|
Oxirene
Oxirene is a heterocyclic chemical compound which contains an unsaturated three-membered ring containing two carbon atoms and one oxygen atom. The molecule was synthesized in low temperature ices and detected upon sublimation by isomer selective photoionization reflectron time-of-flight mass spectrometry. Quantum chemical computational techniques found the configuration to be extremely strained and proposed an antiaromatic Antiaromaticity is a chemical property of a cyclic molecule with a π electron system that has higher energy, i.e., it is less stable due to the presence of 4n delocalised (π or lone pair) electrons in it, as opposed to aromaticity. Unlike aroma ... 4π electron system, as such oxirene is expected to be very high energy. Experimental indications exist that substituted oxirenes (as intermediates or transition states) may be involved in carbonylcarbene rearrangements observed in the Wolff rearrangement. Computational evidence also point to the intermedia ... [...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 organic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of organic 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 organic heterocyclic chemistry focuses especially on organic unsaturated derivatives, and the preponderance of work and applications involves unstrained organic 5- and 6-membered rings. Included are pyridine, thiophene, pyrrole, and furan. Another large class of organic heterocycles refers to those fused to benzene rings. For example, the fused benzene derivatives of py ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Society Of Chemistry
The Royal Society of Chemistry (RSC) is a learned society and professional association in the United Kingdom with the goal of "advancing the chemistry, chemical sciences". It was formed in 1980 from the amalgamation of the Chemical Society, the Royal Institute of Chemistry, the Faraday Society, and the Society for Analytical Chemistry with a new Royal Charter and the dual role of learned society and professional body. At its inception, the Society had a combined membership of 49,000 in the world. The headquarters of the Society are at Burlington House, Piccadilly, London. It also has offices in Thomas Graham House in Cambridge (named after Thomas Graham (chemist), Thomas Graham, the first president of the Chemical Society) where ''RSC Publishing'' is based. The Society has offices in the United States, on the campuses of The University of Pennsylvania and Drexel University, at the University City Science Center in Philadelphia, Pennsylvania, in both Beijing and Shanghai, People' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylene Oxide
Ethylene oxide is an organic compound with the chemical formula, formula . It is a cyclic ether and the simplest epoxide: a three-membered ring (chemistry), ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sweet odor. Because it is a strained ring, ethylene oxide easily participates in a number of addition reactions that result in ring-opening. Ethylene oxide is isomeric with acetaldehyde and with vinyl alcohol. Ethylene oxide is industrially produced by oxidation of ethylene in the presence of a silver catalyst. The reactivity that is responsible for many of ethylene oxide's hazards also makes it useful. Although too dangerous for direct household use and generally unfamiliar to consumers, ethylene oxide is used for making many consumer products as well as non-consumer chemicals and intermediates. These products include detergents, thickeners, solvents, plastics, and various organic chemicals such as ethylen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopropane
Cyclopropane is the cycloalkane with the molecular formula (CH2)3, consisting of three methylene groups (CH2) linked to each other to form a triangular ring. The small size of the ring creates substantial ring strain in the structure. Cyclopropane itself is mainly of theoretical interest but many of its derivatives - cyclopropanes - are of commercial or biological significance. Cyclopropane was used as a clinical inhalational anesthetic from the 1930s through the 1980s. The substance's high flammability poses a risk of fire and explosions in operating rooms due to its tendency to accumulate in confined spaces, as its density is higher than that of air. History Cyclopropane was discovered in 1881 by August Freund, who also proposed the correct structure for the substance in his first paper. Freund treated 1,3-Dibromopropane, 1,3-dibromopropane with sodium, causing an intramolecular Wurtz reaction leading directly to cyclopropane. The yield of the reaction was improved by Gustavson ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aziridine
Aziridine is an organic compound consisting of the three-membered heterocycle . It is a colorless, toxic, volatile liquid that is of significant practical interest. Aziridine was discovered in 1888 by the chemist Siegmund Gabriel. Its derivatives, also referred to as aziridines, are of broader interest in medicinal chemistry. Structure The bond angles in aziridine are approximately 60°, considerably less than the normal hydrocarbon bond angle of 109.5°, which results in angle strain as in the comparable cyclopropane and ethylene oxide molecules. A banana bond model explains bonding in such compounds. Aziridine is less basic than acyclic aliphatic amines, with a pKa of 7.9 for the conjugate acid, due to increased s character of the nitrogen free electron pair. Angle strain in aziridine also increases the barrier to nitrogen inversion. This barrier height permits the isolation of separate ''invertomers'', for example the ''cis'' and ''trans'' invertomers of ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiirane
Thiirane, more commonly known as ethylene sulfide, is the cyclic chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ... with the formula C2H4S. It is the smallest sulfur-containing heterocycle and the simplest episulfide. Like many organosulfur compounds, this species has a highly unpleasant odour. Thiirane is also used to describe any derivative of the parent ethylene sulfide. Structure and properties According to electron diffraction, the C-C and C-S distances in ethylene sulfide are respectively 1.473 and 1.811 Å. The C-C-S and C-S-C angles are respectively 66.0 and 48.0°. The microwave and infrared spectra were studied experimentally and computationally. Preparation and reactions It can be prepared by the reaction of ethylene carbonate and KSCN. For thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiirene
Thiirene is an organosulfur compound with the formula C2H2S. It can be viewed as a derivative of cyclopropene, but with the methylene group replaced by sulfur. It is antiaromatic and very labile. Thiirenes and derivatives No thiirene has been isolated at room temperature, but they have been observed spectroscopically at low temperatures. Thiirene-''S''-oxides and ''S''-alkylthiirenium salts have been characterized by X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th .... References {{organic-compound-stub Sulfur heterocycles Three-membered rings ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saturated And Unsaturated Compounds
A saturated compound is a chemical compound (or ion) that resists addition reactions, such as hydrogenation, oxidative addition, and the binding of a Lewis acids and bases, Lewis base. The term is used in many contexts and classes of chemical compounds. Overall, saturated compounds are less reactive than unsaturated compounds. Saturation is derived from the Latin word ''saturare'', meaning 'to fill'.An unsaturated compound is also a chemical compound (or ion) that attracts reduction reactions, such as dehydrogenation,oxidative reduction Organic chemistry Generally distinct types of unsaturated organic compounds are recognized. For hydrocarbons: *alkene (unsaturated) vs alkane (saturated) *alkyne (unsaturated) vs alkane (saturated) *arene (unsaturated) vs cycloalkane (saturated) For organic compounds containing heteroatoms (other than C and H), the list of unsaturated groups is long but some common types are: *carbonyl, e.g. ketones, aldehydes, esters, carboxylic acids (unsatura ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time-of-flight Mass Spectrometry
Time-of-flight mass spectrometry (TOFMS) is a method of mass spectrometry in which an ion's mass-to-charge ratio is determined by a time of flight measurement. Ions are accelerated by an electric field of known strength. This acceleration results in an ion having the same kinetic energy as any other ion that has the same charge. The velocity of the ion depends on the mass-to-charge ratio (heavier ions of the same charge reach lower speeds, although ions with higher charge will also increase in velocity). The time that it subsequently takes for the ion to reach a detector at a known distance is measured. This time will depend on the velocity of the ion, and therefore is a measure of its mass-to-charge ratio. From this ratio and known experimental parameters, one can identify the ion. Theory The potential energy of a charged particle in an electric field is related to the charge of the particle and to the strength of the electric field: where ''E''p is potential energy, ''q'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Chemistry
Quantum chemistry, also called molecular quantum mechanics, is a branch of physical chemistry focused on the application of quantum mechanics to chemical systems, particularly towards the quantum-mechanical calculation of electronic contributions to physical and chemical properties of Molecule, molecules, Material, materials, and solutions at the atomic level. These calculations include systematically applied approximations intended to make calculations computationally feasible while still capturing as much information about important contributions to the computed Wave function, wave functions as well as to observable properties such as structures, spectra, and Thermodynamics, thermodynamic properties. Quantum chemistry is also concerned with the computation of quantum effects on molecular dynamics and chemical kinetics. Chemists rely heavily on spectroscopy through which information regarding the Quantization (physics), quantization of energy on a molecular scale can be obtained ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antiaromaticity
Antiaromaticity is a chemical property of a cyclic molecule with a pi electron, π electron system that has higher energy, i.e., it is less stable due to the presence of 4n delocalised (π or lone pair) electrons in it, as opposed to aromaticity. Unlike aromatic compounds, which follow Hückel's rule ([4''n''+2] π electrons) and are highly stable, antiaromatic compounds are highly unstable and highly reactive. To avoid the instability of antiaromaticity, molecules may change shape, becoming non-planar and therefore breaking some of the π interactions. In contrast to the Aromatic ring current, diamagnetic ring current present in aromatic compounds, antiaromatic compounds have a paramagnetic ring current, which can be #Antiaromaticity in NMR Spectra, observed by NMR spectroscopy. Examples of antiaromatic compounds are pentalene (A), biphenylene (B), cyclopentadienyl cation (C). The prototypical example of antiaromaticity, cyclobutadiene, is the subject of debate, with some scienti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
