Borohydride compounds

The nitrated model compound, 9, proved even more resistant to reduction than the polymeric analog the dissolving metal technique used to reduce 15 failed on 9, but finally the amino model, 10, was produced by treatment of with a 25-fold excess of sodium borohydride. Compound 1 serves as a difunctional initiator for NCA polymerization. 

Also reported in Scheme 24 are the PhSeBr promoted cyclization reactions of alkenyl aldimines described by De Kimpe [93,94]. As indicated by the reactions of 158 and 161, both, the 5-exo-trig and the 5-endo-trig cyclizations, can take place. The initially formed iminium salts 159 and 162 are converted into the corresponding pyrrolidines 160 and 163 by reduction with sodium borohydride. Compound 163 was obtained as an almost equimolecular mixture of two diastereomers. 

There are many examples of borohydride compounds of these metals, e.g., Cu, Ag, Zn and Cd-BH as neutral and anionic complexes in which the mode of bonding of BH is dependent on the coordination number of the metaP. Higher borane anions also combine with Cu and Ag, yielding both neutral and anionic complexes. Although no borohydrides of Au are isolated, treatment of Au-halide complexes with, e.g., NaBH, is a standard method for the preparation of Au-cluster compounds Copper(I) hydride, first reported in 1844, has the ZnS structure [d(Cn-H) = 0.173 nm (1.73 A) d(Cu-Cu) = 0.289 nm (2.89 A)] and decomposes to the elements when heated. At >100°C the decomposition is explosive. 

Radicals can also be synthesized by the reduction of alkylmercury salts. For example, in the presence of sodium borohydride, compound 5-2 reacts to form the radical, 5-3. 

Borohydride compounds of trivalent actinides are limited to those of uranium. The initial reports of U(BH4)4 indicated it was prepared from thermal or photochemical decomposition of U(BH4)4 as in Equation (6) ... 

The 7V-(o-aminobenzyl)pyrrolidine 267 (n = 0) was obtained from the pyrrolo[2,l-i>]quinazolines 124 and 186 with sodium borohydride. Compounds 330 were also prepared from 205 by reduction with lithium aluminum hydride. - - - When reduction was carried out with sodium borohydride, only the C=N bond was saturated and compounds 332 were formed. The carbonyl group of compounds of type 332 was reduced by lithium aluminum hydride to give compounds of type 330. The C=N bond of compounds of type 333 could not be reduced with sodium borohydride or by catalytic hydrogenation over palladium or Raney nickel. The methoxycarbonyl group of the pyrrolo[2,l-i>]quinazolone 334 was reduced to a hydroxymethyl group with lithium aluminum hydride in tetra-hydrofuran at... 

The dihydride-dihydrogen complex OsH2(Ti2-H2)(CO)(P Pr3)2 (190) can be prepared by stirring of the borohydride compound 184 in methanol at room temperature. If the treatment is prolonged or the temperature is increased, the ci5-dihydride-c/5-dicarbonyl derivative OsH2(CO)2(P Pr3)2 is formed instead of 190 [73]. So, the most suitable method to prepare 190 is that shown in Scheme 51. 

Compound A is a D-aldopentose. When treated with sodium borohydride, compound A is converted into an alditol that exhibits three signals in its C NMR spectrum. Compound A undergoes a Kiliani-Fischer synthesis to produce two aldo-hexoses, compounds B and C. Upon treatment with nitric acid, compound B yields compound D, while compound C yields compound E. Both D and E are optically active aldaric acids. 

The hydride is thus delivered to the ketone from the upper face and the resulting hydroxyl functionahty rests on the lower side of the ring. The solution to this problem proved to be straightforward. Prior to the addition of sodium borohydride compound 84 was treated with sodium hydroxide. The resulting carboxylate anion would experience Coulomb repulsion with the borohydride reagent and attack will occur preferentially from the opposite side of the carboxylate. Indeed, this concept proved to work out nicely, delivering diastereomer 87 as the only observable product. The synthesis was carried on to a common intermediate of thromboxane synthesis. 

UL Subject 2265 C, Handheld or Transportable Fuel Cell Power Units with Fuel Containers—Borohydride Fuel Cartridges, Scope Covers handheld or hand-transportable fuel cells that provide dc outputs rated <60 Vdc and <240 VA and use un-refillable borohydride alkaline fuel. The fuel is either sodium or potassium borohydride compound or a mixture of these compounds. 

Sodium borohydride and lithium aluminum hydride react with carbonyl compounds in much the same way that Grignard reagents do except that they function as hydride donors rather than as carbanion sources Figure 15 2 outlines the general mechanism for the sodium borohydride reduction of an aldehyde or ketone (R2C=0) Two points are especially important about this process... 

The elements listed in the table of Figure 15.2 are of importance as environmental contaminants, and their analysis in soils, water, seawater, foodstuffs and for forensic purposes is performed routinely. For these reasons, methods have been sought to analyze samples of these elements quickly and easily without significant prepreparation. One way to unlock these elements from their compounds or salts, in which form they are usually found, is to reduce them to their volatile hydrides through the use of acid and sodium tetrahydroborate (sodium borohydride), as shown in Equation 15.1 for sodium arsenite. 

Hydrazine—borane compounds are made by the reaction of sodium borohydride and a hydrazine salt in THF (23,24). The mono-(N2H4 BH ) and di-(N2H4 2BH2) adducts are obtained, depending on the reaction conditions. These compounds have been suggested as rocket fuels (25) and for chemical deposition of nickel—boron alloys on nonmetallic surfaces (see Metallic COATINGS) (26). 

R. M. Adams and A. R. Siedle, Boron, Metallo-Boron Compounds andBoranes, Wiley-Interscience, New York, 1964, Chapt. 6, pp. 373—506. Borohydrides. 

When an aqueous effluent stream containing organomercurials cannot be recycled, it may be treated with chlorine to convert the organomercury to inorganic mercury. The inorganic compounds thus formed are reduced to metallic mercury with sodium borohydride. The mercury metal is drained from the reactor, and the aqueous solution discarded. The process utilising sodium borohydride is known as the Ventron process (27). 

With mercuric acetate (Hg(OOCCH2)2), olefins and / fZ-butyl hydroperoxide form organomercury-containing peroxides (66,100). The organomercury compound can be treated with bromine or a mild reducing agent, such as sodium borohydride, to remove the mercury. 

AletalHydrides. Metal hydrides can sometimes be used to prepare amines by reduction of various functional groups, but they are seldom the preferred method. Most metal hydrides do not reduce nitro compounds at all (64), although aUphatic nitro compounds can be reduced to amines with lithium aluminum hydride. When aromatic amines are reduced with this reagent, a2o compounds are produced. Nitriles, on the other hand, can be reduced to amines with lithium aluminum hydride or sodium borohydride under certain conditions. Other functional groups which can be reduced to amines using metal hydrides include amides, oximes, isocyanates, isothiocyanates, and a2ides (64). 

Reduction. Quinoline may be reduced rather selectively, depending on the reaction conditions. Raney nickel at 70—100°C and 6—7 MPa (60—70 atm) results in a 70% yield of 1,2,3,4-tetrahydroquinoline (32). Temperatures of 210—270°C produce only a slightly lower yield of decahydroquinoline [2051-28-7]. Catalytic reduction with platinum oxide in strongly acidic solution at ambient temperature and moderate pressure also gives a 70% yield of 5,6,7,8-tetrahydroquinoline [10500-57-9] (33). Further reduction of this material with sodium—ethanol produces 90% of /ra/ j -decahydroquinoline [767-92-0] (34). Reductions of the quinoline heterocycHc ring accompanied by alkylation have been reported (35). Yields vary widely sodium borohydride—acetic acid gives 17% of l,2,3,4-tetrahydro-l-(trifluoromethyl)quinoline [57928-03-7] and 79% of 1,2,3,4-tetrahydro-l-isopropylquinoline [21863-25-2]. This latter compound is obtained in the presence of acetone the use of cyanoborohydride reduces the pyridine ring without alkylation. 

Isoquinoline also forms Reissert compounds when treated with benzoyl chloride and alkyl cyanide (28), especially under phase-transfer conditions (29). The W-phenylsulfonyl Reissert has been converted to 1-cyanoisoquinoline with sodium borohydride under mild conditions (154). When the AJ-benzoyl-l-alkyl derivative is used, reductive fission occurs and the 1-alkyLisoquinoline is obtained. 

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