The present study describes a preparative gas chromatographic (GC) approach employed to study a series of products arising from reaction of phenylacetylene with para-substituted aryl-iodides under Sonogashira catalysis conditions. GC analysis resolves the isomers from each reaction; however, it cannot provide structural details (their MS data are virtually identical). Since classical liquid chromatography cannot resolve the isomers, preparative-scale GC is the only practical approach to provide further spectroscopic characterization of the isomers. The products are well separated by GC so a single thick-film capillary column is adequate for this case, with operation up to similar to+300 degrees C. By collection of 50+ repeat injections, sufficient material could be isolated for H-1 NMR spectral analysis of the isomers, and for one isomer (isomer I) of a number of analogous related catalytic reaction mixtures, X-ray crystal structure determination enabled complete structural elucidation (absolute configuration) of the substitution pattern of the structure of this isomer. This confirmed isomer I to be the 2-para-aryl-substituted 1,3,5-triphenylbenzene product in all cases. 1H NMR spectra of isomer I products generally had similar patterns but differed markedly from the second major isomer product (isomer II).
Ruhle, C., Niere, J., Morrison, P., Jones, R., Caradoc-Davies, T., Canty, A., Gardiner, M., Tolhurst, V-A., & Marriott, P. (2010). Characterization of tetra-aryl benzene isomers by using preparative gas chromatography with mass spectrometry, nuclear magnetic resonance spectroscopy, and x-ray crystallographic methods. Analytical Chemistry, 82(11), 4501 - 4509. https://doi.org/10.1021/ac100417h