Hydrogenoxalate or hydrogen oxalate ''(IUPAC name: 2-Hydroxy-2-oxoacetate)'' is an
anion
An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
with
chemical formula
A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...
or , derived from
oxalic acid by the loss of a single
proton
A proton is a stable subatomic particle, symbol , Hydron (chemistry), H+, or 1H+ with a positive electric charge of +1 ''e'' (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an e ...
; or, alternatively, from the
oxalate anion by addition of a proton. The name is also used for any
salt
In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...
containing this anion. Especially in older literature, hydrogenoxalates may also be referred to as bioxalates, acid oxalates, or monobasic oxalates. Hydrogenoxalate is
amphoteric, in that it can react both as an acid or a base.
Well characterized salts include
sodium hydrogenoxalate (),
potassium hydrogenoxalate (), ammonium hydrogenoxalate (), rubidium hydrogenoxalate () and dimethylammonium hydrogenoxalate ().
Structure
Most hydrogenoxalate salts are
hydrated. For example, potassium hydrogen oxalate crystallizes as . These materials exhibit extended structures resulting from extensive hydrogen bonding and anion-cation interactions. The hydrates dehydrate upon heating:
:
Proton transfer in hydrogen oxalates has been studied.
See also
*
Bicarbonate
In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula .
Bicarbonate serves a crucial bioche ...
References
{{Authority control
Carboxylate anions