Polycarbonyl, (also known as polymeric-CO, p-CO or poly-CO) is a solid metastable and explosive polymer of carbon monoxide. The polymer is produced by exposing carbon monoxide to high pressures. The structure of the solid appears amorphous, but may include a zig zag of equally spaced CO groups.
Poly-CO can be produced at pressures of 5.2 GPa. Polymerisation is catalysed by blue light at slightly lower pressures in the δ-phase of solid CO. Another white phase can be made at higher temperatures at 6 or 7 GPa. Poly-CO appears to be a yellow to dark red amorphous phase. Whereas the white phase appears to be crystalline.
R. J. Mills discovered this solid, which was first produced in a tungsten carbide anvil in 1947. Originally this was thought to be polymeric carbon suboxide, but the formation does not yield any gas byproduct such as carbon dioxide. The yield of the solid can be up to 95%.
The polymer is stable above about 80K. Below this temperature the ε form of solid molecular CO is formed instead. When the pressure is released the polymer remains stable at atmospheric pressure. The solid dissolves in water, alcohol and acetone. When exposed to the atmosphere it is hygroscopic, becomes gluey, and changes colour, becoming darker. The reaction with water produces carboxylic groups.
The solid stores a high energy. It can decompose explosively forming glassy carbon and carbon dioxide. The energy density stored can be up to 8 kJ/g. During the decomposition the temperature can be 2500K. The density is 1.65 gcm−3, however most of the solid produced is porous, so the true density is likely to be higher.
The solid is electrically insulating with an electronic gap energy of 1.9 eV.
Nuclear magnetic resonance for the material made from 13CO shows sharp resonance at 223 ppm due to ester or lactone attached carbon, and 151 ppm due to C=C double bonds. There is also broad resonance at 109 and 189 ppm. Over time of a few days, the 223 ppm peak reduces and all the other features increase in strength.
Ideas of the structure include a zig zag chain of CO pointing in opposite directions, or five atom rings connected by CO and C-C bonds. The rings are lactones of tetronic acid: -C:-(C=O)-(C-O-)-(C=O)-O-. Interconnections between the rings are zig zags of CO.
Other ideas of the structure of the solid, include graphitic carbon with carbon dioxide under pressure, and a polymer with this C3O2 monomer: -(C=O)-O-(C-)=C<. Yet other ideas are that the solid is the same as the polymer of carbon suboxide with oxalic anhydride.
Cyclobutanetetrone, also called tetraoxocyclobutane, is an organic compound with formula C4O4 or (CO)4, the fourfold ketone of cyclobutane. It would be an oxide of carbon, indeed a tetramer of carbon monoxide.
The compound seems to be thermodynamically unstable. As of 2000, it had yet to be synthesized in significant amounts but may have transient existence as detected by mass spectrometry.Cyclopentanepentone
Cyclopentanepentone, also known as leuconic acid, is a hypothetical organic compound with formula C5O5, the fivefold ketone of cyclopentane. It would be an oxide of carbon (an oxocarbon), indeed a pentamer of carbon monoxide.
As of 2000, the compound had yet to be synthesized in bulk, but there have been reports of trace synthesis.Cyclopropanetrione
Cyclopropanetrione or trioxocyclopropane is a little-known oxide of carbon with formula C3O3. It consists of a ring of three carbon atoms each attached to an oxygen atom with a double bond. Alternately it can be thought as a trimer of carbon monoxide. This compound is thermodynamically unstable, and has not been produced in bulk. However it has been detected using mass spectrometry.It is the neutral equivalent of the deltate anion C3O32−, known since 1975. An equivalent hydrate hexahydroxycyclopropane or cyclopropane-1,1,2,2,3,3-hexol, (-C(OH)2-)3 also exists. This contains geminal hydroxy groups.Geochemistry of carbon
The geochemistry of carbon is the study of the transformations involving the element carbon within the systems of the Earth. To a large extent this study is organic geochemistry, but it also includes the very important carbon dioxide. Carbon is transformed by life, and moves between the major phases of the Earth, including the water bodies, atmosphere, and the rocky parts. Carbon is important in the formation of organic mineral deposits, such as coal, petroleum or natural gas. Most carbon is cycled through the atmosphere into living organisms and then respirated back into the atmosphere. However an important part of the carbon cycle involves the trapping of living matter into sediments. The carbon then becomes part of a sedimentary rock when lithification happens.
Human technology or natural processes such as weathering, or underground life or water can return the carbon from sedimentary rocks to the atmosphere. From that point it can be transformed in the rock cycle into metamorphic rocks, or melted into igneous rocks. Carbon can return to the surface of the Earth by volcanoes or via uplift in tectonic processes. Carbon is returned to the atmosphere via volcanic gases.
Carbon undergoes transformation in the mantle under pressure to diamond and other minerals, and also exists in the Earth's outer core in solution with iron, and may also be present in the inner core.Carbon can form a huge number of different stable compounds. It is an essential component of living matter.
Living organisms can live in a limited range of conditions on the Earth that are limited by temperature and the existence of liquid water. The potential habitability of other planets or moons can also be assessed by the existence of liquid water.Carbon makes up only 0.08% of the combination of the lithosphere, hydrosphere, and atmosphere. Yet it is the twelfth most common element there. In the rock of the lithosphere, carbon commonly occurs as carbonate minerals containing calcium or magnesium. It is also found as fossil fuels in coal and petroleum and gas. Native forms of carbon are mcuh rarer, requiring pressure to form. Pure carbon exists as graphite or diamond.The deeper parts of Earth such as the mantle are very hard to discover. Few samples are known, in the form of uplifed rocks, or xenoliths. Even fewer remain in the same state they were in where the pressure and temperature is much higher. Some diamonds retain inclusions held at pressures they were formed at, but the temperature is much lower at the surface. Iron meteorites may represent samples of the core of an asteroid, but it would have formed under different conditions to the Earth's core. Therefore, experimental studies are conducted in which minerals or substances are compressed and heated to determine what happens in similar conditions to the planetary interior.
The two common isotopes of carbon are stable. On Earth, carbon 12, 12C is by far the most common at 98.894%. Carbon 13 is much rarer averaging 1.106%. This percentage can vary slightly and its value is important in isotope geochemistry whereby the origin of the carbon is suggested.Johannes Thiele (chemist)
Friedrich Karl Johannes Thiele (May 13, 1865 – April 17, 1918) was a German chemist and a prominent professor at several universities, including those in Munich and Strasbourg. He developed many laboratory techniques related to isolation of organic compounds. In 1907 he described a device for the accurate determination of melting points, since named Thiele tube after him.Thiele was born in Ratibor, Prussia, now Racibórz, Poland. Thiele studied mathematics at the University of Breslau but later turned to chemistry, receiving his doctorate from Halle in 1890 . He taught at the University of Munich from 1893 to 1902, when he was appointed professor of chemistry at Strasbourg.He developed the preparation of glyoxal bis(guanylhydrazone).After Kekulé's proposal for benzene structure in 1865, Thiele suggested a "Partial Valence Hypothesis", which concerned double and triple carbon-carbon bonds with which he explains their particular reactivity. In 1899 this led to the prediction of the resonance that existed in benzene, and he proposed a resonance structure, by using a broken circle to represent the partial bonds. Later this problem was completely solved with the advent of quantum theory.
In 1899, Thiele was head of Organic Chemistry at the Bavarian Academy of Sciences in Munich. With his associate Otto Holzinger, he synthesised an iminodibenzyl nucleus: two benzene rings attached together by a nitrogen atom and an ethylene bridge.He discovered the condensation of ketones and aldehydes with cyclopentadiene as a route to fulvenes. He also recognized that these deeply colored species were related to but isomeric with benzene derivatives.According to one of his students Heinrich Otto Wieland, Thiele had a dislike of the chemistry of natural products.Metal nitrosyl complex
Metal nitrosyl complexes are complexes that contain nitric oxide, NO, bonded to a transition metal. Many kinds of nitrosyl complexes are known, which vary both in structure and coligand.
|Compounds derived from oxides|