Chlorine hydrogen exchange

Side chain fluonnaied aryl isocyanates are an important group of substances used in the manufacture of biologically active compounds The synthetic routes to the meta- and para trifluoromethylphenyl isocyanates permit the chlorine-fluonne exchange with hydrogen fluoride to proceed under moderate conditions and in a virtually quantitative manner (equation 22)... 

Another example of a simultaneous chlorine-fluorine exchange and rearrangement IS the reaction of orr/io-methylphenylchloroformate with hydrogen fluoride to give a stable tetrafluorobenzodioxtn [34] (equation 25)... 

Tubesheets form the end barriers to separate the shell-side and tube-side fluids. Most exchangers use single plates for tubesheets. However, for hazardous or corrosive materials such as chlorine, hydrogen chloride, sulfur dioxide, etc., where the intermixing due to leakage from shell- to tube-... 

HN02, 371, 372 dibutylbenzene, bromination of, 133 —, chlorination of, 104 dichloroacetic acid, and hydrogen exchange, 208... 

A chlorine-bromine exchange in fluorodichloromethanesulfenyl chloride by means of hydrogen bromide provides a route to additional sulfenyl bromides (109). After the initial halogen exchange at the sulfur, further addition of hydrogen bromide causes stepwise substitution at the methyl group ... 

Until recently, halogen substituted alkanes were thought to be inert to xenon difluoride, but detailed examination has shown that common solvents such as dichloromethane (3) and chloroform (4) undergo fluorine-chlorine and fluorine-hydrogen exchange at room temperature due to hydrogen fluoride catalysis.15... 

Chloromethyl)oxirane (3) affords 1,3-difluoro- and l-chloro-3-fluoropropan-2-ol (4 and 5) on reaction with potassium hydrogen fluoride in diethylene glycol.76 There is no reaction when potassium fluoride is used which indicates that the epoxy ring in 3 is opened by the hydrogen fluoride present in potassium hydrogen fluoride and later the chlorine is exchanged for fluorine. 

For alkyl substituents, electrophilic substitution (chlorination, bromination, acetylation, trifluoroacetylation, formylation, hydrogen exchange) of 2-alkylthiophenes happens mainly... 

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