Cannizzaro reaction reduction

Aldehydes can undergo an intermolecular oxidation—reduction (Cannizzaro reaction) in the presence of base to produce an alcohol and a carboxylic acid salt. Any aldehyde is capable of participating in such a reaction, however, it is more common for those containing no protons on the alpha carbon, for example... 

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... 

Hydroxyalkylthiazoles are also obtained by cyclization or from alkoxyalkyl-thiazoles by hydrolysis (36, 44, 45, 52, 55-57) and by lithium aluminium hydride reduction of the esters of thiazolecarboxylic acids (58-60) or of the thiazoleacetic adds. The Cannizzaro reaction of 4-thiazolealdehyde gives 4-(hydroxymethyl)-thiazole (53). The main reactions of hydroxyalkyl thiazoles are the synthesis of halogenated derivatives by the action of hydrobroraic acid (55, 61-63), thionyl chloride (44, 45, 63-66), phosphoryl chloride (52, 62, 67), phosphorus penta-chloride (58), tribromide (38, 68), esterification (58, 68-71), and elimination that leads to the alkenylthiazoles (49, 72). 

Furylcarbinol has been prepared by the reduction of furfural with sodium amalgam but the Cannizzaro reaction is the better practical method of preparation. 

The Mecrwein-Ponndoi f-Verlev reaction involves reduction of a ketone by treatment with an excess of aluminum triisopropoxide. The mechanism of the process is closely related to the Cannizzaro reaction in that a hydride ion acts as a leaving group. Propose a mechanism. 

Hydride Transfer In some reactions, a hydride ion is transferred to or from the substrate. The reduction of epoxides with LiAlH4 is an example (10-85). Another is the Cannizzaro reaction (19-60). Reactions in which a carbocation abstracts a hydride ion belong in this category ... 

In the general context of donor/acceptor formulation, the carbonyl derivatives (especially ketones) are utilized as electron acceptors in a wide variety of reactions such as additions with Grignard reagents, alkyl metals, enolates (aldol condensation), hydroxide (Cannizzaro reaction), alkoxides (Meerwein-Pondorff-Verley reduction), thiolates, phenolates, etc. reduction to alcohols with lithium aluminum hydride, sodium borohydride, trialkyltin hydrides, etc. and cyloadditions with electron-rich olefins (Paterno-Buchi reaction), acetylenes, and dienes.46... 

Chemical reduction of aromatic aldehydes to alcohols was accomplished with lithium aluminum hydride [5i], alane [770], lithium borohydride [750], sodium borohydride [757], sodium trimethoxyborohydride [99], tetrabutylam-monium borohydride [777], tetrabutylammonium cyanoborohydride [757], B-3-pinanyl-9-borabicyclo[3.3.1]nonane [709], tributylstannane [756], diphenylstan-nane [114], sodium dithionite [262], isopropyl alcohol [755], formaldehyde (crossed Cannizzaro reaction) [i7i] and others. 

The Cannizzaro reaction is a redox reaction, which requires a concentrated base and a Ccirbonyl group with no a-hydrogen atoms. Normally, the oxidation converts an aldehyde to a carboxylate (ccirboxylic acid), while the reduction generates an alcohol. Figure 11-33 shows an example of a Cannizzaro reaction. 

Cannizzaro reaction An internal oxidation-reduction reaction of aldehydes, carbamide Urea, carcinogenic Cancer causing. 

Unlike the starting material, the product of this reduction contains an asymmetric carbon atom and it was found to be optically active. Since in the case of ketones a Cannizzaro reaction cannot take place, this mechanism for alcohol formation is out of the question. Consideration of the reduction of ketones thus clearly shows that an actual biohydrogenation is involved. 

Phytochemical reduction must be regarded as a special case of oxidation-reduction. Since it is enzymatically conducted it should be distinguished from the analogously formulated Cannizzaro reaction. For this reason Neuberg, Hirsch and Reinfurth suggested the name dismutation for the physiological process, and in the last 25 years... 

The first reaction provides a route for the reduction of alkyl halides since the carbo-cation (isopropyl, in Rl) may be prepared from action of AICI3 on the corresponding alkyl halide. Reactions of the type Rl are also important in the process, catalytic cracking, in the manufacture of gasoline. They have also been studied in mass spectro-metric experiments [235]. Reaction R2 is one route to the preparation of carbocations under stable ion conditions. Reaction R3 is employed in the laboratory synthesis of the tropylium cation. Reaction R4, the (crossed) Cannizzaro reaction, is unusual in that it takes place under strongly basic conditions. The oxy dianion is an intermediate in the reaction of concentrated hydroxide with the aldehyde, R HO. None of R1, R2, or R3 may have hydrogen atoms a to the carbonyl groups. Formaldehyde (R1 = H) is readily... 

Cannizzaro reaction. Aromatic aldehydes (and other aldehydes in which a-hydrogen atoms arc absent, e.g., formaldehyde, trimcthylacetaldehyde, and a-hydroxy-tso-butyraldehyde) under the influence of strong aqueous or alcoholio alkali undergo simultaneous oxidation and reduction yielding the alcohol and corresponding acid. Thus —... 

Several species of bacteria under suitable conditions cause -butyraldehyde to undergo the Cannizzaro reaction (simultaneous oxidation and reduction to butyric acid and butanol, respectively) this reaction can also be catalyzed by Raney nickel (7). The direct formation of butyl butyrate [109-21 -7] or isobutyl isobutyrate (Tishchenko reaction) from the corresponding aldehyde takes place rapidly with aluminum ethylate or aluminum butyrate... 

CANNIZZARO, STANISLAO (1826-1910). Born in Italy, lie extended the research of Avogadro on the molecular concentration of gases and thus was able to prove the distinction between atoms and molecules. His investigations of atomic weights helped to helped lo make possible the discovery of the periodic law hy Mendeleyev. His research in organic chemistry led to the establishment of the Cannizzaro reaction involving the oxidation reduction of an aldehyde in the presence of concentrated alkali. 

Hydroxjrmethylbenzof Jthiophenes are most conveniently prepared by reduction with lithium aluminum hydride of the corresponding carboxylic acid78,100 S37 485,486,521,528,540 or ester.77,87,336,337, 52i, 526 Lesg frequently, they are prepared by reduction of the corresponding aldehyde 100,487 or acid chloride,618 with sodium boro-hydride, or, in the case of 2-hydroxymethylbenzo[6]thiophenes, by reaction of the 2-lithium derivative with formaldehyde.90,628 3-Hydroxymethylbenzo[6]thiophene has been prepared from the corresponding aldehyde by means of a crossed Cannizzaro reaction... 

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