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Determination of the rotational barriers of atropisomeric polychlorinated biphenyls (PCBs) by a novel stopped‐flow multidimensional gas chromatographic technique
Author(s) -
Schurig Volker,
Reich Sabine
Publication year - 1998
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/(sici)1520-636x(1998)10:5<425::aid-chir8>3.0.co;2-4
Subject(s) - chemistry , atropisomer , enantiomer , chromatography , gas phase , gas chromatography , chirality (physics) , analytical chemistry (journal) , stationary phase , stereochemistry , organic chemistry , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
The rotational barriers Δ G † ( T ) of the four atropisomeric polychlorinated biphenyls (PCBs) 2,2′,3,5′,6‐pentachlorobiphenyl (PCB 95), 2,2′3,3′,4,6′‐hexachlorobiphenyl (PCB 132), 2,2′,3,3′,6,6′‐hexachlorobiphenyl (PCB 136), and 2,2′,3,4′,5′,6‐hexachlorobiphenyl (PCB 149) were determined via on‐line enantiomerization kinetics by a new stopped‐flow multidimensional gas chromatographic technique (stopped‐flow MDGC) employing Chirasil‐Dex as chiral stationary phase for enantiomer separation. The calculated rotational barriers Δ G † ( T ) of the trichloro‐ ortho ‐substituted atropisomers are 184 ± 2 kJ/mol for PCB 95, 189 ± 4 kJ/mol for PCB 132, and 184 ± 1 kJ/mol for PCB 149 at 300°C. The rotational barrier Δ G † ( T ) of tetrachloro‐ ortho ‐substituted PCB 136 is at least (or higher than) 210 kJ/mol at 320°C. Chirality 10:425–429, 1998. © 1998 Wiley‐Liss, Inc.