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Hantzsch Ester
Hantzsch ester refers to an organic compound with the formula HN(MeC=C(CO2Et))2CH2 where Me = methyl (CH3) and Et = ethyl (C2H5). It is a colorless solid. The compound is an example of a 1,4- dihydropyridine. It is named after Arthur Rudolf Hantzsch who described its synthesis in 1881. The compound is a hydride donor, e.g., for reduction of imines to amines. It is a synthetic analogue of NADH, a naturally occurring dihydropyridine. Preparation Hantzsch ester can be made with a Hantzsch pyridine synthesis where formaldehyde, two equivalents of ethyl acetoacetate and ammonium acetate are combined to afford the product in high yield. Structure As confirmed by X-ray crystallography, Hantzsch ester has a planar C5N core. Further reading * See also * Hantzsch pyrrole synthesis The Hantzsch Pyrrole Synthesis, named for Arthur Rudolf Hantzsch, is the chemical reaction of β-ketoesters (1) with ammonia (or primary amines) and α-haloketones (2) to give substituted pyrroles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonium Acetate
Ammonium acetate, also known as spirit of Mindererus in aqueous solution, is a chemical compound with the formula NH4CH3CO2. It is a white, hygroscopic solid and can be derived from the reaction of ammonia and acetic acid. It is available commercially. Uses It is the main precursor to acetamide: :NH4CH3CO2 → CH3C(O)NH2 + H2O It is also used as a diuretic. Buffer As the salt of a weak acid and a weak base, ammonium acetate is often used with acetic acid to create a buffer solution. Ammonium acetate is volatile at low pressures. Because of this, it has been used to replace cell buffers that contain non-volatile salts in preparing samples for mass spectrometry. It is also popular as a buffer for mobile phases for HPLC with ELSD detection for this reason. Other volatile salts that have been used for this include ammonium formate. When dissolving ammonium acetate in pure water, the resulting solution typically has a pH of 7, because the equal amounts of acetate and ammonium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterocycle Forming Reactions
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different chemical element, elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of these 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 heterocyclic chemistry focuses especially on unsaturated derivatives, and the preponderance of work and applications involves unstrained 5- and 6-membered rings. Included are pyridine, thiophene, pyrrole, and furan. Another large class of heterocycles refers to those fused to benzene rings. For example, the fused benzene derivatives of pyridine, thiophene, pyrrole, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyridine Forming Reactions
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow, due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. As of 2016, it is synthesized on the scale of about 20,000 tons per year worldwide. Properties Physical properties The molecular electric dipole moment is 2.2 debyes. Pyridine is diamagnetic and has a diamagnetic susceptibility of −48.7 × 10−6 cm3·mol−1. The standard enthalpy of formation is 100.2 kJ·mol−1 in the liquid ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hantzsch Pyrrole Synthesis
The Hantzsch Pyrrole Synthesis, named for Arthur Rudolf Hantzsch, is the chemical reaction of β-ketoesters (1) with ammonia (or primary amines) and α-haloketones (2) to give substituted pyrroles (3). Pyrroles are found in a variety of natural products with biological activity, so the synthesis of substituted pyrroles has important applications in medicinal chemistry. Alternative methods for synthesizing pyrroles exist, such as the Knorr pyrrole synthesis, Knorr Pyrrole Synthesis and Paal-Knorr Synthesis. Mechanism Below is one published mechanism for the reaction: The mechanism starts with the amine (1) attacking the β carbon of the β-ketoesters (2), and eventually forming an enamine (3). The enamine then attacks the carbonyl carbon of the α-haloketone (4). This is followed by the loss of H2O, giving an imine (5). This intermediate undergoes an intramolecular nucleophilic attack, forming a 5-membered ring (6). Finally, a hydrogen is eliminated and the pi-bonds are r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemische Berichte
''Chemische Berichte'' (usually abbreviated as ''Ber.'' or ''Chem. Ber.'') was a German-language scientific journal of all disciplines of chemistry founded in 1868. It was one of the oldest scientific journals in chemistry, until it merged with ''Recueil des Travaux Chimiques des Pays-Bas'' to form ''Chemische Berichte/Recueil'' in 1997. ''Chemische Berichte/Recueil'' was then merged with other European journals in 1998 to form ''European Journal of Inorganic Chemistry''. History Founded in 1868 as ''Berichte der Deutschen Chemischen Gesellschaft'' (, CODEN BDCGAS), it operated under this title until 1928 (Vol. 61). The journal was then split into: * ''Berichte der Deutschen Chemischen Gesellschaft, A: Vereins-Nachrichten'' (, CODEN BDCAAS), and * ''Berichte der Deutschen Chemischen Gesellschaft, B: Abhandlungen'' (, CODEN BDCBAD). Vol. 78 and 79 (1945–1946) were omitted and not published due to World War II. The journal was renamed ''Chemische Berichte'' (, CODEN CHBEAM) in 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information. Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic, and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among various mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethyl Acetoacetate
The organic compound ethyl acetoacetate (EAA) is the ethyl ester of acetoacetic acid. It is a colorless liquid. It is widely used as a chemical intermediate in the production of a wide variety of compounds. It is used as a flavoring for food. Preparation Ethyl acetoacetate is produced industrially by treatment of diketene with ethanol. The preparation of ethyl acetoacetate is a classic laboratory procedure. It is prepared via the Claisen condensation of ethyl acetate. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol. : Reactivity Acidity Ethyl acetoacetate is diprotic: :CH3C(O)CH2CO2Et + NaH → CH3C(O)CH(Na)CO2Et + H2 :CH3C(O)CH(Na)CO2Et + BuLi → LiCH2C(O)CH(Na)CO2Et + BuH Keto-enol tautomerism Ethyl acetoacetate is subject to keto-enol tautomerism. In the neat liquid at 33 °C, the enol consists of 15% of the total. Multicarbon building block Ethyl acetoacetic acid is a building block in organic synthesis since the protons alp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl
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] |
Formaldehyde
Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section Forms below), hence it is stored as an aqueous solution (formalin), which is also used to store animal specimens. It is the simplest of the aldehydes (). The common name of this substance comes from its similarity and relation to formic acid. Formaldehyde is an important precursor to many other materials and chemical compounds. In 1996, the installed capacity for the production of formaldehyde was estimated at 8.7 million tons per year. It is mainly used in the production of industrial resins, e.g., for particle board and coatings. Forms Formaldehyde is more complicated than many simple carbon compounds in that it adopts several diverse forms. These compounds can often be used interchangeably and can be interconverted. *Molecular formald ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hantzsch Pyridine Synthesis
The Hantzsch pyridine synthesis or Hantzsch dihydropyridine synthesis is a multi-component organic reaction between an aldehyde such as formaldehyde, 2 equivalents of a β-keto ester such as ethyl acetoacetate and a nitrogen donor such as ammonium acetate or ammonia. The initial reaction product is a dihydropyridine which can be oxidized in a subsequent step to a pyridine. The driving force for this second reaction step is aromatization. This reaction was reported in 1881 by Arthur Rudolf Hantzsch. A 1,4-dihydropyridine dicarboxylate is also called a 1,4-DHP compound or a Hantzsch ester. These compounds are an important class of calcium channel blockers and as such commercialized in for instance nifedipine, amlodipine or nimodipine. The reaction has been demonstrated to proceed in water as reaction solvent and with direct aromatization by ferric chloride, manganese dioxide or potassium permanganate in a one-pot synthesis. The Hantzsch dihydropyridine synthesis has been eff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
