Sodium amalgam, reduction

D,L-Mannitol has been obtained by sodium amalgam reduction of D,L-mannose. The identical hexitol is formed from the formaldehyde polymer, acrose, by conversion through its osazone and osone to D,L-fmctose (a-acrose) followed by reduction (83). 

Sodium amalgam reductions of M2(CO)iq give Na+[M(CO)5] and, indeed, further reduction leads to the super reduced species [M(CO)4] in which the metals exhibit their lowest known formal oxidation state of —3. On the other hand, treatment of [M(CO)5Cl] with AICI3 and CO under pressure produces [M(CO)6]" AlCl4 from which other salts of the cation can be obtained. 

Recently, Bercaw and co-workers have described the preparation of the first ethylene complex of titanium (64). The sodium amalgam reduction of a toluene solution of (Tj-C5Me5)2TiCl2 under an ethylene atmosphere afforded (T C5Me5)2Ti(T -C2H4) in 80% yield. Treatment of this complex with CO at low temperature resulted in the displacement of C2H4 and quantitative formation of (rj-C5Me5)2Ti(CO)2 (27). 

D-Glucitol (Sorbitol or Hexanhexol), HOCH2(CHaOH)4CH2OH raw 182.17, ndls (with lA or 1 w), tnp about ll0°(dry), -100° or less (with w), very hygr when dry sol in w hot ale. Found in various fruits prepd by sodium amalgam reduction of d-sorbose or by pressure hydrogenation of dextrose with Ni catalyst. Used far prepn of ascorbic acid (Vitamin C), for synthesis of resins, surface-active agents, varnishes, syrups, cosmetic creams aod for explosive Sorbitol Hexanitrate... 

For the procedure that follows, Na[Mo(f/5-C5H5)(CO)3] should be prepared in advance by reaction of Na( /5-C5H5) with Mo(CO)6,6 or by sodium amalgam reduction of [Mo(//5-C5H5)(CO)3]2 (Strem). 

Since our initial report we have noted three other transition metal mercury complexes in which the mercury bridges two or more metal atoms, which have been reported as products from sodium amalgam reductions, (a) D. Duffy, K. Mackay, and B. Nicholson, J. Chem. Soc. Dalton Trans., 1981,381 (b) R. Jones, F. Real, and G. Wilkinson, J. Chem. Soc. Dalton Trans., 1981,126 (c) J. Deutsche, S. Fadel, and M. Ziegler, Angew Chem. Int. Ed. Engl. 16,704 (1977). 

The principal sources of ytterbium are euxenite, gadolinite, monazite, and xenotime. the latter being the most important. Ytterbium is separated from a mixture of yttrium and the heavy Lanthanides by using the sodium amalgam reduction technique. Ytterbium metal is obtained by heating a mixture of lanthanum metal and ytterbium oxide under high vacuum. The ytterbium sublimes and is collected on condenser plates whereas the lanthanum is oxidized to the sesquioxide. 

Allylsilanes.1 A general route to allylsilanes involves addition of the anion of 1 lo aldehydes and ketones to form an adduct (2). Mesylation in situ, of the adducts followed by sodium amalgam reduction, results in allylsilanes (4) in 85-95% overall yield, based on the carbonyl compound. 

N. Sperber, H. E. Zaugg, and W. M. Sandstrom, The controlled sodium amalgam reduction of aldonolactones and their esters to aldoses and an improved synthesis of D-arabinose, J. Am. Chem. Soc., 69 (1947) 915-920 and references cited therein. 

Rosenmund reduction of pyrazole acid chlorides to aldehydes never causes reduction of the ring.834,635,744,745 Attempts to prepare the aldehydes by the sodium amalgam reduction of the anilides, however, gave only traces of the required products,635 but the fate of the pyrazole ring is not recorded. It is the authors experience that pyrazoles unsubstituted on nitrogen are usually unaffected by sodium and alcohol, although the reduction to pyrazoline by sodium and alcohol at 130° and 20 atmospheres pressure has been patented.746 Reduction of Ar-phonyIpyrazoles is somewhat easier sodium and alcohol reduce them to A-phenylpyrazolines,77,78, 207,235, 447,567,... 

For comparative purposes the syntheses and properties of formally seven-coordinate d4 biscyclopentadienyl alkyne complexes will be presented. The absence of a vacant dir orbital places these d4 complexes unambiguously in the two-electron alkyne category, i.e., N = 2 applies where N is defined as the formal electron donor number for the alkyne ligand. As in the porphyrin case a reductive ligation route provided access to these molecules. Sodium amalgam reduction of Cp2MoQ2 in the presence of alkyne yields Cp2Mo(RC=CR) [Eq. (28)] (82). Note that, in... 

The first reported synthesis (9,76) (78%) of Cp2V2(CO)5 (7) involved protonation of the dianion [CpV(CO)3]2- made by sodium amalgam reduction of CpV(CO)4. No vanadium hydride is isolated in this reaction. A slightly better yield (89%) results from the photolysis of CpV(CO)4 in THF using a falling-film photoreactor (77). The product 7 is produced via dimerization of an intermediate solvent complex CpV(CO)3(THF) followed by a further carbonyl loss (35). The corresponding Cp complex 7 is also available by an exactly analogous photolysis of Cp V(CO)4 or by protonation of [Cp V(CO)3]2- (JO). 

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