Oxocarbon anion
Encyclopedia
In chemistry, an oxocarbon anion is a negative ion consisting solely of carbon
and oxygen
atoms, and therefore having the general formula CxOyn− for some integers x, y, and n.
The most common oxocarbon anions are carbonate
, CO32−, and oxalate
, C2O42−. There is however a large number of stable anions in this class, including several ones that have research or industrial use. There are also many unstable anions, like CO4−, that have a fleeting existence during some chemical reactions; and many hypothetical species, like CO44−, that have been the subject of theoretical studies but have yet to be observed.
Stable oxocarbon anions form salts with a large variety of cations. Unstable anions may persist in very rarefied gaseous state, such as in interstellar cloud
s. Most oxocarbon anions have corresponding moieties
in organic chemistry
, whose compounds are usually esters. Thus, for example, the oxalate moiety [–O–(C=O–)2–O–] occurs in the ester dimethyl oxalate H3C–O–(C=O–)2–O–CH3.
s responsible for the negative electric charge
s behaves as if it were distributed over several atoms. Some of the electron pairs responsible for the covalent bond
s also behave as if they were delocalized. These phenomena are often explained as a resonance
between two or more conventional molecular structures that differ on the location of those charges and bonds. The carbonate ion, for example, is considered to have an "average" of three different structures
so that each oxygen has the same negative charge equivalent to 2/3 of one electron, and each C–O bond hs the same average valence of 4/3. This model accounts for the observed threefold symmetry of the anion.
Similarly, in a deprotonated carboxyl group –, each oxygen is often assumed to have a charge of −1/2 and each C–O bond to have valence 3/2, so the two oxygens are equivalent. The croconate anion also has fivefold symmetry, that can be explained as the superposition of five states leading to a charge of −2/5 on each oxygen. These resonances are believed to contribute to the stability of the anions.
s from a corresponding acid
CxHnOy. Carbonate CO32−, for example, can be seen as the anion of carbonic acid
H2CO3. Sometimes the "acid" is actually an alcohol
or other species; this is the case, for example, of acetylenediolate C2O22− that would yield acetylenediol
C2H2O2. However, the anion is often more stable than the acid (as is the case for carbonate); and sometimes the acid is unknown or is expected to be extremely unstable (as is the case of methanetetracarboxylate
C(COO−)4).
(oxide
of carbon) with the same composition and structure except for the negative charge. As a rule, however, these neutral oxocarbons are less stable than the corresponding anions. Thus, for example, the stable carbonate anion corresponds to the extremely unstable neutral carbon trioxide
CO3; oxalate C2O42− correspond to the even less stable 1,2-dioxetanedione
C2O4; and the stable croconate
anion C5O52− corresponds to the neutral cyclopentanepentone
C5O5, which has been detected only in trace amounts.
C6O62− can be reduced to the tetrahydroxybenzoquinone (THBQ) anion C6O64− and then to benzenehexolate
C6O66−..
CO2. The correspondence is not always well-defined since there may be several ways of performing this formal dehydration, including joining two or more anions to make an oligomer
or polymer
. Unlike neutralization, this formal dehydration sometimes yields fairly stable oxocarbons, such as mellitic anhydride
C12O9 from mellitate C12O126− via mellitic acid
C12H6O126−
, and hydrogenoxalate is known as binoxalate.
The hydrogenated anions may be stable even if the fully protonated acid is not (as is the case of bicarbonate).
anions, such as acetylide C22− and methanide C4−, could be seen as extreme cases of oxocarbon anions CxOyn−, with y equal to zero. The same could be said of oxygen-only anions such as oxide
O2−, peroxide
, O22−, and ozonide
O3−.
Several other oxocarbon anions have been detected in trace amounts, such as , a singly ionized version of rhodizonate.
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
atoms, and therefore having the general formula CxOyn− for some integers x, y, and n.
The most common oxocarbon anions are carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
, CO32−, and oxalate
Oxalate
Oxalate , is the dianion with formula C2O42− also written 22−. Either name is often used for derivatives, such as disodium oxalate, 2C2O42−, or an ester of oxalic acid Oxalate (IUPAC: ethanedioate), is the dianion with formula C2O42− also written (COO)22−. Either...
, C2O42−. There is however a large number of stable anions in this class, including several ones that have research or industrial use. There are also many unstable anions, like CO4−, that have a fleeting existence during some chemical reactions; and many hypothetical species, like CO44−, that have been the subject of theoretical studies but have yet to be observed.
Stable oxocarbon anions form salts with a large variety of cations. Unstable anions may persist in very rarefied gaseous state, such as in interstellar cloud
Interstellar cloud
Interstellar cloud is the generic name given to an accumulation of gas, plasma and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium. Depending on the density, size and temperature of a given cloud, the hydrogen in it...
s. Most oxocarbon anions have corresponding moieties
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
in organic chemistry
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...
, whose compounds are usually esters. Thus, for example, the oxalate moiety [–O–(C=O–)2–O–] occurs in the ester dimethyl oxalate H3C–O–(C=O–)2–O–CH3.
Distributed charges and resonances
In many oxocarbon anions each of the extra electronElectron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s responsible for the negative electric charge
Electric charge
Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...
s behaves as if it were distributed over several atoms. Some of the electron pairs responsible for the covalent bond
Covalent bond
A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....
s also behave as if they were delocalized. These phenomena are often explained as a resonance
Resonance (chemistry)
In chemistry, resonance or mesomerism is a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by one single Lewis formula...
between two or more conventional molecular structures that differ on the location of those charges and bonds. The carbonate ion, for example, is considered to have an "average" of three different structures
so that each oxygen has the same negative charge equivalent to 2/3 of one electron, and each C–O bond hs the same average valence of 4/3. This model accounts for the observed threefold symmetry of the anion.
Similarly, in a deprotonated carboxyl group –, each oxygen is often assumed to have a charge of −1/2 and each C–O bond to have valence 3/2, so the two oxygens are equivalent. The croconate anion also has fivefold symmetry, that can be explained as the superposition of five states leading to a charge of −2/5 on each oxygen. These resonances are believed to contribute to the stability of the anions.
Oxocarbon acids
An oxocarbon anion CxOyn− can be seen as the result of removing all protonProton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s from a corresponding acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
CxHnOy. Carbonate CO32−, for example, can be seen as the anion of carbonic acid
Carbonic acid
Carbonic acid is the inorganic compound with the formula H2CO3 . It is also a name sometimes given to solutions of carbon dioxide in water, because such solutions contain small amounts of H2CO3. Carbonic acid forms two kinds of salts, the carbonates and the bicarbonates...
H2CO3. Sometimes the "acid" is actually an alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
or other species; this is the case, for example, of acetylenediolate C2O22− that would yield acetylenediol
Acetylenediol
Acetylenediol, or ethynediol, is a chemical substance with formula HO-C≡C-OH. It is the diol of acetylene. Acetylenediol is unstable in the condensed phase, although its tautomer glyoxal H2H is well known.-Detection:...
C2H2O2. However, the anion is often more stable than the acid (as is the case for carbonate); and sometimes the acid is unknown or is expected to be extremely unstable (as is the case of methanetetracarboxylate
Methanetetracarboxylate
In chemistry, methanetetracarboxylate is a tetravalent anion with formula C5O84− or C4. It has four carboxylate groups attached to a central carbon atom; so it has the same carbon backbone as neopentane...
C(COO−)4).
Neutralized species
Every oxocarbon anion CxOyn− can be matched in principle to the electrically neutral (or oxidized) variant CxOy, an oxocarbonOxocarbon
An oxocarbon or oxide of carbon is an inorganic compound consisting only of carbon and oxygen.The simplest and most common oxocarbons are carbon monoxide and carbon dioxide...
(oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....
of carbon) with the same composition and structure except for the negative charge. As a rule, however, these neutral oxocarbons are less stable than the corresponding anions. Thus, for example, the stable carbonate anion corresponds to the extremely unstable neutral carbon trioxide
Carbon trioxide
Carbon trioxide is an unstable oxide of carbon . Three possible isomers of carbon trioxide, denoted Cs, D3h, and C2v, have been most studied by theoretical methods, and the C2v state has been shown to be the ground state of the molecule.Carbon trioxide should not be confused with the stable...
CO3; oxalate C2O42− correspond to the even less stable 1,2-dioxetanedione
1,2-Dioxetanedione
The chemical compound 1,2-dioxetanedione, or 1,2-dioxacyclobutane-3,4-dione, often called peroxyacid ester, is an unstable oxide of carbon with formula C2O4...
C2O4; and the stable croconate
Croconic acid
Croconic acid or 4,5-dihydroxycyclopentenetrione is a chemical compound with formula C5H2O5 or 32. It has a cyclopentene backbone with two hydroxyl groups adjacent to the double bond and three ketone groups on the remaining carbon atoms...
anion C5O52− corresponds to the neutral cyclopentanepentone
Cyclopentanepentone
Cyclopentanepentone, also known as leuconic acid, is a hypothetical organic compound with formula C5O5, the fivefold ketone of cyclopentane...
C5O5, which has been detected only in trace amounts.
Reduced variants
Conversely, some oxocarbon anions can be reduced to yield other anions with the same structural formula but greater negative charge. Thus rhodizonateRhodizonic acid
Rhodizonic acid is a chemical compound with formula C6H2O6 or 42. It can be seen as a two-fold alcohol and four-fold ketone of cyclohexene, more precisely 5,6-dihydroxycyclohex-5-ene-1,2,3,4-tetrone....
C6O62− can be reduced to the tetrahydroxybenzoquinone (THBQ) anion C6O64− and then to benzenehexolate
Benzenehexol
Benzenehexol, also called hexahydroxybenzene, is an organic compound with formula C6H6O6 or C66. It is a six-fold alcohol of benzene. The product is also erroneously called hexaphenol, but this name has been used also for other substances....
C6O66−..
Acid anhydrides
An oxocarbon anion CxOyn− can also be associated with the anhydride of the corresponding acid. The latter would be another oxocarbon with formula CxOy−n/2; namely, the acid minus n/2 water molecules H2O. The standard example is the connection between carbonate CO32− and carbon dioxideCarbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
CO2. The correspondence is not always well-defined since there may be several ways of performing this formal dehydration, including joining two or more anions to make an oligomer
Oligomer
In chemistry, an oligomer is a molecule that consists of a few monomer units , in contrast to a polymer that, at least in principle, consists of an unlimited number of monomers. Dimers, trimers, and tetramers are oligomers. Many oils are oligomeric, such as liquid paraffin...
or polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
. Unlike neutralization, this formal dehydration sometimes yields fairly stable oxocarbons, such as mellitic anhydride
Mellitic anhydride
Mellitic anhydride, anhydride of mellitic acid, is organic compound with formula C12O9.Mellitic anhydride is oxide of carbon , like CO2, CO, and C3O2. It is white sublimable solid, apparently obtained by Liebig and Wöhler in 1830 in their study of mellite , who assigned it the formula C4O3. The...
C12O9 from mellitate C12O126− via mellitic acid
Mellitic acid
Mellitic acid, also called graphitic acid or benzenehexacarboxylic acid, is an acid first discovered in 1799 by M. H. Klaproth in the mineral mellite , which is the aluminium salt of the acid.- Preparation :...
C12H6O126−
Hydrogenated anions
For each oxocarbon anion CxOyn− there are in principle n−1 partially hydrogenated anions with formulas HkCxOy(n−k)−, where k ranges from 1 to n−1. These anions are generally indicated by the prefixes "hydrogen"-, "dihydrogen"-, "trihydrogen"-, etc. Some of them, however, have special names: hydrogencarbonate is commonly called bicarbonateBicarbonate
In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...
, and hydrogenoxalate is known as binoxalate.
The hydrogenated anions may be stable even if the fully protonated acid is not (as is the case of bicarbonate).
Extreme cases
The carbideCarbide
In chemistry, a carbide is a compound composed of carbon and a less electronegative element. Carbides can be generally classified by chemical bonding type as follows: salt-like, covalent compounds, interstitial compounds, and "intermediate" transition metal carbides...
anions, such as acetylide C22− and methanide C4−, could be seen as extreme cases of oxocarbon anions CxOyn−, with y equal to zero. The same could be said of oxygen-only anions such as oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....
O2−, peroxide
Peroxide
A peroxide is a compound containing an oxygen–oxygen single bond or the peroxide anion .The O−O group is called the peroxide group or peroxo group. In contrast to oxide ions, the oxygen atoms in the peroxide ion have an oxidation state of −1.The simplest stable peroxide is hydrogen peroxide...
, O22−, and ozonide
Ozonide
Ozonide is an unstable, reactive polyatomic anion O3−, derived from ozone, or an organic compound similar to organic peroxide formed by a reaction of ozone with an unsaturated compound.-Inorganic ozonides:...
O3−.
List of oxocarbon anions
Here is an incomplete list of the known or conjectured oxocarbon anions
Diagram
Formula
Name
Acid
Anhydride
Neutralized
carbonate CarbonateIn chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
CH2O3 Carbonic acidCarbonic acid is the inorganic compound with the formula H2CO3 . It is also a name sometimes given to solutions of carbon dioxide in water, because such solutions contain small amounts of H2CO3. Carbonic acid forms two kinds of salts, the carbonates and the bicarbonates...
CO2 Carbon dioxideCarbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
CO3 Carbon trioxideCarbon trioxide is an unstable oxide of carbon . Three possible isomers of carbon trioxide, denoted Cs, D3h, and C2v, have been most studied by theoretical methods, and the C2v state has been shown to be the ground state of the molecule.Carbon trioxide should not be confused with the stable...
peroxocarbonate PeroxocarbonateIn chemistry, peroxocarbonate is a divalent anion with formula CO42−. It is an oxocarbon anion that consists solely of carbon and oxygen. It would be the anion of an hypothetical peroxocarbonic acid HO–CO–O–OH....
CO3 Carbon trioxideCarbon trioxide is an unstable oxide of carbon . Three possible isomers of carbon trioxide, denoted Cs, D3h, and C2v, have been most studied by theoretical methods, and the C2v state has been shown to be the ground state of the molecule.Carbon trioxide should not be confused with the stable...
CO4 Carbon tetroxideCarbon tetroxide is a highly unstable oxide of carbon with formula . It was proposed as an intermediate in the O-atom exchange between carbon dioxide and oxygen at high temperatures....
orthocarbonate
C(OH)4 orthocarbonic acid Orthocarbonic acidOrthocarbonic acid or methanetetraol is the name given to a hypothetical compound with the chemical formula H4CO4 or C4. Its molecular structure consists of a single carbon atom bonded to four hydroxyl groups. It would be therefore a fourfold alcohol...
CO2 Carbon dioxideCarbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
CO4 Carbon tetroxideCarbon tetroxide is a highly unstable oxide of carbon with formula . It was proposed as an intermediate in the O-atom exchange between carbon dioxide and oxygen at high temperatures....
acetylenediolate
C2H2O2 acetylenediol AcetylenediolAcetylenediol, or ethynediol, is a chemical substance with formula HO-C≡C-OH. It is the diol of acetylene. Acetylenediol is unstable in the condensed phase, although its tautomer glyoxal H2H is well known.-Detection:...
C2O2 Ethylene dioneEthylene dione or ethylenedione, also called dicarbon dioxide, ethenedione, or ethene 1,2-dione, is the name given to a hypothetical chemical compound with the formula C2O2 or O=C=C=O. It would be an oxide of carbon , specifically a dimer of carbon monoxide...
oxalate OxalateOxalate , is the dianion with formula C2O42− also written 22−. Either name is often used for derivatives, such as disodium oxalate, 2C2O42−, or an ester of oxalic acid Oxalate (IUPAC: ethanedioate), is the dianion with formula C2O42− also written (COO)22−. Either...
C2H2O4 Oxalic acidOxalic acid is an organic compound with the formula H2C2O4. This colourless solid is a dicarboxylic acid. In terms of acid strength, it is about 3,000 times stronger than acetic acid. Oxalic acid is a reducing agent and its conjugate base, known as oxalate , is a chelating agent for metal cations...
C2O3 Oxalic anhydrideOxalic anhydride or ethanedioic anhydride, also called oxiranedione, is a hypothetical organic compound with the formula C2O3, which can be viewed as the anhydride of oxalic acid or the two-fold ketone of ethylene oxide. It is an oxide of carbon .The simple compound apparently has yet to be...
, C4O6Dioxane tetraketoneDioxane tetraketone is an organic compound with the formula C4O6. It is an oxide of carbon , which can be viewed as the fourfold ketone of dioxane...
C2O4 1,2-DioxetanedioneThe chemical compound 1,2-dioxetanedione, or 1,2-dioxacyclobutane-3,4-dione, often called peroxyacid ester, is an unstable oxide of carbon with formula C2O4...
dicarbonate DicarbonateIn organic chemistry, a dicarbonate is a compound containing the divalent [-O--O--O-] or 2• functional group, which consists of two carbonate groups sharing an oxygen atom. These compounds can be viewed as double esters of a hypothetical dicarbonic acid, or HO--O--OH...
C2H2O5
C2O4 1,3-DioxetanedioneThe chemical compound 1,3-dioxetanedione, or 1,3-dioxacyclobutane-2,4-dione is a hypothetical oxide of carbon with formula C2O4. It can be considered a cyclic dimer of carbon dioxide or as a double ketone of 1,3-dioxetane ....
peroxodicarbonate PeroxodicarbonateIn chemistry, peroxodicarbonate is a divalent anion with formula C2O62−. It is one of the oxocarbon anions, that consist solely of carbon and oxygen...
deltate Deltic acidDeltic acid or dihydroxycyclopropenone is a chemical substance with the chemical formula C3O2. It can be viewed as a ketone and double alcohol of cyclopropene...
C3O(OH)2 Deltic acidDeltic acid or dihydroxycyclopropenone is a chemical substance with the chemical formula C3O2. It can be viewed as a ketone and double alcohol of cyclopropene...
(CO)3
mesoxalate
C3H2O5 Mesoxalic acidMesoxalic acid, also called oxomalonic acid or ketomalonic acid, is an organic compound with formula C3H2O5 or HO-3-OH.Mesoxalic acid is both a dicarboxylic acid and a ketonic acid. It readily loses two protons to yield the divalent anion C3O52−, called mesoxalate, oxomalonate, or ...
acetylenedicarboxylate AcetylenedicarboxylateAcetylenedicarboxylate is a divalent anion with formula C4O42− or [O2C–C≡C–CO2]2−; or any salt or ester thereof. The anion can be derived from acetylenedicarboxylic acid C4H2O4 by the loss of two protons...
C4H2O4 Acetylenedicarboxylic acidAcetylenedicarboxylic acid or butynedioic acid is an organic compound with the formula C4H2O4 or HO2C-C≡C-CO2H. It is a crystalline solid that is soluble in diethyl ether....
squarate
C4O2(OH)2 Squaric acidSquaric acid, also called quadratic acid, because its four carbon atoms approximately form a square, is an organic compound with chemical formula 424....
(CO)4
dioxosuccinate
C4H2O6 Dioxosuccinic acidDioxosuccinic acid or dioxobutanedioic acid is an organic compound with formula C4H2O6 or HO-4-OH.Removal of two protons from the molecule would yield the dioxosuccinate anion, C4O62− or 2−. This is one of the oxocarbon anions, which consist solely of carbon and oxygen...
croconate
C5O3(OH)2 Croconic acidCroconic acid or 4,5-dihydroxycyclopentenetrione is a chemical compound with formula C5H2O5 or 32. It has a cyclopentene backbone with two hydroxyl groups adjacent to the double bond and three ketone groups on the remaining carbon atoms...
(CO)5 CyclopentanepentoneCyclopentanepentone, also known as leuconic acid, is a hypothetical organic compound with formula C5O5, the fivefold ketone of cyclopentane...
methanetetracarboxylate MethanetetracarboxylateIn chemistry, methanetetracarboxylate is a tetravalent anion with formula C5O84− or C4. It has four carboxylate groups attached to a central carbon atom; so it has the same carbon backbone as neopentane...
C5H4O8
rhodizonate
(CO)4(COH)2 Rhodizonic acidRhodizonic acid is a chemical compound with formula C6H2O6 or 42. It can be seen as a two-fold alcohol and four-fold ketone of cyclohexene, more precisely 5,6-dihydroxycyclohex-5-ene-1,2,3,4-tetrone....
(CO)6 CyclohexanehexoneCyclohexanehexone, also known as hexaketocyclohexane and triquinoyl, is a organic compound with formula C6O6, the sixfold ketone of cyclohexane...
benzoquinonetetraolate; THBQ anion
(CO)2(COH)4 THBQ
(CO)6 CyclohexanehexoneCyclohexanehexone, also known as hexaketocyclohexane and triquinoyl, is a organic compound with formula C6O6, the sixfold ketone of cyclohexane...
benzenehexolate
C6(OH)6 benzenehexol BenzenehexolBenzenehexol, also called hexahydroxybenzene, is an organic compound with formula C6H6O6 or C66. It is a six-fold alcohol of benzene. The product is also erroneously called hexaphenol, but this name has been used also for other substances....
(CO)6 CyclohexanehexoneCyclohexanehexone, also known as hexaketocyclohexane and triquinoyl, is a organic compound with formula C6O6, the sixfold ketone of cyclohexane...
ethylenetetracarboxylate
C6H4O8 Ethylenetetracarboxylic acidEthylenetetracarboxylic acid is an organic compound with formula , or 2C=C2.By removal of four protons, the acid yields the anion , ethylenetetracarboxylate, which is one of the oxocarbon anions Ethylenetetracarboxylic acid is an organic compound with formula , or (HO(OC)-)2C=C(-(CO)OH)2.By removal...
C6O6 Ethylenetetracarboxylic dianhydrideEthylenetetracarboxylic dianhydride is a chemical compound with formula , that can be seen as the twofold anhydride of ethylenetetracarboxylic acid . Its molecular backbone consists of two five-atom maleic anhydride rings, each containing one oxygen atom and four carbon atoms, sharing a pair of...
furantetracarboxylate
C8H4O9 Furantetracarboxylic acidIn chemistry, furantetracarboxylic acid is an organic compound with formula , or 4, which can be viewed as deriving from furan through replacement of the four hydrogen atoms by carboxyl functional groups -OH....
benzoquinonetetracarboxylate
mellitate
C6(COOH)6 Mellitic acidMellitic acid, also called graphitic acid or benzenehexacarboxylic acid, is an acid first discovered in 1799 by M. H. Klaproth in the mineral mellite , which is the aluminium salt of the acid.- Preparation :...
C6(COC)3 Mellitic anhydrideMellitic anhydride, anhydride of mellitic acid, is organic compound with formula C12O9.Mellitic anhydride is oxide of carbon , like CO2, CO, and C3O2. It is white sublimable solid, apparently obtained by Liebig and Wöhler in 1830 in their study of mellite , who assigned it the formula C4O3. The...
Several other oxocarbon anions have been detected in trace amounts, such as , a singly ionized version of rhodizonate.