Cannizarro reaction

Thus, formaldehyde is not an efficient reductant in electroless Cu solutions, not that this is an issue, given its continuous depletion by the parasitic homogeneous Cannizarro reaction. 

It undergoes a parasitic Cannizarro reaction as readily as H2CO, yielding glycolate and oxalate as products ... 

Benzaldehydes are not subject to base catalyzed aldol condensations, and under the reaction conditions Cannizarro reactions are not important. 

Reduction of ethyl 1-dibenzothiophenecarboxylate with LAH affords 1-hydroxymethyldibenzothiophene (96%), which is smoothly converted into the chloromethyl derivative with thionyl chloride (70%). Both the Cannizarro reaction and LAH reduction of 2-dibenzothiophenecarboxaldehyde yield the 2-hydroxymethyl derivative in good yields. 3-Hydroxymethyl-4-methyldibenzothiophene has been prepared via Cannizarro reaction of the corresponding 3-aldehyde however, 3-hydroxymethyldibenzothiophene itself has not been recorded, although the necessary precursors are available. Considerable interest has centered around 4-hydroxymethyldibenzothiophene, which... 

The usual range of reactions has been recorded for the aldehydes of dibenzothiophene. Oxidation yields the corresponding acid, - reduction with LAH the corresponding alcohol, reduction under Huang-Minlon conditions the corresponding methyl compound, and two examples of the Cannizarro reaction have been described. ... 

Fragmentation and recombination reactions predominate in nearneutral, alkaline solutions. Fragments from the cleavage of the carbohydrate, and from its dehydration products, undergo further dehydration, condensation, and intermolecular, Cannizarro-type reactions. The benzilic acid rearrangement, an intramolecular Cannizarro reaction, seems to be inoperative. 

Hayami and his coworkers have studied the mechanism of formation of acetol and pyruvic acid from D-glucose- -14C, -6-14C, and -3,4-14C2, reacting in a concentrated, phosphate buffer solution.148-151 Their data supported the supposition that the products are formed from pyruvaldehyde by way of a Cannizarro reaction. As in the formation of lactic acid, the pyruvaldehyde can be formed either from the reducing or the nonreducing end of the D-glucose molecule, and the distribution of radioactivity in the pyruvic acid and acetol... 

In the Cannizarro reaction, benzaldehyde is both oxidized and reduced to form benzoic acid (as the benzoate salt) and benzyl alcohol. 

Hydroxymethylation of 1 to 9 in the first reactor is very fast at 40 °C. In principle, a strongly basic ion exchange resin may be used as a solid catalyst, but as expected the catalyst failed in test runs due to inactivation by formic acid produced by Cannizarro reaction. 

Effective molarity measurements for intramolecular hydride transfers are scarce, and a conclusion that high effective molarities are a feature of hydride shifts would be premature. Only two other measurements are available, a low value of 13 for the Cannizarro reaction of phthalaldehyde (McDonald and Sibley, 1981), discussed below, and a larger value, 200, for... 

The aldol reaction appears to have taken place but there has been reduction of the ketone product. The only possible reducing agent is more formaldehyde and reduction is by the Car" reaction (p. 1081). The aldol can be successful if a weaker base (Na2C03 will do) is used Cannizarro reaction requires a dianion. 

Treatment of tributyltin hydride with a Grignard reagent enables preparation of the corresponding organotin anion, which undergoes the Cannizarro reaction with pentanal providing an acyl stannane (Scheme 12.130) [233]. 

One obvious candidate for a reactive non-enolisable carbonyl compound is formaldehyde, CH2O. The trouble with this compound is that it is rather too reactive, adding repeatedly and transforming the product by Cannizarro reactions to give such compounds as (40). 

Condensation of (31) to (32) requires formaldehyde and base. Reduction to (33) occurs under these conditions by the Cannizarro reaction so the synthesis is shorter than seemed likely. The reverse Diels-Alder reaction to (30) goes at high temperature. 

N) The hydroxyl group is selectively oxidized to the ketone by a variation of the Oppenauer oxidation, namely a disproportionation process similar to the Cannizarro reaction. The alcohol is oxidized to ketone while an alcohol is formed from the reduction of another ketone. The reaction is reversible depending on the concentration of the reactants. 

Note NaOH cannot be used (instead of NagCOg) for affecting alkalinity, because it may produce BENZOIC ACID by the Cannizarro Reaction from the unchanged/unreacted portion of Benzaldehyde.]... 

More detailed information about acid/base extraction can be found in any organic practical book. The details of the Cannizarro reaction are from J. C. Gilbert and S. F. Martin, Experimental Organic Chemistry, Harcourt, Fort Worth, 2002. The reduction of amides to amines comes from B. S. Furniss, A. J. Hannaford, P. W. G. Smith,... 

Summary This is an exampie of the Cannizarro reaction, aithough in this case hydride transfer is intramoiecuiar ... 

Base-catalyzed disproportionation reaction of aromatic or aliphatic aldehydes with no a-hydrogen to corresponding acid and alcohol. If the aldehydes are different, the reaction is called the crossed Cannizarro reaction ... 

The Cannizarro reaction under heterogenous conditions catalysed by barium hydroxide is considerably accelerated (Scheme 28) by sonication. The yields are 100% after 10 min, whereas no reaction is observed during this period with the use of ultrasound/ ... 

The following is called the Cannizarro reaction. This is a base-catalyzed disproportionation of aldehydes that have no a-hydrogens (e.g., R = phenyl). Write a mechanism for this reaction showing all electron pushing. Derive a kinetic expression for your mechanism and predict the kinetic order in aldehyde and hydroxide. What experiments would you perform to test the validity of your mechanism Can you write an alternative mechanism that would give different experimental... 

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