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Methylidene Group
In organic chemistry, a methylidene group is any part of a molecule that consists of two hydrogen atoms bound to a carbon atom, which is connected to the remainder of the molecule by a double bond. The group may be represented as , where the '=' denotes the double bond. This stands in contrast to methylene, the group, which is connected to the rest of the molecule by two single bonds The distinction is often important, because the double bond is chemically different from two single bonds. The same name (methylidene) was used for the distinct molecule , also known as carbene. Formerly the methylene name was used for all three isomers (methylene, methylidene, and carbene). Many organic compounds are named and classified as if they were the result of substituting a methylidene group for two adjacent hydrogen atoms of some parent molecule (even if they are not actually obtained that way). Thus, for example, methylenecyclopropene is named after cyclopropene. See also * Meth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propene Methylidene Structural Formulae V
Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petroleum-like odor. Production Steam cracking The dominant technology for producing propylene is steam cracking. The same technology is applied to ethane to ethylene. These two conversions are the #2 and #1 processes in the chemical industry, as judged by their scale. In this process, propane undergoes dehydrogenation. The by-product is hydrogen: :CH3CH2CH3 → CH3CH=CH2 + H2 The yield of propene is about 85 m%. By-products are usually used as fuel for the propane dehydrogenation reaction. Steam cracking is one of the most energy-intensive industrial processes. The feedstock is naphtha or propane, especially in the Middle East, where there is an abundance of propane from oil/gas operations. Propene can be separated by fractional distilla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substituent
A substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. (In organic chemistry and biochemistry, the terms ''substituent'' and ''functional group'', as well as ''side chain'' and '' pendant group'', are used almost interchangeably to describe those branches from the parent structure, though certain distinctions are made in polymer chemistry. In polymers, side chains extend from the backbone structure. In proteins, side chains are attached to the alpha carbon atoms of the amino acid backbone.) The suffix ''-yl'' is used when naming organic compounds that contain a single bond replacing one hydrogen; ''-ylidene'' and ''-ylidyne'' are used with double bonds and triple bonds, respectively. In addition, when naming hydrocarbons that contain a substituent, positional numbers are used to indicate which carbon atom the substituent attaches to when such information is needed to distinguish between isomers. Su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methine
In organic chemistry, a methine group or methine bridge is a trivalent functional group , derived formally from methane. It consists of a carbon atom bound by two single covalent bond, bonds and one double bond, where one of the single bonds is to a hydrogen. The group is also called methyne or methene; its International Union of Pure and Applied Chemistry, IUPAC systematic name is methylylidene or methanylylidene (2007''Methanylylidene group''in the Chemical Entities of Biological Interest (ChEBI) database. Accessed on 2015-03-05. This group is sometimes called "methylidyne", however that name belongs properly to either the methylidyne group (connected to the rest of the molecule by a triple bond) or to the methylidyne radical (the two atoms as a free molecule with dangling bonds). The name "methine" is also widely used in non-systematic nomenclature for the methanetriyl group (IUPAC): a carbon atom with four single bonds, where one bond is to a hydrogen (). (2007''Methan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl Group
In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many organic compounds. It is a very stable group in most molecules. While the methyl group is usually part of a larger molecule, bounded to the rest of the molecule by a single covalent bond (), it can be found on its own in any of three forms: methanide anion (), methylium cation () or methyl radical (). The anion has eight valence electrons, the radical seven and the cation six. All three forms are highly reactive and rarely observed. Methyl cation, anion, and radical Methyl cation The methylium cation () exists in the gas phase, but is otherwise not encountered. Some compounds are considered to be sources of the cation, and this simplification is used pervasively in organic chemistry. For example, protonation of methanol gives an elect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylene (compound)
Methylene (systematically named methylidene and dihydridocarbon; also called carbene) is an organic compound with the chemical formula (also written ). It is a colourless gas that fluoresces in the mid-infrared range, and only persists in dilution, or as an adduct. Methylene is the simplest carbene.Roald Hoffman (2005), ''Molecular Orbitals of Transition Metal Complexes''. Oxford. It is usually detected only at very low temperatures, or as a short-lived intermediate in chemical reactions. W. B. DeMore and S. W. Benson (1964), Preparation, properties, and reactivity of methylene'. In ''Advances in Photochemistry'', John Wiley & Sons, 453 pages. Nomenclature The trivial name ''carbene'' is the preferred IUPAC name. The systematic names ''methylidene'' and ''dihydridocarbon'', valid IUPAC names, are constructed according to the substitutive and additive nomenclatures, respectively. ''Methylidene'' is viewed as methane with two hydrogen atoms removed. By default, this name ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopropene
Cyclopropene is an organic compound with the formula . It is the simplest cycloalkene. Because the ring is highly strained, cyclopropene is difficult to prepare and highly reactive. This colorless gas has been the subject for many fundamental studies of bonding and reactivity. It does not occur naturally, but derivatives are known in some fatty acids. Derivatives of cyclopropene are used commercially to control ripening of some fruit. Structure and bonding The molecule has a triangular structure. The reduced length of the double bond compared to a single bond causes the angle opposite the double bond to narrow to about 51° from the 60° angle found in cyclopropane. As with cyclopropane, the carbon–carbon bonding in the ring has increased p character: the alkene carbon atoms use sp2.68 hybridization for the ring. Synthesis of cyclopropene and derivatives Early syntheses The first confirmed synthesis of cyclopropene, carried out by Dem'yanov and Doyarenko, involved the the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylenecyclopropene
3-Methylenecyclopropene, also called methylenecyclopropene or triafulvene, is a hydrocarbon with chemical formula . It is a colourless gas that polymerizes readily as a liquid or in solution but is stable as a gas.W. E. Billups , Long Jin Lin , Edward W. Casserly "Synthesis of Methylenecyclopropene" J. Am. Chem. Soc., 1984, volume 106, pp 3698–3699. This highly strained and reactive molecule was synthesized and characterized for the first time in 1984, and has been the subject of considerable experimental and theoretical interest. It is an example of a cross-conjugated alkene, being composed of cyclopropene with an exocyclic double bond attached. Description Methylenecyclopropene is the smallest of the fulvenes (a family of unstable, cyclic molecules, conjugated transversally with an odd number of carbon atoms in the ring). The structure of methylenecyclopropene has two interacting double bonds, which represents the simplest transversally conjugated π-bonding system. It i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geminal
In chemistry, the descriptor geminal () refers to the relationship between two atoms or functional groups that are attached to the same atom. A geminal diol, for example, is a diol (a molecule that has two alcohol functional groups) attached to the same carbon atom, as in methanediol. Also the shortened prefix ''gem'' may be applied to a chemical name to denote this relationship, as in a ''gem''-dibromide for "geminal dibromide". The concept is important in many branches of chemistry, including synthesis and spectroscopy, because functional groups attached to the same atom often behave differently from when they are separated. Geminal diols, for example, are easily converted to ketones or aldehydes with loss of water.Peter Taylor (2002)''Mechanism and synthesis'' Book 10 of ''Molecular world''. Open University, Royal Society of Chemistry; . 368 pages The related term vicinal refers to the relationship between two functional groups that are attached to adjacent atoms. The rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbene
In organic chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is or where the R represents substituents or hydrogen atoms. The term "carbene" may also refer to the specific compound , also called methylene, the parent hydride from which all other carbene compounds are formally derived. Carbenes are classified as either singlets or triplets, depending upon their electronic structure. Most carbenes are very short lived, although persistent carbenes are known. One well-studied carbene is dichlorocarbene , which can be generated ''in situ'' from chloroform and a strong base. Structures and bonding The two classes of carbenes are singlet and triplet carbenes. Singlet carbenes are spin-paired. In the language of valence bond theory, the molecule adopts an sp2 hybrid structure. Triplet carbenes have two unpaired electrons. Most carbenes have a nonlinear triplet ground state, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistry''. Oxford University Press. pp. 1–15. . Study of structure determines their structural formula. Study of properties includes physical and chemical properties, and evaluation of chemical reactivity to understand their behavior. The study of organic reactions includes the chemical synthesis of natural products, drugs, and polymers, and study of individual organic molecules in the laboratory and via theoretical ( in silico) study. The range of chemicals studied in organic chemistry includes hydrocarbons (compounds containing only carbon and hydrogen) as well as compounds based on carbon, but also containing other elements, especially oxygen, nitrogen, sulfur, phosphorus (included in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylenecyclopropene
3-Methylenecyclopropene, also called methylenecyclopropene or triafulvene, is a hydrocarbon with chemical formula . It is a colourless gas that polymerizes readily as a liquid or in solution but is stable as a gas.W. E. Billups , Long Jin Lin , Edward W. Casserly "Synthesis of Methylenecyclopropene" J. Am. Chem. Soc., 1984, volume 106, pp 3698–3699. This highly strained and reactive molecule was synthesized and characterized for the first time in 1984, and has been the subject of considerable experimental and theoretical interest. It is an example of a cross-conjugated alkene, being composed of cyclopropene with an exocyclic double bond attached. Description Methylenecyclopropene is the smallest of the fulvenes (a family of unstable, cyclic molecules, conjugated transversally with an odd number of carbon atoms in the ring). The structure of methylenecyclopropene has two interacting double bonds, which represents the simplest transversally conjugated π-bonding system. It i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylene Group
In organic chemistry, a methylene group is any part of a molecule that consists of two hydrogen atoms bound to a carbon atom, which is connected to the remainder of the molecule by two single bonds. The group may be represented as , where the '<' denotes the two bonds. This can equally well be represented as . This stands in contrast to a situation where the carbon atom is bound to the rest of the molecule by a double bond, which is preferably called a , represented . Formerly the methylene name was used for both isomers. The name ““ can be used for the single-bonded isomer, to emphatically exclude methylidene. The distinction is often important, because the double bond is chemically di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
