Characterization of tetra-aryl benzene isomers by using preparative gas chromatography with mass spectrometry, nuclear magnetic resonance spectroscopy, and X-ray crystallographic methods.
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 approximately +300 degrees C. By collection of 50+ repeat injections, sufficient material could be isolated for (1)H 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. (1)H NMR spectra of isomer I products generally had similar patterns but differed markedly from the second major isomer product (isomer II).
Rühle
Christian P G
CP
Australian Centre for Research on Separation Science, School of Applied Sciences, RMIT University, GPO Box 2476, Melbourne 3001, Australia.
Niere
Julie
J
Morrison
Paul D
PD
Jones
Roderick C
RC
Caradoc-Davies
Tom
T
Canty
Allan J
AJ
Gardiner
Michael G
MG
Tolhurst
Vicki-Anne
VA
Marriott
Philip J
PJ
D000114:Acetylene / Q000031:analogs & derivatives / Q000737:chemistry; D001554:Benzene / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007455:Iodine / Q000737:chemistry; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*
C044736:phenylacetylene; D007455:Iodine; D001554:Benzene; D000114:Acetylene