Orthocarbonic acid
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Orthocarbonic acid, carbon hydroxide, or methanetetrol is the name given to a hypothetical compound with the chemical formula Template:Chem2 or Template:Chem2. Its molecular structure consists of a single carbon atom bonded to four hydroxyl groups. It would be therefore a fourfold alcohol. In theory it could lose four protons to give the hypothetical oxocarbon anion orthocarbonate Template:Chem2, and is therefore considered an oxoacid of carbon.
Orthocarbonic acid is highly unstable. Calculations show that it decomposes into carbonic acid and water:[1][2]
Orthocarbonic acid is one of the group of ortho acids that have the general structure of Template:Chem2. The term ortho acid is also used to refer to the most hydroxylated acid in a set of oxoacids.
Researchers predict that orthocarbonic acid is stable at high pressure; hence it may form in the interior of the ice giant planets Uranus and Neptune, where water and methane are common.[3]
Orthocarbonate anions
By loss of one through four protons, orthocarbonic acid could yield four anions: Template:Chem2 (trihydrogen orthocarbonate), Template:Chem2 (dihydrogen orthocarbonate), Template:Chem2 (hydrogen orthocarbonate), and Template:Chem2 (orthocarbonate).
Numerous salts of fully deprotonated Template:Chem2, such as Template:Chem2 (calcium orthocarbonate) or Template:Chem2 (strontium orthocarbonate), have been synthesized under high pressure conditions and structurally characterized by X-ray diffraction.[4][5][6][7] Strontium orthocarbonate, Template:Chem2, is stable at atmospheric pressure. Orthocarbonate is tetrahedral in shape, and is isoelectronic to orthonitrate. The C-O distance is 1.41 Å.[8] Template:Chem2 is an oxide orthocarbonate (tristrontium orthocarbonate oxide), also stable at atmospheric pressure.[9]
Orthocarbonate esters
The tetravalent moiety Template:Chem2 is found in stable organic compounds; they are formally esters of orthocarbonic acid, and therefore are called orthocarbonates. For example, tetraethoxymethane can be prepared by the reaction between chloropicrin and sodium ethoxide in ethanol.[10] Polyorthocarbonates are stable polymers that might have applications in absorbing organic solvents in waste treatment processes,[11] or in dental restorative materials.[12] The explosive trinitroethylorthocarbonate possesses an orthocarbonate core.
A linear polymer which can be described as a (spiro) orthocarbonate ester of pentaerythritol, whose formula could be written as Template:Chem2, was synthesized in 2002.[13]
The carbon atom in the spiro ester bis-catechol orthocarbonate was found to have tetrahedral bond geometry, contrasting with the square planar geometry of the silicon atom in the analogous orthosilicate ester.[14]
Orthocarbonates may exist in several conformers, that differ by the relative rotation of the C–O–C bridges. The conformation structures of some esters, such as tetraphenoxymethane, tetrakis(3,5-dimethyl-phenoxy)methane, and tetrakis(4-bromophenoxy)methane have been determined by X-ray diffraction.[15]
See also
References
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- ↑ Script error: No such module "Citation/CS1".
- ↑ Carboxylic Acids and Derivatives Template:Webarchive IUPAC Recommendations on Organic & Biochemical Nomenclature
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- ↑ Orthocarbonic acid, tetraethyl ester Template:Webarchive Organic Syntheses, Coll. Vol. 4, p. 457 (1963); Vol. 32, p. 68 (1952).
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- ↑ David T. Vodak, Matthew Braun, Lykourgos Iordanidis, Jacques Plévert, Michael Stevens, Larry Beck, John C. H. Spence, Michael O'Keeffe, Omar M. Yaghi (2002): "One-Step Synthesis and Structure of an Oligo(spiro-orthocarbonate)". Journal of the American Chemical Society, volume 124, issue 18, pages 4942–4943. Script error: No such module "CS1 identifiers".
- ↑ H. Meyer, G. Nagorsen (1979): "Structure and reactivity of the orthocarbonic and orthosilicic acid esters of pyrocatechol". Angewandte Chemie International Edition in English, volume 18, issue 7, pages 551-553. Script error: No such module "CS1 identifiers".
- ↑ N. Narasimhamurthy, H. Manohar, Ashoka G. Samuelson, Jayaraman Chandrasekhar (1990): "Cumulative anomeric effect: A theoretical and x-ray diffraction study of orthocarbonates". Journal of the American Chemical Society, volume 112, issue 8, pages 2937–2941. Script error: No such module "CS1 identifiers".
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