It is used in flavorings, foods, perfumes, and pharmaceuticals. Vanillin is used as a chemical intermediate in the manufacture of several important drugs and other products. 

Production of vanillin from guaiacol is synthesized through electrophilic aromation substitution on reaction with glycoxylic acid; which results in synthesis of vanillylmandelic acid which is then converted 4-hydroxy-3-methoxyphenylglyoxylic acid and vanillin by oxidative decarboxylation

Vanillin is most prominent as the principal flavor and aroma compound in vanilla. Cured vanilla pods contain about 2% by dry weight vanillin; on cured pods of high quality, relatively pure vanillin may be visible as a white dust or "frost" on the exterior of the pod.

Vanillin is one of the components that contribute to the distinct aroma of vanilla. It is an organic crystal that forms on the outside of the vanilla bean. ... Fragrance oils that contain Vanillin or Ethyl Vanillin will oxidize faster than fragrance oils that do not contain this ingredient.

VANILLIN FOR SYNTHESIS LR