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Neopentane
Neopentane, also called 2,2-dimethylpropane, is a double-branched-chain alkane with five carbon atoms. Neopentane is a flammable gas at room temperature and pressure which can condense into a highly volatile liquid on a cold day, in an ice bath, or when compressed to a higher pressure. Neopentane is the simplest alkane with a quaternary carbon, and has achiral tetrahedral symmetry. It is one of the three structural isomers with the molecular formula C5H12 (pentanes), the other two being ''n''-pentane and isopentane. Out of these three, it is the only one to be a gas at standard conditions; the others are liquids. It was first synthesized by Russian chemist in 1870. Nomenclature The traditional name neopentane, coined by William Odling in 1876, was still retained in the 1993 IUPAC recommendations, but is no longer recommended according to the 2013 recommendations. The preferred IUPAC name is the systematic name 2,2-dimethylpropane, but the substituent numbers are su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentane
Pentane is an organic compound with the chemical formula, formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomerism, structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the ''n''-pentane isomer, in which case pentanes refers to a mixture of them; the other two are called isopentane (methylbutane) and neopentane (dimethylpropane). Cyclopentane is not an isomer of pentane because it has only 10 hydrogen atoms where pentane has 12. Pentanes are components of some fuels and are employed as specialty solvents in the laboratory. Their properties are very similar to those of butanes and hexanes. History Normal pentane was discovered in 1862 by Carl Schorlemmer, who, while analyzing pyrolysis products of the cannel coal mined in Wigan, identified, separated by fractional distillation and studied a series of liquid hydrocarbons inert to Nitric acid, nitric and Sulfuric acid, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkane
In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula . The alkanes range in complexity from the simplest case of methane (), where ''n'' = 1 (sometimes called the parent molecule), to arbitrarily large and complex molecules, like hexacontane () or 4-methyl-5-(1-methylethyl) octane, an isomer of dodecane (). The International Union of Pure and Applied Chemistry (IUPAC) defines alkanes as "acyclic branched or unbranched hydrocarbons having the general formula , and therefore consisting entirely of hydrogen atoms and saturated carbon atoms". However, some sources use the term to denote ''any'' saturated hydrocarbon, including those that are either monocyclic (i.e. the cycloalkanes) or polycycl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isopentane
Isopentane, also called methylbutane or 2-methylbutane, is a branched-chain saturated hydrocarbon (an alkane) with five carbon atoms, with formula or . Isopentane is a volatile and flammable liquid. It is one of three structural isomers with the molecular formula C5H12, the others being pentane (''n''-pentane) and neopentane (2,2-dimethylpropane). Isopentane is commonly used in conjunction with liquid nitrogen to achieve a liquid bath temperature of −160 °C. Natural gas typically contains 1% or less isopentane, but it is a significant component of natural gasoline.Ivan F. Avery, L. V. Harvey (1958): Natural-gasoline and Cycling Plants in the United States', Information circular, U.S. Department of the Interior, Bureau of Mines. 12 pages. History Although the mixture of pentanes was first isolated from the destructive distillation (pyrolysis) products of the boghead coal by Charles Greville Williams in 1862. In 1864–1865 two chemists tried to extract same hydro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quaternary Carbon
A quaternary carbon is a carbon atom bound to four other carbon atoms. For this reason, quaternary carbon atoms are found only in hydrocarbons having at least five carbon atoms. Quaternary carbon atoms can occur in branched alkanes, but not in linear alkanes. Synthesis The formation of chiral quaternary carbon centers has been a synthetic challenge. Chemists have developed asymmetric Diels–Alder reactions, Heck reaction, Enyne cyclization, cycloaddition reactions, C–H activation, Allylic substitution, Pauson–Khand reaction,Ishizaki, M.; Niimi, Y.; Hoshino, O.; Hara, H.; Takahashi, T. Tetrahedron In geometry, a tetrahedron (: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex (geometry), vertices. The tet ... Volume 2001, Issue 61, Pages 4053–4065 etc. to construct asymmetric quaternary carbon atoms. One of the most ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Structural Isomerism
In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a chemical compound, compound is a compound that contains the same number and type of atoms, but with a different connectivity (i.e. arrangement of chemical bond, bonds) between them. The term metamer was formerly used for the same concept. For example, butanol , methyl propyl ether , and diethyl ether have the same molecular formula but are three distinct structural isomers. The concept applies also to polyatomic ions with the same total charge. A classical example is the cyanate ion and the fulminate ion . It is also extended to ionic compounds, so that (for example) ammonium cyanate and urea are considered structural isomers,William F. Bynum, E. Janet Browne, Roy Porter (2014)''Dictionary of the History of Science'' page 218. and so are methylammonium formate and ammonium acetate . Structural isomerism is the most radical type of isomerism. It is opposed to stereoisomerism, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetramethylstannane
Tetramethyltin is an organometallic compound with the formula (CH3)4Sn. This liquid, one of the simplest organotin compounds, is useful for transition-metal mediated conversion of acid chlorides to methyl ketones and aryl halides to aryl methyl ketones. It is volatile and toxic, so care should be taken when using it in the laboratory. Synthesis and structure Tetramethyltin is synthesized by reaction of the Grignard reagent methylmagnesium iodide, with tin tetrachloride, which is synthesized by reacting tin metal with chlorine gas. :4 CH3MgI + SnCl4 → (CH3)4Sn + 4 MgICl In tetramethyltin, the metal surrounded by four methyl groups in a tetrahedral structure is a heavy analogue of neopentane. Applications Precursor to methyltin compounds Tetramethyltin is a precursor to trimethyltin chloride (and related methyltin halides), which are precursors to other organotin compounds. These methyltin chlorides are prepared via the so-called Kocheshkov redistribution reaction. Thus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entropy Of Fusion
In thermodynamics, the entropy of fusion is the increase in entropy when melting a solid substance. This is almost always positive since the degree of disorder increases in the transition from an organized crystalline solid to the disorganized structure of a liquid; the only known exception is helium. It is denoted as \Delta S_ and normally expressed in joules per mole-kelvin, J/(mol·K). A natural process such as a phase transition will occur when the associated change in the Gibbs free energy is negative. :\Delta G_ = \Delta H_ - T \times \Delta S_ < 0, where is the enthalpy of fusion. Since this is a thermodynamic equation, the symbol refers to the absolute , measured in |
Enthalpy Of Fusion
In thermodynamics, the enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid, at constant pressure. The enthalpy of fusion is the amount of energy required to convert one mole of solid into liquid. For example, when melting 1 kg of ice (at 0 °C under a wide range of pressures), 333.55 kJ of energy is absorbed with no temperature change. The heat of solidification (when a substance changes from liquid to solid) is equal and opposite. This energy includes the contribution required to make room for any associated change in volume by displacing its environment against ambient pressure. The temperature at which the phase transition occurs is the melting point or the freezing point, according to context. By convention, the pressure is assumed to be unless otherwise specified. Overview T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neptunium
Neptunium is a chemical element; it has chemical symbol, symbol Np and atomic number 93. A radioactivity, radioactive actinide metal, neptunium is the first transuranic element. It is named after Neptune, the planet beyond Uranus in the Solar System, which uranium is named after. A neptunium atom has 93 protons and 93 electrons, of which seven are valence electrons. Neptunium metal is silvery and tarnishes when exposed to air. The element occurs in three allotrope, allotropic forms and it normally exhibits five oxidation states, ranging from +3 to +7. Like all actinides, it is Radioactive decay, radioactive, radiation poisoning, poisonous, pyrophoricity, pyrophoric, and capable of accumulating in bones, which makes the handling of neptunium dangerous. Although many false claims of its discovery were made over the years, the element was first synthesized by Edwin McMillan and Philip H. Abelson at the Berkeley Radiation Laboratory in 1940. Since then, most neptunium has been and still ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neopentyl Alcohol
Neopentyl alcohol is a compound with formula (CH3)3CCH2OH. It is a colorless solid. The compound is one of the eight isomers of pentyl alcohol. Preparation and reactions Neopentyl alcohol can be prepared from the hydroperoxide of diisobutylene. It can also be prepared by the reduction of trimethylacetic acid with lithium aluminium hydride. Neopentyl alcohol was the first described in 1891 by L. Tissier, who prepared it by reduction of a mixture of trimethyl acetic acid and trimethylacetyl chloride with sodium amalgam. Neopentyl alcohol can be converted to neopentyl iodide by treatment with triphenylphosphite/methyl iodide Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one h ...: :(CH3)3CCH2OH + H3(C6H5O)3Psup>+I− → (CH3)3CCH2I + Pentaerythritol">H3(C6H5O)2PO + C6H5OH S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substituent
In organic chemistry, a substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. 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. Substituents can be a combination of the inductive effect and the mesomeric effect. Such effects are also described as electron-rich and electron withdrawing. Additional steric effects result from the volume occupied by a substituent. The phrases ''most-substituted'' and ''least-substituted'' are frequently used to describe or compare molecules that are products of a chemical reaction. In this terminology, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
