Deltic acid or dihydroxycyclopropenone is a
chemical substance with the chemical formula C
3O(OH)
2. It can be viewed as a
ketone
In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...
and double
alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
of
cyclopropene. At room temperature, it is a stable white solid, soluble in
diethyl ether, that decomposes (sometimes explosively) between 140 °C and 180 °C, and reacts slowly with water.
Derivatives
Deltate and salts
Deltic acid is considered an
acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
because it is a particularly acidic
enediol
In organic chemistry, alkenols (shortened to enols) are a type of reactive structure or intermediate in organic chemistry that is represented as an alkene (olefin) with a hydroxyl group attached to one end of the alkene double bond (). The ter ...
, with
hydroxyl groups relatively easily losing their
proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
s (p''K''
a1 = 2.57, p''K''
a2 = 6.03), leaving behind the symmetric deltate
anion, .
The first deltate
salts (of
lithium and
potassium) were described in 1976, also by Eggerding and West. Lithium deltate Li
2C
3O
3 is a water-soluble white solid.
Like the other cyclic dianions with formula , the deltate anion has a pronounced
aromatic character which contributes to its relative stability.
Analogs
An analog of the deltate anion can be obtained by replacing the three oxygen atoms (=O or −O
−) by
cyanoimino groups (=N−C≡N or −N=C=N
−) to yield the symmetric anion .
Replacement of the three oxygen atoms by dicyanomethylene (=C(CN)
2) provides an oxidizing species that is readily reduced to a stable radical anion and dianion.
Synthesis
Deltic acid was originally obtained by
photolysis
Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by photons. It is defined as the interaction of one or more photons with one target molecule. ...
of the
ester bis(trimethylsilyl)
squarate
Squaric acid, also called quadratic acid because its four carbon atoms approximately form a square, is a diprotic organic acid with the chemical formula C4O2(OH)2.
The conjugate base of squaric acid is the hydrogensquarate anion ; and the conjug ...
, which converted into bis(trimethylsilyl) derivative. Upon irradiation with
UV light
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
, the disilyl compound decarbonylates. Decomposition of the latter by
butanol yielded deltic acid.
The acid can also be prepared by reaction of
silver squarate and
trimethylsilyl chloride.
The deltate anion has also been obtained by direct
cyclotrimerization
In organic chemistry, an alkyne trimerisation is a +2+2nbsp;cycloaddition reaction in which three alkyne units () react to form a benzene ring. The reaction requires a metal catalyst. The process is of historic interest as well as being applica ...
of
carbon monoxide at ambient conditions. Carbon monoxide dissolved in
pentane
Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the ' ...
reacted with a
uranium coordination compound
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...
yielding a deltate anion bound to two uranium atoms.
See also
*
Acetylenediol
*
Croconic acid
*
Rhodizonic acid
*
Cyclopropenone
Cyclopropenone is an organic compound with molecular formula C3H2O consisting of a cyclopropene carbon framework with a ketone functional group. It is a colorless, volatile liquid that boils near room temperature. Neat cyclopropenone polymerizes ...
References
{{reflist
Non-benzenoid aromatic carbocycles
Ketones
Oxocarbons
Cyclopropenes
Enediols