Dechlorinated Analogues of Dechlorane Plus

Abstract

Degradation products of the chlorinated additive flame retardant Dechlorane Plus (DP) have been discovered globally. However, the identity of many of these species remains unknown due to a lack of available analytical standards, hindering the ability to quantitatively measure the amounts of these compounds in the environment. In the present study, synthetic routes to possible dechlorinated DP derivatives were investigated in an effort to identify the environmentally significant degradation products. The methano-bridge chlorines of anti- and syn-DP were selectively replaced by hydrogen atoms to give six new hydrodechlorinated DP analogues. The identity and absolute configuration of all of these compounds were confirmed by GC-MS, NMR spectroscopy, and X-ray diffraction studies. These compounds were observed in sediment samples from streams and rivers in relatively rural areas of Ontario and are thus environmentally relevant.

Interactions between Humic Substances and Microorganisms and Their Implications for Nature-like Bioremediation Technologies

“…Byzov and coauthors [ 107 ] explained the ability of bacteria to decompose HSs by means of extracellular polyphenol oxidase activity. Other scientists [ 124 ] related HS bacterial degradation to cellulases, endohemicellulases, and debranching and oligosaccharide-degrading enzymes.…”

“…Unlike enzymatic processes involved mainly in the aerobic degradation of HSs, less well understood are the anaerobic pathways [ 105 , 124 ]. A role of the anaerobic ammonium oxidation (Anammox) process in HS degradation under anaerobic conditions was shown for the heterotrophic bacteria consortium by [ 2 ].…”

“…It was hypothesized that the oxygen functional groups, such as C=O of quinoid and ketones, C–O of carboxylic acids, and phenolic O–H, might be of particular importance here. Recently, the electron-donating properties of HSs were also demonstrated in the process of dissimilatory iron reduction in the presence of an Ignavibacterium/Melioribacter [ 124 ].…”

“…HSs have been demonstrated to have three distinct roles as electron carriers, namely (1) electron acceptors for respiration, (2) redox mediators for reduction processes, and (3) electron donors to microorganisms [ 17 , 183 , 184 ]. HSs act as electron acceptors and electron mediators for microbial respiration and the oxidation of several substances, including organic compounds [ 15 , 16 , 185 , 186 , 187 ], hydrogen [ 15 ], and metals [ 86 , 124 , 188 ]. HSs themselves can act as terminal electron acceptors in anaerobic microbial respiration [ 189 ].…”

“…HSs themselves can act as terminal electron acceptors in anaerobic microbial respiration [ 189 ]. As electron donors, HSs could aid microbial respiration and the reduction of nitrate [ 190 ], sulfide [ 191 ], and Fe(III) oxides [ 17 , 52 , 124 , 192 , 193 , 194 ]. Though all three types of electron transfer can be executed by HSs, under anoxic conditions HSs are most often considered as terminal electron acceptors during microbial respiration and as electron shuttles driving the redox bioconversion of metals and organic molecules [ 15 , 16 , 17 , 185 , 187 , 195 ].…”