ChemInform Abstract: Reductive Dehalogenation of Aliphatic vic-Dihalides with Metallic Samarium in a Methanolic Medium.

ChemInform ◽  
2010 ◽  
Vol 28 (16) ◽  
pp. no-no
Author(s):  
R. YANADA ◽  
N. NEGORO ◽  
K. YANADA ◽  
T. FUJITA
Keyword(s):  
Reductive Dehalogenation ◽  
Methanolic Medium

Reductive dehalogenation of aliphatic vic-dihalides with metallic samarium in a methanolic medium

1996 ◽  
Vol 37 (52) ◽  
pp. 9313-9316 ◽  
Author(s):  
Reiko Yanada ◽  
Nobuyuki Negoro ◽  
Kazuo Yanada ◽  
Tetsuro Fujita
Keyword(s):  
Reductive Dehalogenation ◽  
Methanolic Medium

Reductive Dehalogenation of Environmental Contaminants: A Critical Review

1989 ◽  
Vol 24 (2) ◽  
pp. 299-322 ◽  
Author(s):  
R. M. Baxter
Keyword(s):  
Hydrogen Atom ◽  
Aromatic Compounds ◽  
Reductive Dechlorination ◽  
Halogen Atom ◽  
Environmental Contaminants ◽  
Methanogenic Bacteria ◽  
Photochemical Reactions ◽  
Reductive Dehalogenation ◽  
Iron Porphyrins ◽  
Aliphatic Compounds

Abstract It is generally recognized that reductive processes are more important than oxidative ones in transforming, degrading and mineralizing many environmental contaminants. One process of particular importance is reductive dehalogenation, i.e., the replacement of a halogen atom (most commonly a chlorine atom) by a hydrogen atom. A number of different mechanisms are involved in these reactions. Photochemical reactions probably play a role in some instances. Aliphatic compounds such as chloroethanes, partly aliphatic compounds such as DDT, and alicyclic compounds such as hexachlorocyclohexane are readily dechlorinated in the laboratory by reaction with reduced iron porphyrins such as hematin. Many of these are also dechlorinated by cultures of certain microorganisms, probably by the same mechanism. Such compounds, with a few exceptions, have been found to undergo reductive dechlorination in the environment. Aromatic compounds such as halobenzenes, halophenols and halobenzoic acids appear not to react with reduced iron porphyrins. Some of these however undergo reductive dechlorination both in the environment and in the laboratory. The reaction is generally associated with methanogenic bacteria. There is evidence for the existence of a number of different dechlorinating enzymes specific for different isomers. Recently it has been found that many components of polychlorinated biphenyls (PCBs), long considered to be virtually totally resistant to environmental degradation, may be reductively dechlorinated both in the laboratory and in nature. These findings suggest that many environmental contaminants may prove to be less persistent than was previously feared.

Biotreatability test of bleach wastewaters from pulp and paper mills

1997 ◽  
Vol 35 (2-3) ◽  
pp. 101-108
Author(s):  
X. Wang ◽  
T. H. Mize ◽  
F. M. Saunders ◽  
S. A. Baker
Keyword(s):  
Wastewater Treatment ◽  
Pulp And Paper ◽  
Reductive Dehalogenation ◽  
Continuous Reactor ◽  
Batch Reactors ◽  
Aerobic Treatment ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Degradation Rates ◽  
Adsorbable Organic Halide

Research is focused on an integrated way to simultaneously optimize the bleaching operations and subsequent wastewater treatment for pulp and paper mills. Bleach wastewaters from ClO2-bleached pulping studies at Institute of Paper Science and Technology (IPST) were used as the feed for batch reactors to test and rank the treatability and kinetics. The key aspect of the system is the use of sequential anaerobic/aerobic phases to enhance reductive dehalogenation of chloro-organic materials. Two continuous reactor systems, one operated in an anaerobic-aerobic mode and a second in an aerobic-aerobic mode, received bleaching wastewater obtained from a full-scale plant. Acclimated cultures from both continuous reactors were used to quantify the AOX (Adsorbable Organic Halide) and COD removal from various bleaching wastewaters. In general, the sequential anaerobic/aerobic treatment of bleach wastewater can improve both biotreatability and degradation rates.

scholarly journals Dehalogenation of the Herbicides Bromoxynil (3,5-Dibromo-4-Hydroxybenzonitrile) and Ioxynil (3,5-Diiodino-4-Hydroxybenzonitrile) by Desulfitobacterium chlororespirans

2005 ◽  
Vol 71 (7) ◽  
pp. 3741-3746 ◽  
Author(s):  
Alison M. Cupples ◽  
Robert A. Sanford ◽  
Gerald K. Sims
Keyword(s):  
Electron Acceptor ◽  
Pure Culture ◽  
Electron Acceptors ◽  
Reductive Dehalogenation ◽  
First Report ◽  
Lactate Uptake ◽  
Standard Deviations ◽  
Doubling Times

ABSTRACT Desulfitobacterium chlororespirans has been shown to grow by coupling the oxidation of lactate to the metabolic reductive dehalogenation of ortho chlorines on polysubstituted phenols. Here, we examine the ability of D. chlororespirans to debrominate and deiodinate the polysubstituted herbicides bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), ioxynil (3,5-diiodo-4-hydroxybenzonitrile), and the bromoxynil metabolite 3,5-dibromo-4-hydroxybenzoate (DBHB). Stoichiometric debromination of bromoxynil to 4-cyanophenol and DBHB to 4-hydroxybenzoate occurred. Further, bromoxynil (35 to 75 μM) and DBHB (250 to 260 μM) were used as electron acceptors for growth. Doubling times for growth (means ± standard deviations for triplicate cultures) on bromoxynil (18.4 ± 5.2 h) and DBHB (11.9 ± 1.4 h), determined by rate of [14C]lactate uptake into biomass, were similar to those previously reported for this microorganism during growth on pyruvate (15.4 h). In contrast, ioxynil was not deiodinated when added alone or when added with bromoxynil; however, ioxynil dehalogenation, with stoichiometric conversion to 4-cyanophenol, was observed when the culture was amended with 3-chloro-4-hydroxybenzoate (a previously reported electron acceptor). To our knowledge, this is the first direct report of deiodination by a bacterium in the Desulfitobacterium genus and the first report of an anaerobic pure culture with the ability to transform bromoxynil or ioxynil. This research provides valuable insights into the substrate range of D. chlororespirans.

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