Acetylenediol
Encyclopedia
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
H(C=O)2H is well known.
in a solid argon
matrix
at 10 kelvin (-263.2 °C).
s) are formally derived from ethynediol by loss of two hydrogen ions
, but they are not normally generated in that way.
The typical synthesis route for these salts is the reduction of carbon monoxide. Potassium acetylenediolate K2C2O2 was first obtained by Liebig
in 1834, from the reaction of carbon monoxide
with metallic potassium
; but for a long time the product was assumed to be "potassium carbonyl" KCO. Over the next 130 years were described the "carbonyls" of sodium
(Johannis, 1893), barium
(Gunz and Mentrel, 1903), strontium
(Roederer, 1906), and lithium
, rubidium
, and caesium
(Pearson, 1933). The reaction was eventually shown to yield a mixture of the potassium acetylenediolate and potassium benzenehexolate .
The true structure of these salts was clarified only in 1963 by Werner Büchner and E. Weiss.
Acetylenediolates can also be prepared by the rapid reaction of CO and a solution of the corresponding metal in liquid ammonia
at low temperature. Potassium acetylenediolate is a pale yellow solid that reacts explosively with air, halogens, halogenated hydrocarbons, alcohols, water, and any substance which possesses an acidic hydrogen.
Acetylenediolate and related anions such as deltate
and squarate have been obtained from carbon monoxide under mild conditions by reductive coupling of CO ligands in organouranium complexes
.
s diisopropoxyethyne ((CH3)2CH)-O-C≡C-O-(CH(CH3)2) and di-tert-butoxyethyne ((CH3)3C)-O-C≡C-O-(C(CH3)3).
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 formula HO-C≡C-OH. It is the diol
Diol
A diol or glycol is a chemical compound containing two hydroxyl groups A geminal diol has two hydroxyl groups bonded to the same atom...
of acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...
. Acetylenediol is unstable in the condensed phase, although its tautomer glyoxal
Glyoxal
Glyoxal is an organic compound with the formula OCHCHO. This yellow colored liquid is the smallest dialdehyde . Its tautomer acetylenediol is unstable.-Production:...
H(C=O)2H is well known.
Detection
Acetylenediol was first observed in 1986 by J. K. Terlouw and others in gas-phase by mass spectrometry. In 1995, the compound was obtained by Günther Maier and Christine Rohr through photolysis of squaric acidSquaric acid
Squaric acid, also called quadratic acid, because its four carbon atoms approximately form a square, is an organic compound with chemical formula 424....
in a solid argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...
matrix
Matrix Isolation
Matrix isolation is an experimental technique used in chemistry and physics which generally involves a material being trapped within an unreactive matrix. A host matrix is a continuous solid phase in which guest particles are embedded. The guest is said to be isolated within the host matrix...
at 10 kelvin (-263.2 °C).
Alkoxide derivatives
Although the diol has only fleeting existence in concentrated form, salts of the acetylenediolate (ethynediolate) dianion (O-C≡C-O)2− are well known. These organometallic compounds (specifically, alkoxideAlkoxide
An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO−, where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands...
s) are formally derived from ethynediol by loss of two hydrogen ions
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....
, but they are not normally generated in that way.
The typical synthesis route for these salts is the reduction of carbon monoxide. Potassium acetylenediolate K2C2O2 was first obtained by Liebig
Justus von Liebig
Justus von Liebig was a German chemist who made major contributions to agricultural and biological chemistry, and worked on the organization of organic chemistry. As a professor, he devised the modern laboratory-oriented teaching method, and for such innovations, he is regarded as one of the...
in 1834, from the reaction 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...
with metallic 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...
; but for a long time the product was assumed to be "potassium carbonyl" KCO. Over the next 130 years were described the "carbonyls" of sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
(Johannis, 1893), barium
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
(Gunz and Mentrel, 1903), strontium
Strontium
Strontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
(Roederer, 1906), and 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...
, rubidium
Rubidium
Rubidium is a chemical element with the symbol Rb and atomic number 37. Rubidium is a soft, silvery-white metallic element of the alkali metal group. Its atomic mass is 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other elements in group 1, such as very rapid...
, and caesium
Caesium
Caesium or cesium is the chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C , which makes it one of only five elemental metals that are liquid at room temperature...
(Pearson, 1933). The reaction was eventually shown to yield a mixture of the potassium acetylenediolate and potassium benzenehexolate .
The true structure of these salts was clarified only in 1963 by Werner Büchner and E. Weiss.
Acetylenediolates can also be prepared by the rapid reaction of CO and a solution of the corresponding metal in liquid ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
at low temperature. Potassium acetylenediolate is a pale yellow solid that reacts explosively with air, halogens, halogenated hydrocarbons, alcohols, water, and any substance which possesses an acidic hydrogen.
Coordination complexes
Acetylenediol can form coordination compounds, such as [TaH(HOC≡COH)(dmpe)2Cl]+Cl− where dmpe is bis(1,2-dimethylphosphino)ethane.Acetylenediolate and related anions such as deltate
Deltic acid
Deltic acid or dihydroxycyclopropenone is a chemical substance with the chemical formula C3O2. It can be viewed as a ketone and double alcohol of cyclopropene...
and squarate have been obtained from carbon monoxide under mild conditions by reductive coupling of CO ligands in organouranium complexes
Organouranium chemistry
Organouranium chemistry is the science exploring the properties, structure and reactivity of organouranium compounds, which are organometallic compounds containing a carbon to uranium chemical bond...
.
Other derivatives
Although again not derived from acetylenediol, a variety of structurally related compounds are known. Examples include the dietherEther
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...
s diisopropoxyethyne ((CH3)2CH)-O-C≡C-O-(CH(CH3)2) and di-tert-butoxyethyne ((CH3)3C)-O-C≡C-O-(C(CH3)3).