Vanilla and Vanillin
Vanilla is a flavoring obtained from vanilla pods or produced artificially. Natural vanilla is the second-most expensive spice after saffron. The chemical compound vanillin (4-hydroxy-3-methoxybenzaldehyde) is the major contributor to the characteristic flavor and aroma of natural vanilla. Artificial vanilla flavoring is often a solution of pure vanillin, usually of synthetic origin.
The majority of chemical-synthesized vanillin comes from the petrochemical precursor guaiacol (2-Methoxyphenol). The most significant method for the chemical synthesis of vanillin from guaiacol is condensation of glyoxylic acid with guaiacol (1) to give vanillylmandelic acid (2), which is oxidized to produce 4-Hydroxy-3-methoxyphenylglyoxylic acid (3). This acid undergoes a decarboxylation to afford vanillin (4).