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Hexazine
Hexazine (also known as hexaazabenzene) is a hypothetical allotrope of nitrogen composed of 6 nitrogen atoms arranged in a ring-like structure analogous to that of benzene. It would be the final member of the azabenzene (azine) series, in which all of the methine groups of the benzene molecule have been replaced with nitrogen atoms. The two last members of this series, hexazine and pentazine, have not been observed, although all other members of the azine series have (such as pyridine, pyrimidine, pyridazine, pyrazine, triazines, and tetrazines). Stability The hexazine molecule bears a structural similarity to the very stable benzene molecule. Like benzene, it has been calculated that hexazine is likely an aromatic molecule. Despite this, it has yet to be synthesized. Additionally, it has been predicted computationally that the hexazine molecule is highly unstable, possibly due to the lone pairs on the nitrogen atoms, which may repel each other electrostatically and/or cause electr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octaazacubane
Octaazacubane is a hypothetical explosive allotrope of nitrogen with formula N8, whose molecules have eight atoms arranged into a cube. (By comparison, nitrogen usually occurs as the diatomic molecule N2.) It can be regarded as a cubane-type cluster, where all eight corners are nitrogen atoms bonded along the edges. It is predicted to be a metastable molecule, in which despite the thermodynamic instability caused by bond strain, and the high energy of the N–N single bonds, the molecule remains kinetically stable for reasons of orbital symmetry. Explosive and fuel Octaazacubane is predicted to have an energy density (assuming decomposition into N2) of 22.9 MJ/ kg, which is over 5 times the standard value of TNT. It has therefore been proposed (along with other exotic nitrogen allotropes) as an explosive, and as a component of high performance rocket fuel. Its velocity of detonation is predicted to be 15,000 m/s, much (48.5%) more than octanitrocubane, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexaphosphabenzene
Hexaphosphabenzene is a valence isoelectronic analogue of benzene and is expected to have a similar planar structure due to resonance stabilization. Although several other allotropes of phosphorus are stable, no evidence for the existence of has been reported. Preliminary ab initio calculations on the trimerisation of leading to the formation of the cyclic were performed, and it was predicted that hexaphosphabenzene would decompose to free with an energy barrier of 13−15.4 kcal mol−1, and would therefore not be observed in the uncomplexed state under normal experimental conditions. The presence of an added solvent, such as ethanol, might lead to the formation of intermolecular hydrogen bonds which may block the destabilizing interaction between phosphorus lone pairs and consequently stabilize . The moderate barrier suggests that hexaphosphabenzene could be synthesized from a +2+2cycloaddition of three molecules. Currently, this is a synthetic endeavour which remains to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetranitrogen
Tetranitrogen is a neutrally charged polynitrogen allotrope of the chemical formula and consists of four nitrogen atoms. The tetranitrogen cation is the positively charged ion, , which is more stable than the neutral tetranitrogen molecule and is thus more studied. History Polynitrogen compounds have been well known and characterized by chemists for many years. The commonplace molecular (diatomic) nitrogen () was first isolated by Daniel Rutherford in 1772 and the azide ion () was discovered by Theodor Curtius in 1890. Discoveries of other related nitrogenous allotypes during the twentieth century include the aromatic molecule pentazole and the radical molecule . However, none of these complexes could be isolated or synthesized on a macroscopic scale like and azide; it was not until 1999 that a large scale synthesis was devised for a third nitrogen allotrope, the pentazenium () cation. This increased interest in polynitrogen compounds in the late twentieth century was due to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allotrope
Allotropy or allotropism () is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements. Allotropes are different structural modifications of an element: the atoms of the element are bonded together in a different manner. For example, the allotropes of carbon include diamond (the carbon atoms are bonded together to form a cubic lattice of tetrahedra), graphite (the carbon atoms are bonded together in sheets of a hexagonal lattice), graphene (single sheets of graphite), and fullerenes (the carbon atoms are bonded together in spherical, tubular, or ellipsoidal formations). The term ''allotropy'' is used for elements only, not for compounds. The more general term, used for any compound, is polymorphism, although its use is usually restricted to solid materials such as crystals. Allotropy refers only to different forms of an element within the same physical phase (the state of matter, such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diazine
In organic chemistry, diazines are a group of organic compounds having the molecular formula . Each contains a benzene ring in which two of the C-H fragments have been replaced by isolobal nitrogen. There are three structural isomers: * pyridazine (1,2-diazine) 55px * pyrimidine (1,3-diazine) 45px * pyrazine (1,4-diazine) 50px See also * 6-membered rings with one nitrogen atom: pyridines * 6-membered rings with three nitrogen atoms: triazines * 6-membered rings with four nitrogen atoms: tetrazine Tetrazine is a compound that consists of a six-membered aromatic ring containing four nitrogen atoms with the molecular formula C2 H2 N4. The name ''tetrazine'' is used in the nomenclature of derivatives of this compound. Three core-ring isome ...s * 6-membered rings with five nitrogen atoms: pentazines * 6-membered rings with six nitrogen atoms: hexazines References {{Reflist Simple aromatic rings ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothetical Chemical Compounds
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous observations that cannot satisfactorily be explained with the available scientific theories. Even though the words "hypothesis" and "theory" are often used interchangeably, a scientific hypothesis is not the same as a scientific theory. A working hypothesis is a provisionally accepted hypothesis proposed for further research in a process beginning with an educated guess or thought. A different meaning of the term ''hypothesis'' is used in formal logic, to denote the antecedent of a proposition; thus in the proposition "If ''P'', then ''Q''", ''P'' denotes the hypothesis (or antecedent); ''Q'' can be called a consequent. ''P'' is the assumption in a (possibly counterfactual) ''What If'' question. The adjective ''hypothetical'', meaning "havi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromatic Compounds
Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past grouping of molecules based on smell, before their general chemical properties are understood. The current definition of aromatic compounds does not have any relation with their smell. Heteroarenes are closely related, since at least one carbon atom of CH group is replaced by one of the heteroatoms oxygen, nitrogen, or sulfur. Examples of non-benzene compounds with aromatic properties are furan, a heterocyclic compound with a five-membered ring that includes a single oxygen atom, and pyridine, a heterocyclic compound with a six-membered ring containing one nitrogen atom. Hydrocarbons without an aromatic ring are called aliphatic. Benzene ring model Benzene, C6H6, is the least complex aromatic hydrocarbon, and it was the first one named as such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azines (heterocycles)
Azines are a functional class of organic compounds with the connectivity RR'C=N-N=CRR'. These compounds are the product of the condensation of hydrazine with ketones and aldehydes, although in practice they are often made by alternative routes. Ketazines are azines derived from ketones. For example, acetone azine is the simplest ketazine. Aldazines are azines derived from aldehydes. Preparation The usual method of industrial production is the peroxide process, starting from the ketone, ammonia, and hydrogen peroxide. : In the laboratory, azines are typically prepared by condensation of hydrazine with two equivalents of a carbonyl. Azines are also produced when chalcone reacts with a hydrazone to produce 3,5-diphenyl-1''H''-pyrazole, in a conversion also carried out with hydrazine hydrate. : Reactions Azines characteristically undergo hydrolysis to hydrazines. The reaction proceeds by the intermediacy of a hydrazone: :R2C=N-N=CR2 + H2O → R2C=N-NH2 + R2C=O :R2C=N-NH ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Physics Letters
''Chemical Physics Letters'' is a biweekly peer-reviewed scientific journal covering research in chemical physics and physical chemistry. It was established in 1967 and is published by Elsevier. The editors-in-chief An editor-in-chief (EIC), also known as lead editor or chief editor, is a publication's editorial leader who has final responsibility for its operations and policies. The highest-ranking editor of a publication may also be titled editor, managing ... are David C. Clary, B. Dietzek, K-L. Han, anA. Karton External links * Chemical physics journals Publications established in 1967 Elsevier academic journals English-language journals {{chem-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angewandte Chemie International Edition
''Angewandte Chemie'' (, meaning "Applied Chemistry") is a weekly peer-reviewed scientific journal that is published by Wiley-VCH on behalf of the German Chemical Society (Gesellschaft Deutscher Chemiker). Publishing formats include feature-length reviews, short highlights, research communications, minireviews, essays, book reviews, meeting reviews, correspondences, corrections, and obituaries. This journal contains review articles covering all aspects of chemistry. According to the '' Journal Citation Reports'', the journal had a 2021 impact factor of 16.823. Editions The journal appears in two editions with separate volume and page numbering: a German edition, ''Angewandte Chemie'' ( (print), (online)), and a fully English-language edition, ''Angewandte Chemie International Edition'' ( (print), (online)). The editions are identical in content with the exception of occasional reviews of German-language books or German translations of IUPAC recommendations. Business mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of The American Chemical Society
The ''Journal of the American Chemical Society'' is a weekly peer-reviewed scientific journal that was established in 1879 by the American Chemical Society. The journal has absorbed two other publications in its history, the ''Journal of Analytical and Applied Chemistry'' (July 1893) and the ''American Chemical Journal'' (January 1914). It covers all fields of chemistry. Since 2021, the editor-in-chief is Erick M. Carreira ( ETH Zurich). In 2014, the journal moved to a hybrid open access publishing model. Abstracting and indexing The journal is abstracted and indexed in Chemical Abstracts Service, Scopus, EBSCO databases, ProQuest databases, Index Medicus/ MEDLINE/ PubMed, and the Science Citation Index Expanded. According to the '' Journal Citation Reports'', the journal has a 2021 impact factor of 16.383. Editors-in-chief The following people are or have been editor-in-chief: * 1879–1880 – Hermann Endemann * 1880–1881 – Gideon E. Moore * 1881–1882 – Hermann ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borazine
Borazine, also known as borazole, is a non-polar inorganic compound with the chemical formula B3H6N3. In this cyclic compound, the three BH units and three NH units alternate. The compound is isoelectronic and isostructural with benzene. For this reason borazine is sometimes referred to as “inorganic benzene”. Like benzene, borazine is a colourless liquid with an aromatic smell. Synthesis The compound was reported in 1926 by the chemists Alfred Stock and Erich Pohland by a reaction of diborane with ammonia. Borazine can be synthesized by treating diborane and ammonia in a 1:2 ratio at 250–300 °C with a conversion of 50%. :3 B2H6 + 6 NH3 → 2 B3H6N3 + 12 H2 An alternative more efficient route begins with sodium borohydride and ammonium sulfate: :6 NaBH4 + 3 (NH4)2SO4 → 2 B3N3H6 + 3 Na2SO4 + 18 H2 In a two-step process to borazine, boron trichloride is first converted to trichloroborazine: :3 BCl3 + 3 NH4Cl → Cl3B3H3N3 + 9 HCl The B-Cl bonds are subseq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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