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Phosphonium
In polyatomic cations with the chemical formula (where R is a hydrogen or an alkyl, aryl, or halide group). These cations have tetrahedral structures. The salts are generally colorless or take the color of the anions. Types of phosphonium cations Protonated phosphines The parent phosphonium is as found in the iodide salt, phosphonium iodide. Salts of the parent are rarely encountered, but this ion is an intermediate in the preparation of the industrially useful tetrakis(hydroxymethyl)phosphonium chloride: :PH3 + HCl + 4 CH2O → Many organophosphonium salts are produced by protonation of primary, secondary, and tertiary phosphines: :PR3 + H+ → The basicity of phosphines follows the usual trends, with R = alkyl being more basic than R = aryl. Tetraorganophosphonium cations The most common phosphonium compounds have four organic substituents attached to phosphorus. The quaternary phosphonium cations include tetraphenylphosphonium, (C6H5)4P+ and tetramethylphospho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetraphenylphosphonium Chloride
Tetraphenylphosphonium chloride is the chemical compound with the formula (C6H5)4PCl, abbreviated Ph4PCl or PPh4Cl. Tetraphenylphosphonium and especially tetraphenylarsonium salts were formerly of interest in gravimetric analysis of perchlorate and related oxyanions. This colourless salt is used to generate lipophilic salts from inorganic and organometallic anions. Thus, Ph4P+ is useful as a phase-transfer catalyst, again because it allows inorganic anions to dissolve in organic solvents. Structure and basic properties The cation is tetrahedral. PPh4Cl crystallises as the anhydrous salt, which is normal item of commerce, as well as a monohydrate and a dihydrate. In X-ray crystallography, salts are of interest as they often crystallise easily. The rigidity of the phenyl groups facilitates packing and elevates the melting point relative to alkyl-based quaternary ammonium salts. Also, since these salts are soluble in organic media, a wide range of solvents can be employed for their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrakis(hydroxymethyl)phosphonium Chloride
Tetrakis(hydroxymethyl)phosphonium chloride (THPC) is an organophosphorus compound with the chemical formula (CH2OH)4l. The cation P(CH2OH)4+ is four-coordinate, as is typical for phosphonium salts. THPC has applications as a precursor to fire-retardant materials,Svara, Jürgen; Weferling, Norbert ; Hofmann, Thomas. Phosphorus Compounds, Organic. Ullmann's Encyclopedia of Industrial Chemistry. John Wiley & Sons, Inc, 2008 as well as a microbiocide in commercial and industrial water systems. Synthesis and reactions THPC can be synthesized with high yield by treating phosphine with formaldehyde in the presence of hydrochloric acid. :PH3 + 4 H2C=O + HCl → (CH2OH)4l THPC converts to tris(hydroxymethyl)phosphine upon treatment with aqueous sodium hydroxide: : (CH2OH)4l + NaOH → P(CH2OH)3 + H2O + H2C=O + NaCl Application in textiles THPC has industrial importance in the production of crease-resistant and flame-retardant finishes on cotton textiles and other cellulosic fabrics. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wittig Reagents
In organic chemistry, Wittig reagents are organophosphorus compounds of the formula R3P=CHR', where R is usually phenyl. They are used to convert ketones and aldehydes to alkenes: : Preparation Because they typically hydrolyze and oxidize readily, Wittig reagents are prepared using air-free techniques. They are typically generated and used in situ. THF is a typical solvent. Some are sufficiently stable to be sold commercially. ;Formation of phosphonium salt Wittig reagents are usually prepared from a phosphonium salt, which is in turn prepared by the quaternization of triphenylphosphine with an alkyl halide. Wittig reagents are usually derived from a primary alkyl halide. Quaternization of triphenylphosphine with secondary halides is typically inefficient. For this reason, Wittig reagents are rarely used to prepare tetrasubstituted alkenes. ;Bases for deprotonation of phosphonium salts The alkylphosphonium salt is deprotonated with a strong base such as ''n''-butyllithium: : ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Michaelis–Arbuzov Reaction
The Michaelis–Arbuzov reaction (also called the Arbuzov reaction) is the chemical reaction of a trivalent phosphorus ester with an alkyl halide to form a pentavalent phosphorus species and another alkyl halide. The picture below shows the most common types of substrates undergoing the Arbuzov reaction; phosphite esters (1) react to form phosphonates (2), phosphonites (3) react to form phosphinates (4) and phosphinites (5) react to form phosphine oxides (6). The reaction was discovered by August Michaelis in 1898, and greatly explored by Aleksandr Arbuzov soon thereafter. This reaction is widely used for the synthesis of various phosphonates, phosphinates, and phosphine oxides. Several reviews have been published. The reaction also occurs for coordinated phosphite ligands, as illustrated by the demethylation of 2+ to give −, which is called the Klaui ligand. Reaction mechanism center, 600px, The mechanism of the Michaelis–Arbuzov reaction The Michaelis–Arbuzov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylphosphine
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether. Preparation and structure Triphenylphosphine can be prepared in the laboratory by treatment of phosphorus trichloride with phenylmagnesium bromide or phenyllithium. The industrial synthesis involves the reaction between phosphorus trichloride, chlorobenzene, and sodium: :PCl3 + 3 PhCl + 6 Na → PPh3 + 6 NaCl Triphenylphosphine crystallizes in triclinic and monoclinic modification. In both cases, the molecule adopts a pyramidal structure with propeller-like arrangement of the three phenyl groups. Principal reactions with chalcogens, halogens, and acids Oxidation Triphenylphosphine undergoe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyltriphenylphosphonium Bromide
Methyltriphenylphosphonium bromide is the organophosphorus compound with the formula C6H5)3PCH3r. It is the bromide salt of a phosphonium cation. It is a white salt that is soluble in polar organic solvents. Synthesis and reactions Methyltriphenylphosphonium bromide is produced by treating triphenylphosphine with methyl bromide Bromomethane, commonly known as methyl bromide, is an organobromine compound with formula C H3 Br. This colorless, odorless, nonflammable gas is produced both industrially and biologically. It has a tetrahedral shape and it is a recognized ozo ...: :Ph3P + CH3Br → Ph3PCH3Br Methyltriphenylphosphonium bromide is the principal precursor to methylenetriphenylphosphorane, a useful methylenating reagent. This conversion is achieved by treating methyltriphenylphosphonium bromide with strong base.{{cite journal, doi = 10.1080/00397918508063883, title = The Wittig Reaction Using Potassium-tert-butoxide High Yield Methylenations of Sterically Hindered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylphosphine Dichloride
Triphenylphosphine dichloride, Ph3PCl2, is a chlorinating agent widely used in organic chemistry. Applications include the conversion of alcohols and ethers to alkyl chlorides, the cleavage of epoxides to vicinal dichlorides and the chlorination of carboxylic acids to acyl chlorides. Structure In polar solvents such as acetonitrile, Ph3PCl2 adopts an ionic phosphonium salt structure, h3PCl+l−, whereas in non-polar solvents like diethyl ether it exists as a non-solvated trigonal bipyramidal molecule. Two h3PCl+species can also adopt an unusual dinuclear ionic structure—both interacting with a Cl− via long Cl–Cl contacts. File:Chlorotriphenylphosphonium-chloride-2D.png File:Chlorotriphenylphosphonium-chloride-DCM-solvate-from-xtal-3D-balls.png File:Chlorotriphenylphosphonium-chloride-DCM-solvate-from-xtal-3D-vdW.png Synthesis Triphenylphosphine dichloride is usually prepared fresh by the addition of chlorine to triphenylphosphine. :Ph3P + Cl2 → Ph3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphonium Iodide
Phosphonium iodide is a chemical compound with the formula . It is an example of a salt containing an unsubstituted phosphonium cation (). Phosphonium iodide is commonly used as storage for phosphine and as a reagent for substituting phosphorus into organic molecules. Preparation Phosphonium iodide is prepared by mixing diphosphorus tetraiodide () with elemental phosphorus and water at 80 °C and allowing the salt to sublime. Properties Structure Its crystal structure has the tetragonal space group P4/nmm, which is a distorted version of the NH4Cl crystal structure; the unit cell has approximate dimensions 634×634×462 pm. The hydrogen bonding in the system causes the cations to orient such that the hydrogen atoms point toward the anions. Chemical At 62 °C and atmospheric pressure, phosphonium iodide sublimates and dissociates reversibly into phosphine and hydrogen iodide (HI). It oxidizes slowly in air to give iodine and phosphorus oxides; it is hygroscopi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetramethylphosphonium Bromide
Tetramethylphosphonium bromide is an organophosphorus compound with the formula (CH3)4PBr. It is a white, water-soluble solid, the salt of the cation tetramethylphosphonium and the bromide anion. It is prepared by treating trimethylphosphine with methyl bromide Bromomethane, commonly known as methyl bromide, is an organobromine compound with formula C H3 Br. This colorless, odorless, nonflammable gas is produced both industrially and biologically. It has a tetrahedral shape and it is a recognized ozo .... Reactions Deprotonation gives methylenetrimethylphosphine ylide, which can sustain a second deprotonation: :(CH3)4PBr + BuLi → CH3)3P=CH2 + LiBr + BuH :CH3)3P=CH2 + BuLi → CH3)2P(CH2)2Li + BuH The latter is a precursor to many coordination complexes, e.g., the dicuprous complex Cu2 Me2P(CH2)2sub>2.{{cite journal, author=Schmidbaur, H., title=Phosphorus Ylides in the Coordination Sphere of Transition Metals: An Inventory, journal=Angewandte Chemie Interna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphine
Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting fish, due to the presence of substituted phosphine and diphosphane (). With traces of present, is spontaneously flammable in air (pyrophoric), burning with a luminous flame. Phosphine is a highly toxic respiratory poison, and is immediately dangerous to life or health at 50 ppm. Phosphine has a trigonal pyramidal structure. Phosphines are compounds that include and the organophosphines, which are derived from by substituting one or more hydrogen atoms with organic groups. They have the general formula . Phosphanes are saturated phosphorus hydrides of the form , such as triphosphane. Phosphine, PH3, is the smallest of the phosphines and the smallest of the phosphanes. History Philippe Gengembre (1764–1838), a student of Lavoisie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quaternary Compound
In chemistry, a quaternary compound is a compound consisting of exactly four chemical elements. In another use of the term in organic chemistry, a quaternary compound is or has a cation consisting of a central positively charged atom with four substituents, especially organic (alkyl and aryl) groups, discounting hydrogen atoms. The best-known quaternary compounds are quaternary ammonium salts, having a nitrogen atom at the centre. For example, in the following reaction, the nitrogen atom is said to be quaternized as it has gone from 3 to 4 substituents: :R3N + RCl -> R4N+Cl- Other examples include substituted phosphonium salts (), substituted arsonium salts () like arsenobetaine, as well as some arsenic-containing superconductors. Substituted stibonium () and bismuthonium salts () have also been described. See also *Binary compound In materials chemistry, a binary phase or binary compound is a chemical compound containing two different elements. Some binary phase com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorus Pentachloride
Phosphorus pentachloride is the chemical compound with the formula PCl5. It is one of the most important phosphorus chlorides, others being PCl3 and POCl3. PCl5 finds use as a chlorinating reagent. It is a colourless, water-sensitive and moisture-sensitive solid, although commercial samples can be yellowish and contaminated with hydrogen chloride. Structure The structures for the phosphorus chlorides are invariably consistent with VSEPR theory. The structure of PCl5 depends on its environment. Gaseous and molten PCl5 is a neutral molecule with trigonal bipyramidal geometry and (''D''3h) symmetry. The hypervalent nature of this species (as well as of , see below) can be explained with the inclusion of non-bonding molecular orbitals ( molecular orbital theory) or resonance ( valence bond theory). This trigonal bipyramidal structure persists in nonpolar solvents, such as CS2 and CCl4. In the solid state PCl5 is an ionic compound, formulated . In solutions of polar s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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