Thermolysis of the polyyne C8H2 in hexane and methanol: Experimental and theoretical study

摘要

The mean lifetimes of polyyne C8H2 in hexane were determined at 50, 60, 80, and 100 degrees C and in methanol at 60 degrees C. The reactions are second order at all temperatures: In k(2) = 20.5 +/- 1.5-10303 +/- 5207(-1) and the corresponding activation energy is 85.7 +/- 6.3 kJ mol(-1) (7164 cm(-1)). Extrapolation suggests that solutions at 1 mM concentration are significantly unstable at room temperature. Quantum chemical calculations show that polyynes CmH2 + CnH2 (m + n = 16) could be products, but these were not detected. Alternatively, C16H2 isomers could form. IR spectra of the solid residues from hexane and methanol solutions were obtained. (C) 2005 Elsevier Ltd. All rights reserved.