Degradation dichloromethane

One of the chief uses of chloromethane is as a starting material from which sili cone polymers are made Dichloromethane is widely used as a paint stripper Trichloromethane was once used as an inhalation anesthetic but its toxicity caused it to be replaced by safer materials many years ago Tetrachloromethane is the starting mate rial for the preparation of several chlorofluorocarbons (CFCs) at one time widely used as refrigerant gases Most of the world s industrialized nations have agreed to phase out all uses of CFCs because these compounds have been implicated m atmospheric processes that degrade the Earth s ozone layer... 

Traditionally, dried or powdered plant material is used and extracts can be obtained by mixing the material with food-grade solvents like dichloromethane or acetone followed by washing, concentration, and solvent removal. The result is an oily product that may contain variable amounts of pheophytins and other chlorophyll degradation compounds usually accompanied by lipid-soluble substances like carotenoids (mainly lutein), carotenes, fats, waxes, and phospholipids, depending on the raw material and extraction techniques employed. This product is usually marketed as pheophytin after standardization with vegetable oils. 

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). 

Heraty LJ, ME Fuller, L Huang, T Abrajano, NC Sturchio (1999) Isotope fractionation of carbon and chlorine by microbial degradation of dichloromethane. Org Geochem 30 793-799. 

As mentioned previously, P-carotene oxidation products substantially reduce mitochondrial activity in an RPE cell line, 28 SV4, derived from fetal human RPE cells (Hurst et al., 2005). In these experiments P-carotene was degraded in dichloromethane/methanol/water solution by hypochlorite, NaOCl. Exposure of the 28 SV4 cells to a mixture of the degradation products corresponding... 

Figure 6. Absorption spectra of dichloromethane solutions of chemically degraded PVC containing trifluoroacetic acid (0.1 M) (a) after mixing (b) after 20 min and...

Figure 7. Changes in the absorbance at (a) 590, (b) 660, (c) 730, and (d) 790 nm for dichloromethane solutions of chemically degraded PVC containing trifluoro-...

Figure 8. Effect of changing triffuoroacetic acid concentration on the rate of increase in absorbance at 790 nm for dichloromethane solutions of chemically degraded PVC (a) 0.7M (b) 0.2M (c) 0.3M (d) 0.5M.

Figure 11. Spectrum of dichloromethane solutions of chemically degraded PVC extracted at 0.2 °C for 1 h before dilution...

Figure 12. Changes with time in the absorption spectrum at 35°C of dichloromethane solutions of chemically degraded PVC (38J. Increasing absorbances correspond to 0, 10, 20, 40, SO, 60, 70, 80, 90, 100, 110, 120, 130, 150, 170, 200, and...

The LLE of relatively polar and water-soluble organic compounds is, in general, difficult. The recovery obtained from 11 of water with dichloromethane is 90% for Atrazine but lower for its more polar, degradation products, i.e., di-isopropyl- (16%), di-ethyl- (46%),andhydroxy-atrazine (46%). By carrying out LLE with a mixture of dichloromethane and ethyl acetate with 0.2 mol/1 ammonium formate, the extraction recoveries for the three degradation products were increased to 62 %, 87 %, and 65 %, respectively [437]. 

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