vanilla is more heat resistant than one would expect for the main reason it is the result of a long fermentation (cooking) process. The fermented vanilla bean pods are loaded with resin that are not very volatile and very heat stable. Their shelf life is also much longer than what manufacturers would let you believe.
Vanillin, the main component that gives the distinctive taste of vanilla, has a boiling point of 285 C!
(look no further than Wikipedia: http://en.wikipedia.org/wiki/Vanillin).
Vanilla extract has been added to lard to make great tasting french fries. It can survive in caramel and candy making. Burnt hardwoods, like oak, contains lots of vanillin... think whiskey.
Edited by Luc_H - 10/16/14 at 8:49pm