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Pyridine

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	Pyridine
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	Topics Pyridine Topic Home Pyridine is a chemical compoundChemical compound Overview A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a ... with the formula C₅Carbon Carbon is a chemical element in the periodic table that has the symbol C and atomic number 6.... H₅Hydrogen \|-\| Triple point \|\| 13.8033 K, 7.042 kPa... NNitrogen Nitrogen is a chemical element which has the symbol N and atomic number 7 in the periodic table.... . It is a liquid with a distinctively putrid, fish-like odour. Pyridine is a simple and fundamentally important heterocyclic aromatic organic compoundOrganic compound An organic compound is any member of a large class of chemical compounds whose molecules contain carbon and hydrogen; theref... . It is structurally related to benzeneBenzene Benzene, also known as benzol, is an organic chemical compound with the formula C6H6.... , wherein one CH group in the six-membered ring is replaced by a nitrogenNitrogen Nitrogen is a chemical element which has the symbol N and atomic number 7 in the periodic table.... atom. The pyridine ring occurs in many important compounds, including the nicotinamideNicotinamide Summary Nicotinamide, also known as niacinamide and nicotinic acid amide, is the amide of nicotinic acid .... s. Pyridine is sometimes used as a ligandLigand In chemistry, a ligand is an atom, ion, or molecule that generally donates one or more of its electrons through a coordinat... in coordination chemistry. As a ligand, it is usually abbreviated "py". Basicity The nitrogen atom on pyridine features a basic lone pairLone pair A lone pair is an electron pair without bonding or sharing with other atoms.... of electronElectron The electron is a fundamental subatomic particle that carries an electric charge.... s. Because this lone pair is not delocalized into the aromatic pi-system, pyridine is basicBase (chemistry) DefinitionA base is a substance which has a free pair of electrons to bind a proton .... with chemical properties similar to tertiary amines. The pKaPKA PKA or pKa may be:* PKA, an acronym for Previously Known As... of the conjugate acidConjugate acid Within the Brnsted-Lowry theory of acids and bases, a conjugate acid is the acid member, HX, of a pair of two compounds tha... is 5.21. Pyridine is protonatedProtonation Protonation is the addition of a proton to an atom, molecule, or ion.... by reactionChemical reaction A chemical reaction is a process that results in the interconversion of chemical substances .... with acidAcid An acid is traditionally considered any chemical compound that when dissolved in water, gives a solution with a pH of less ... s and forms a positively charged aromatic polyatomic ionFacts About Polyatomic ion A polyatomic ion is an ion consisting of a molecule with covalently bonded atoms or of a metal complex that can be considere... called pyridiniumPyridinium Pyridinium refers to the cationic form of pyridine.... cation. The bond lengthBond length Bond length or bond distance in molecular geometry is the distance between two bonded atoms in a molecule.... s and bond angles in pyridine and the pyridinium ion are almost identical because protonation does not disrupt the aromatic pi system. In addition, the pyridinium cation is isoelectronic with benzene. Pyridine as a solvent Pyridine is a widely used and versatile solventSolvent A solvent is a fluid phase that dissolves a solid, liquid, or gaseous solute, resulting in a solution.... : it is polar but aproticProtic solvent Overview In chemistry any solvent that carries hydrogen attached to oxygen as in a hydroxyl group, nitrogen as in an amine group, or, more ... . It is miscible with a broad range of solvents including hexaneFacts About Hexane Hexane is an alkane hydrocarbon with the chemical formula CH34CH3.... and waterWater Water is a tasteless, odorless substance that is essential to all known forms of life and is known as the universal solve... . Deuterated pyridine, called pyridine-d₅, is a common solvent for¹H NMR spectroscopyNMR spectroscopy Nuclear Magnetic Resonance Spectroscopy most commonly known as NMR Spectroscopy is the name given to the technique whi... . Role in chemical synthesis Pyridine is important in industrial chemistry, both as a fundamental building block and as a solvent and reagent in organic synthesisOrganic synthesis Organic synthesis is the construction of organic molecules via chemical processes.... . It is used as a solvent in Knoevenagel condensationKnoevenagel condensation The Knoevenagel condensation reaction is an organic reaction named after Emil Knoevenagel.... s. It is also a starting material in the synthesis of compounds used as an intermediate in making insecticides, herbicides, pharmaceuticals, food flavorings, dyeDye A dye can generally be described as a colored substance that has an affinity to the to which it is being applied.... s, rubberRubber Rubber is an elastic hydrocarbon polymer which occurs as a milky emulsion in the sap of several varieties of plants.... chemicals, adhesiveAdhesive An adhesive is a compound that adheres or bonds two items together.... s, paintPaint Paint is the general term for a family of products used to protect and add color to an object or surface by covering it with... s, explosives and disinfectants. Pyridine is also used as a denaturant for antifreezeAntifreeze Antifreeze is a water-based liquid coolant used in gasoline and diesel engines.... mixtures, for ethyl alcohol, for fungicideFungicide A Fungicide is one of three main methods of pest control- chemical control of fungi in this case.... s, and as a dyeingDyeing Dyeing is the process of changing the colour of a yarn or cloth by treatment with a dye.... aid for textiles. Role in chemical analysis Pyridine, along with barbituric acidBarbituric acid Barbituric acid or malonylurea or 4-hydroxyuracyl is an organic compound based on a pyrimidine heterocyclic skel... , is commonly used in colorimetric determinations of cyanideCyanide A cyanide is any chemical compound that contains the cyano group -C=N, with the carbon atom triple-bonded to the nitro... in aqueousAqueous Aqueous means pertaining to, related to, similar to, or dissolved in water.... matrices. Pyridine reacts with cyanogen chloride (formed in an earlier step by reaction of the cyanide anion with chloramine-TChloramine-T N-chloro tosylamide sodium salt, sold as chloramine-T, is a N-chlorinated and N-deprotonated sulfonamide ... ) to form a conjugated species that couples two molecules of barbituric acid together, forming a red-colored dye. Color intensity is directly proportional to cyanide concentration. Pyridine was originally used as the base in the Karl Fischer titrationKarl Fischer titration Karl Fischer titration is a classic titration method in analytical chemistry that uses coulometric or volumetric titration t... , but has since been largely replaced by imidazoleImidazole Imidazole is a heterocyclic aromatic organic compound.... , which is more basic than pyridine, allowing for a more stable equivalence pointEquivalence point Equivalence point occurs during a chemical titration when the amount of titrant added is equivalent, or equal, to the amount... and a faster reaction rateReaction rate The reaction rate for a reactant or product in a particular reaction is defined as the amount of the chemical that is formed... . Imidazole also has the advantage of being odorless. Preparation and occurrence Many methods exist in industry and in the laboratory (some of them named reactions) for the synthesis of pyridine and its derivatives: Pyridine was originally isolated industrially from crude coal tarCoal tar Coal tar is the liquid by-product of the distillation of coal to make coke.... . It is currently synthesizedChemical synthesis In chemistry, chemical synthesis is purposeful execution of chemical reactions in order to get a product, or several product... from acetaldehydeAcetaldehyde Acetaldehyde, systematically known as ethanal, is an organic chemical compound.... , formaldehydeFormaldehyde The chemical compound formaldehyde , is a gas with a pungent smell.... and ammoniaFacts About Ammonia Ammonia is a compound of nitrogen and hydrogen with the formula NH3.... , a process that involves the intermediacy of acroleinAcrolein In organic chemistry, acrolein or propenal is the simplest unsaturated aldehyde.... : CH₂O + NH₃ + 2 CH₃CHO ? C₅H₅N + 3 H₂O By substituting other aldehydes for acetaldehyde, one obtains alkyl and aryl substituted pyridines. 26,000 tons were produced worldwide in 1989. The Hantzsch pyridine synthesisHantzsch pyridine synthesis The Hantzsch pyridine synthesis or Hantzsch dihydropyridine synthesis is a multi-component organic reaction between an... is a multicomponent reaction involving formaldehyde, a keto-ester and a nitrogen donor. Other examples of the pyridine class can be formed by the reaction of 1,5-diketoneKetone A ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a chemical co... s with ammonium acetateAmmonium acetate Ammonium acetate is CH3COONH4. This salt is derived from the reaction of ammonia and acetic acid.It is widely available com... in acetic acidAcetic acid Summary Acetic acid, also known as ethanoic acid, is an organic chemical compound best recognized for giving vinegar its sour ... followed by oxidation. This reaction is called the Kröhnke pyridine synthesis. Pyridinium salts can be obtained in the Zincke reactionZincke reaction The Zincke reaction is an organic reaction in which a pyridine is transformed into a pyridinium salt by reaction with 2,4-di... . The Ciamician-Dennstedt Rearrangement (1881) is the ring-expansion of pyrrolePyrrole Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H5N.... with dichlorocarbeneDichlorocarbene Dichlorocarbene is a carbene commonly encountered in organic chemistry.... to 3-chloropyridine and HCl In the Chichibabin pyridine synthesisChichibabin pyridine synthesis The Chichibabin pyridine synthesis is a method for synthesizing pyridine rings.... the reactants are three equivalents of a linear aldehydeAldehyde An aldehyde is an organic compound containing... and ammoniaAmmonia Ammonia is a compound of nitrogen and hydrogen with the formula NH3.... In the Gattermann-Skita synthesis (1916) a malonate ester salt reacts with dichloromethylamine Organic reactions In organic reactionOrganic reaction Organic reactions are chemical reactions involving organic compounds.... s pyridine behaves both as a tertiary amineAmine Amines are organic compounds and a type of functional group that contain nitrogen as the key atom.... , undergoing protonationFacts About Protonation Protonation is the addition of a proton to an atom, molecule, or ion.... , alkylationAlkylation Alkylation is the transfer of an alkyl group from one molecule to another.... , acylationAcylation In chemistry, acylation is the process of adding an acyl group to a compound.... , and N-oxidation at nitrogen, and as an aromatic compoundAromatic compound Aromatic compound has different meanings depending on the context:... , undergoing Nucleophilic substitutionNucleophilic substitution In chemistry, nucleophilic substitution is a class of substitution reaction in which an electron-rich nucleophile attacks a ... s. Pyridine is a good nucleophileNucleophile In chemistry, a nucleophile is a reagent that forms a chemical bond to its reaction partner by donating both bonding elect... with a donor numberDonor number In chemistry a donor number or DN is a qualitative measure of lewis basicity.... of 33.1. It is easily attacked by alkylating agents to give N-alkylpyridinium salts. Nucleophilic aromatic substitutionNucleophilic aromatic substitution A nucleophilic substitution is a substitution reaction in organic chemistry in which the nucleophile displaces a good leavi... occurs at C2/C4. For example in the Chichibabin reactionChichibabin reaction The Chichibabin reaction is a method for producing 2-aminopyridine derivatives by the reaction of pyridine with sodium amide... , pyridine reacts with sodium amideSodium amide Sodium amide, also called sodamide, is NaNH2.... to give 2-aminopyridine. In the Emmert reaction pyridine reacts with a ketoneFacts About Ketone A ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a chemical co... in presence of aluminiumAluminium Aluminium or aluminum is the chemical element in the periodic table that has the symbol Al and atomic number 13... or magnesiumMagnesium Magnesium is the chemical element in the periodic table that has the symbol Mg and atomic number 12 and an atomic mass... and mercuric chloride to give the carbinol also at C2. Safety and environmental The LD₅₀ in rats (oral) is 891 mg kg^–1. It is volatile and can be absorbed through skin. Available data indicate that "exposure to pyridine in drinking-water led to reduction of sperm motility at all dose levels in mice and increased estrous cycle length at the highest dose level in rats". Currently its evaluations as a possible carcinogenic agent showed there is inadequate evidence in humans for the carcinogenicity of pyridine, albeit there is limited evidence of carcinogenic effects on animals. Effects of an acute pyridine intoxication include dizziness, headache, nausea and anorexia. Further symptoms include abdominal pain and pulmonary congestion. Although resistant to oxidation, pyridine is readily degraded by bacteria to ammonia and carbon dioxide. Derivatives Pyridine-boraneBorane A borane is an inorganic chemical compound of boron and hydrogen.... , C₅H₅NBH₃ (m.p. 10–11 °C) is a mild reducing agent with improved stability relative to NaBH₄ in protic solvents and improved solubility in aprotic organic solvents. Pyridine-sulfur trioxideSulfur trioxide pyridine complex Sulfur trioxide pyridine complex is a complex formed where the lone pair on the nitrogen of the pyridine binds to the sulfur... , C₅H₅NSO₃ (mp 175 °C) is a sulfonation agent used to convert alcohols to sulfonates, which in turn undergo C-O bond scission upon reduction with hydride agents. Related compounds Structurally or chemically related compounds are DMAP is short for 4-dimethylaminopyridine BipyridineFacts About Bipyridine Bipyridine is one of the simplest polypyridine compounds.... and viologenViologen The Viologens are diquaternary derivatives of 4,4'-bipyridyl.... are simple polypyridine compounds consisting of two pyridine molecules joined by a single bond TerpyridineTerpyridine In chemistry, terpyridine is a polypyridine compound in which three pyridine molecules are bound with a single bond.... , a molecule of three pyridine rings connected together by two single bonds. QuinolineQuinoline Quinoline, also known as 1-azanaphthalene, 1-benzazine, or benzo[b]pyridine, is a heterocyclic aromatic or... and IsoquinolineIsoquinoline Overview Isoquinoline, also known as benzo[c]pyridine or 2-benzanine, is a heterocyclic aromatic organic compound.... have pyridine and a benzene ring fused together. AnilineAniline Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2.... is a benzene derivative with an attached NH₂ group and NOT a pyridine DiazineDiazine Diazine refers to a group of organic compounds having the molecular formula C4H4N2.... s are compounds with one more carbon replaced by nitrogen such as PyrazinePyrazine Pyrazine is a symmetrical molecule. it is found in vitamin B-10 in the form of pteridine.... and Pyramidine TriazineTriazine A triazine is one of three organic chemicals, isomeric with each other, whose empirical formula is 333.... s are compounds with two more carbons replaced by nitrogen and a tetrazineTetrazine Tetrazine is the hypothetical compound that consists of a six-membered aromatic ring containing four nitrogen atoms with the... has four nitrogen atoms 2,6-Lutidine2,6-Lutidine Overview 2,6-Lutidine is a natural heterocyclic aromatic organic compound.... is a trivial name for 2,6-dimethylpyridine. Collidine is the trivial name for 2,4,6-trimethylpyridine. Pyridinium p-toluenesulfonate (PPTS) is a salt formed by proton exchange between pyridine and p-toluenesulfonic acidP-Toluenesulfonic acid Toluenesulfonic acid, or tosic acid,, is the organic compound with the formula CH3C6H4SO3H.... 2-Chloropyridine is a toxic environmentally significant component of the breakdown of the pesticide imidaclopridImidacloprid Imidacloprid-N-nitroimidazolidin-2-ylideneamine) is an insecticide manufactured by Bayer Cropscience.... . See also Simple aromatic ringSimple aromatic ring Simple aromatic rings are aromatic organic compounds that consist only of conjugated planar ring systems with delocalized pi... s 6-Membered aromatic rings with one carbon replaced by another group: borabenzeneBorabenzene A borabenzene is a heteroaromatic compound that has a boron atom instead of the carbon atom of a benzene molecule.... , silabenzeneSilabenzene Silabenzene is a heteroaromatic compound containing a silicon atom instead of the carbon atom in benzene, so silabenzene has... , germanabenzeneGermanabenzene Germanabenzene is the parent representative of a group of chemical compounds containing in their molecular structure a benze... , stannabenzeneStannabenzene Stannabenzene is the parent representative of a group of chemical compounds containing in their molecular structure a benzen... , phosphorinePhosphorine Phosphorine is a heavy benzene containing a phosphorus atom instead of a CH moiety, so it is considered to be a heavier elem... , pyrylium saltPyrylium salt A pyrylium compound is a conjugated 6 membered carbon ring system with one carbon atom replaced by a positively charged oxyg... 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