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The Cannizzaro reaction, named after its discoverer Stanislao Cannizzaro, is a chemical reaction which involves the base-induced disproportionation of two molecules of a non-enolizable aldehyde to give a primary alcohol and a carboxylic acid. [1] [2]
Pentaerythritol was first reported in 1891 by German chemist Bernhard Tollens and his student P. Wigand. [5] It may be prepared via a base-catalyzed multiple-addition reaction between acetaldehyde and 3 equivalents of formaldehyde to give pentaerythrose (CAS: 3818-32-4), followed by a Cannizzaro reaction with a fourth equivalent of formaldehyde to give the final product plus formate ion.
Neopentyl glycol is synthesized industrially by the aldol reaction of formaldehyde and isobutyraldehyde. This creates the intermediate hydroxypivaldehyde, which can be converted to neopentyl glycol by either a Cannizzaro reaction with excess formaldehyde, or by hydrogenation using palladium on carbon. [2]
Formaldehyde is readily oxidized by atmospheric oxygen into formic acid. For this reason, commercial formaldehyde is typically contaminated with formic acid. Formaldehyde can be hydrogenated into methanol. In the Cannizzaro reaction, formaldehyde and base react to produce formic acid and methanol, a disproportionation reaction.
Sodium formate is also unavoidably formed as a by-product in the final step of the pentaerythritol synthesis and in the crossed Cannizzaro reaction of formaldehyde with the aldol reaction product trimethylol acetaldehyde [3-hydroxy-2,2-bis(hydroxymethyl)propanal].
In the context of butanol fuel, isobutyraldehyde is of interest as a precursor to isobutanol. E. coli as well as several other organisms has been genetically modified to produce isobutanol. α-Ketoisovalerate, derived from oxidative deamination of valine, is prone to decarboxylation to give isobutyraldehyde, which is susceptible to reduction to the alcohol: [3]
In organic synthesis, the Casiraghi formylation is the formation of a salicylaldehyde from a phenol and paraformaldehyde.The reaction requires a strong Brønsted base and a weak Lewis acid, and gives a methanol coproduct: [1]
The reaction is catalyzed by nucleophiles such as a cyanide or an N-heterocyclic carbene (usually thiazolium salts). The reaction mechanism was proposed in 1903 by A. J. Lapworth . [ 7 ] In the first step in this reaction, the cyanide anion (as sodium cyanide ) reacts with the aldehyde in a nucleophilic addition .