Cannizzaro reaction, acid catalyzed

CANNIZZARO REACTION. Base catalyzed dismulation of aromatic aldehydes or aliphatic aldehydes with no a-hydrogen into the corresponding acids and alcohols. When the aldehydes arc not identical, the reaction is called the "crossed Cannizzaro reaction."... 

Formaldehyde is readily reduced to methanol by hydrogen over many metal and metal oxide catalysts. It is oxidized to formic acid or carbon dioxide and water. The Cannizzaro reaction gives formic acid and methanol. Similarly, a vapor-phase Tischenko reaction is catalyzed by copper (34) and boric acid (38) to produce methyl formate ... 

Cannizzaro Reaction The formation of an acid and an alcohol through the base-catalyzed disproportionation of an aliphatic or aromatic aldehyde with no a-hydrogen atoms. 

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... 

The effects of micellization on reactivity have been investigated for a wide variety of ionic organic reactions other than those discussed previously in Sections IV and V, e.g. the Cannizzaro reaction, racemiza-tion, acid catalyzed enolization, base catalyzed hydrolysis of a,]8-un-saturated ketones, and coupling of quinonediimines with phenols. In the case of the Cannizzaro reaction of benzaldehyde (equation 43), the cationic surfactants eicosanyltrimethylammonium bromide and octa-decyltrimethylammonium bromide increased and the anionic surfactant... 

The overall reaction is currently regarded as an apparent hydride transfer (for review, see ) because a) hydrogen is transferred directly between the reactants in most cases, without exchange with the solvent, 2) the base-catalyzed disproportionation of benzaldehyde to benzyl alcohol and benzoic acid (Cannizzaro reaction) i ems to be a hydride transfer (3) stereospecificity can be observed in model reactions. In addition, Verhoeven and coworkers have analyzed the thermodynamics of the photoinduced reaction between l-benzyl-3-carbamido-l,4-dihydropyridine and l,l-dimethyl-4,4 -bipyridylium dication, and have concluded that a thermal 1 e reaction between a 1-alkyl-1,4-dihydronicotinamide and a carbonyl compound is unlikely. 

The conversion of aldehydes into carboxylic acids as a result of disproportionation occurs in the Cannizzaro and Guerbet reactions. The Cannizzaro reaction takes place when aromatic aldehydes are treated with alkali hydroxides and results in the formation of carboxylic acids and the corresponding alcohols. Yields of the acids can therefore be 50% at a maximum. The reaction is catalyzed by silver [363] and silver oxide [362], which is sometimes generated in situ from silver nitrate [364] see equation 357). 

Russell, A. E., Miller, S. P., Morken, J. P. Efficient Lewis acid catalyzed intramolecular Cannizzaro reaction. J. Org. Chem. 2000, 65, 8381-8383. 

If the Cannizzaro reaction of racemic 2-methylbutanal is catalyzed by H4Ru4(CO)8(R,7 -DIOP)2, an enantiomeric selection takes place for 2-methylbutanoic acid... 

Dihydroquinazolines have been formed by the acid- or base-catalyzed disproportionation of 4-alkoxy(or hydroxy)-3-phenyl-3,4-dihydroquinazo-line-2(l//)-thiones(or -ones). These gave a mixture of 3-phenylquinazolin-4-one-2(liJ)-thione(or -one) and 3-phenyl-3,4-dihydroquinazoline-2(lf/)-thione(or -one). The disproportionation is akin to a Cannizzaro reaction. ... 

Step 6 is the final step in the cellulose-to-lactic acid cascade, involving the isomerization of the 2-keto-hemi-acetal (here pyruvic aldehyde hydrate) into a 2-hydroxy-carboxyhc acid. This reaction is known to proceed in basic media following a Cannizzaro reaction with 1,2-hydride shift [111], Under mild conditions, Lewis acids are able to catalyze this vital step, which can also be seen as an Meerwein-Ponndorf-Verley reduction reaction mechanism. The 1,2-hydride shift has been demonstrated with deuterium labeled solvents [110, 112], Attack of the solvent molecule (water or alcohol) on pymvic aldehyde (step 5) and the hydride shift (step 6) might occur in a concerted mechanism, but the presence of the hemiacetal in ethanol has been demonstrated for pyruvic aldehyde with chromatography by Li et al. [113] andfor4-methoxyethylglyoxal with in situ CNMRby Dusselier et al. (see Sect. 7) [114]. 

On. long standing, beta polyox meth leiie becomes partially insoluble in dihite alkali and sodium sulfite solution. This is apparently due to reactions cataly2ed by. suUuric acid, resulting in the formation of small amounts of polyoxynnethylene dimethjd ethers. Staiidiiigei has demonstrated that methyl alcohol is produced by the action of sulfmic acid on formaldehy de, and the methyl alcohol accountable for the dimethyd ether formation is probably formed in this way. Sulfuric acid catalyzes the Cannizzaro reaction as well as the ether formation. 

The released end-group forms an a-dicarbonyl structure which rearranges by an intramolecular, Cannizzaro type of reaction to yield saccharinates. Intramolecular reactions of the Cannizzaro type can occur not only with dialdehydes but also with a-ketoaldehydes and a-diketones ( benzilic acid rearrangement ) they can be exemplified by the base-catalyzed rearrangement of phenylglyoxal (VIII) [or of (2,4,6-trimethylphenyl)-glyoxal ] to the salt of mandelic acid (IX) (or of 2,4,6-trimethylmandelic acid). 

Figure 12.6 presents the process flow diagram of the catalytic production of xylitol. Three main sections are (i) pretreatment, (ii) reaction-condensation, and (iii) crystallization. The pretreatment section deals with the pH adjustment and the removal of the impurities contained in the feed stream, soluble and insoluble solids, and remnants of the hydrolysis of biomass. But the main goal is the removal of the alkalis, whose presence catalyzes the conversion of xylose to xylonic acid (Cannizzaro mechanism). The first step of the downstream processes (unit PI) involves a series of treatment by ionic resins, activated carbon column, and chromatographic separations. Then, the pH is adjusted (unit Rl) in a range of 5-6 through the neutralization of acids (mainly acetic acid) by 1M solution of calcium hydroxide (Ca(OH)2) ... 

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