Deltic acid
Encyclopedia
Deltic acid or dihydroxycyclopropenone is a chemical substance
with the chemical formula C3O(OH)2. It can be viewed as a ketone
and double alcohol
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.
The synthesis of deltic acid was first described in 1975 by David Eggerding and Robert West
.
because unlike most alcohols
, the hydroxyl
groups lose their protons
(pK1 =2.57, pK2=6.03), leaving behind the symmetric deltate
anion, C3O32−.
The first deltate salts (of lithium
and potassium
) were described in 1976, also by Eggerding and West. Lihium deltate Li2C3O3 is a water-soluble white solid. Like the other cyclic dianions with formula (CO)n2−, the deltate anion has a pronounced aromatic
character which contributes to its relative stability.
bis(trimethylsilyl) squarate
, which by loss of one carbonyl
group (CO) from the ring was turned into bis(trimethylsilyl) deltate. Decomposition of the latter by butanol
yielded deltic acid.
The acid can also be prepared by reaction of silver squarate
and trimethylsilyl chloride
.
Recently the deltate anion has been obtained by direct cyclotrimerization of carbon monoxide
at ambient conditions. Carbon monoxide dissolved in pentane
reacted with a uranium
coordination compound yielding a deltate anion bound to two uranium atoms.
Chemical substance
In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. They can be solids, liquids or gases.Chemical substances are...
with the chemical formula C3O(OH)2. It can be viewed as a ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...
and double 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....
of cyclopropene
Cyclopropene
Cyclopropene is an organic compound with the formula 34. It is the simplest isolable cycloalkene. It has a triangular structure. Because the ring is highly strained, cyclopropene is both difficult to prepare and interesting to study. Like cyclopropane, the carbon ring of cyclopropene is planar...
. At room temperature, it is a stable white solid, soluble in diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...
, that decomposes (sometimes explosively) between 140°C and 180°C, and reacts slowly with water.
The synthesis of deltic acid was first described in 1975 by David Eggerding and Robert West
Robert West
Robert C. West is E. G. Rochow Professor of Chemistry Emeritus at the University of Wisconsin–Madison; Director of the Organosilicon Research Center, University of Wisconsin–Madison 1999–present; President, Silatronix, Inc...
.
Deltate and salts
Deltic acid is considered an acidAcid
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...
because unlike most alcohols
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....
, the hydroxyl
Hydroxyl
A hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...
groups lose their protons
Proton
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....
(pK1 =2.57, pK2=6.03), leaving behind the symmetric deltate
anion, C3O32−.
The first deltate salts (of lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
and potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
) were described in 1976, also by Eggerding and West. Lihium deltate Li2C3O3 is a water-soluble white solid. Like the other cyclic dianions with formula (CO)n2−, the deltate anion has a pronounced aromatic
Aromaticity
In organic chemistry, Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. The earliest use of the term was in an article by August...
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 .Synthesis
Deltic acid was originally obtained by photolysis of the esterEster
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
bis(trimethylsilyl) squarate
Squaric acid
Squaric acid, also called quadratic acid, because its four carbon atoms approximately form a square, is an organic compound with chemical formula 424....
, which by loss of one carbonyl
Carbonyl
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....
group (CO) from the ring was turned into bis(trimethylsilyl) deltate. Decomposition of the latter by butanol
Butanol
Butanol or butyl alcohol can refer to any of the four isomeric alcohols of formula C4H9OH:*n-Butanol, butan-1-ol, 1-butanol, n-butyl alcohol;*Isobutanol, 2-methylpropan-1-ol, isobutyl alcohol;...
yielded deltic acid.
The acid can also be prepared by reaction of silver squarate
Squaric acid
Squaric acid, also called quadratic acid, because its four carbon atoms approximately form a square, is an organic compound with chemical formula 424....
and trimethylsilyl chloride
Trimethylsilyl chloride
Trimethylsilyl chloride, also known as chlorotrimethylsilane is a silyl halide, with a variety of different uses in chemistry. It has the formula 3SiCl, and under standard conditions it is a colourless liquid, which is stable in the absence of water...
.
Recently the deltate anion has been obtained by direct cyclotrimerization of carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
at ambient conditions. Carbon monoxide dissolved in pentane
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 n-pentane isomer; the other two being called...
reacted with a uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
coordination compound yielding a deltate anion bound to two uranium atoms.