Ortho acid
Ortho acids are hypothetical organic compounds having the structure RC(OH)3 (R=alkyl or aryl).[1]
Ortho acids themselves are unstable and cannot be isolated. However orthoesters can be synthesized by the Pinner reaction, in which nitriles react with alcohols under acid catalysis:
- RCN + 3 R′OH → RC(OR′)3 + NH3
Historic definition
Historically the prefixes “hypo-”, “per-”, “ortho-”, “meta-”, and “pyro-” were used to distinguish between different oxyacids of the same element, of these ortho acid is the most highly oxidised or hydroxylated. For example dehydration of orthoperiodic acid gives metaperiodic acid. Such naming conventions are now obsolete, however various traditional names containing these prefixes have been retained in IUPAC nomenclature (e.g. orthosilicic acid (Si(OH)4), orthotelluric acid (Te(OH)6) and orthophosphoric acid (PO(OH3)).
References
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "ortho acids". doi:10.1351/goldbook.O04331