Английская Википедия:Aldol

Материал из Онлайн справочника
Перейти к навигацииПерейти к поиску

Шаблон:Short description

Файл:Aldol2.svg
Generalized structure of the aldol moiety: When R3 is -H, it is a β-hydroxy aldehyde, otherwise it is a β-hydroxy ketone.

In organic chemistry, an aldol describes a structural motif consisting of a 3-hydroxy ketone, Шаблон:Chem2, or 3-hydroxyaldehyde, Шаблон:Chem2. Both are composed of a hydroxy group (Шаблон:Chem2) and either a ketone (Шаблон:Chem2) or an aldehyde (Шаблон:Chem2, which is merely a ketone with a hydrogen substituent). An aldol consisting of a 3-hydroxy ketone is called a β-hydroxy ketone, and an aldol consisting of a 3-hydroxy aldehyde is called a β-hydroxy aldehyde. The term "aldol" may refer to 3-hydroxybutanal.[1][2]

Synthesis and reactions

Файл:Isomers of generalized aldol.jpg
Isomers of generalized aldol.

Aldols are usually the product of aldol addition, i.e. the condensation of two aldehydes.[1] Stereoselective syntheses of aldols is an active area of asymmetric synthesis.

The chemistry of aldols is dominated by one reaction, dehydration:

RC(O)CH2CH(OH)R' → RC(O)CH=CHR' + H2O

Applications

When two molecules of aldehydes react to form an aldol (β-hydroxy aldehyde), the aldol usually produces secondary compounds since it is unstable.[1] Secondary compounds can be diols, unsaturated aldehydes, or alcohols.[1] The aldol 3-hydroxybutanal is a precursor to quinaldine, a precursor to the dye quinoline Yellow SS.[1]

Aldols are also used as intermediates in the synthesis of natural products and drugs.[3][4] The synthesis of Oseltamivir, an antiviral medicine used to treat the flu, involves the aldol reaction.[5]

The structural motif of aldols is often found in polyketide natural products, which can be used to manufacture antibiotics.[3]

Hydroxypivaldehyde is a rare example of a relatively robust aldol.[6]

See also

References

Шаблон:Reflist

Шаблон:Organic-chemistry-stub