Bouveault-Blanc

Bouveault-Blanc reduction The reduction of esters to alcohols by nascent hydrogen gen-... 

This is an example of the reduction of an ester of a dibasic acid to the corre spending glycol (Bouveault-Blanc reduction) ... 

Benzilic acid rearrangement Benzoin reaction (condensation) Blanc chloromethylation reaction Bouveault-Blanc reduction Bucherer hydantoin synthesis Bucherer reaction Cannizzaro reaction Claisen aldoi condensation Claisen condensation Claisen-Schmidt reaction. Clemmensen reduction Darzens glycidic ester condensation Diazoamino-aminoazo rearrangement Dieckmann reaction Diels-Alder reaction Doebner reaction Erlenmeyer azlactone synthesis Fischer indole synthesis Fischer-Speior esterification Friedel-Crafts reaction... 

Methods Primarily of Historical Interest. In the Bouveault-Blanc deduction (79,80) phenylacetic ester is reduced with sodium and alcohol to... 

Die praparativ bedeutende Reduktion von Carbonsaure-estern zu Alkoholen mit Hy-drideii verlauft gut und ohne Nebenreaktionen auch in den Fallen, wo die klassischen Me-thoden (metallisches Natrium in Alkohol nach Bouveault-Blanc, katalytische Druckhy-drierung) versagen, z.B. bei Halogen-, Hydroxy-, Nitro- und Amino-carbonsaure-estern, bei Polyen-carbonsaure-estern und bei enolisierbaren Carbonsaure-estern. 

Sodium in Ethanol This is called the Bouveault-Blanc procedure and was more popular for the reduction of carboxylic esters (19-38) than of aldehydes or ketones before the discovery of LiAlH4. 

One study showed that the Cram s mle product predominates with metal hydride reducing agents, but the other product with Bouveault-Blanc and dissolving metal reductions Yamamoto, Y. Matsuoka, K. Nemoto, H. J. Am. Chem. Soc., 1988, 110, 4475. 

Naturally occurring fatty alcohols used in the fragrance industry are produced principally by reduction of the methyl esters of the corresponding carboxylic acids, which are obtained by transesterification of natural fats and oils with methanol. Industrial reduction processes include catalytic hydrogenation in the presence of copper-chromium oxide catalysts (Adkins catalysts) and reduction with sodium (Bouveault—Blanc reduction). Unsaturated alcohols can also be prepared by the latter method. Numerous alcohols used in flavor compositions are, meantime, produced by biotechnological processes [11]. Alcohols are starting materials for aldehydes and esters. 

The Riihlmann modification (Bouveault-Blanc Condensation or Riihlmann Reaction) traps the dienolate as a TMS derivative. This protocol generally results in improved yields. 

Boiling-point composition curves, 7-12 Bond refractions, 1036 Boring of corks, 55, 56 Boron trifluoride, 183, 862, 864, 865 Bouveault-Blanc reduction, 247, 249, 250, 812, 832... 

Octanol has previously been prepared from ethyl caprylate by catalytic hydrogenolysis,21 and by the Bouveault-Blanc method using sodium and alcohol in toluene.22 Other preparative methods include the reaction between fi-hexylmagnesium... 

Primary alcohols may be conveniently prepared by the reduction of esters with sodium and absolute ethanol (the Bouveault-Blanc reduction, Expt 5.37). 

Desulfonylation of a-sulfonylacetates. Desulfonylation of these substrates is not satisfactory by the usual methods (Zn-HOAc, Raney Ni-C,H5OH, sodium amalgam), but can be conducted in 70-75% yield with sodium-ethanol in THF (modified Bouveault-Blanc reduction). The substrates (2) are obtained by Wolff rearrangement of a-acyl-a-benzyl-sulfonyldiazomethanes (1).1... 

Methods to transform ketones into alcohols are based on using of alkali metals as electron donors. One of these methods is the Bouveault-Blanc reaction A ketone is dissolved in an alcohol and boiled with an excess of sodium. Sometimes, a ketone-alcohol mixture is rapidly added to molten sodium. Sodium reacts with both ketone and alcohol. 

Ruhlmann and co-workers found194-196 that carboxylic acid esters react under dimerisation to form acyloins if they are treated with sodium/TMS-Cl (142) in inert solvents. This Bouveault-Blanc-like synthesis has many parallels to the reductive silyl-ation (vide supra). 

If the reaction is carried out in the presence of a proton donor, such as alcohol, simple reduction of the ester to the alcohol takes place (Bouveault-Blanc Reduction). 

The first commercial production of fatty alcohols in the 1930 s employed a sodium reduction process (Bouveault-Blanc) (2). However, the high usage (4 mol/mol alcohol) of expensive sodium soon led to replacement of this method of reduction by catalytic hydrogenation. 

This important fragrance material probably was introduced in commercial perfumery during the first decade of the twentieth century with the discovery of the Bouveault-Blanc reduction of esters by sodium and an alcohol (10). This is the first of several methods of preparation shown in Figure 16. Large quantities of phenylethyl alcohol were made by sodium reduction of butyl phenylacetate in normal butanol. The basic raw materials were readily available at low cost from benzyl chloride, sodium cyanide and fermentation butanol. 

The reaction of esters with sodium in ethanol is referred to as the Bouveault-Blanc reaction. Prior to the discovery of complex metal hydrides, this reaction was the only method for the reduction of esters to alcohols. The diesters shown in Figure 17.59 produce a diol in this way. 

The mechanism of the Bouveault-Blanc reduction is shown in rows 1 and 2 of Figure 17.59. It starts with the sequence ester —t radical anion C —> hydroxylated radical... 

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