Steven P. Hopper

Halomethyl-metal compounds : LVII. A convenient synthesis of aryl(trifluoromethyl)mercury compounds☆

Abstract Phenyl(trifluoromethyl)mercury, a useful difluorocarbene precursor, is conveniently prepared by the sequence: HgO→Hg(O2CCF3)2→CF3HgO2CCF3→ CF3HgBr→PhHgCF3. The last step involves a substituent exchange reaction between CF3HgBr and diphenylmercury. Similar substituent exchanges between CF3HgI, CF3HgCl and CF3HgO2CCF3 and diphenylmercury are described. A recent report (J. Organometal. Chem., 36 (1972)227) that fluorophenyl(trifluoromethyl)mercury compounds can be prepared by decarboxylation of the respective fluorophenylmercuric trifluoroacetates in 1,2-dimethoxyethane at 60–70° is shown to be incorrect by comparison of the claimed products with authentic m- and p-FC6H4HgCF3 and FC6H4HgO2CCF3. 19F NMR data for a number of CF3—Hg compounds are reported.

Halomethyl—metal compounds : LXVII. The application of phenyl(trihalomethyl)mercury compounds in the synthesis of highly halogenated oxiranes

Abstract Phenyl(trihalomethyl)mercury compounds react with highly halogenated ketones [(CF3)2CO, CF3COCF2Cl, (CF2Cl)2CO, CF2ClCOCFCl2], aldehydes (n-C3F7CHO, CCl3CHO) and acid chlorides (CF3COCl, CCl3COCl) to add CX2 to the Cue5fbO bond, giving oxiranes. In the case of hexachloroacetone and n-C3F7OCF(CF3)CF2OCF(CF3)C(O)F, ketones were obtained instead. In the reactions with the acid chlorides, ketones also were formed in addition to the oxiranes. Reaction of PhHgCCl2Br with oxalyl chloride produced the expected oxirane, 2,3,3-trichloro-2,3-epoxypropenoyl chloride, as well as trichloropyruvyl chloride, trichloroacetyl chloride and hexachlorobiacetyl. A reaction of this mercury reagent with benzil gave PhC(O)-CClPh-C(O)(Cl, most likely via rearrangement of the initially formed oxirane.

Halomethyl-metal compounds : XXVIII. Phenyl(dibromochloromethyl)mercury as a bromochlorocarbene source☆

Abstract A number of gem-bromochlorocyclopropanes has been prepared by the reaction of PhHgCClBr2-derived bromochlorocarbene with olefins (cyclohexene, cyclooctene, 1-heptene, tetramethylethylene, cis- and trans-2-butene, styrene, acrylonitrile, vinyl acetate, allyltrimethylsilane, vinyltrimethylsilane, cis- and trans-1,2-dichloroethylene). Reaction of phenyl(dibromochloromethyl)mercury with 2,5-dihydrofuran gave an equimolar amount of the expected Cue5fbC addition product and the Cue5f8H insertion product, 2-(bromochloromethyl)-2,5-dihydrofuran. Similar Cue5f8H insertion was observed with tetrahydrofuran. With cumene CClBr insertion occurred exclusively into the benzylic position.

Halomethyl-metal compounds LV. The synthesis of phenyl(trifluoromethyl)mercury by fluorination of phenyl(tribromomethyl)mercury

Abstract The reaction of phenylmercuric hydroxide with aqueous hydrofluoric acid gives a material which appears to be an HF adduct of phenylmercuric fluoride (“PhHgF·HF”). This material has been found to fluorine phenyl(tribromomethyl)-mercury in benzene or toluene medium at room temperature to give phenyl(trifluoromethyl)mercury in yields avaraging 60–65% when the reaction is carried out in the presence of 48% HF. Phenyl(trichloromethyl)mercury can be fluorinated to PhHgCF 3 in this manner, but a reaction temperature of 90° is required. Partial fluorination in good yield of phenyl(bromodichloromethyl)mercury to phenyl-(fluorodichloromethyl)mercury could be achieved at room temperature, but attempted partial fluorination of PhHgCBr 3 , PhHgCClBr 2 and PhHgCFBr 2 was unsuccessful, PhHgCF 3 being the major product obtained. The possible mechanism of this novel fluorination process is discussed.

Halomethyl-metal compounds : XXXV. The preparation of dibromomethyl and bromochloromethyl derivatives of silicon and germanium by the (trihalomethyl)mercurial route and their reduction to monohalomethyl compounds☆

Abstract The reaction of phenyl(dibromochloromethyl)mercury and phenyl(tribromomethyl)mercury with organosilicon and organogermanium hydrides gave bromochloromethyl- and dibromomethyl-substituted derivatives of silicon and germanium via dihalocarbene insertion into the Siue5f8H and Geue5f8H bonds. The reduction of these products with tri-n-butyltin hydride at room temperature gave the respective monohalomethyl compounds, the bromochloromethyl derivatives being reduced to the chloromethyl compounds, the dibromomethyl derivatives to the bromomethyl compounds. Excellent yields were obtained in both steps of this new synthesis of monohalomethyl derivatives of silicon and germanium.