Degradation dichloroethane

Hage JC, S Hartmans (1999) Monooxygenation-mediated 1,2-dichloroethane degradation by Pseudomonas sp. strain DCAl. Appl Environ Microbiol 65 2466-2470. 

FIGURE 7.62 Degradation of 1,2-dichloroethane by Xanthobacter autotrophicus strain GJIO. (From Neilson, A.H. and Allard, A.-S., The Handbook of Environmental Chemistry, Vol. 3R, pp. 1-74, Springer, 2002. With permission.)... 

A number of haloalkanes including dichloromethane, chloroform, 1,1-dichloroethane and 1,2-dichloroethane may be degraded by the soluble MMO system of Methylosinus trichosporium (Oldenhuis et al. 1989). 

The degradation of 1,2-dichloroethane by Pseudomonas sp. strain DCAl was initiated not by hydrolysis, but by monooxygenation with the direct formation of 1,2-dichloroethanol that spontaneously decomposed to chloroacetaldehyde (Hage and Hartmans 1999). 

Studies by Pintauro and co-workers have shown that poly [(3-methylphenoxy) (phenoxy) phosphazene] and poly [bis (3-methylphenoxy) phosphazene] (Figure 37) can be sulfonated by adding an SO3 solution in dichloroethane dropwise to a polymer/dichloroethane solution.A high ion exchange capacity (up to 2.0 mequiv/g) material was reported with no detectable polymer degradation. 

An index is included at the end of the book which lists potential sources or origins for the contaminant of concern of interest. The index also includes compounds for which degradation products are known, e.g., the presence of 1,1-dichloroethane at a site may be indicative of a release containing 1,1,1-trichloroethane (where 1,1-dichloroethane is present as an impnrity) or it may be a degradation product of 1,1,1-trichloroethane. Therefore, under the 1,1-dichloroethane entry, the reader is directed to the chemical profile 1,1,1-trichloroethane. Moreover, the index inclndes compounds which occur as additives to various products, e.g., acrolein nsually contains hydroqninone to prevent polymerization. Many commercial prodncts released into the enviromnent may contain other compounds present as impurities, e.g., 1,4-dioxane may contain the impurities acetic acid, 2-methyl-1,3-dioxolane, and bis(2-chloroethyl) ether. 

Biological. 1,1-Dichloroethane showed significant degradation with gradual adaptation in a static-culture flask-screening test (settled domestic wastewater inoculum) conducted at 25 °C. At concentrations of 5 and 10 mg/L, percent losses after 4 wk of incubation were 91 and 83, respectively. At a substrate concentration of 5 mg/L, 19% was lost due to volatilization after 10 d (Tabak et ah, 1981). Under anoxic conditions, indigenous microbes in uncontaminated sediments produced vinyl chloride (Barrio-Lage et al, 1986). 

Chemical/Physical. A glass bulb containing air and 1,1-dichloroethane degraded outdoors to carbon dioxide and HCl. The half-life for this reaction was 17 wk (Pearson and McConnell, 1975). Hydrolysis of 1,1-dichloroethane under alkaline conditions yielded vinyl chloride, acetaldehyde, and HCl (Kollig, 1993). The reported hydrolysis half-life at 25 °C and pH 7 is 61.3 yr (Jeffers et al., 1989). 

A methanogenic consortium derived from municipal anaerobic digester sludge was placed into a reactor containing 1,1,1-trichloroethane. The reactor was operated at 20 °C on an average 50-d hydraulic retention time. Degradation followed first-order kinetics and reported rate coefficients for filtered and unfiltered supernatant from the settled consortium were 0.11 and 0.12/day, respectively. 1,1-Dichloroethane was the only product detected which accounted for 46% of the initial 1,1,1-trichloroethane concentration (Gander et al, 2002). 

Chen et al. (1999) studied the anaerobic transformation of 1,1,1-trichloroethane, 1,1-dichloroethane, and choroethane in a lab-scale, municipal wastewater sludge digester. 1,1,1-Trichloroethane degraded via reductive dechlorination to give 1,1-dichloroethane, chloroethane, and then ethane. When cell-free extracts were used, 1,1,1-trichloroethane degraded to acetic acid (90% yield) and 1,1-dichloroethylene, the latter degrading to ethylene. 

Groundwater. Under aerobic conditions, 1,1,1-trichloroethane slowly degraded to 1,1-dichloroethane (Parsons and Lage, 1985 Parson et al, 1985). Based on a study conducted by Bouwer and McCarty (1984), the estimated half-life of 1,1,1-trichloroethane in groundwater three months after injection was 200-300 d. 

Photolytic. Dalapon (free acid) is subject to photodegradation. When an aqueous solution (0.25 M) was irradiated with UV light at 253.7 nm at 49 °C, 70% degraded in 7 h. Pyruvic acid is formed which is subsequently decarboxylated to acetaldehyde, carbon dioxide, and small quantities of 1,1-dichloroethane (2-4%) and a water-insoluble polymer (Kenaga, 1974). The photolysis of an aqueous solution of dalapon (free acid) by UV light (X = 2537 A) yielded chloride ions, carbon dioxide, carbon monoxide, and methyl chloride at quantum yields of 0.29, 0.10, 0.02, and 0.02, respectively (Baxter and Johnston, 1968). 

Rhodium acetylacetonate differed considerably from the other metal chelates in the acetylation reaction (26). Under the same conditions that had given extensive acetylation of the cobalt and chromium acetylacetonates, the rhodium chelate reacted very slowly and formed only a small amount of the monoacetylated compound (XX). Fortunately, the hydrolytic stability of rhodium acetylacetonate is such that the Friedel-Crafts reaction can be carried out under vigorous conditions that would rapidly degrade the chromium and cobalt chelates. Thus treatment of rhodium acetylacetonate with acetyl chloride and aluminum chloride in dichloroethane afforded the mono- and diacetylated chelates (XX and XXI). No triacetylated chelate was isolated from this reaction. In a similar manner butyryl-and benzoyl-substituted rhodium chelates (XXIII and XXIV) have been prepared. These and other experiments indicate that the rhodium acetylacetonate ring is less reactive than the cobalt or chromium rings. 

Egli, C., R. Scholtz, A. M. Cook, and T. Leisinger, Anaerobic dechlorination of tetrachloromethane and 1,2-dichloroethane to degradable products by pure cultures of Desulfobacterium sp. and Methanobacterium sp. FEMS Microbiol. Lett., 43, 257-261 (1987). 

Some examples of the behavior of unsaturated ketonucleosides under alkaline conditions have also been reported. The enol acetate 61a is more stable than the parent ketonucleoside 36a. In 0.1 M methanolic sodium hydroxide, free theophylline was detected only after 4 h, by which time, loss of the acetyl group was complete a reaction time of more than 18 h was needed for complete cleavage of the glycosylic bond.51 In alcoholic solution, the unsaturated 4 -ketonucleoside 66 was very sensitive to nucleophilic attack, and decomposed rapidly, with elimination of the nitrogenous base.31 Thus, treatment with sodium borohydride at — 70° led to complete decomposition within 10 min but, when sodium borohydride was added to a solution of 66 in 1,2-dichloroethane containing acetic acid, fast reduction occurred, and no degradation was observed.31... 

Figure 1 shows the results obtained when samples of triethyloxonium tetrafluoroborate are allowed to react to completion with a series of polyglycols in 1,2-dichloroethane solution. Equal weights (0.86 g) of polymer were taken for all experiments so the essential difference between runs with polymers of molecular weight 1540,4000, 6000 and 20.000 lies in the hydroxyl content of the solutions. With sufficient oxonium salt the polymers were completely degraded and the only reaction product was dioxane. 

Barak and Tuma (1981) described the assay of choline by use of periodide. A colored complex is formed, and its absorbance is measured in 1,2-dichloroethane. The limit of detection is close to 0.5 p.g choline. If phosphocholine is present also, then it must be degraded by a phosphatase to yield free choline. 

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