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In 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 materials, i.e., matter in its various forms that contain carbon atoms.Clay ...
, a dicarbonate, also known as a pyrocarbonate, is a compound containing the divalent
In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules.
Description
The combining capacity, or affinity of a ...
��O−(C=O)−O−(C=O)−O−or −− functional group
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the res ...
, which consists of two carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonat ...
groups sharing an oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as we ...
atom. These compounds can be viewed as double ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...
s of a hypothetical dicarbonic acid, or HO−(C=O)−O−(C=O)−OH. Two important examples are dimethyl dicarbonate
Dimethyl dicarbonate (DMDC) is a colorless liquid and a pungent odor at high concentration at room temperature. It is primarily used as a beverage preservative, processing aid, or sterilant ( INS No. 242) being highly active against typical bever ...
H3C−C2O5−CH3 and di-''tert''-butyl dicarbonate (H3C−)3C−C2O5−C(−CH3)3.
It is one of the oxocarbon anion
In chemistry, an oxocarbon anion is a negative ion consisting solely of carbon and oxygen atoms, and therefore having the general formula for some integers ''x'', ''y'', and ''n''.
The most common oxocarbon anions are carbonate, , and oxalat ...
s, consisting solely of oxygen and carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes ...
. Dicarbonate salts are apparently unstable at ambient conditions, but can be made under pressure and may have a fleeting existence in carbonate solutions.
The term "dicarbonate" is sometimes used erroneously to refer to 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 bioch ...
, the common name of the hydrogencarbonate anion or organic group the ROCO2H.
Inorganic salts
PbC2O5 can be formed at 30GPa
Grading in education is the process of applying standardized measurements for varying levels of achievements in a course. Grades can be assigned as letters (usually A through F), as a range (for example, 1 to 6), as a percentage, or as a numbe ...
and 2000K from PbCO3 and CO2. It forms white monoclinic
In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic ...
crystals, with space group
In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it ...
''P''21/''c'' and four formula units per unit cell. At 30 GPa the unit cell has a=4.771 b=8.079 c=7.070 Å and β=91.32°. The unit cell volume is 272.4 Å3 and density 7.59.
SrC2O5 is very similar to the lead compound, and also has monoclinic structure with space group ''P''21/''c'' and four formula units per unit cell. At 30 GPa the unit cell has a=4.736 b=8.175 c=7.140 Å and β=91.34°. The unit cell volume is 276.3 Å3 and density 4.61. The double Sr=O bonds have lengths of 1.22, 1.24, and 1.25 Å. The single Sr-O bonds have lengths of 1.36 and 1.41 Å. The angles subtended at the carbon atoms are slightly less than 120°, and the angle at the C-O-C is larger.
See also
*Oxalate
Oxalate (IUPAC: ethanedioate) is an anion with the formula C2O42−. This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (Na2C2O4), and several esters such as dimethyl ...
*Peroxodicarbonate
In chemistry, peroxydicarbonate (sometimes peroxodicarbonate) is a divalent anion with the chemical formula . It is one of the oxocarbon anions, which consist solely of carbon and oxygen. Its molecular structure can be viewed as two carbonate anio ...
*Pyrophosphate
In chemistry, pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a P–O–P linkage. A number of pyrophosphate salts exist, such as disodium pyrophosphate (Na2H2P2O7) and tetrasodium pyrophosphate (Na4P2O7), among o ...
*Pyrosulfate
In chemistry, disulfate or pyrosulfate is the anion with the molecular formula . Disulfate is the IUPAC name.
It has a dichromate-like structure and can be visualised as two corner-sharing SO4 tetrahedra, with a bridging oxygen atom.
In this a ...
*Tricarbonate In organic chemistry, a tricarbonate is a compound containing the divalent ��O–(C=O)–O–(C=O)–O–(C=O)–O–functional group, which consists of three carbonate groups in tandem, sharing two oxygen atoms. These compounds can be viewed as d ...
References
{{Oxides of carbon Oxyanions Carbonate esters Functional groups Dicarbonates