TOPOCHEMICAL PHOTOPOLYMERIZATION OF MUCONIC DERIVATIVES IN THE CRYSTALLINE STATE VIA A RADICAL-CHAIN REACTION-MECHANISM

The photoreaction behaviors of various muconic derivatives, dialkyl (Z ,Z)-muconates (1), N,N'-dialkyl-(Z,Z)-muconamides (2), and di(alkylamm onium) (Z,Z)-muconates (3) in the crystalline state were investigated. The crystals of these compounds provided the corresponding (E,E)-isom ers or tritactic polymers as the photoproducts during irradiation usin g a high-pressure mercury lamp, depending on the structure of alkyl su bstituents. The isomerization and polymerization were revealed to proc eed via a crystal-to-crystal process based on the powder X-ray diffrac tion. The ammonium derivatives with higher n-alkyl substituents were f ound to have a high polymerization reactivity to yield a polymer with a meso-diisotactic-trans-2,5-structure and high molecular weight, simi lar to the polymerization of the previously reported diethyl ester.