Production of Toxaphene Enantiomers by Enantioselective HPLC after Isolation of the Compounds from an Anaerobically Degraded Technical Mixture

Vetter, Walter; Kirchberg, Doreen

doi:10.1021/es000174g

Cited by 12 publications

(10 citation statements)

References 30 publications

(43 reference statements)

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“…The internal standard perdeuterated α‐hexachlorocyclohexane (α‐ PDHCH) was synthesized [25]. The technical product Melipax (1 kg unit, unopened) was found in a garden shed in Jena (Germany) [24]. This sample showed a slightly different CTT pattern compared to a standard solution of Camphechlor (LGC Promochem).…”

Section: Methodsmentioning

confidence: 99%

Anaerobic transformation of compounds of technical toxaphene. I. Regiospecific reaction of chlorobornanes with geminal chlorine atoms

Ruppe

Neumann

Vetter

2003

Enviro Toxic and Chemistry

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Technical toxaphene (Melipax) and the single compounds of technical toxaphene (CTTs) 2,2,5-endo,6-exo,8,8,9,10-octachlorobornane (B8-806), 2,2,5-endo,6-exo, 8,9,9,10-octachlorobornane (B8-809), 2,2,5,5,8,9,9,10,10-nonachlorobornane (B9-1025), 2-endo,3-exo,5-endo,6-exo,8,8,9,10,10-nonochlorobornane (B9-1679), 2-endo,3-exo,5-endo,6-exo,8,9,10,10-octachlorobornane (B8-1414), 2-endo,3-exo,5-endo,6-exo,8,8,9,10-octachlorobornane (B8-1412), and 2-exo,3-endo,5-exo,9,9,10,10-heptachlorobornane (B7-1453) were treated with suspensions of the anaerobic bacterium Dehalospirillum multivorans. After 7 d, more than 50% of technical toxaphene was transformed, and the relative amount of early eluting CTTs increased. After 16 d, only 2-exo,3-endo,6-exo, 8,9,10-hexachlorobornane (B6-923), 2-endo,3-exo,5-endo,6-exo, 8,9,10-heptachlorobornane (B7-1001), and a few minor penta- and hexachloro-CTTs were detected in the samples. The result of the transformation was comparable with observations in naturally contaminated sediments and soil. However, the performance with D. multivorans was more simple and reproducible, as well as faster, than use of soil, sediment, or anaerobic sewage sludge. In agreement with reports in the literature, reductive dechlorination at geminal chlorine atoms (gem-C1s) was found to be the major CTT transformation pathway. Experiments conducted with CTTs and gem-C1s at both primary and secondary carbons clarified that the initial C1 --> H substitution takes place at the secondary carbon C2. Furthermore, the 2-endo-C1 position was preferably substituted with hydrogen. In the case of B8-806, the dechlorination at the secondary carbon C2 was approximately 20-fold faster than the subsequent, slow reduction at the primary carbon C8. The three different formerly unknown heptachloro-CTTs, 2-exo,3-endo,6-exo,8,9,9,10-heptachlorobornane (B7-1473), 2-exo, 3-endo,6-endo,8,9,9,10-hepatchlorobornane (B7-1461), and 2-exo, 3-endo,6-exo,8,8,9,10-heptachlorobornane (B7-1470) were found as intermediates of the B8-806/809 transformation. Treatment of B9-1679 with D. multivorans indicated that gem-C1s on the bridge (C8 and C9) are dechlorinated faster than gem-C1s on the bridgehead (C10).

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Section: Methodsmentioning

confidence: 99%

Anaerobic transformation of compounds of technical toxaphene. I. Regiospecific reaction of chlorobornanes with geminal chlorine atoms

Ruppe

Neumann

Vetter

2003

Enviro Toxic and Chemistry

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“…Today, these phenomena are not well understood and subject to controversial discussion. Recently, pure enantiomers of 10 important CTTs were obtained after enantioselective HPLC using a Chira Dex column (Merck, Darmstadt, Germany) (122). Synthesized single CTTs were racemic (40,194,195).…”

Section: Vettermentioning

confidence: 99%

Enantioselective Fate of Chiral Chlorinated Hydrocarbons and Their Metabolites in Environmental Samples

Vetter

2001

Food Reviews International

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Gas chromatographic enantioseparation of chiral organochlorines (α-HCH, cis-and trans-chlordane, heptachlor, heptachlor epoxide, oxychlordane, o, p -DDT, compounds of technical toxaphene, stable atropisomeric PCBs and methylsulfonyl-PCBs) has been achieved during the last decade. For this purpose chiral stationary phases based on cyclodextrin derivatives have been applied in combination with GC/ECD, GC/MS, MDGC, and MS/MS. With these techniques methods have been developed which have been used to study the enantioselective fate of the chiral organochlorines. Changes in the enantioratios and conclusions drawn are reviewed. phenomenon of plane-polarized light (Malus, 1809) and optical rotation (Biot,113

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“…Structure of bornane with the carbon numbering and substituted orientation. Letters represent conformations on primary carbons and exo/endo refers to orientation on secondary carbons (Vetter and Kirchberg, 2001).…”

Section: Toxaphene Background Chemistry and Synthesismentioning

confidence: 99%

Risk Assessment of Toxaphene and its Breakdown Products: Time for a Change?

Lamb

Neal

Goodman

2008

Critical Reviews in Toxicology

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Technical toxaphene (TT) was last used in commerce in about 1982. Any environmental exposure to toxaphene in this century is to environmentally degraded forms of toxaphene, termed weathered toxaphene. Several hundred chlorinated bornane congeners have been identified in technical toxaphene. The degradation of technical toxaphene to weathered toxaphene can result in various congener mixtures, but the primary mode of degradation is dechlorination. The U.S. Environmental Protection Agency (EPA) presently estimates the risk of exposure to toxaphene by relying upon rat and mouse toxicology studies performed on technical toxaphene. No adjustment is made for the dechlorination of toxaphene in the environment. The European Union (EU), however, has modeled toxaphene risks from eating fish with chlorinated bornane residues through a series of studies on toxaphene degraded by either ultraviolet light, or biodegradation in fish. The EU risk assessment relies upon rat liver studies in vivo and mouse in vitro studies on the inhibition of gap junction intercellular communication (GJIC).This article reviews the current state of knowledge of technical and weathered toxaphene toxicology. We discuss the various current methods and opportunities to advance the risk assessment of weathered toxaphene beyond the existing U.S. EPA assessment of technical toxaphene.

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Production of Toxaphene Enantiomers by Enantioselective HPLC after Isolation of the Compounds from an Anaerobically Degraded Technical Mixture

Cited by 12 publications

References 30 publications

Anaerobic transformation of compounds of technical toxaphene. I. Regiospecific reaction of chlorobornanes with geminal chlorine atoms

Anaerobic transformation of compounds of technical toxaphene. I. Regiospecific reaction of chlorobornanes with geminal chlorine atoms

Enantioselective Fate of Chiral Chlorinated Hydrocarbons and Their Metabolites in Environmental Samples

Risk Assessment of Toxaphene and its Breakdown Products: Time for a Change?

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