Mercury, dehalogenations

Mercury can be used to dehalogenate acyl halides to ketenes when a halogen IS present next to the COCl group [67] (equation 35)... 

Reductive dehalogenation cannot be completely controlled, and mostly complicated mixtures were formed which are difficult to separate. Salt elimination opens the possibility of a reaction aimed at polysilane formation. Some examples are shown in Fig. 2. The key compounds are the alkali metal cyclosilanes, which we have isolated via the mercury compounds by the action of sodium/potassium alloy and used for the first time [13]. 

Halogenation and Dehalogenation Reactions. Usually, reactions of this type take place readily without utilizing catalysts. However, when selectivity of the desired product is low or it is necessary to run the reaetion at a lower temperature, the use of a catalyst is desirable. Supported copper and silver halides can be used for the halogenation of hydrocarbons. Hydrochlorination reactions can be carried out with mercury copper or zinc halides. 

Reductive dehalogenation of appropriate dioxolanes such as (165) to give (166) can be achieved using either magnesium with a catalytic amount of I2 and a mercury promoter <83USP4393227>, or LAH/TiCU <89GEP3842986> (Equation (22)), and convenient reductive dehalogenation of4,5-dihalo-... 

Kawasaki, H., H. Yahara, and K. Tonomura. 1981. Isolation and characterization of plasmid pUOl mediating dehalogenation of haloacetate and mercury resistance in Moraxella sp. B. Agric. Biol. Chem. 45 1477-1481. 

Wagner-Dobler I, von Canstein H, Li Y, Timmis KN, Deckwer W-D (2000) Removal of mercury from chemical wastewater by microorganisms in technical scale. Environ Sci Technol 34 4628-4634 Wiegel J, Zhang X, Wu Q (1999) Anaerobic dehalogenation of hydroxylated polychlorinated biphenyls by Desulfitobacterium dehalogenans. Appl Environ Microbiol 65 2217—2221... 

A mixture of the imines jy -CFO NF (39%), a r/-CFO NF (52%), CFj NF (9%), and Ca, NF (trace) is product when A /V -difluorodichloro-fluoromethylamine is heated (100 Q with mercury and the iViV-difluoro-amines CF,CI-NF CFC1, NF and COj-NF, can be dechlorofluorinated with pentacarbonyliron in carbon tetrachloride at -30 to -t-20 Ctogivethe corresponding A -fluorodihalogenoimines, a procedure that apparently fails to convert the tetrafluoro-compound CHFj NF, into CHF NF but has been adapted to dehalogenate the tetrafluorohydrazine-fluoro-olefin adducts F,N CF, CXF NF, (X = F, Cl, or H) to provide cyanogen, the imine FN CF-CN, and a compound believed to be the nitrile FjN-CFj-CN. ... 

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