Lithium bronze

Reduction of — C C(CH1),OH.2 Lithium bronze is the most effective reagent for conjugate reduction of homopropargylic alcohols to homoallylic alcohols.. 

REDUCTION, REAGENTS Aluminum amalgam. Borane-Dimethyl sulfide. Borane-Tetrahydrofurane. t-Butylaminoborane. /-Butyl-9-borabicyclo[3.3.1]nonane. Cobalt boride— f-Butylamineborane. Diisobutylaluminum hydride. Diisopropylamine-Borane. Diphenylamine-Borane. Diphenyltin dihydride. NB-Enantrane. NB-Enantride. Erbium chloride. Hydrazine, lodotrimethylsilane. Lithium-Ammonia. Lithium aluminum hydride. Lithium borohydride. Lithium bronze. Lithium n-butylborohydride. Lithium 9,9-di-n-butyl-9-borabicyclo[3.3.11nonate. Lithium diisobutyl-f-butylaluminum hydride. Lithium tris[(3-ethyl-3pentylK>xy)aluminum hydride. Nickel-Graphite. Potassium tri-sec-butylborohydride. Samarium(II) iodide. Sodium-Ammonia. Sodium bis(2-mcthoxyethoxy)aluminum hydride. 

HOMOALLYLIC ALCOHOLS Cerium amalgam. Chromium(II) chloride. Fluorodimethoxyborane. Hypochlorous acid. Lithium bronze. Manganesc(II) chloride-Lithium aluminum hydride. Methylenetriphenylphosphorane. Organotitanium reagents. Tetrakis(triphenylphosphine)palladium. Tin. Tin(II) fluoride. 

Lithium bronze, Li 4NH3. The reagent is prepared by condensation of a slight excess of NH3 into a flask containing Li metal. It resembles mercury in appearance, andean he kept at 20" for 2-3 weeks if protected from air. Follow instructions for handling.1... 

Conjugate reduction of tt,fi-enones. Lithium bronze can be used in place of lithium blue for conjugate reduction of cyclic a,(3-enones to the saturated ketone in high yield it requires an added proton source ((-butyl alcohol). 

ESR at 9500 Me. both at room temperature and at 77° K. gave single absorption lines for lithium-vanadium bronze and sodium-vanadium bronze, centered at g = 1.96. The number of spins is roughly one per alkali metal atom. For the lithium bronze, the intensity as a function of temperature suggests a constant number of fairly localized spins. The observed g-f actor is the same as that reported for V+4 centers in other compounds (1, 12, 17). 

Figure 3. Electrical resistivity vs. temperature for a semiconducting lithium bronze...

REDUCTION, REAGENTS Bis(triphenyl-phosphine)copper tetrahydroborate. Borane-Pyridine. Calcium-Methylamine/ ethylenediaminc. Chlorobis(cyclopenta-dienyl)tetrahydroboratozirconium(IV). Chromium(II)-Amine complexes. Copper(0)-lsonitrile complexes. 2,2-Dihydroxy-l, 1-binaphthyl-Lithium aluminum hydride. Di-iododimethylsilane. Diisobutyl-aluminum 2,6-di-/-butylphenoxide. Diisobutyl aluminum hydride. Dimethyl sulfide-Trifluoroacetic anhydride. Disodium tetracarbonylferrate. Lithium-Ammonia. Lithium-Ethylenediamine. Lithium bronze. Lithium aluminum hydride. Lithium triethylborohydride. Potassium-Graphite. 1,3-Propanedithiol. Pyridine-Sulfur trioxide complex. 

A wide variety of a. -unsaturated ketones have been reduced to saturated ketones, usually in good yield, by metal solutions, mainly in liquid ammonia.The reduction is applicable to compounds with any degree of substitution on the double bond. Although only 2 equiv. of these metals are required for the conversion of an enone to a saturated ketone, it is often convenient to employ the metal in excess. A suspension of lithium bronze (Li4NH3) in ether allows the employment of the metal in stoichiometric amounts. Proton donors are often employed to reduce competing side reactions, such as dimerization. The presence of proton donors in the medium may lead to the conversion of an a,p-unsaturated ketone to the saturated alcohol, but at least 4 equiv. of metal must obviously be present for this type of reduction to take place. 

The direct intercalation of polyanihne doped with 12-phosphormohbdic acid (PANI-PMA) into V2O5 xerogels was reported by Posudievsky et al. Treatment of an aqueous solution of the xerogel or its lithium bronze with a solution of PANI-PMA in m-cresol, in equal amounts, led to the formation of (PANI-PMAo.o7)o.34V205. The conductivity of the nanocomposite was found to be 5.0 x 10 S cm [32]. 

Aromatic steroids are virtually insoluble in liquid ammonia and a cosolvent must be added to solubilize them or reduction will not occur. Ether, ethylene glycol dimethyl ether, dioxane and tetrahydrofuran have been used and, of these, tetrahydrofuran is the preferred solvent. Although dioxane is often a better solvent for steroids at room temperature, it freezes at 12° and its solvent effectiveness in ammonia is diminished. Tetrahydrofuran is infinitely miscible with liquid ammonia, but the addition of lithium to a 1 1 mixture causes the separation of two liquid phases, one blue and one colorless, together with the separation of a lithium-ammonia bronze phase. Thus tetrahydrofuran and lithium depress the solubilities of each other in ammonia. A tetrahydrofuran-ammonia mixture containing much over 50 % of tetrahydrofuran does not become blue when lithium is added. In general, a 1 1 ratio of ammonia to organic solvents represents a reasonable compromise between maximum solubility of steroid and dissolution of the metal with ionization. 

The second group is the group of oxyfluorides that are derived from ferroelectric oxides by means of fluorine-oxygen substitution. The basic oxides are usually perovskite, tetragonal tungsten bronze, pyrochlore, lithium tantalate etc. [400]. 

Figure 1. Specific charge (thick line) and discharge (thin line) capacity of tin electrode without annealing. Bronze interface is absent. Current collector - copper. Testing mode C/5. Counter electrode - lithium foil. Separators - 2 layers of unwoven polypropylene (Mogilev, Belarus).

Silver vanadium oxide, Ag2V4011> is a semiconducting vanadium oxide bronze which adopts at least two related structures based on V4Ou layers with silver atoms located between them (Fig. 4.17). The open structure allows facile diffusion of lithium ions. Ag2V4Oi ( can be lithiated with up to seven lithium atoms to form Li7Ag2V4Ou. 

Kawakita, J., Y. Katayama, T. Miura, and T. Kishi. 1997. Lithium insertion behavior of silver vanadium bronze. Solid State Ionics. 99 71-78. 

Chakrabarthy et al.81 found for the dehydration of propan-2-ol by V205 and lithium vanadium bronzes, that lithium increases the dehydration, in contradiction with the view that this reaction takes place at the acid centers, but correlating well with the semiconductor properties. 

Compound 85 was dehydrogenated at 300° over palladium black under reduced pressure to a pyridine derivative 96 which was independently synthesized by the following route. Anisaldehyde (86) was treated with iodine monochloride in acetic acid to give the 3-iodo derivative 87. The Ullmann reaction of 87 in the presence of copper bronze afforded biphenyldialdehyde (88). The Knoevenagel condensation with malonic acid yielded the unsaturated diacid 91. The methyl ester (92) was also prepared alternatively by a condensation of 3-iodoanisaldehyde with malonic acid to give the iodo-cinnamic acid (89), followed by the Ullmann reaction of its methyl ester (90). The cinnamic diester was catalytically hydrogenated and reduced with lithium aluminium hydride to the diol 94. Reaction with phosphoryl chloride afforded an amorphous dichloro derivative (95) which was condensed with 2,6-lutidine in liquid ammonia in the presence of potassium amide to yield pyridine the derivative 96 in 27% yield (53). 

Bis dimethylthieno 1,4,5,8-tetratellurafulvalene4 3,4-Dibromo-2,5-dimethylthiophene in tetrahydrofuran is treated at — 78° with 2 equivalents of tert.-butyl lithium. After 2 h one equivalent of tellurium powder is added. The mixture is slowly warmed to 0° and kept at 0° until all the tellurium has dissolved. The mixture is cooled again to — 78°, treated with tert.-butyl lithium and then with tellurium at 0°. The ditellurolate solution is cooled to — 78°, mixed with 0.5 equivalent of tetrachloroethene, stirred for 18 h, and allowed to warm to 20°. The brown solid is isolated by filtration and extracted with carbon disulfide. The extract is evaporated and the residue recrystallized from 1,1,2-trichloroethane to give bronze-colored crystals yield 75% m.p. 295-298°. 

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