bis (2— quinolidene)‐ diamine gives a purple‐red complex with copper ions with a λmax at 530 mμ. The optimum pH for production of this complex is approximately 9.5. None of the metallic ions of the analytical groups II and III give rise to red complexes with the above Schiff base. Manganous (Mn2+) and stannous (Sn2+)ions as well as reducing agents such as hydrazine or hydroxylamine exert a catalytic effect on the rate of formation of these copper complexes. The thermal stability of the copper complex formed from the Schiff bases (2‐quinoline‐aldehyde with NH2‐(CH2)n‐NH2) is greater for diamine for which n = 4–6 than for n = 2–3.