From dichlorofluoromethane

ChLorofluorocarbene generated by the thermal decomposition of dichlorofluoro-methylphenylmercury reacts with 2,3-dimethylindole to give 3-fluoro-2,4-di-methylquinoline, 3-chloro-2,4-dimethylqumoline and 3-(chlorofluoromethyl)-2,3-dimethylindole [f] (equation 1). Similar results are obtained when the chloro-fluorocarbene is generated from dichlorofluoromethane by base-catalyzed de-hydrohalogenation using a phase-transfer catalyst in an aqueous-organic solvent system [21 (equation 1). 

Chlorofluorocarbcne has been generated from dichlorofluoromethane using the following reagents and conditions sodium hydroxide in 2.5.8.11,14-pentaoxapentadecane (tetraglyme) at 95 C, potassium hydroxidc/water/18-crown-6, sodium hydroxide or potassium hy-droxidc/water/pliase-transfer catalyst. alkyllithium reagents. potassium /m-butox-ide, and ethylene oxide/triethylammonium bromide." ... 

Table 5. 1-Chloro-l-fluorocyclopropanes from Dichlorofluoromethane, Base/Catalyst and Alkenes...

Chlorofluorocarbene. Schlosser et al. have found that this crown ether is significantly superior to the commonly used ammonium salts for generation of chlorofluorocarbene from dichlorofluoromethane by the two-phase technique. They used potassium hydroxide as base rather than sodium hydroxide, since crown ethers bind potassium ions more selectively than sodium ions. They used the carbene for synthesis of fluorodienes. The method is illustrated for the conversion of methallyl chloride (1) into 2-fluoro-3-methyl-l, 3-butadiene (3-fluoro-isoprene), (4). The conversion of (3) into (4) involves a 1,4-elimination of ICl ... 

Dehmlov and coworkers" extended their investigations to a study of the addition of chlorofluorocarbene to highly substituted alkynes. They synthesized the carbene from dichlorofluoromethane and sodium hydroxide under phase-transfer conditions. Although yields are low, chlorofluorocarbene appeared to be more reactive than dichlorocarbene towards alkynes, especially towards alkynes with bulky substituents. 

Full details have been published of the use of chldrofluoromethylenetri-phenylphosphorane, generated in situ from sodium dichlorofluoroacetate and triphenylphosphine or from dichlorofluoromethane, potassium t-butoxide, and triphenylphosphine, in the synthesis of olefins of the type RfRC CFC1 (Rp = perfluoroalkyl or CFuCl R = alkyl, aryl, or aralkyl) from appropriate ketones. ... 

In the context of Scheme 11-1 we are also interested to know whether the variation of K observed with 18-, 21-, and 24-membered crown ethers is due to changes in the complexation rate (k ), the decomplexation rate (k- ), or both. Krane and Skjetne (1980) carried out dynamic 13C NMR studies of complexes of the 4-toluenediazo-nium ion with 18-crown-6, 21-crown-7, and 24-crown-8 in dichlorofluoromethane. They determined the decomplexation rate (k- ) and the free energy of activation for decomplexation (AG i). From the values of k i obtained by Krane and Skjetne and the equilibrium constants K of Nakazumi et al. (1983), k can be calculated. The results show that the complexation rate (kx) does not change much with the size of the macrocycle, that it is most likely diffusion-controlled, and that the large equilibrium constant K of 21-crown-7 is due to the decomplexation rate constant k i being lower than those for the 18- and 24-membered crown ethers. Izatt et al. (1991) published a comprehensive review of K, k, and k data for crown ethers and related hosts with metal cations, ammonium ions, diazonium ions, and related guest compounds. 

The first use of supercritical fluid extraction (SFE) as an extraction technique was reported by Zosel [379]. Since then there have been many reports on the use of SFE to extract PCBs, phenols, PAHs, and other organic compounds from particulate matter, soils and sediments [362, 363, 380-389]. The attraction of SFE as an extraction technique is directly related to the unique properties of the supercritical fluid [390]. Supercritical fluids, which have been used, have low viscosities, high diffusion coefficients, and low flammabilities, which are all clearly superior to the organic solvents normally used. Carbon dioxide (C02, [362,363]) is the most common supercritical fluid used for SFE, since it is inexpensive and has a low critical temperature (31.3 °C) and pressure (72.2 bar). Other less commonly used fluids include nitrous oxide (N20), ammonia, fluoro-form, methane, pentane, methanol, ethanol, sulfur hexafluoride (SF6), and dichlorofluoromethane [362, 363, 391]. Most of these fluids are clearly less attractive as solvents in terms of toxicity or as environmentally benign chemicals. Commercial SFE systems are available, but some workers have also made inexpensive modular systems [390]. 

In rats, 90 day exposures to 1000 and 5000 ppm caused bilateral hair loss, extensive liver damage, and excessive mortality. The chronic toxicity of dichlorofluoromethane appears to be quite different from difluorinated methanes and more similar to the hepatotoxin chloroform. In mice 100,000 ppm induced arrhythmias and sensitized the heart to epinephrine. 

In connection with the study of the role Freon compounds play in the depletion of ozone in the atmosphere, a demand has arisen for 13C-labeled fluorinated hydrocarbons in infrared spectroscopic examination. For this purpose,13C-isotopically enriched trichlorofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane, trifluoromethane, chlorodifluoromethane, and dichlorofluoromethane have been prepared from 13CC 4 and 13CHC13.73... 

The preparation of orthoformic acid esters from chloroform and alkali metal alkoxides is a long known procedure, " which can be performed under phase transfer catalysis. If small amounts of alcohol are present in the phase-catalyz process, cyclopropanes (372 Scheme 67) can be produced by aHHifinn of dichlorocarbene to l,2-dialkoxy-l,2-dichloroethylenes, which are thought to be intermediates. " Al-kenes of this kind, e.g. (373 equation 176), have been observed as byproducts in the synthesis of tri-r-butylorthoformate from chlorodifluoromethane or dichlorofluoromethane and potassium r-butoxide. Trimethoxyacetonitrile was prepared from trichloroacetonitrile and sodium methoxide. ... 

Halomethanes have numerous industrial applications (Table 3.2). One of the most important of the group, chloroform, is used mainly as a solvent and an intermediate in the production of various products. Chloromethane and tribromomethane are also employed as chemical intermediates, whereas dichloromethrae is widely used as a solvent. Tribromomethane is a common fumigant, and fluoro-derivatives find general application as refrigerants and aerosol propellants. Recent restrictions placed on the use of fluorocarbons have resulted in a decrease in US production of fluoro-derivatives. During the last decade, production of trichlorofluoromethane declined from 1.3 to 0.7 X 10 tons while dichlorofluoromethane fell from 2.0 to 1.5 X 10 tons (Table 3.1). Production of other halomethanes has shown a consistent albeit small increase in recent years (Table 3.1). Total dichloromethane production now exceeds 2.5 X 10 tons compared with 1.5 and 1.8X itf tons for chloromethane and chloroform, respectively. It is estimated that bromo-methane production will be only about 2.0 X 10 tons in 1982. 

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