It is completely unneccessary to put titanium dioxide in food. Just because the FDA approves of it doesn't mean it is a good thing. Titanium Dioxide is basically white paint, or rather, the pigment that forms white paint. So why would you want to ingest it?
Personally, I use Cooks Pure Vanilla Powder, which avoids the slight brownish color that regular liquid vanilla will leave in a Vanilla Cake. You should be able order it from Amazon. If not Cook's brand, than some other brand of Vanilla Powder.