Synthesis of PCB methylsulfone: Some differences in mass and proton magnetic resonance spectroscopy

Eighty-six positional isomers of polychlorinated biphenyl methylsulfones (MSF-PCBs) containing two to seven chlorine atoms have been synthesized and characterized by mass spectrometry (MS) and proton magnetic resonance (PMR) spectroscopy. Some differences in mass fragmentation and PMR chemical shifts were observed between 2-, 3- and 4-MSF-PCBs. The PMR signals of the methyl and the aromatic proton adjacent to the MSF group shifted to downfield by the chlorine substitution at the lateral positions of the MSF group. 3- and 4-MSF-PCBs were found to be differentiated by their chemical shifts when no chlorine was substituted at the lateral positions.