My question is simply whether anyone knows what are the transition metals that the phenol group of the vanillin molecule could react with, and thereby produce discolorations.

This question is particularly relevant to the flavors and fragrances industries, where vanillin is a widely used flavor and fragrance ingredient. It is unfortunately prone to purple discoloration when it reacts with trace amounts of iron (according to chapter 4 of Chemistry and Technology of Flavours and Fragrances).

I am curious to know what is the full list of transition metals that vanillin could react with, and what complexes and their colors could be produced as such.

Thank you.

  • $\begingroup$ Are you also interested in complexes with o-vanillin? $\endgroup$ – andselisk Aug 2 '17 at 4:48
  • $\begingroup$ Also, I'm not very familiar with the processing of vanillins in the industriy of fragrances and flavors -- are there also other chemicals in the same system that can a source additional ligands (water, nitrate/nitrite, azide, pyridine etc.)? This can also influence complexation and the color. $\endgroup$ – andselisk Aug 2 '17 at 9:20