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Thiopyran
Thiopyran is a heterocyclic compound with the chemical formula C5H6S. There are two isomers, 2''H''-thiopyran and 4''H''-thiopyran, which differ by the location of double bonds. Thiopyrans are analogous to pyrans in which the oxygen atoms have been replaced by sulfur atoms. See also * Thiopyrylium * Thio- The prefix thio-, when applied to a chemical, such as an ion, means that an oxygen atom in the compound has been replaced by a sulfur atom. This term is often used in organic chemistry. For example, from the word ''ether,'' referring to an oxyg ... References Sulfur heterocycles Six-membered rings {{heterocyclic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterocyclic Compound
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of these heterocycles. Examples of heterocyclic compounds include all of the nucleic acids, the majority of drugs, most biomass (cellulose and related materials), and many natural and synthetic dyes. More than half of known compounds are heterocycles. 59% of US FDA-approved drugs contain nitrogen heterocycles. Classification The study of heterocyclic chemistry focuses especially on unsaturated derivatives, and the preponderance of work and applications involves unstrained 5- and 6-membered rings. Included are pyridine, thiophene, pyrrole, and furan. Another large class of heterocycles refers to those fused to benzene rings. For example, the fused benzene derivatives of pyridine, thiophene, pyrrole, and furan are quinol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyran
In chemistry, pyran, or oxine, is a six-membered heterocyclic, non-aromatic ring, consisting of five carbon atoms and one oxygen atom and containing two double bonds. The molecular formula is C5H6O. There are two isomers of pyran that differ by the location of the double bonds. In 2''H''-pyran, the saturated carbon is at position 2, whereas, in 4''H''-pyran, the saturated carbon is at position 4. 4''H''-Pyran was first isolated and characterized in 1962 via pyrolysis of 2-acetoxy-3,4-dihydro-2''H''-pyran. It was found too unstable, particularly in the presence of air. 4''H''-pyran easily disproportionates to the corresponding dihydropyran and the pyrylium ion, which is easily hydrolyzed in aqueous medium. Although the pyrans themselves have little significance in chemistry, many of their derivatives are important biological molecules, such as the pyranoflavonoids. The term pyran is also often applied to the saturated ring analog, which is more properly referred to as tetrahydrop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiopyrylium
Thiopyrylium is a cation with the chemical formula C5H5S+. It is analogous to the pyrylium cation with the oxygen atom replaced by a sulfur atom. Thiopyrylium salts are less reactive than the analogous pyrylium salts due to the higher polarizability of the sulfur atom. Among the chalcogenic 6-membered unsaturated heterocycles, thiopyrylium is the most aromatic, due to sulfur having the similar Pauling electronegativity as carbon and only a slightly higher covalent radius. In water, thiopyrylium reacts to it and forms a mixture of 2-hydroxythiopyran and 4-hydroxythiopyran. Thiopyrylium salts can be synthesized by hydrogen abstraction from thiopyran by a hydride ion acceptor, such as trityl perchlorate. The thiopyrylium analogue of 2,4,6-trisubstituted pyrylium salts can be synthesized by treatment with sodium sulfide followed by precipitation with acid. This reaction causes the oxygen atom in the pyrylium cation to be substituted with sulfur. See also * 6-membered aromatic ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thio-
The prefix thio-, when applied to a chemical, such as an ion, means that an oxygen atom in the compound has been replaced by a sulfur atom. This term is often used in organic chemistry. For example, from the word ''ether,'' referring to an oxygen-containing compound having the general chemical structure , where R and R′ are organic functional groups and O is an oxygen atom, comes the word ''thioether'', which refers to an analogous compound with the general structure , where S is a sulfur atom covalently bonded to two organic groups. A chemical reaction involving the replacement of oxygen to sulfur is called thionation or thiation. Thio- can be prefixed with ''di-'' and ''tri-'' in chemical nomenclature. The word derives (which occurs in Greek epic poetry as grc, θέ(ϝ)ειον, théweion, label=none and may come from the same root as Latin (Indo-European ''dh-w'') and may have originally meant "fumigation substance".) Examples * Thioamide * Thiocyanate * Thioether * Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Heterocycles
Sulfur (or sulphur in British English) is a chemical element with the Symbol (chemistry), symbol S and atomic number 16. It is abundance of the chemical elements, abundant, Polyvalency (chemistry), multivalent and nonmetallic. Under standard conditions for temperature and pressure, normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula octasulfur, S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature. Sulfur is the tenth most abundant element by mass in the universe and the fifth most on Earth. Though sometimes found in pure, native element minerals, native form, sulfur on Earth usually occurs as sulfide minerals, sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, history of China#Ancient China, China, and ancient Egypt. Historically and in literature sulfur is also called brimstone, which means "burning stone". To ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
