Trichlorophenol, dechlorinating

In situ hybridization was also used to reveal the structure of microbial consortia. Wang and Hegemann [121], used this technique to study the structure of a consortium capable of reductively dechlorinating trichlorophenol. Their analysis showed that the consortium contain major subpopulations that are phylogenetically affiliated to the gamma and delta subclass of Proteobacteria. 

Kiyohara H, T Hatta, Y Ogawa, T Kakuda, H Yokoyama, N Takizawa (1992) Isolation of Pseudomonas pick-ettii strains that degrade 2,4,6-trichlorophenol and their dechlorination of chlorophenols. Appl Environ Microbiol 58 1276-1283. 

A spore-forming strain of Desulfitobacterium chlororespirans was able to couple the dechlorination of 3-chloro-4-hydroxybenzoate to the oxidation of lactate to acetate, pyruvate, or formate (Sanford et al. 1996). Whereas 2,4,6-trichlorophenol and 2,4,6-tribro-mophenol supported growth with the production of 4-chlorophenol and 4-bromophenol, neither 2-bromophenol nor 2-iodophenol was able to do so. The membrane-bound dehalogenase contains cobalamin, iron, and acid-labile sulfur, and is apparently specific for ortho-substituted phenols (Krasotkina et al. 2001). 

Reddy GVB, MDS Gelpke, MH Gold (1998) Degradation of 2,4,6-trichlorophenol by Phanerochaete chrysosporium. involvement of reductive dechlorination. J Bacteriol 180 5159-5164. 

Xun L, CM Webster (2004) A monooxygenase catalyzes sequential dechlorination of 2,4,6-trichlorophenol by oxidative and hydrolytic reactions. J Biol Chem 279 6696-6700. 

The k can be obtained using the initial rate method by overdosing H202. For example, at the overdosed H202 concentration of 5 x 10 M and constant pH of 3.5, the k can be obtained by plotting the l/r0vs. 1/Fe2+ during the dechlorination of 2,3,4-trichlorophenol. 

As discussed earlier, the effects of the meta, para, and ortho positions of chlorine on the dechlorination kinetics of monochlorophenols, dichlorophenols, and trichlorophenols during Fenton oxidation were evaluated by comparing the rate constants of the kinetic model (Tang and Huang, 1995). This study proposed a pseudo first-order steady state with respect to organic concentration. The proposed reaction pathways considered that the hydroxyl radicals would attack unoccupied sites of the aromatic ring. 

Ferrari RP, Laurenti E, Trotta F (1999) Oxidative dechlorination of 2, 4, 6-trichlorophenol catalyzed by horseradish peroxidase. J Biol Inorg Chem 4 232-237... 

Chen, G., Wang, Z. and Xia, D. (2004) Electrochemically reductive dechlorination of micro amounts of 2,4,6-trichlorophenol in aqueous medium on molybdenum oxide containing supported palladium. Electrochim. Acta 50, 933-937. 

Trichlorophenol was also used as a substrate in this study. It was sequentially dechlorinated to 3-CP, which was not further degraded and accumulated in the cultures. It provides another example of biotransformation but not biodegradation of a compound. 

Although it is generally believed that under anaerobic conditions dechlorination, either reductive or hydrolytic, precedes ring fission, this pathway has been clearly documented only for the methanogenic studies. The physical proof and transient appearance of each dechlorinated metabolite (e.g., 2,3,6-trichlorophenol — 2,3-dichlorophenol — 3-monochlorophenol), which is seen in methanogenic cultures, has not been observed for the sulfidogenic or denitrifying cultures. It is still unclear whether this indicates that there is indeed a different mechanistic pathway or whether the rates of metabolite transformation are so rapid that they preclude their detection. 

Q1 the reactor columa With the optimized reaction conditions (450 °C / 25.3 MPa, 1.5 mL/min SCCO2), a feedstock of 10% (w/V) PCP in 1,2-dimethoxyethane, delivered at 0.1 mL/min was used to collect sue traps of effluent. The resulting chromatograms indicated the loss of approximatdy 50% of the PCP peak area and the formation of 4-chlorophenol, 3,5-dichlorophenol, 2,3,5-trichlorophenol, 2,3,4-trichlorophenol and 2,3,4,5-tetrachlorophenol that comprised the remainder of the products. Only a trace of phenol was detected in any of the duate solutions. Thus, thermally induced dechlorination is inefficient relative to the action of the Ag /Fe" particles. 

Lu S, Huang J, Peng Z, Li X, Yan J. BaU milling 2,4,6-trichlorophenol with calcium oxide dechlorination experiment and mechanism considerations. Chem Eng J 2012 195-196 62-8. 

Hexachlorocyclohexane is produced industrially by the reaction of an excess of benzene with chlorine at 15 to 25 °C in a glass reactor under the influence of UV light at atmospheric pressure. Care must be taken to exclude oxygen and catalysts, such as iron, which favor substitution. When 5 to 8% of the benzene has been chlorinated, the fi-isomer begins to precipitate. After benzene and unreacted chlorine have been evaporated at temperatures of from 85 to 88 °C, a hexachlorocyclohexane mixture with a y-isomer content of 12 to 14% remains. The y-isomer is recovered by fractional crystallization. The other isomers are converted into tri-and tetrachlorobenzenes by thermal or catalytic dechlorination tri- and tetra-chlorobenzenes are used as the precursors for 2,4,5-trichlorophenol (see Chapter 5.3.4.5). 

Biological. 2,4,5-T degraded in anaerobic sludge by reductive dechlorination to 2,4,5-trichlorophenol, 3,4-dichlorophenol and 4-chlorophenol (Mikesell and Boyd, 1985). An... 

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