FORMATION OF AZULENE AND NAPHTHALENE FROM PIPERYLENE

Piperylene mixed with air is converted into a mixture of aromatics con taining azulene and naphthalene on contact with bismuth oxide at simil ar to 600 degrees C. The yield of azulene and naphthalene is 6-8 %. Th e reaction is accompanied by burning of some of the piperylene and by the reduction of Bi2O3 to Bi metal. When the initial mixture is dilute d willi steam no reduction occurs. The reaction is believed to involve elimination of the allylic hydrogen, formation of dienyl radicals, th eir dimerization, and subsequent aromatization.