Isomer specific synthesis using the Suzuki-coupling. Polychlorinated terphenyls as standards for environmental analysis M. Bahadir a, * , A. Pieper a , R. Vogt a , H. Wichmann a , J. Grunenberg b , H. Hopf b a Institute of Ecological Chemistry and Waste Analysis, TU Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany b Institute of Organic Chemistry, TU Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany Received 25 April 2002; received in revised form 23 September 2002; accepted 2 October 2002 Abstract Defined polychlorinated terphenyl (PCT) single congeners as reference standards are the prerequisite for the de- velopment of analytical methods for their determination and quantification in the environment. The selective synthesis ofPCTsforenvironmentalanalyticalpurposesbyapplicationoftheSuzuki-couplingreactionisdescribed.Undereasily modifiedstandardreactionconditionsofthiscouplingprocessthePCTscanbeobtainedbyreactionofbenzeneboronic acids with dibromobenzenes mostly in good yields, as described by the synthesis of following PCT congeners: p-PCT (3,3 00 ,5,5 00 -tetrachloro-, 2,2 00 ,4,4 00 -tetrachloro-, 2 0 ,3,3 00 ,5,5 00 -pentachloro-); m-PCT (3,3 00 ,5,5 00 -tetrachloro-) and o-PCT (3,3 00 ,5,5 00 -tetrachloro-). The terphenyl congeners were characterized by NMR ( 1 H, 13 C)- and FT-IR-spectroscopy. Their purity was checked by GC/MS analysis. The experimental and quantum-chemically calculated FT-IR-spectra werecomparedanditwasshown,thatthedeterminationofthechlorinesubstitutionpatternintheterphenylcongeners by their typical absorption spectra is possible. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Polychlorinated terphenyls; PCT; Suzuki-coupling; Regioselective synthesis; Environmental analysis; Single congeners; Reference standards 1. Introduction Starting from 1955 about 60,000 tons of polychlori- nated terphenyls (PCT) were manufactured in different countries,whereasproductionwaslargelystoppedatthe beginning of the 1980s. The total production quantity was 15–20 times lower than that of the PCBs, which does not diminish, however, their environmental toxi- cological relevance (de Boer, 2000). The application patterns of PCT were similar to those of PCBs due to similar chemical and physical properties of both sub- stance groups, such as high chemical stability, high heat capacity, excellent dielectric properties, etc., why they were, for instance, used in transformers. But in con- trasttothePCBstheywerepredominantlyappliedinso- called open systems for coatings, as insulating paints for wires and flame retarding paintings (Birn and Jung, 1993). From the former application fields as well as from landfills PCTs are emitted into the environment as low volatile, persistent, and bioaccumulating sub- stances. Analytical investigation of PCTs in environmental samples has so far hardly been performed, due to the Chemosphere 50 (2003) 1151–1156 www.elsevier.com/locate/chemosphere * Corresponding author. Tel.: +49-531-391-5960; fax: +49- 531-391-5799. E-mail address: m.bahadir@tu-bs.de (M. Bahadir). 0045-6535/03/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0045-6535(02)00647-1