chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

, an imidic acid is any molecule that contains the -C(=NH)-OH

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest ...

. It is the

tautomer Tautomers () are structural isomers (constitutional isomers) of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hydr ...

of an

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is ...

and the

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

of an

oxime In organic chemistry, an oxime is a organic compound belonging to the imines, with the general formula , where R is an organic side-chain and R’ may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted ...

. The term "

imino acid In organic chemistry, an imino acid is any molecule that contains both imine (>C=NH) and carboxyl (-C(=O)-OH) functional groups. Imino acids are structurally related to amino acids, which have amino group instead of imine—a difference of si ...

" is an obsolete term for this group that should not be used in this context because it has a different molecular structure.{{GoldBookRef , file=I02959 , title=Imino acids , accessdate=2012-04-02 Imidic acids can be formed by metal-catalyzed dehydrogenation of geminal

amino alcohol In organic chemistry, alkanolamines are organic compounds that contain both hydroxyl () and amino (, , and ) functional groups on an alkane backbone. The term alkanolamine is a broad class term that is sometimes used as a subclassification. Meth ...

s. For example,

methanolamine Aminomethanol is the amino alcohol with the chemical formula of H2NCH2OH. With an amino group and an alcohol group on the same carbon atom, the compound is also an hemiaminal. In aqueous solution, methanolamine exists in equilibrium with formal ...

, the parent compound of the amino alcohols, can be dehydrogenated to methanimidic acid, the parent compound of the imidic acids. :H₂NCH₂OH → HNCHOH + H₂ (tautomer of

formamide Formamide is an amide derived from formic acid. It is a colorless liquid which is miscible with water and has an ammonia-like odor. It is chemical feedstock for the manufacture of sulfa drugs and other pharmaceuticals, herbicides and pesticide ...

) Geminal amino alcohols with side chains similarly form imidic acids with the same side chains: :H₂NCHROH → HNCROH + H₂ Another way to form imidic acids is the reaction of carboxylic acids with

azanone Nitroxyl (common name) or azanone (IUPAC name) is the chemical compound HNO. It is well known in the gas phase. Nitroxyl can be formed as a short-lived intermediate in the solution phase. The conjugate base, NO−, nitroxide anion, is the redox re ...

. For example, the reaction for

carbamic acid Carbamic acid, which might also be called aminoformic acid or aminocarboxylic acid, is the chemical compound with the formula . It can be obtained by the reaction of ammonia and carbon dioxide at very low temperatures, which also yields an equ ...

: :H₂NCOOH + HNO → H₂NCNHOH + O₂ (tautomer of

urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important r ...

) And the general reaction for substituted imidic acids: :RCOOH + R'NO → RCNR'OH + O₂ Another mechanism is the reaction of carboxylic acids with

diazene Diimide, also called diazene or diimine, is a compound having the formula (NH)2. It exists as two geometric isomers, ''E'' (''trans'') and ''Z'' (''cis''). The term diazene is more common for organic derivatives of diimide. Thus, azobenzene is ...

or other

azo compounds Azo compounds are organic compounds bearing the functional group diazenyl (, in which R and R′ can be either aryl or alkyl groups). IUPAC defines azo compounds as: "Derivatives of diazene (diimide), , wherein both hydrogens are substituted ...

, forming

. :RCOOH + HNNH → RCNHOH + HNO Imidic acids tautomerize to

amides In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is ...

by a hydrogen shift from the oxygen to the nitrogen atom. Amides are more stable in an environment with oxygen or water, whereas imidic acids dominate the equilibrium in solution with ammonia or methane. :HNCHOH ⇌ HCONH₂ :RNCR'OH ⇌ R'CONHR

References

Amides Functional groups

See also

References