Blue carotenoids

A review on the chemistry of blue carotenoids, emphasizing own contributions, is presented. Treated are violerythrin, carotenoid oxonium ions, preparation and characterization of carotenoid cations (< C-40, C-40, > C-40-skeletal analogs), the Carr-Price Vitamin A blue colour reaction, carotenoid-iodine complexes and blue carotenoproteins.