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Lithium Borohydride
Lithium borohydride (LiBH4) is a borohydride and known in organic synthesis as a reducing agent for esters. Although less common than the related sodium borohydride, the lithium salt offers some advantages, being a stronger reducing agent and highly soluble in ethers, whilst remaining safer to handle than lithium aluminium hydride.Luca Banfi, Enrica Narisano, Renata Riva, Ellen W. Baxter, "Lithium Borohydride" e-EROS Encyclopedia of Reagents for Organic Synthesis, 2001, John Wiley & Sons. . Preparation Lithium borohydride may be prepared by the metathesis reaction, which occurs upon ball-milling the more commonly available sodium borohydride and lithium bromide: : NaBH4 + LiBr → NaBr + LiBH4 Alternatively, it may be synthesized by treating boron trifluoride with lithium hydride in diethyl ether: : BF3 + 4 LiH → LiBH4 + 3 LiF Reactions Lithium borohydride is useful as a source of hydride (H–). It can react with a range of carbonyl substrates and other polarized c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrile
In organic chemistry, a nitrile is any organic compound that has a functional group. The name of the compound is composed of a base, which includes the carbon of the , suffixed with "nitrile", so for example is called " propionitrile" (or propanenitrile). The prefix '' cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons. Inorganic compounds containing the group are not called nitriles, but cyanides instead. Though both nitriles and cyanides can be derived from cyanide salts, most nitriles are not nearly as toxic. Structure and basic properties The N−C−C geom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distilled Water
Distilled water is water that has been purified by boiling it into vapor then condensing it back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. History Drinking water has been distilled from seawater since at least about AD 200, when the process was clearly described by Alexander of Aphrodisias. Its history predates this, as a passage in Aristotle's '' Meteorologica'' refers to the distillation of water. Captain Israel Williams of the ''Friendship'' (1797) improvised a way to distill water, which he described in his journal. Applications In chemical and biological laboratories, as well as in industry, in some appliances, deionized water or reverse osmosis water can be used instead of distilled water as a cheaper alternative. If exceptionally high-purity water is required, double distilled water is used. In general, non-purified water could cause or interfere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degassing
Degassing, also known as degasification, is the removal of dissolved gases from liquids, especially water or aqueous solutions. There are numerous methods for removing gases from liquids. Gases are removed for various reasons. Chemists remove gases from solvents when the compounds they are working on are possibly air- or oxygen-sensitive (air-free technique), or when bubble formation at solid-liquid interfaces becomes a problem. The formation of gas bubbles when a liquid is frozen can also be undesirable, necessitating degassing beforehand. Pressure reduction The solubility of gas obeys Henry's law, that is, the amount of a dissolved gas in a liquid is proportional to its partial pressure. Therefore, placing a solution under reduced pressure makes the dissolved gas less soluble. Sonication and stirring under reduced pressure can usually enhance the efficiency. This technique is often referred to as ''vacuum degasification''. Specialized vacuum chambers, called vacuum degassers, ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aqueous Solution
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, also known as sodium chloride (NaCl), in water would be represented as . The word ''aqueous'' (which comes from ''aqua'') means pertaining to, related to, similar to, or dissolved in, water. As water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Since water is frequently used as the solvent in experiments, the word solution refers to an aqueous solution, unless the solvent is specified. A ''non-aqueous solution'' is a solution in which the solvent is a liquid, but is not water. Characteristics Substances that are ''hydrophobic'' ('water-fearing') do not dissolve well in water, whereas those that are '' hydrophilic'' ('water-friendly') do. An example of a hydrophilic substance is sodium chloride. In an aqueous solution the hydrogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Journal Of Hydrogen Energy
The ''International Journal of Hydrogen Energy'' is a peer-reviewed scientific journal covering all aspects of hydrogen energy, including hydrogen generation and storage. It is published by Elsevier and is an official journal of the International Association for Hydrogen Energy. Established in 1976, the journal became monthly in 1982, biweekly in 2008, 36/yr in 2013, and weekly in 2015. The editor in chief is Emre Veziroglu and the founding editor in chief is his father Turhan Nejat Veziroğlu (University of Miami). In 2023, the journal was criticized for rejecting papers that do not cite enough of the journal's previously published papers. Abstracting and indexing The journal is abstracted and indexed in: According to the ''Journal Citation Reports'', the journal has a 2023 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a type of journal ranking. Journals with higher impact factor values are considered more prestigious o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tertiary (chemistry)
Tertiary is a term used in organic chemistry to classify various types of compounds (e. g. alcohols, alkyl halides, amines) or reactive intermediates (e. g. alkyl radicals, carbocations). See also * Primary (chemistry) Primary is a term used in organic chemistry to classify various types of compounds (e.g. alcohols, alkyl halides, amines) or reactive intermediates (e.g. alkyl radicals, carbocations). {{clear See also * Secondary (chemistry) * Tertiary (che ... * Secondary (chemistry) * Quaternary (chemistry) References {{Navbox stereochemistry Chemical nomenclature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary (chemistry)
Secondary is a term used in organic chemistry to classify various types of compounds (e. g. alcohols, alkyl halides, amines) or reactive intermediates (e. g. alkyl radicals, carbocations). An atom is considered secondary if it has two 'R' Groups attached to it. An 'R' group is a carbon containing group such as a methyl (CH3). A secondary compound is most often classified on an alpha carbon (middle carbon) or a nitrogen. The word secondary comes from the root word 'second' which means two. This nomenclature can be used in many cases and further used to explain relative reactivity. The reactivity of molecules varies with respect to the attached atoms. Thus, a primary, secondary, tertiary and quaternary molecule of the same function group will have different reactivities. Secondary alcohols Secondary alcohols have the formula RCH(OH)R' where R and R' are organyl. Secondary amines A secondary amine has the formula RR'NH where R and R' are organyl. Secondary amides Se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkyl Halides
The haloalkanes (also known as halogenoalkanes or alkyl halides) are alkanes containing one or more halogen substituents of hydrogen atom. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalkanes are widely used commercially. They are used as flame retardants, fire extinguishants, refrigerants, propellants, solvents, and pharmaceuticals. Subsequent to the widespread use in commerce, many halocarbons have also been shown to be serious pollutants and toxins. For example, the chlorofluorocarbons have been shown to lead to ozone depletion. Methyl bromide is a controversial fumigant. Only haloalkanes that contain chlorine, bromine, and iodine are a threat to the ozone layer, but fluorinated volatile haloalkanes in theory may have activity as greenhouse gases. Methyl iodide, a naturally occurring substance, however, does not have ozone-depleting properties and the United States Environmental Protection Agency has designated the compo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbamic Acid
Carbamic acid, which might also be called aminoformic acid or aminocarboxylic acid, is the chemical compound with the formula . It can be obtained by the reaction of ammonia and carbon dioxide at very low temperatures, which also yields ammonium carbamate . The compound is stable only up to about 250 K (−23 °C); at higher temperatures it decomposes into those two gases. The solid apparently consists of dimer (chemistry), dimers, with the two molecules connected by hydrogen bonds between the two carboxyl groups –COOH.J. B. Bossa, P. Theulé, F. Duvernay, F. Borget and T. Chiavassa (2008): "Carbamic acid and carbamate formation in NH3:CO2 ices – UV irradiation versus thermal processes". ''Astronomy and Astrophysics'', volume 492, issue 3, pages 719-724. Carbamic acid could be seen as both an amine and carboxylic acid, and therefore an amino acid;R. K. Khanna and M. H. Moore (1999): "Carbamic acid: molecular structure and IR spectra". ''Spectrochimica Acta Part A: M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitro Group
In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups (). The nitro group is one of the most common explosophores (functional group that makes a compound explosive) used globally. The nitro group is also strongly electron-withdrawing. Because of this property, bonds alpha (adjacent) to the nitro group can be acidic. For similar reasons, the presence of nitro groups in aromatic compounds retards electrophilic aromatic substitution but facilitates nucleophilic aromatic substitution. Nitro groups are rarely found in nature. They are almost invariably produced by nitration reactions starting with nitric acid. Synthesis Preparation of aromatic nitro compounds Aromatic nitro compounds are typically synthesized by nitration. Nitration is achieved using a mixture of nitric acid and sulfuric acid, which produce the nitronium ion (), which is the electrophile: + The nitration product produced on the largest scale, by f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epoxide
In organic chemistry, an epoxide is a cyclic ether, where the ether forms a three-atom ring: two atoms of carbon and one atom of oxygen. This triangular structure has substantial ring strain, making epoxides highly reactive, more so than other ethers. They are produced on a large scale for many applications. In general, low molecular weight epoxides are colourless and nonpolar, and often volatile. Nomenclature A compound containing the epoxide functional group can be called an epoxy, epoxide, oxirane, and ethoxyline. Simple epoxides are often referred to as oxides. Thus, the epoxide of ethylene (C2H4) is ethylene oxide (C2H4O). Many compounds have trivial names; for instance, ethylene oxide is called "oxirane". Some names emphasize the presence of the epoxide functional group, as in the compound ''1,2-epoxyheptane'', which can also be called ''1,2-heptene oxide''. A polymer formed from epoxide precursors is called an ''epoxy''. However, few if any of the epoxy groups i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
