Chlorinated Hydrocarbons

Rossberg, Manfred; Lendle, Wilhelm; Pfleiderer, Gerhard; Tögel, Adolf; Dreher, Eberhard-Ludwig; Langer, Ernst; Rassaerts, Heinz; Kleinschmidt, Peter; Strack, Heinz; Cook, Richard; Beck, Uwe; Lipper, Karl-August; Torkelson, T. R.; Löser, E.; Beutel, Klaus K.

doi:10.1002/14356007.a06_233

Cited by 27 publications

(39 citation statements)

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“…2,3,5,6 In this case, no information is readily available in the open literature concerning catalyst stability.…”

Section: Introductionmentioning

confidence: 99%

“…This compound is an excellent solvent for fats, oils, resins, lacquers, asphalt, and bitumen and is used in refineries to adjust the chlorine content of catalysts. 2 However, because of its harmful health effects, the levels of 12dcp vapors allowed in the workplace are limited by the Occupational Safety and Health Administration to less than 75 ppm for an 8-h workday and to 110 ppm for a 15-min exposure. Some data on the conversions of 1,3-dichloropropane and 3-chloropropene (allyl chloride) are also reported.…”

Section: Introductionmentioning

confidence: 99%

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A Study of the Dehydrochlorination of 1,2-Dichloropropane over Silica−Alumina Catalysts

Pistarino

Finocchio

Larrubia

et al. 2001

Ind. Eng. Chem. Res.

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The conversions of 1,2-dichloropropane (12dcp), 1,3-dichloropropane (13dcp), and allyl chloride (3-chloropropene, 3cpd) over a silica-alumina bed have been investigated. Both 12dcp and 13dcp undergo dehydrochlorination above 500 K, mainly resulting in the two 1-chloropropene (1cpd) geometric isomers, which, above 650 K, further eliminate HCl to give propyne and burn in the presence of oxygen. Small amounts of 3cpd were also observed. 12dcp was found to react more rapidly than 13dcp. The conversion of 3cpd gives essentially CO x above 700 K and small amounts of benzene in the range 600-700 K. The reaction order is zero. The activation energy for the conversion of 12dcp was found to be 14.4 kcal/mol (60.6 kJ/mol). IR data show that a reversible adsorption step is followed by a nucleophilic substitution by an active surface oxide species, giving rise to an alkoxide species. The slow step is likely the E1 elimination of the alkoxide. The conversion of the primary 3-chloro-1-propyl carbenium ion to a 1-chloro-2-propyl carbenium ion plays a relevant role. The catalyst deactivates progressively at 523 K, its activity being nearly halved after 4 h, but it attains a plateau after 7 h. At higher temperatures, the stable total conversion of 12dcp was obtained after 10 h.

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“…2,3,5,6 In this case, no information is readily available in the open literature concerning catalyst stability.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Study of the Dehydrochlorination of 1,2-Dichloropropane over Silica−Alumina Catalysts

Pistarino

Finocchio

Larrubia

et al. 2001

Ind. Eng. Chem. Res.

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“…They have applications as solvents, biocides, plasticizers, and intermediates for chemical synthesis (34). Tetrachloroethene (PCE) and trichlorethene (TCE) are the most prevalent chlorinated organic compounds due to their widespread uses in dry-cleaning, equipment maintenance, and metal degreasing (8,30).…”

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confidence: 99%

Influence of Vitamin B ₁₂ and Cocultures on the Growth of Dehalococcoides Isolates in Defined Medium

Holmes

Lee

et al. 2007

Appl Environ Microbiol

184

188

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Bacteria belonging to the genus Dehalococcoides play a key role in the complete detoxification of chloroethenes as these organisms are the only microbes known to be capable of dechlorination beyond dichloroethenes to vinyl chloride (VC) and ethene. However, Dehalococcoides strains usually grow slowly with a doubling time of 1 to 2 days and have complex nutritional requirements. Here we describe the growth of Dehalococcoides ethenogenes 195 in a defined mineral salts medium, improved growth of strain 195 when the medium was amended with high concentrations of vitamin B 12 , and a strategy for maintaining Dehalococcoides strains on lactate by growing them in consortia. Although strain 195 could grow in defined medium spiked with ϳ0.5 mM trichloroethene (TCE) and 0.001 mg/liter vitamin B 12 , the TCE dechlorination and cellular growth rates doubled when the vitamin B 12 concentration was increased 25-fold to 0.025 mg/liter. In addition, the final ratios of ethene to VC increased when the higher vitamin concentration was used, which reflected the key role that cobalamin plays in dechlorination reactions. No further improvement in dechlorination or growth was observed when the vitamin B 12 concentration was increased to more than 0.025 mg/liter. In defined consortia containing strain 195 along with Desulfovibrio desulfuricans and/or Acetobacterium woodii and containing lactate as the electron donor, tetrachloroethene (ϳ0.4 mM) was completely dechlorinated to VC and ethene and there was concomitant growth of Dehalococcoides cells. In the cultures that also contained D. desulfuricans and/or A. woodii, strain 195 cells grew to densities that were 1.5 times greater than the densities obtained when the isolate was grown alone. The ratio of ethene to VC was highest in the presence of A. woodii, an organism that generates cobalamin de novo during metabolism. These findings demonstrate that the growth of D. ethenogenes strain 195 in defined medium can be optimized by providing high concentrations of vitamin B 12 and that this strain can be grown to higher densities in cocultures with fermenters that convert lactate to generate the required hydrogen and acetate and that may enhance the availability of vitamin B 12 .

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“…PCBs are still used in limited industrial settings. In addition, ~40% of old PCBs remain in the environment due to their resistance to degradation (Rossberg et al, ).…”

Section: Introductionmentioning

confidence: 99%

Prenatal exposure to PCBs in Cyp1a2 knock‐out mice interferes with F₁ fertility, impairs long‐term potentiation, reduces acoustic startle and impairs conditioned freezing contextual memory with minimal transgenerational effects

Hufgard

Sprowles

Pitzer

et al. 2018

J of Applied Toxicology

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Polychlorinated biphenyls (PCBs) are toxic environmental pollutants. Humans are exposed to PCB mixtures via contaminated food or water. PCB exposure causes adverse effects in adults and after exposure in utero. PCB toxicity depends on the congener mixture and CYP1A2 gene activity. For coplanar PCBs, toxicity depends on ligand affinity for the aryl hydrocarbon receptor (AHR). Previously, we found that perinatal exposure of mice to a three‐coplanar/five‐noncoplanar PCB mixture induced deficits in novel object recognition and trial failures in the Morris water maze in Cyp1a2−/−::Ahrb1 C57BL6/J mice compared with wild‐type mice (Ahrb1 = high AHR affinity). Here we exposed gravid Cyp1a2−/−::Ahrb1 mice to a PCB mixture on embryonic day 10.5 by gavage and examined the F1 and F3 offspring (not F2). PCB‐exposed F1 mice exhibited increased open‐field central time, reduced acoustic startle, greater conditioned contextual freezing and reduced CA1 hippocampal long‐term potentiation with no change in spatial learning or memory. F1 mice also had inhibited growth, decreased heart rate and cardiac output, and impaired fertility. F3 mice showed few effects. Gene expression changes were primarily in F1 PCB males compared with wild‐type males. There were minimal RNA and DNA methylation changes in the hippocampus from F1 to F3 with no clear relevance to the functional effects. F0 PCB exposure during a period of rapid DNA de‐/remethylation in a susceptible genotype produced clear F1 effects with little evidence of transgenerational effects in the F3 generation. While PCBs show clear developmental neurotoxicity, their effects do not persist across generations for effects assessed herein.

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Chlorinated Hydrocarbons

Cited by 27 publications

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A Study of the Dehydrochlorination of 1,2-Dichloropropane over Silica−Alumina Catalysts

A Study of the Dehydrochlorination of 1,2-Dichloropropane over Silica−Alumina Catalysts

Influence of Vitamin B ₁₂ and Cocultures on the Growth of Dehalococcoides Isolates in Defined Medium

Prenatal exposure to PCBs in Cyp1a2 knock‐out mice interferes with F₁ fertility, impairs long‐term potentiation, reduces acoustic startle and impairs conditioned freezing contextual memory with minimal transgenerational effects

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Chlorinated Hydrocarbons

Cited by 27 publications

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A Study of the Dehydrochlorination of 1,2-Dichloropropane over Silica−Alumina Catalysts

A Study of the Dehydrochlorination of 1,2-Dichloropropane over Silica−Alumina Catalysts

Influence of Vitamin B 12 and Cocultures on the Growth of Dehalococcoides Isolates in Defined Medium

Prenatal exposure to PCBs in Cyp1a2 knock‐out mice interferes with F1 fertility, impairs long‐term potentiation, reduces acoustic startle and impairs conditioned freezing contextual memory with minimal transgenerational effects

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Influence of Vitamin B ₁₂ and Cocultures on the Growth of Dehalococcoides Isolates in Defined Medium

Prenatal exposure to PCBs in Cyp1a2 knock‐out mice interferes with F₁ fertility, impairs long‐term potentiation, reduces acoustic startle and impairs conditioned freezing contextual memory with minimal transgenerational effects