TCBTs structures

Polychlorinated biphenyls (PCBs) were detected as ubiquitous contaminations. Since PCBs are used in a wide field of applications they are not suitable as specific anthropogenic markers. In contrast, the PCB substituents tetrachlorobenzyltoluenes (TCBT) [Structure 6 Appendix] can serve as marker compounds of industrial emissions because of their higher specifity due to their limited technical applications. In Europe... 

There are 96 possible isomers (congeners) of TCBTs. Based on analogy to PCBs, Ehmann and Ballschmiter have developed a systematic numbering for the isomers [84]. Structures and numbers of the six major components of Ugileg 141 are shown below. 

Because 3,5-dichlorotoluene was formed only in very small amounts in the first step of technical TCBT synthesis, the number of relevant isomers in the final Ugilec 141 product was 70. Structures of these congeners were identified by syntheses of defined TCBT reference mixtures and using GC with three phases of differing polarity [84]. 

Fig. 4 Molecular structures of 1 - Polybrominated naphthalenes, PBNs, 2 -Tetrachlorobenzyltoluenes, TCBTs, 3 - Polybrominated diphenylethers, PBDEs, 4 - Polychlorinated terphenyls, PCTs, 5 - Polychlorinated triphenylmethanes, PCTPM, 6 - Polychlorinated dibenzothiophenes, PCDBT.

A central C-C bond. [TCYT]2 can decompose into the radical anion of 4,4, 6,6 -tetracyano-2,2 -bitriazine, [TCYBT] —, the one-electron reduced form of planar D2J,) TCBT, which is also structurally characterized as the [TMPD][TCYBT] CT complex (TMPD) (A1A1A, A -tetramethyl-/i-phenylenediamine) with a 1.492(2)A central sp -sp C-C bond (Scheme 8). Although crystals could not be obtained for the radical anion [TCYBT] , the electrochemistry, EPR, and theoretical calculations support the formation of [TCYBT] <2003JOC3367>. 

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