Organic acid anhydride Organic acid anhydride An organic acid anhydride is an acid anhydride that is an organic compound. An acid anhydride is a compound that has two acyl groups bonded to the same oxygen atom. A common type of organic acid anhydride is a carboxylic anhydride, where the parent acid is a carboxylic acid, the formula of the anhydride being (RC(O))O. Symmetrical acid anhydrides of this type are named by replacing the word "acid" in the name of the parent carboxylic acid by the word "anhydride". Thus, (CHCO)O is called "acetic anhydride." Mixed (or unsymmetrical) acid anhydrides, such as acetic formic anhydride
Chemical formula formulas. See IUPAC nomenclature of organic chemistry and IUPAC nomenclature of inorganic chemistry 2005 for examples. In addition, linear naming systems such as International Chemical Identifier (InChI) allow a computer to construct a structural formula, and simplified molecular-input line-entry system (SMILES) allows a more human-readable ASCII input. However, all these nomenclature systems go beyond the standards of chemical formulas, and technically are chemical naming systems, not formula systems. For polymers in condensed chemical formulas, parentheses are placed around the repeating unit. For example, a hydrocarbon molecule that is described as CH(CH)CH, is a molecule with fifty repeating units. If the