The Tishchenko reaction is an organic

chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...

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 gro ...

in the presence of an

alkoxide In chemistry, an alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They are written as , where R is the organic substituent. Alkoxides are strong bases and, whe ...

. The reaction is named after Russian organic chemist Vyacheslav Tishchenko, who discovered that aluminium

s are effective catalysts for the reaction. In the related Cannizzaro reaction, the base is

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and al ...

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 ...

product is a

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxyli ...

and the reduction product is an alcohol.

History

The reaction involving

benzaldehyde Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. It is a colorless liquid with a characteristic almond-like odor. ...

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 (). T ...

izable aldehydes are not amenable to Claisen's conditions. Vyacheslav Tishchenko discovered that aluminium

s allowed the conversion of enolizable aldehydes to esters.

Examples

* The Tishchenko reaction of

acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the ...

gives the commercially important solvent ethyl acetate. 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. Par ...

in the presence of aluminum methylate or magnesium methylate forms methyl formate. *

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. Par ...

reacts with boric acid to form methyl formate. The key step in the

reaction mechanism In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs. A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage o ...

for this reaction is a 1,3- hydride shift 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 In organic chemistry, a nucleophilic addition reaction is an addition reaction where a chemical compound with an electrophilic double or triple bond reacts with a nucleophile, such that the double or triple bond is broken. Nucleophilic additions d ...

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