Phosphorus trichloride is a chemical compound of phosphorus and chlorine, having the chemical formula PCl3. It has a trigonal pyramidal shape, it is the most important of the three phosphorus chlorides. It is an important industrial chemical, being used for the manufacture of organophosphorus compounds for a wide variety of applications, it has a 31P NMR signal at around +220 ppm with reference to a phosphoric acid standard. The phosphorus in PCl3 is considered to have the +3 oxidation state and the chlorine atoms are considered to be in the −1 oxidation state. Most of its reactivity is consistent with this description. PCl3 is a precursor to other phosphorus compounds, undergoing oxidation to phosphorus pentachloride, thiophosphoryl chloride, or phosphorus oxychloride. If an electric discharge is passed through a mixture of PCl3 vapour and hydrogen gas, a rare chloride of phosphorus is formed, diphosphorus tetrachloride. Phosphorus trichloride is the precursor to organophosphorus compounds that contain one or more P atoms, most notably phosphites and phosphonates.
These compounds do not contain the chlorine atoms found in PCl3. PCl3 reacts vigorously with water to form phosphorous acid, H3PO3 and HCl: PCl3 + 3 H2O → H3PO3 + 3 HClA large number of similar substitution reactions are known, the most important of, the formation of phosphites by reaction with alcohols or phenols. For example, with phenol, triphenyl phosphite is formed: 3 PhOH + PCl3 → P3 + 3 HClwhere "Ph" stands for phenyl group, -C6H5. Alcohols such as ethanol react in the presence of a base such as a tertiary amine: PCl3 + 3 EtOH + 3 R3N → P3 + 3 R3NH+Cl−In the absence of base, the reaction proceeds with the following stoichiometry to give diethylphosphite: PCl3 + 3 EtOH → 2PH + 2 HCl + EtClSecondary amines form aminophosphines, e.g. trisphosphine. Thiols form P3. An industrially relevant reaction of PCl3 with amines is phosphonomethylation, which employs formaldehyde: R2NH + PCl3 + CH2O → 2PCH2NR2 + 3 HClAminophosphonates are used as sequestring and antiscale agents in water treatment.
The large volume herbicide glyphosate is produced this way. The reaction of PCl3 with Grignard reagents and organolithium reagents is a useful method for the preparation of organic phosphines with the formula R3P such as triphenylphosphine, Ph3P. 3 PhMgBr + PCl3 → Ph3P + 3 MgBrClUnder controlled conditions or with bulky organic groups, similar reactions afford less substituted derivatives such as chlorodiisopropylphosphine. Phosphorus trichloride has a lone pair, therefore can act as a Lewis base, e.g. forming a 1:1 adduct Br3B-PCl3. Metal complexes such as Ni4 are known, again demonstrating the ligand properties of PCl3; this Lewis basicity is exploited in the Kinnear–Perren reaction to prepare alkylphosphonyl dichlorides and alkylphosphonate esters. Alkylation of phosphorus trichloride is effected in the presence of aluminium trichloride give the alkyltrichlorophosphonium salts, which are versatile intermediates: PCl3 + RCl + AlCl3 → RPCl+3 + AlCl−4The RPCl+3 product can be decomposed with water to produce an alkylphosphonic dichloride RPCl2.
World production exceeds one-third of a million tonnes. Phosphorus trichloride is prepared industrially by the reaction of chlorine with a refluxing solution of white phosphorus in phosphorus trichloride, with continuous removal of PCl3 as it is formed. P4 + 6 Cl2 → 4 PCl3Industrial production of phosphorus trichloride is controlled under the Chemical Weapons Convention, where it is listed in schedule 3. In the laboratory it may be more convenient to use the less toxic red phosphorus, it is sufficiently inexpensive. PCl3 is important indirectly as a precursor to PCl5, POCl3 and PSCl3, which are used in many applications, including herbicides, plasticisers, oil additives, flame retardants. For example, oxidation of PCl3 gives POCl3, used for the manufacture of triphenyl phosphate and tricresyl phosphate, which find application as flame retardants and plasticisers for PVC, they are used to make insecticides such as diazinon. Phosphonates include the herbicide glyphosate. PCl3 is the precursor to triphenylphosphine for the Wittig reaction, phosphite esters which may be used as industrial intermediates, or used in the Horner-Wadsworth-Emmons reaction, both important methods for making alkenes.
It can be used to make trioctylphosphine oxide, used as an extraction agent, although TOPO is made via the corresponding phosphine. PCl3 is used directly as a reagent in organic synthesis, it is used to convert primary and secondary alcohols into alkyl chlorides, or carboxylic acids into acyl chlorides, although thionyl chloride gives better yields than PCl3. PCl3 is toxic, with a concentration of 600 ppm being lethal in just a few minutes. PCl3 is classified as toxic and corrosive under EU Directive 67/548/EEC, the risk phrases R14, R26/28, R35 and R48/20 are obligatory. Government agencies in the United States have set occupational exposure limits for PCl3; the Occupational Safety and Health Administration has set a permissible exposure limit at 0.5 ppm over a time-weighted average of 8 hours, while the National Institute for Occupational Safety and Health has set a recommended exposure limit at 0.2 ppm over a time-weighted average of 8 hours. Additionally, PCl3 has been designated IDLH with a maximum exposure limit at 25 ppm.
Phosphorus trichloride was first prepared in 1808 by the French chemists Joseph Louis Gay-Lussac and Louis Jacques Thénard by heatin
In chemistry, recrystallization is a technique used to purify chemicals. By dissolving both impurities and a compound in an appropriate solvent, either the desired compound or impurities can be removed from the solution, leaving the other behind, it is named for the crystals formed when the compound precipitates out. Alternatively, recrystallization can refer to the natural growth of larger ice crystals at the expense of smaller ones. In chemistry, recrystallization is a procedure for purifying compounds; the most typical situation is that a desired "compound A" is contaminated by a small amount of "impurity B". There are various methods of purification that may be attempted, recrystallization being one of them. There are different recrystallization techniques that can be used such as: Typically, the mixture of "compound A" and "impurity B" is dissolved in the smallest amount of hot solvent to dissolve the mixture, thus making a saturated solution; the solution is allowed to cool. As the solution cools the solubility of compounds in solution drops.
This results in the desired compound dropping from solution. The slower the rate of cooling, the bigger the crystals form. In an ideal situation the solubility product of the impurity, B, is not exceeded at any temperature. In that case the solid crystals will consist of pure A and all the impurity will remain in solution; the solid crystals are collected by filtration and the filtrate is discarded. If the solubility product of the impurity is exceeded, some of the impurity will co-precipitate. However, because of the low concentration of the impurity, its concentration in the precipitated crystals will be less than its concentration in the original solid. Repeated recrystallization will result in an purer crystalline precipitate; the purity is checked after each recrystallization by measuring the melting point, since impurities lower the melting point. NMR spectroscopy can be used to check the level of impurity. Repeated recrystallization results in some loss of material because of the non-zero solubility of compound A.
The crystallization process requires an initiation step, such as the addition of a "seed" crystal. In the laboratory a minuscule fragment of glass, produced by scratching the side of the glass recrystallization vessel, may provide the nucleus on which crystals may grow. Successful recrystallization depends on finding the right solvent; this is a combination of prediction/experience and trial/error. The compounds must be more soluble at the higher temperature than at the lower temperatures. Any insoluble impurity is removed by the technique of hot filtration; this method is the same as the above but. This relies on "impurity B" being soluble in a first solvent. A second solvent is added. Either "compound A" or "impurity B" will be insoluble in this solvent and precipitate, whilst the other of "compound A"/"impurity B" will remain in solution, thus the proportion of first and second solvents is critical. The second solvent is added until one of the compounds begins to crystallize from solution and the solution is cooled.
Heating can be used. The reverse of this method can be used where a mixture of solvent dissolves both A and B. One of the solvents is removed by distillation or by an applied vacuum; this results in a change in the proportions of solvent causing either "compound A" or "impurity B" to precipitate. Hot filtration can be used to separate "compound A" from both "impurity B" and some "insoluble matter C"; this technique uses a single-solvent system as described above. When both "compound A" and "impurity B" are dissolved in the minimum amount of hot solvent, the solution is filtered to remove "insoluble matter C"; this matter may be anything from a third impurity compound to fragments of broken glass. For a successful procedure, one must ensure that the filtration apparatus is hot in order to stop the dissolved compounds crystallizing from solution during filtration, thus forming crystals on the filter paper or funnel. One way to achieve this is to heat a conical flask containing a small amount of clean solvent on a hot plate.
A filter funnel is rested on the mouth, hot solvent vapors keep the stem warm. Jacketed filter funnels may be used; the filter paper is preferably fluted, rather than folded into a quarter. It is simpler to do the filtration and recrystallization as two independent and separate steps; that is dissolve "compound A" and "impurity B" in a suitable solvent at room temperature, remove the solvent and recrystallize using any of the methods listed above. Crystallization requires an initiation step; this can be spontaneous or can be done by adding a small amount of the pure compound to the saturated solution, or can be done by scratching the glass surface to create a seeding surface for crystal growth. It is thought that dust particles can act as simple seeds. Growing crystals for X-ray crystallography can be quite difficult. For X-ray analysis, single perfect crystals are required. A small amount of pure compound is used, crystals are allowed to grow slowly. Several techniques can be used to grow these perfect crystals: Slow evaporation of a single solvent - the compound is dissolved in a suitable solvent and the solvent is allowed to evaporate.
Once the solution is saturated crystals can form. Slow evaporation of a multi-solvent system - the same as above, however as the solvent composition changes due to eva
Phosphorus tribromide is a colourless liquid with the formula PBr3. It is a colourless liquid that fumes in moist air has a penetrating odour, it is used in the laboratory for the conversion of alcohols to alkyl bromides. PBr3 is prepared by treating red phosphorus with bromine. An excess of phosphorus is used in order to prevent formation of PBr5: 2 P + 3 Br2 → 2 PBr3Because the reaction is exothermic, it is conducted in the presence of a diluent such as PBr3. Phosphorus tribromide, like PCl3 and PF3, has both properties of a Lewis acid. For example, with a Lewis acid such as boron tribromide it forms stable 1:1 adducts such as Br3B · PBr3. At the same time PBr3 can react as an electrophile or Lewis acid in many of its reactions, for example with amines; the most important reaction of PBr3 is with alcohols, where it replaces an OH group with a bromine atom to produce an alkyl bromide. All three bromides can be transferred. PBr3 + 3 ROH → 3 RBr + HP2The mechanism involves formation of a phosphorus ester, followed by an SN2 substitution.
Because of the SN2 substitution step, the reaction works well for primary and secondary alcohols, but fails for tertiary alcohols. If the reacting carbon centre is chiral, the reaction occurs with inversion of configuration at the alcohol alpha carbon, as is usual with an SN2 reaction. In a similar reaction, PBr3 converts carboxylic acids to acyl bromides. PBr3 + 3 RCOOH → 3 RCOBr + HP2 The main use for phosphorus tribromide is for conversion of primary or secondary alcohols to alkyl bromides, as described above. PBr3 gives higher yields than hydrobromic acid, it avoids problems of carbocation rearrangement- for example neopentyl bromide can be made from the alcohol in 60% yield. Another use for PBr3 is as a catalyst for the α-bromination of carboxylic acids. Although acyl bromides are made in comparison with acyl chlorides, they are used as intermediates in Hell-Volhard-Zelinsky halogenation. PBr3 reacts with the carboxylic acid to form the acyl bromide, more reactive towards bromination; the overall process can be represented as On a commercial scale, phosphorus tribromide is used in the manufacture of pharmaceuticals such as alprazolam and fenoprofen.
It is a potent fire suppression agent marketed under the name PhostrEx. PBr3 evolves corrosive HBr, is toxic, reacts violently with water and alcohols. In reactions that produce phosphorous acid as a by-product, when working up by distillation be aware that this can decompose above about 160 °C to give phosphine which can cause explosions in contact with air. Greenwood, Norman N.. Chemistry of the Elements. Butterworth-Heinemann. ISBN 978-0-08-037941-8. Lide, D. R. ed.. Handbook of Chemistry and Physics. Ann Arbor, MI: CRC Press. ISBN 978-0849304712. March, J.. Advanced Organic Chemistry. New York: Wiley. P. 723. ISBN 978-0471601807. Stecher, P. G. ed.. The Merck Index. Rahway, NJ, USA: Merck & Co. Holmes, R. R.. "An Examination of the Basic Nature of the Trihalides of Phosphorus and Antimony". Journal of Inorganic and Nuclear Chemistry. 12: 266–275. Doi:10.1016/0022-190280372-7
Triphenylphosphine is a common organophosphorus compound with the formula P3 - abbreviated to PPh3 or Ph3P. It is used in the synthesis of organic and organometallic compounds. PPh3 exists as air stable, colorless crystals at room temperature, it dissolves in non-polar organic solvents such as diethyl ether. 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 and sodium.: PCl3 + 3 PhCl + 6 Na → PPh3 + 6 NaClTriphenylphosphine crystallizes in triclinic and monoclinic modification In both cases, the molecule adopts a pyramidal structure with propeller-like arrangement of the three phenyl groups. Triphenylphosphine undergoes slow oxidation by air to give triphenylphosphine oxide, Ph3PO: 2 PPh3 + O2 → 2 OPPh3This impurity can be removed by recrystallisation of PPh3 from either hot ethanol or hot isopropanol; this method capitalizes on the fact that OPPh3 is more polar and hence more soluble in polar solvents than PPh3.
Triphenylphosphine abstracts sulfur from polysulfide compounds and elemental sulfur. Simple organosulfur compounds such as thiols and thioethers are unreactive, however; the phosphorus-containing product is triphenylphosphine sulfide, Ph3PS. This reaction can say vulcanized rubber. Triphenylphosphine selenide, Ph3PSe, may be prepared via treatment of PPh3 with red Se. Salts of selenocyanate, SeCN−, are used as the Se0 source. PPh3 can form an adduct with Te, although this adduct exists as 2Te rather than PPh3Te. Aryl azides react with PPh3 to give analogues of OPPh3, via the Staudinger reaction. Illustrative is the preparation of triphenylphosphine phenylimide: PPh3 + PhN3 → PhNPPh3 + N2The phosphanimine can be hydrolyzed to the amine; the intermediate phosphanimine is not isolated. PPh3 + RN3 + H2O → OPPh3 + N2 + RNH2Cl2 adds to PPh3 to give triphenylphosphine dichloride, which exists as the moisture-sensitive phosphonium halide, This reagent is used to convert alcohols to alkyl chlorides in organic synthesis.
PPh3 does form stable salts with strong acids such as HBr. The product contains the phosphonium cation +. PPh3 is pyramidal with a chiral propeller-like arrangement of the three phenyl rings; the rigidity of PPh3 contributes to the ease. PPh3 is used in organic synthesis; the properties that guide its usage are its nucleophilicity and its reducing character. The nucleophilicity of PPh3 is indicated by its reactivity toward electrophilic alkenes, such as Michael-acceptors, alkyl halides, it is used in the synthesis of biaryl compounds, such as the Suzuki reaction. PPh3 combines with alkyl halides to give phosphonium salts; the facility of the quaternization reaction follows the usual pattern whereby alkyl iodides and benzylic and allylic halides are efficient reactants: PPh3 + CH3I → +I−These salts, which are isolated as crystalline solids, react with strong bases to form ylides: Such ylides are key reagents in the Wittig reactions, used to convert aldehydes and ketones into alkenes. Nickel salts are required to react PPh3 with PhBr to give Br.
The tetraphenylphosphonium cation is used to prepare crystallizable lipophilic salts. In this reaction, a mixture of PPh3 and diisopropyl azodicarboxylate converts an alcohol and a carboxylic acid to an ester; the DIAD is reduced as it serves as the hydrogen acceptor, the PPh3 is oxidized to OPPh3. In this reaction, PPh3 and CX4 are used to convert alcohols to alkyl halides, forming OPPh3 as a byproduct. PPh3 + CBr4 + RCH2OH → OPPh3 + RCH2Br + HCBr3This reaction commences with nucleophilic attack of PPh3 on CBr4, an extension of the quaternization reaction listed above; the easy oxygenation of PPh3 is exploited in its use to deoxygenate organic peroxides, which occurs with retention of configuration: PPh3 + RO2H → OPPh3 + ROH It is used for the decomposition of organic ozonides to ketones and aldehydes, although dimethyl sulfide is more popular for the reaction as the side product, dimethyl sulfoxide is more separated from the reaction mixture than triphenylphosphine oxide. Aromatic N-oxides are reduced to the corresponding amine in high yield at room temperature with irradiation: Sulfonation of PPh3 gives trisphosphine, P3 isolated as the trisodium salt.
In contrast to PPh3, TPPTS is water-soluble. Rhodium complexes of TPPTS are used in certain industrial hydroformylation reactions. Lithium in THF as well as Na or K react with PPh3 to give Ph2PM; these salts are versatile precursors to tertiary phosphines. For example, 1,2-dibromoethane and Ph2PM react to give Ph2PCH2CH2PPh2. Weak acids such ammonium chloride, convert Ph2PM into diphenylphosphine: 2PM + H2O → 2PH + MOH Triphenylphosphine binds well to most transition metals those in the middle and late transition metals of groups 7–10. In terms of steric bulk, PPh3 has a Tolman cone angle of 145°, intermediate between those of P3 and P3. In an early application in homogeneous catalysis, NiBr22 was used by Walter Reppe for the synthesis of acrylate esters from alkynes, carbon monoxide, alcohols. Wilkinson further popularized the use of PPh3, in part through the revolutionary hydroformylation catalyst
Phosphorus mononitride is an inorganic compound with the chemical formula PN. Containing only phosphorus and nitrogen, this material is classified as a binary nitride, it is the first identified phosphorus compound in the interstellar medium. It is the atmospheres of Jupiter and Saturn. Triphosphorus pentanitride
Copper phosphide, Cu3P copper phosphide, cuprous phosphide and phosphor copper, is a compound of copper and phosphorus, a phosphide of copper. It has the appearance of yellowish-grey brittle mass of crystalline structure, it does not react with water. Copper phosphide has a role in copper alloys, namely in phosphor bronze, it is a good deoxidizer of copper. Copper phosphide can be produced in a reverberatory furnace or in a crucible, e.g. by a reaction of red phosphorus with a copper-rich material. It can be prepared photochemically, by irradiating cupric hypophosphite with ultraviolet radiation; when subjected to ultraviolet light, copper phosphide shows fluorescence. A blue-black film of copper phosphide forms on white phosphorus when subjected to a solution of copper salt; the particles can be removed, helped by their fluorescence. Formation of protective layer of copper phosphide is used in cases of phosphorus ingestion, when gastric lavage with copper sulfate is employed as part of the cure
Phosphorus pentabromide is a reactive, yellow solid of formula PBr5, which has the structure PBr4+ Br− in the solid state but in the vapor phase is dissociated to PBr3 and Br2. Rapid cooling of this phase to 15 K leads to formation of the ionic species phosphorus heptabromide, it can be used in organic chemistry to convert carboxylic acids to acyl bromides. It is corrosive, it decomposes above 100 °C to give phosphorus tribromide and bromine: PBr5 → PBr3 + Br2Reversing this equilibrium to generate PBr5 by addition of Br2 to PBr3 is difficult in practice because the product is susceptible to further addition to yield phosphorus heptabromide