organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, ortho acids are

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...

hypothetical chemical compound A hypothetical chemical compound is a chemical compound that has been conceived of, but is not known to have been synthesized, observed, or isolated (identified or shown to exist). Some hypothetical compounds cannot form at all, due to steric ef ...

s having the structure (R =

alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl group is derived from a cy ...

aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used ...

). Ortho acids themselves are unstable and cannot be isolated. However,

ortho ester In organic chemistry, an ortho ester is a functional group containing three alkoxy groups attached to one carbon atom, i.e. with the general formula . Orthoesters may be considered as products of exhaustive alkylation of unstable orthocarboxylic ...

s can be synthesized by the

Pinner reaction The Pinner reaction refers to the acid catalysed reaction of a nitrile with an alcohol to form an imino ester salt (alkyl imidate salt); this is sometimes referred to as a Pinner salt. The reaction is named after Adolf Pinner, who first described ...

, in which

nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The name of the compound is composed of a base, which includes the carbon of the , suffixed with "nitrile", so for example is called " propionitrile" (or pr ...

s react with

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 ...

s under acid catalysis: :

Historic definition

Historically the prefixes "''hypo''-", "''per''-", "''ortho''-", "''

meta- ''Meta'' (from the , '' meta'', meaning 'after' or 'beyond') is an adjective meaning 'more comprehensive' or 'transcending'. In modern nomenclature, the prefix meta can also serve as a prefix meaning self-referential, as a field of study or endea ...

''", and "''pyro''-" were used to distinguish between different

oxyacid An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce ...

s of the same element, of these ortho acid is the most highly

oxidised 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 ...

hydroxylated In chemistry, hydroxylation refers to the installation of a hydroxyl group () into an organic compound. Hydroxylations generate alcohols and phenols, which are very common functional groups. Hydroxylation confers some degree of water-solubility ...

. For example,

dehydration In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild deh ...

orthoperiodic acid Periodic acid ( ) is an oxoacid of iodine. It can exist in two forms: orthoperiodic acid, with the chemical formula , and metaperiodic acid, which has the formula . Periodic acids are colourless crystals. Periodic acid features iodine in the hig ...

gives

metaperiodic acid Periodic acid ( ) is an oxoacid of iodine. It can exist in two forms: orthoperiodic acid, with the chemical formula , and metaperiodic acid, which has the formula . Periodic acids are colourless crystals. Periodic acid features iodine in the hi ...

. Such naming conventions are now obsolete; however, various traditional names containing these prefixes have been retained in

IUPAC nomenclature IUPAC nomenclature is a set of recommendations for naming chemical compounds and for describing chemistry and biochemistry in general. The International Union of Pure and Applied Chemistry (IUPAC) is the international authority on chemical nomenc ...

, namely: *

orthosilicic acid Orthosilicic acid () is an inorganic compound with the formula . Although rarely observed, it is the key compound of silica and silicates and the precursor to other silicic acids . Silicic acids play important roles in biomineralization and tec ...

, * orthotelluric acid, *

orthophosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, w ...

, * orthoboric acid,

Hypothetical chemical compounds

orthoacetic acid Orthoacetic acid or ethane-1,1,1-triol is an hypothetical organic compound with formula or H3C-C(OH)3. It would be an ortho acid with the ethane backbone. Orthoacetic acid is believed to be impossible to isolate, since it would readily decom ...

, *

orthocarbonic acid Orthocarbonic acid, carbon hydroxide, or methanetetrol is the name given to a hypothetical compound with the chemical formula or . Its molecular structure consists of a single carbon atom bonded to four hydroxyl groups. It would be therefore a ...

, *

orthoformic acid Orthoformic acid or methanetriol is a chemical compound with the formula . In this molecule, the central carbon atom is bound to one hydrogen and three hydroxyl groups. Orthoformic acid was long held to be a hypothetical chemical compound, as ...

References

Acids Chemical nomenclature Hypothetical chemical compounds {{Acid-stub