7-Hydroxy- and 6-hydroxyflavone have been chloromethylated and the structures of the monochloromethyl derivatives proved by converting them into the known formyl derivatives by Sommelet reaction. Similarly simple- and 7-methoxyflavanone have been chloromethylated and the structures of the monomethyl derivatives proved by reduction to the methyl derivatives and converting these methyl derivatives into flavones of known structures.