Sodium borohydridc

Alkyl mercuric hydrides are generated in situ by reduction of an alkyl mercuric salt with sodium borohydridc (Scheme 3.91). Their use as radical traps was first reported by Hill and Whitesides491 and developed for the study of radical-olefin reactions by Giese,489490 Tirrell492 and coworkers. Careful choice of reagents and conditions provides excellent yields of adducts of nucleophilic radicals (e.g. -hexyl, cyclohexyl, /-butyl, alkoxyalkyl) to electron-deficient monomers (e.g. acrylics). 

Only the trifluoromethyl group has been subjected to reduction in this class of compound. Although not reduced by zinc in acetic acid or by sodium in ethanol, diethyl 2-methyl-4-(tri-fluoromethyl)-1//-pyrrole-3,5-dicarboxylate (1) is reduced at the trifluoromethyl group with an excess of lithium aluminum hydride to give the corresponding tetramethyl derivative 2 sodium borohydridc in ethanol is quite inefficient.104... 

Although there is little toxicity information published on hydrides, a threshold limit value tTLV) for lithium hydride in air of 25 pg/ra has been established. More extensive data arc available for sodium borohydridc in the powder and solution forms. The acute oral LDso of NaBHj is 50- 100 nig/kg For NaBHj and 500-1000 mg/kg for the solution, The acute dermal LDsn Ion dry skim is 4-8 g/kg lor NaBHj and 100-500 mg/kg for the solution. The reuetiun or decomposition by-product sodium inelaborate is slightly toxic orally (LDy, is 2000-4IXXI mg/kg) and ilonioxic demially. 

Table 7.4.1. UV spectral properties of carbonyl-containing lignin model compounds on reduction with sodium borohydridc (Adler and Marton 1959)...

Recently, two new methods have been introduced for this transformation. In one, formic acid is replaced by sodium borohydridc. Thus treatment of a steroidal amine of type (I) with a large excess of formaldehyde in methanol followed by reduction with sodium borohydridc gives the methylated amine (2) in about 85% yield. 

Hydrogenation catalyst. Russell and Hoy have described a nickel boride catalyst which is useful for selective reduction of C=C bonds without hydrogenolysis of liydruxylic subslilueiils or hydrogenation of carbonyl or epoxide groups. The black colloidal catalyst is prepared by reduction of nickel acetate in ethanol with. 0M sodium borohydridc solution. 

Such condensation had been effected previously, but in lower yields, by a system comprising nickel(II) acetylacetonate, Ni(C5H702)2, diisopropoxyphenylphosphine, and sodium borohydridc. The borohydride in this case is essential to effect good conversions. I be order of reactivity of nickel salts in the butadiene-amine-dialkoxyphenyl-phosphine system is... 

Quinazolines 14, especially those bearing no substituents at position 4, are reduced to 3,4-dihydroquinazolines 15 by various reducing agents, e.g. sodium borohydridc," - or sodium in tetrahydrofuran, ° or catalytically. - yields obtained by catalytic hydro-... 

Markownikov hydration of olefins. H. C. Brown and Geoghegan39 report that Markownikov hydration of olefins can be achieved very simply by oxymercuration with mercuric acetate followed by demercuration with sodium borohydridc. 

Sodium borohydridc-Orium(lH) chloride (Luche reagent)... 

Others in the Schreiber group had also observed the hydrolysis of esters as a side reaction in sodium borohydridc reductions. 

Sodium borohydridc, now commercially available, may be prepared without recourse to diborane by the reaction (108) ... 

Nickel boride (lee also Sodium borohydridc-Nickel chloride), 197 Nickel carbonyl, 198 Nickel chloride-Uthium, 197... 

Severin and co workers (108) gave an original method for the pieparation of dinitrocyclohcxcne derivatives by acting w itli sodium borohydridc on aromatic diriitro compounds 12 >)... 

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