2892-51-5 Usage
Chemical Properties
Squaric acid (3,4-dihydroxycyclobut-3-ene-1,2-dione), also known as quadratic acid, has the fascinating structure, and is a vinylogous carboxylic acid. The parent compound is a white,crystalline powder which melts at~300℃. It is highly acidic (pKa 1.5 for the first proton and 3.4 for the second) due to resonance stabilization of the anion and exhibits IR resonances indicative of strong hydrogen bonding [2326cm-1 (OH),1818 cm-1 (C=O), and 1639cm-1 (C=C)].The UV absorption spectrum suggests that the acid is essentially completely ionized. Squaric acid is freely soluble in water but has poor solubility in many organic solvents.Solutions give an intense purple color with iron(III) chloride, and are also known to decolorize bromine water, cerium(IV) nitrate, and permanganate solutions.As the carbonyl groups are similar to those of carboxylic acids rather than those of ketones, squaric acid does not react in the phenylhydrazine test.The squarate dianion is thought to be completely symmetrical (unlike squaric acid itself), with all C-C and C-O bond lengths being, respectively, identical, as the negative charges are equally distributed between allthe oxygen atoms.The IR spectrum of dipotassium squarate (dipotassium 3,4-dioxocy-clobut-1-ene-1,2-diolate) differs greatly from that of squaric acid, with the loss of the car-bonyl (C=O) and alkene(C=C) absorptions seen in the protonated form, and supportsthe proposed symmetrical structure.
Uses
Different sources of media describe the Uses of 2892-51-5 differently. You can refer to the following data:
1. Squaric acid used as intermediate for squaraine dyes and heterocycles. Squaric acid is an immunotherapy used to treat common warts. This treatment is non-toxic, and easy to use. The treatment activated your immune system to combat the warts and therefore it may cause an allergic reaction , similar to poison oak. This reaction can be managed with a topical cortisone cream. Blistering and lightening of the skin may occur, but rarely.Squaric acid derivatives – synthetic targets for ring expansion reactions
2. 3,4-Dihydroxy-3-cyclobutene-1,2-dione is used to produce diethoxy-cyclobutenedione by heating, pharmaceutical intermediates, squarylium dyes, and photoconducting squaraines; The dibutylester is used as a contact sensitizer in the treatment of alopecia and warts.
3. 3,4-Dihydroxy-3-cyclobutene-1,2-dione can be used:In fluorescence detection in immunoassays, hybridization assays, enzymatic reactions, and other analytical procedures.To form diffraction quality crystals. To synthesize a squarate dianion, which is used as a building block to create uncharged polymeric networks. These ordered structures are used in catalysis, nonlinear optics, electrical conductivity, molecular recognition, and molecular sieves.
Definition
ChEBI: A carbon oxoacid that consists of 1,2-diketocyclobut-3-ene bearing two enolic hydroxy substituents at positions 3 and 4.
Synthesis Reference(s)
Journal of the American Chemical Society, 88, p. 1533, 1966 DOI: 10.1021/ja00959a040Tetrahedron Letters, 18, p. 4437, 1977
General Description
3,4-dihydroxy-3-cyclobutene-1,2 dione, commonly known as squaric acid, is widely used in bioorganic and medicinal chemistry. It is an inhibitor of glyoxylase, semiqauric acid, pyruvate dehrogenase, and transketolase. It is used as a replacement for phosphate in a peptide-based ligand for an SH2 domain. Its derivatives are high-affinity ligands for excitatory amino acid receptors. These derivatives are also used as dyes for fluorescence detection of small biological molecules.
Biotechnological Applications
squaric acid is widely used in bioorganic and medicinal chemistry. It is an inhibitor of glyoxylase, semiqauric acid, pyruvate dehrogenase, and transketolase. It is used as a replacement for phosphate in a peptide-based ligand for an SH2 domain. Its derivatives are high-affinity ligands for excitatory amino acid receptors. These derivatives are also used as dyes for fluorescence detection of small biological molecules.squaric acid can be used:In fluorescence detection in immunoassays, hybridization assays, enzymatic reactions, and other analytical procedures.To form diffraction quality crystals.To synthesize a squarate dianion, which is used as a building block to create uncharged polymeric networks. These ordered structures are used in catalysis, nonlinear optics, electrical conductivity, molecular recognition, and molecular sieves.
Purification Methods
Purify squaric acid by recrystallisation from H2O — this is quite simple because the acid is ~ 7% soluble in boiling H2O and only 2% at room temperature. It is not soluble in Me2CO or Et2O; hence it can be rinsed with these solvents and dried in air or a vacuum. It is not hygroscopic and gives an intense purple colour with FeCl3. It has IR max at 1820 (C=O) and 1640 (C=C) cm-1, and UV max at 269.5nm ( 37K M-1cm -1). [Cohn et al. J Am Chem Soc 81 3480 1959, Park et al. J Am Chem Soc 84 2919 1962] See also pKa values of 0.59 ±0.09 and 3.48 ±0.023 [Scwartz & Howard J Phys Chem 74 4374 1970]. [Schmidt & Reid Synthesis 869 1978, Beilstein 8 IV 2701.]
Check Digit Verification of cas no
The CAS Registry Mumber 2892-51-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,8,9 and 2 respectively; the second part has 2 digits, 5 and 1 respectively.
Calculate Digit Verification of CAS Registry Number 2892-51:
(6*2)+(5*8)+(4*9)+(3*2)+(2*5)+(1*1)=105
105 % 10 = 5
So 2892-51-5 is a valid CAS Registry Number.
InChI:InChI=1/C4H2O4/c5-1-2(6)4(8)3(1)7/h1,5H
2892-51-5Relevant articles and documents
MECHANISMS AND INTERMEDIATES FOR SQUARIC ACID SYNTHESIS FROM HEXACHLOROBUTADIENE AND MORPHOLINE
Paine, Anthony James
, p. 135 - 138 (1984)
The mechanistic course of the 3-stage synthesis of squaric acid from hexachlorobutadiene and morpholine has been elucidated, and 5 novel intermediates isolated and characterized.
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Cohen et al.
, p. 3480 (1959)
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Kinetic Analysis and Mechanism of the Hydrolytic Degradation of Squaramides and Squaramic Acids
Ximenis, Marta,Bustelo, Emilio,Algarra, Andrés G.,Vega, Manel,Rotger, Carmen,Basallote, Manuel G.,Costa, Antonio
, p. 2160 - 2170 (2017)
The hydrolytic degradation of squaramides and squaramic acids, the product of partial hydrolysis of squaramides, has been evaluated by UV spectroscopy at 37 °C in the pH range 3-10. Under these conditions, the compounds are kinetically stable over long time periods (>100 days). At pH >10, the hydrolysis of the squaramate anions shows first-order dependence on both squaramate and OH-. At the same temperature and [OH-], the hydrolysis of squaramides usually displays biphasic spectral changes (A → B → C kinetic model) with formation of squaramates as detectable reaction intermediates. The measured rates for the first step (k1 ≈ 10-4 M-1 s-1) are 2-3 orders of magnitude faster than those for the second step (k2 ≈ 10-6 M-1 s-1). Experiments at different temperatures provide activation parameters with values of ΔH? ≈ 9-18 kcal mol-1 and ΔS? ≈ -5 to -30 cal K-1 mol-1. DFT calculations show that the mechanism for the alkaline hydrolysis of squaramic acids is quite similar to that of amides.
Structural effects on interconversion of oxygen-substituted bisketenes and cyclobutenediones
Fu, Nanyan,Allen, Annette D.,Kobayashi, Shinjiro,Tidwell, Thomas T.,Vukovic, Sinisa,Matsuoka, Takeshi,Mishima, Masaaki
, p. 1768 - 1773 (2008/09/18)
(Graph Presented) Cyclobutenediones 5 disubstituted with HO (a), MeO (b), EtO (c), i-PrO (d), t-BuO (e), PhO (f), 4-MeOC6H4O (g), 4-O2NC6H4O (h), and 3,4-bridging OCH 2CH2O (i) substituents upon laser flash photolysis gave the corresponding bisketenes 6a-i, as detected by their distinctive doublet IR absorptions between 2075 and 2106 and 2116 and 2140 cm-1. The reactivities in ring closure back to the cyclobutenediones were greatest for the group 6b-e, with the highest rate constant of 2.95 ×107 s -1 at 25°C for 6e (RO = t-BuO) in isooctane, were less for 6a (RO = OH, k = 2.57 × 106 s-1 in CH3CN), while 6f- i were the least reactive, with the lowest rate constant of 3.8 × 104 s-1 in CH3CN for 6h (RO = 4-O 2NC6H4O). The significantly reduced rate constants for 6f-i are attributed to diminution of the electron-donating ability of oxygen to the cyclobutenediones 5f-h by the ArO substituents compared to alkoxy groups and to angle strain in the bridged product cyclobutenedione 5i. The reactivities of the ArO-substituted bisketenes 6f-h in CH3CN varied by a factor of 50 and gave an excellent correlation of the observed rate constants log k with the σp constants of the aryl substituents. Computational studies at the B3LYP/6-31G(d) level of ring-closure barriers are consistent with the measured reactivities. Photolysis of squaric acid (5a) in solution provides a convenient preparation of deltic acid (7).
Electro-organic reactions. Part 27. The mechanism of cathodic cleavage of activated esters; oxalates, squarates and oxamates
Islam, Nazar-ul,Sopher, David W.,Utley, James H.P.
, p. 959 - 970 (2007/10/02)
Esters of oxalic acid, 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid), and oxamic acid, are reduced cathodically at modest potentials. In aprotic solvent, and on the cyclic voltammetric time scale, the esters are cleaved to the corresponding alkane. For oxalates, the mechanism of cathodic cleavage was investigated thoroughly by voltammetry, coulometry, and detailed product analysis. On the time scale of controlled potential electrolysis the rapid electrogenerated base-catalysed hydrolysis of the esters by adventitious water competes with cathodic cleavage. Similarly, rapid base-catalysed transesterification involving oxalates and added alcohols is observed which provides a practical method of reductively cleaving alcohols to alkanes by co-electrolysis of a mixture of alcohol and readily available oxalate (e.g. diethyloxalate). The leaving group in such cathodic fragmentation is the half-ester anion and the efficiency of reaction depends on the stability of the other, radical, fragment.
