With a bit of googling I found the following:
As common as vanilla may be as a flavor nowadays, there was once a point in history when it was a rare commodity, according to Scientific American. That's because, at the time, things that were flavored "vanilla" had to be made with actual vanilla beans, or, at the very least, extract of vanilla beans. Of course, that hasn't been the case since the turn of the 20th century, which is when chemists invented "vanillin," which can be manufactured without a lick of actual vanilla bean. Rather, Scientific American reports that vanillin can be "synthesized variously from pine bark, clove oil, rice bran, and lignin." And since that time, "of the roughly 18,000 metric tons of vanilla flavor produced annually, about 85% is vanillin synthesized from the petrochemical precursor guaiacol," with the rest from lignin.
