HIGH-PRESSURE SYNTHESIS OF CYCLIC PHENYLACETYLENE OLIGOMER

New conjugated oligomers were prepared by reacting phenylacetylene under high pressure of 0.11 to 0.92 GPa at 100-200 degrees C for 0-5 h. The number-average molecular weight (M) over bar(n), the weight-average molecular weight (M) over bar(omega), and the oligomer yield increased with pressure, temperature, and time. The average molecular weight of the oligomer showed the maximum value ((M) over bar(n): 830, (M) over bar(omega): 2400) under 0.92 GPa, the maximum pressure, where phenylacetylene was oligomerized at a constant temperature. The structure of the oligomer was investigated from ESR, infrared, UV-VIS, field desorption mass (FDMS) spectra, and C-13 NMR spectrum. Analysis of the FDMS spectrum revealed that the molecular weight of the oligomer was multiple of the monomer. C-13 NMR spectrum of the oligomer showed the absence of sp-carbon (-C=). We found that the oligomer had a cyclic structure. The cyclic oligomers of pentamer or more were new compounds. (C) 1995 John Wiley & Sons, Inc.