Deltic acid

Deltic acid
IUPAC name 2,3-dihydroxycycloprop-2-en-1-one
Identifiers
CAS number	54826-91-4
PubChem	11679790
ChemSpider	9854518
Jmol-3D images	Image 1
SMILES O=C1C(/O)=C1/O
InChI InChI=1/C3H2O3/c4-1-2(5)3(1)6/h4-5H Key: SPXGBDTUWODGLI-UHFFFAOYAW
Properties
Molecular formula	C3H2O3
Molar mass	86.05 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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.^[1]

The synthesis of deltic acid was first described in 1975 by David Eggerding and Robert West.^[2]

Derivatives

Deltate and salts

Deltic acid is considered an acid 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.^[1] Like the other cyclic dianions with formula (CO)_n²⁻, the deltate anion has a pronounced aromatic character which contributes to its relative stability.^[1]

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 C₃O₃(NCN)2−
3.^[3]

Synthesis

Deltic acid was originally obtained by photolysis of the ester 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.^[2]

The acid can also be prepared by reaction of silver squarate and trimethylsilyl chloride.^[1][4]

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.^[5]

See also

• Acetylenediol
• Croconic acid
• Rhodizonic acid

References

1. ^ ^{a b c d} David Eggerding and Robert West (1976), Synthesis and properties of deltic acid (dihydroxycyclopropenone) and the deltate ion. J. American Chemical Society, volume 98, p, 3641–3644. doi:10.1021/ja00428a043.
2. ^ ^{a b} David Eggerding, Robert West (1975), Synthesis of dihydroxycyclopropenone (deltic Acid). J. American Chemical Society, volume 97, issue 1, pp 207–208. doi:10.1021/ja00834a047.
3. ^ Johannes Beck and Petra Krieger-Beck (2006), Crystal structure of 1,2-bis(cyanoimino)-3-triethylammonio-cyclopropenylide. Analytical Sciences, volume 22, page x239. doi:10.2116/analscix.22.x239.
4. ^ M. T. Reetz, G. Neumeier, and M. Kaschube (1975), Thermische umlagerung von quadratsäure-bis(trimethylsilyl)ester. Tetrahedron Letters, page 1295. doi:10.1016/S0040-4039(00)72653-0.
5. ^ Owen T. Summerscales, F. Geoffrey N. Cloke, Peter B. Hitchcock, Jennifer C. Green, Nilay Hazari (2006), Reductive cyclotrimerization of carbon monoxide to the deltate dianion by an organometallic uranium complex. Science, volume 311, issue 5762 (10 February 2006), pp. 829 - 831. doi:10.1126/science.1121784.