The Tishchenko reaction is an organic

chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

that involves disproportionation of an

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

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

and then the

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

product is a

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

and the reduction product is an

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

History

The reaction involving

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

was discovered by Claisen using sodium benzylate as base. The reaction produces benzyl benzoate. Tishchenko reaction

Enol In organic chemistry, enols are a type of functional group or intermediate in organic chemistry containing a group with the formula (R = many substituents). The term ''enol'' is an abbreviation of ''alkenol'', a portmanteau deriving from "-ene ...

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 compound, organic chemical compound with the chemical formula, formula , sometimes abbreviated as . It is a colorless liquid or gas, boiling near room temperature. It is one of the most ...

gives the commercially important solvent

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

. 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 Aluminium oxide (or aluminium(III) oxide) is a chemical compound of aluminium and oxygen with the chemical formula . It is the most commonly occurring of several Aluminium oxide (compounds), aluminium oxides, and specifically identified as alum ...

). * 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 Methyl formate, also called methyl methanoate, is the methyl ester of formic acid. The simplest example of a carboxylate ester, it is a colourless liquid with an ethereal odour, high vapor pressure, and low surface tension. The gas form is odourl ...

. *

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

to form

. 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 reaction occurs. A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage ...

for this reaction is a 1,3- hydride shift in the

hemiacetal In organic chemistry, a hemiacetal is a functional group the general formula , where is a hydrogen atom or an organic substituent. They generally result from the nucleophilic Addition reaction, addition of an Alcohol (chemistry), alcohol (a compo ...

intermediate formed from two successive

nucleophilic addition In organic chemistry, a nucleophilic addition (AN) 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 addit ...

reactions, the first one from the catalyst. The hydride shift regenerates the alkoxide catalyst.

References

* {{cite journal , first1=V. E. , last1=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) Organic reactions Name reactions

History

Examples

See also

References

Further reading