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With Organic Bromides

When refluxed in an excess of a vicinal organic dibromide with or without a solvent, diaryl tellurium compounds produced diaryl tellurium dibromides in high yields. The following dibromides effected these conversions 1,2-dibromoethane, 1,2-dibromocyclohexane, dibromocholesterol, and l,2-dibromo-2-phenylpropanoic acid. Allyl bromide (but not butylbromide) transferred bromine to tellurium at 180 . Diphenyl tellurium dihalides were observed as by-products when diphenyl tellurium was heated with iodoacetic acid or 1 -bromopropanoic acid.  [Pg.561]

Dibutyl tellurium induced cyclopropanation of a,/ -unsaturated esters, ketones, and nitriles with dibromomalonic acid derivatives and was converted in these reactions to dihutyl tellurium dibromide.  [Pg.561]


This reaction gives fair-to-good yields of monoorganotin tribromides and trichlorides when quaternary ammonium or phosphonium catalysts are used (149). Better yields are obtained with organic bromides and staimous bromide than with the chlorides. This reaction is also catalyzed by tri alkyl antimony compounds at 100—160°C, bromides are more reactive than chlorides in this preparation (150,151). a,C0-Dihaloalkanes also react in good yield giving CO-haloalkyltin trihaHdes when catalyzed by organoantimony compounds (152). [Pg.74]

Iron(III) chloride forms numerous addition compounds, especially with organic molecules which contain donor atoms, for example ethers, alcohols, aldehydes, ketones and amines. Anhydrous iron(III) chloride is soluble in, for example, ether, and can be extracted into this solvent from water the extraction is more effective in presence of chloride ion. Of other iron(III) halides, iron(III) bromide and iron(III) iodide decompose rather readily into the +2 halide and halogen. [Pg.394]

Solvent extraction techniques are useful in the quantitative analysis of niobium. The fluoro complexes are amenable to extraction by a wide variety of ketones. Some of the water-insoluble complexes with organic precipitants are extractable by organic solvents and colorimetry is performed on the extract. An example is the extraction of the niobium—oxine complex with chloroform (41). The extraction of the niobium—pyrocatechol violet complex with tridodecylethylammonium bromide and the extraction of niobium—pyrocatechol—sparteine complex with chloroform are examples of extractions of water-soluble complexes. Colorimetry is performed on the extract (42,43). Colorimetry may also be performed directly on the water-soluble complex, eg, using ascorbic acid and 5-nitrosahcyhc acid (44,45). [Pg.25]

Tin tetrachloride has been used to prepare the stericaHy hindered triisopropylchlorosilane [13154-24-0] (119). Organobromosdanes are obtained under similar conditions through reaction with cupric and mercuric bromide. These reactions are most suitable for stepwise displacement of hydrogen to form mixed hydridochlorosilanes or in systems sensitive to halogen (120). Hydrides have also been displaced using organic bromides. Heating triethylsilane and... [Pg.27]

The methods of preparation of ferrocene have been reviewed by Pauson and by Fischer. Ferrocene has been made by the reaction of ferric chloride with cyclopentadienylmagnesium bromide, by the direct thermal reaction of cyclopentadiene with iron metal, by the direct interaction of cyclopentadiene with iron carbonyl, by the reaction of ferrous chloride with cyclopentadiene in the presence of organic bases such as diethyl-amine, by the reaction of ferrous chloride with sodium cyclo-[lentadienide in liquid ammonia, and from cyclopentadiene and... [Pg.33]

Perfluorinated organic bromides can be oxidatively fluonnated with elemental fluorine to derivatives containing tn- [124] and pentavalent [/25 126 127] bromine in yields up to 42% Perfluoroheptylbromine tetrafluoride has been used to fluonnate double bonds in halogenated alkenes [127]... [Pg.48]

Organolithium reagents (Section 14.3) Lithium metal reacts with organic halides to produce organolithium compounds. The organic halide may be alkyl, alkenyl, or aryl. Iodides react most and fluorides least readily bromides are used most often. Suitable solvents include hexane, diethyl ether, and tetrahy-drofuran. [Pg.615]

The Hunsdiecker reaction is the treatment of the dry silver salt of a carboxylic acid with bromine in carbon tetrachloride. Decarboxylation occurs, and the product isolated is the corresponding organic bromide 16). Since dry silver salts are tedious to prepare, a modification of the reaction discovered by Cristol and Firth (77) is now... [Pg.149]

Polarization also occurs in coupling and disproportionation reactions of Grignard reagents with alkyl halides. The vinyl protons of isobutene produced in the reaction of t-butylmagnesium chloride with t-butyl bromide show A/E polarization as do the methyl protons of isobutane (Ward et al., 1970). Similar results arise in the reaction of diethyl-magnesium with organic halides (Kasukhin et al., 1972). [Pg.115]

Normally, the addition of C-nucleophiles to chiral a-alkoxyaldehydes in organic solvents is opposite to Cram s rule (Scheme 8.15). The anti-Cram selectivity has been rationalized on the basis of chelation control.142 The same anti preference was observed in the reactions of a-alkoxyaldehydes with allyl bromide/indium in water.143 However, for the allylation of a-hydroxyaldehydes with allyl bromide/indium, the syn isomer is the major product. The syn selectivity can be as high as 10 1 syn anti) in the reaction of arabinose. It is argued that in this case, the allylindium intermediate coordinates with both the hydroxy and the carbonyl function leading to the syn adduct. [Pg.246]


See other pages where With Organic Bromides is mentioned: [Pg.79]    [Pg.363]    [Pg.215]    [Pg.475]    [Pg.688]    [Pg.279]    [Pg.561]    [Pg.95]    [Pg.5202]    [Pg.561]    [Pg.5201]    [Pg.53]    [Pg.301]    [Pg.256]    [Pg.112]    [Pg.130]    [Pg.79]    [Pg.363]    [Pg.215]    [Pg.475]    [Pg.688]    [Pg.279]    [Pg.561]    [Pg.95]    [Pg.5202]    [Pg.561]    [Pg.5201]    [Pg.53]    [Pg.301]    [Pg.256]    [Pg.112]    [Pg.130]    [Pg.165]    [Pg.242]    [Pg.1142]    [Pg.230]    [Pg.249]    [Pg.160]    [Pg.294]    [Pg.84]    [Pg.343]    [Pg.478]    [Pg.481]    [Pg.211]    [Pg.242]    [Pg.1142]    [Pg.761]    [Pg.180]    [Pg.148]    [Pg.220]    [Pg.227]    [Pg.438]    [Pg.53]    [Pg.240]   


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