Bromotrichloromethane

Pyrolysis. Pyrolysis of 1,2-dichloroethane in the temperature range of 340—515°C gives vinyl chloride, hydrogen chloride, and traces of acetylene (1,18) and 2-chlorobutadiene. Reaction rate is accelerated by chlorine (19), bromine, bromotrichloromethane, carbon tetrachloride (20), and other free-radical generators. Catalytic dehydrochlorination of 1,2-dichloroethane on activated alumina (3), metal carbonate, and sulfate salts (5) has been reported, and lasers have been used to initiate the cracking reaction, although not at a low enough temperature to show economic benefits. 

Radicals react at the sulfur, and decomposition generating an acyloxy radical ensues. The acyloxy radical undergoes decarboxylation. Usually, the radieal then gives produet and another radical which can continue a chain reaction. The process can be illustrated by the reactions with tri-w-butylstannane and bromotrichloromethane. 

Bromotrichloromethane can also be used effectively in the addition reaction. Because of the preferential abstraction of bromine, a trichloromethyl unit is added to the less substituted carbon atom of the alkene ... 

The addition of bromotrichloromethane to cyclohexene gives a nearly 1 1 mixture of the two possible stereoisomers ... 

Intramolecular hydrogen abstraction reactions have also been observed in mediumsized rings. The reaction of cyclooctene with carbon tetrachloride is an interesting case. As shown in the equation below, whereas bromotrichloromethane adds to cyclooctene in a completely normal manner, carbon tetrachloride gives some 4-chloro-l-trichloromethyl-cyclooctane as well as the expected product ... 

No product derived from the transannular hydrogen abstraction is observed in the addition of bromotrichloromethane because bromine-atom abstraction is sufficiently rapid to prevent effective competition by the intramolecular hydrogen abstraction. 

Primary alkyl chlorides are fairly stable to fluorine displacement. When fluorinated, 1-chloropropane is converted to 1-chloroheptafluoropropane and 1-chloto-2-methylbutane produces 39% l-chlorononafluoro-2-methylbutane and 19% perfluoro-2-methylbutane. Secondary and tertiary alkyl chlorides can undergo 1,2-chlorine shifts to afford perfluonnated primary alkyl chlorides 2-Chloro-2-methylpropane gives l-chlorononafluoro-2-methylpropane, and three products are obtained by the fluorination of 3-chloropentane [7] (equation 1). Aerosol fluorina-tion of dichloromethane produces dichlorodifluoromethane which is isolated in 98% purity [4 (equation 2). If the molecule contains only carbon and halogens, the picture is different. Molecular beam analysis has shown that the reaction of fluorine with carbon tetrachlonde, lodotrichloromethane, or bromotrichloromethane proceeds first by abstraction of halogen to form a trichloromethyl radical [5]... 

The isoselective relationship is illustrated by the reactions of alkyl radicals with bromotrichloromethane and tetrachloromethane as in Eq. (10-45). The lines intersect at T- = 50 10 °C. Data are from Ref. 21. 

Of bromochloromethanes reacting mainly at C— Br bonds, bromotrichloro-methane has been the most investigated compound. Both the various monomers and diversified routes of initiations were used in the studies of CCl3Br. The addition of bromotrichloromethane to a-olefines under common conditions of radical initiation has been described by a number of examples (ref. 3). 

The reaction of bromotrichloromethane with alkenylcyclopropanes (ref. 15) is of interest from the synthesis of polyfunctional compounds standpoint. 

A set of works has been recently published, which show the possibility of stereochemical control in the processes of radical additions and telomerization. Photochemical telomerization of bromotrichloromethane with chiral 2,5-dimethyl-pirrolidine acrylamide has been described (ref. 16) ... 

Addition of bromotrichloromethane to substituted N-acryloyloxazolidines is also sufficiently selective stereochemically (ref. 17). 

One more example of the similar reaction is the addition of bromotrichloromethane to (S)-l-acryloyl-2-methoxycarbonylpirrolidine catalyzed with system [Fe(CO)5 + PPh3] (75°C) (ref, 18). In this case the authors managed to exclude telomerization virtually and obtain adduct in 80 % yield, which is one of two possible diastereomers. 

Corongiu, F.P., Lai, M. and Milia, A. (1983). Carbon tetrachloride, bromotrichloromethane and ethanol acute intoxication. New chemical evidence for lipid peroxidation in rat tissue microsomes. Biochem. J. 212, 625-631. 

The reaction can be carried out efficiently using aryl diazonium tetrafluoroborates with crown ethers, polyethers, or phase transfer catalysts.103 In solvents that can act as halogen atom donors, the radicals react to give aryl halides. Bromotrichloromethane gives aryl bromides, whereas methyl iodide and diiodomethane give iodides.104 The diazonium ions can also be generated by in situ methods. Under these conditions bromoform and bromotrichloromethane have been used as bromine donors and carbon tetrachloride is the best chlorine donor.105 This method was used successfully for a challenging chlorodeamination in the vancomycin system. 

See Bromotrichloromethane, and Carbon tetrachloride, and Chlorotrifluoroethy-lene, all above Tetralluoroethylene, below... 

Pohl, L.R., Branchflower, R.V., Highet, R.J., et al. 1981. The formation of diglutathionyl dithiocarbonate as a metabolite of chloroform, bromotrichloromethane, and carbon tetrachloride. Drug. Metab. Dispos. 9 334—338. 

Sipes, I.G., Krishna, G., and Gillette, J.R. 1977. Bioactivation of carbon tetrachloride, chloroform, and bromotrichloromethane role of cytochrome P-450. Life Sciences. 20 1541-1548. 

Bromides are less reactive than the corresponding iodides in atom transfer processes. However, activated bromides such as diethyl bromomalonate [36] and bromomalonitrile [53] react with olefins under Et3B/02 initiation. Kha-rasch type reactions of bromotrichloromethane with alkenes are also initiated by Et3B/02 [41]. On the other hand, a remarkable Lewis acid effect was reported by Porter. Atom-transfer reactions of an a-bromooxazolidinone amide with alkenes are strongly favored in the presence of Lewis acids such as Sc(0Tf)3 or Yb(0Tf)3, this reaction was successively applied to the... 

Agarwal AK, Mehendale HM. 1982. Potentiation of bromotrichloromethane hepatotoxicity and lethality by chlordecone preexposure in the rat. Fundam Appl Toxicol 2(4) 161-167. 

Faroon OM, Henry RW, Soni MG, et al. 1991. Potentiation of bromotrichloromethane hepatotoxicity by chlordecone Biochemical and ultrastructural study. Toxicol Appl Pharmacol 110(2) 185-97. 

Faroon OM, Mehendale HM. 1990. Bromotrichloromethane hepatotoxicity The role of stimulated hepatocellular regeneration in recovery Biochemical and histopathological studies in control and chlordecone pretreated male rats. Toxicol Pathol 18(14) 667-77. 

Rao SB, Young RA, Mehendale HM. 1990. Perturbations in polyamines and related enzymes following chlordecone-potentiated bromotrichloromethane hepatotoxicity. J Biochem Toxicol 5(1) 23-32. 

Thakore KN, Gargas ML, Andersen ME, et al. 1991. PB-PK derived metabolic constants, hepatotoxicity, and lethality of bromotrichloromethane in rats pretreated with chlordecone, phenobarbital, or mirex. Toxicol Appl Pharmacol 109(3) 514-528. 

Allenylcobaloximes, e.g. 26, react with bromotrichloromethane, carbon tetrachloride, trichloroacetonitrile, methyl trichloroacetate and bromoform to afford functionalized terminal alkynes in synthetically useful yields (Scheme 11.10). The nature of the products formed in this transformation points to a y-specific attack of polyhaloethyl radicals to the allenyl group, with either a concerted or a stepwise formation of coba-loxime(II) 27 and the substituted alkyne [62, 63]. Cobalt(II) radical 27 abstracts a bromine atom (from BrCCl3) or a chlorine atom (e.g. from C13CCN), which leads to a regeneration of the chain-carrying radical. It is worth mentioning that the reverse reaction, i.e. the addition of alkyl radicals to stannylmethyl-substituted alkynes, has been applied in the synthesis of, e.g., allenyl-substituted thymidine derivatives [64],... 

Bromotrichloromethane was purchased from Aldrich Chemical Company, Inc., and used as received. 

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