Chlorinated aliphatic compounds sources

Chlorinated aliphatic compounds are globally distributed. Natural product organohalides such as chloromethane and chloramphenicol are probably produced in diverse soil environments. Many halogenated organic compounds are biosynthesized by marine organisms (Neidleman Geigert, 1986), so the oceans area source as well. 

In some cases, microorganisms can transform a contaminant, but they are not able to use this compound as a source of energy or carbon. This biotransformation is often called co-metabolism. In co-metabolism, the transformation of the compound is an incidental reaction catalyzed by enzymes, which are involved in the normal microbial metabolism.33 A well-known example of co-metabolism is the degradation of (TCE) by methanotrophic bacteria, a group of bacteria that use methane as their source of carbon and energy. When metabolizing methane, methanotrophs produce the enzyme methane monooxygenase, which catalyzes the oxidation of TCE and other chlorinated aliphatics under aerobic conditions.34 In addition to methane, toluene and phenol have been used as primary substrates to stimulate the aerobic co-metabolism of chlorinated solvents. 

Chlorinated organic compounds (COCs) refer to the substitution of one or more hydrogen in aliphatic and aromatic hydrocarbons and their derivatives by chlorine. COCs are widely used in the fields of chemistry, medicine, electronics, pesticides, etc. Many COCs are endocrine disturbance substances, show carcinogenic effects, and have been listed as priority pollutants by the US Environmental Protection Agency (USEPA). When released into the environment, COCs are transported in both air and water. However, COCs are chemically stable and difficult to destroy, and they are eventually deposited in soils and sediments due to their hydrophobic-ity. Soils and sediments contaminated with COCs are long-term sources of pollutants and pose great threats to human health and ecosystems. Therefore, remediation of these contaminated soils and sediments is of great importance. 

In a hood, through a rapidly stirred suspension of 76 gm (0.396 mole) of cyclohexanoneazine in 300 ml of petroleum ether (b.p. 60°-90°C) cooled to —60°C is passed a slow stream of gaseous chlorine until a slight excess of the gas is noted. The excess of chlorine is removed by ventilation at the water aspirator. Then the solution is concentrated to half-volume by gentle evaporation at reduced pressure. The reaction system is filtered free from tarry impurities and the filtrate is allowed to stand for 24 hr at room temperature. The product gradually separates out and is isolated by filtration. Evaporation of the mother liquor may afford another crop of product. The total yield is 81.5 gm (78 %). The product, after recrystallization from petroleum ether, has a melting point of 66°C. (NOTE Since aliphatic azo compounds are inherently unstable and may serve as free radical sources, the stability of the product should always be checked with due precautions, and excessive exposure to heat should always be avoided.)... 

---