Nickel boride sulfides

The halide is not the only metal compound used as source of metal. Metal oxides and sulfides are employed to prepare vanadium, chromium, iron and nickel borides in this way from sulfides at lower reaction T than those required by reaction sintering of the elements . 

Aliphatic and aromatic sulfides undergo desulfurization with Raney nickel [673], with nickel boride [673], with lithium aluminum hydride in the presence of cupric chloride [675], with titanium dichloride [676], and with triethyl phosphite [677]. In saccharides benzylthioethers were not desulfurized but reduced to toluene and mercaptodeoxysugars using sodium in liquid ammonia [678]. This reduction has general application and replaces catalytic hydrogenolysis, which cannot be used [637]. 

Partial desulfurization of disulfides to sulfides was accomplished by treatment with tris(diethylamino)phosphine in good yields [303]. 1,2-Dithiacy-clohexane was thus quantitatively converted to thiophane (tetrahydrothio-phene) at room temperature [303]. Complete desulfurization to hydrocarbons resulted when disulfides were refiuxed in ethanol with Raney nickel or nickel boride (yields 86 and 72%, respectively) [673]. 

Tetrasubstituted viodinitro compounds have been converted to olefins by treatment with amalgamated calcium.3214 Various functional groups, such as CN and COOR, did not affect the reaction. Other reagents that have been used include sodium sulfide in DMF,32V nickel boride and ultrasound,330 Bu3SnH,331 and SnCI2.332 Radical-ion mechanisms are likely in all these cases. 

Reductive deseleneniation.1 Aryl selenides and selenoketals can be reduced efficiently by nickel boride, generated in situ from NiCl2-6H20 and NaBH4. Selective deseleneniation is possible in the presence of aryl sulfides and carbon-carbon double bonds. This method is a useful alternative to reduction with triphenyltin hydride (8, 521-522 10, 451-452). 

REDUCTION, REAGENTS Bis(N-methylpi-perazinyl)aluminum hydride. Borane-Di-methyl sulfide. Borane-Tetrahydrofurane. Borane-Pyridine. n-Butyllithium-Diisobu-tylaluminum hydride. Calcium-Amines. Diisobutylaluminum hydride. 8-Hydroxy-quinolinedihydroboronite. Lithium aluminum hydride. Lithium 9-boratabicy-clo[3.3.1]nonane. Lithium n-butyldiisopro-pylaluminum hydride. Lithium tri-j c-butylborohydride. Lithium triethylborohy-dride. Monochloroalane. Nickel boride. 2-Phenylbenzothiazoline. Potassium 9-(2,3-dimethyl-2-butoxy)-9-boratabicy-clo[3.3.1]nonane. Raney nickel. Sodium bis(2-methoxyethoxy)aluminum hydride. Sodium borohydride. Sodium borohy-dride-Nickel chloride. Sodium borohy-dride-Praeseodymium chloride. So-dium(dimethylamino)borohydride. Sodium hydrogen telluride. Thexyl chloroborane-Dimethyl sulfide. Tri-n-butylphosphine-Diphenyl disulfide. Tri-n-butyltin hydride. Zinc-l,2-Dibromoethane. Zinc borohydride. 

Hydrogenolysis of compounds with sulfur atoms attached to aromatic rings such as benzenethiols, and aryl sulfides, disulfides, sulfoxides and sulfones takes place on refluxing with Raney nickel or nickel boride. Sulfur combines with nickel, and hydrogen replaces the sulfur-containing group. 

Raney nickel is a stronger desulfurizing agent than nickel boride. On the other hand nickel boride, prepared from nickel(II) chloride and sodium borohydride, is more selective since it does not desulfurize aromatic sulfones. An example of such selectivity is desulfurization of p-phenylsulfonylphenyl p-tolyl sulfide (33), which affords diphenyl sulfone in 91% yield and toluene in 84% yield. In contrast. Raney nickel desulfurizes both the sulfide and the sulfone giving a mixture of benzene and toluene (equation 82). 5... 

Nickel boride has been used to reduce benzylic dithioacetals to sulfides or hydrocarbons (equation... 

The product alkyl-2-pyridyl sulfides are of synthetic interest by virtue of their ability to form a chelated lithio anion for reaction with carbon electrophiles. Subsequent removal of the sulfide can then be achieved using either nickel boride or tri- -butyl stannane [4] (Scheme 8). 

The power of this methodology becomes fully apparent however on further synthetic manipulation of the geminally functionalized pyridyl sulfide adducts, with two general reactions being reductive removal of the sulfide by Raney nickel, nickel boride or tri-n-butyltin hydride, or controlled oxidation to the sulfoxide and subsequent thermal syn elimination (Scheme 31). 

Nickel boride (Ni B) Nickel boride (Ni B) Nickel(II) bromide Nickel(II) chloride Nickel(II) fluoride Nickel(II) iodide Nickel(II) oxide Nickel(II) sulfide Nickel disulfide Nickel subsulfide Niobium... 

Bis(acrylonitrile)nickel(0), 2312 l,2-Bis(dichlorophosphino)ethane, 0797 Bis(trimethylsilyl) phosphonite, 2611 Bromodimethylborane, 0887 Calcium silicide, 3943 Cerium trisulfide, 3967 Chromium(II) acetate, 1493 Chromium(II) oxide, 4241 Cobalt(III) nitride, 4214 Cobalt(II) sulfide, 4218 Dicobalt boride, 0128 Dimethyl ethanephosphonite, 1732 Europium(II) sulfide, 4293 2-Furaldehyde, 1836 Indium(II) oxide, 4641... 

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. 

The bulk metal is oxidized by air or steam only at high temperatures, but Raney nickel (see Section 21.2) is pyrophoric. Nickel reacts with F2 to give a coherent coating of NiF2 which prevents further attack hence the use of nickel and its alloy Monel metal in apparatus for handling F2 or xenon fluorides. With CI2, Bt2 and I2, Ni(II) halides are formed. At elevated temperatures, Ni reacts with P, S and B and a range of different phosphide (see Section 14.6), sulfide and boride (see Section 12.10) phases are known. 

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