The Tishchenko reaction is an organic

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

that involves

disproportionation In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can ...

of an

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...

in the presence of an alkoxide. The reaction is named after Russian organic chemist Vyacheslav Tishchenko, who discovered that aluminium alkoxides are effective catalysts for the reaction. In the related

Cannizzaro reaction 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. ...

, the base is sodium hydroxide and then the

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

product is a carboxylic acid and the reduction product is an alcohol.

History

The reaction involving benzaldehyde was discovered by Claisen using sodium benzylate as base. The reaction produces

benzyl benzoate Benzyl benzoate is an organic compound which is used as a medication and insect repellent. As a medication it is used to treat scabies and lice. For scabies either permethrin or malathion is typically preferred. It is applied to the skin as a ...

Enol In organic chemistry, alkenols (shortened to enols) are a type of reactive structure or intermediate in organic chemistry that is represented as an alkene ( olefin) with a hydroxyl group attached to one end of the alkene double bond (). The t ...

izable aldehydes are not amenable to Claisen's conditions. Vyacheslav Tishchenko discovered that aluminium alkoxides allowed the conversion of enolizable aldehydes to esters.

Examples

* The Tishchenko reaction of acetaldehyde gives the commercially important solvent

ethyl acetate Ethyl acetate ( systematically ethyl ethanoate, commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues ...

. The reaction is catalyzed by aluminium alkoxides. * The Tishchenko reaction is used to obtain isobutyl isobutyrate, a specialty solvent. * Hydroxypivalic acid neopentyl glycol ester is produced by a Tishchenko reaction from hydroxypivaldehyde in the presence of a basic catalyst (e.g., aluminium oxide). * The Tishchenko reaction of

paraformaldehyde Paraformaldehyde (PFA) is the smallest polyoxymethylene, the polymerization product of formaldehyde with a typical degree of polymerization of 8–100 units. Paraformaldehyde commonly has a slight odor of formaldehyde due to decomposition. Paraf ...

in the presence of aluminum methylate or magnesium methylate forms

methyl formate Methyl formate, also called methyl methanoate, is the methyl ester of formic acid. The simplest example of an ester, it is a colorless liquid with an ethereal odour, high vapor pressure, and low surface tension. It is a precursor to many other co ...

. *

Paraformaldehyde Paraformaldehyde (PFA) is the smallest polyoxymethylene, the polymerization product of formaldehyde with a typical degree of polymerization of 8–100 units. Paraformaldehyde commonly has a slight odor of formaldehyde due to decomposition. Paraf ...

reacts with

boric acid Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen borate or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolve ...

to form

. The key step in the reaction mechanism for this reaction is a 1,3-

hydride shift A sigmatropic reaction in organic chemistry is a pericyclic reaction wherein the net result is one σ-bond is changed to another σ-bond in an uncatalyzed intramolecular reaction. The name ''sigmatropic'' is the result of a compounding of the lon ...

in the

hemiacetal A hemiacetal or a hemiketal has the general formula R1R2C(OH)OR, where R1 or R2 is hydrogen or an organic substituent. They generally result from the addition of an alcohol to an aldehyde or a ketone, although the latter are sometimes called hemi ...

intermediate formed from two successive nucleophilic addition reactions, the first one from the catalyst. The hydride shift regenerates the alkoxide catalyst.

* V. E. Tishchenko , title= О действии алкоголятов алюминия на альдегиды. Сложного-эфира конденсации, как новый вид уплотнения альдегида. , trans-title=On the effect of aluminium alkoxides on aldehydes. Ester condeNsation, as a new kind of aldehyde condensation. , journal=Журнал Русского Физико-Химического Общества (Journal of the Russian Physico-Chemical Society) , volume=38 , year=1906 , pages=355–418 , url= https://books.google.com/books?id=iy9CAQAAMAAJ&pg=PA355#
482–540.
(in Russian) * В. Е. Тищенко and Г. Н. Григорьева (V. E. Tishchenko and G. N. Grigor'eva) (1906
"О действии амальгамы магния на изомасляного альдегида"
(On the effect of magnesium amalgam on isobutyric aldehyde), ''Журнал Русского Физико-Химического Общества'' (Journal of the Russian Physico-Chemical Society), 38 : 540–547. (in Russian) * М. П. Воронҝова and В. Е. Тищенко (M. P. Voronkova and V. E. Tishchenko) (1906
"О действии амальгамы магния на уксусный альдегид"
(On the effect of magnesium amalgam on acetic aldehyde), ''Журнал Русского Физико-Химического Общества'' (Journal of the Russian Physico-Chemical Society), 38 : 547–550. (in Russian) * В. Тищенко (V. Tishchenko) (1899
"Действие амальгамированного алюминия на алкоголь. Алкоголятов алюминия, их свойства и реакции."
(Effect of amalgamated aluminium on alcohol. Aluminium alkoxides, their properties and reactions.), ''Журнал Русского Физико-Химического Общества'' (Journal of the Russian Physico-Chemical Society), 31 : 694–770. (in Russian)

References

{{Reflist, 30em Organic reactions Name reactions

History

Examples

Further reading

Related topics

References