NICKEL(0)-CATALYZED CYCLOADDITION COPOLYMERIZATION INVOLVING 2 DIYNESAND CARBON-DIOXIDE TO POLY(2-PYRONE)

A copolymerizability order of five diynes, i.e., 3,11-tetradecadiyne ( A), 2,6-octadiyne (B), 1,4-di(2-hexynyl)benzene (C), 1,3-di(2-hexynyl) benzene (D), and 1,7-cyclotridecadiyne (E), in the nickel(0)-catalyzed 1:1 cycloaddition copolymerization of the diyne with CO2 to the poly( 2-pyrone) was determined by the nickel(0)-catalyzed copolymerization i nvolving two diynes and CO2. The copolymerizability order obtained by analyzing the copolymer composition using H-1 NMR spectroscopy was A > E > B > C > D. This order was explained in terms of the steric hindra nce exerted by the substituent on the terminal C=C bond of the cooligo mer or the copolymer to its cycloaddition along with mobility of its t erminal C=C bond moiety for the cycloaddition. An order of cycloadditi on reactivity of the diyne, which is related to formation of the cooli gomer, was determined by measuring the unreacted diyne in the copolyme rization involving five diynes and CO2 using gas chromatography. The r esult was E > B > C > D > A. Thus high copolymerizability of diyne A i s noteworthy.