Patent GB-707961-A (GB)
Title: Improvements in or relating to the production of organic phosphorus compounds
Inventor: PERREN EDWARD ARTHUR
IPC: C07F9/42
Filed: 1948-04-30
Abstract: Organic phosphonyl dichlorides are obtained by additively combining an organic chloride of the formula RCl in which R is an alkyl, cycloalkyl or aralkyl radical, or an alkenyl radical containing at least three carbon atoms, or a chloroalkyl radical, with phosphorus trichloride or a monoalkoxy phosphorus dichloride in the presence of anhydrous aluminium trichloride, and subjecting the resulting aluminium complex compound to decomposition by controlled hydrolysis. The process may be carried out in a modified form by first forming an organic chloride RCl in which R is an alkyl or chloroalkyl radical and a monoalkoxy or monochloroalkoxy phosphorus dichloride by reacting phosphorus trichloride and a dialkyl ether (or a sym.-dichlorodialkyl ether) in the presence of anhydrous aluminium chloride and then allowing the reaction to proceed to form the aluminium complex compound which is then subjected to decomposition by controlled hydrolysis.  In another modification adapted for the production of an ester of a phosphonic acid the aluminium complex compound formed by reacting the organic chloride RCl with phosphorus trichloride or a monoalkoxy phosphorus dichloride in the presence of anhydrous aluminium chloride is treated with an alcohol, e.g. by the addition of an excess of ethyl alcohol, and the product then decomposed with water.  The radical R in the first-mentioned formula RCl may be methyl, ethyl, n-propyl, isopropyl, n-, iso-, secondary- and tertiary-butyl, cetyl (hexadecyl), phenymethyl, and cyclohexyl. R also includes higher alkane radicals, thus the compound RCl may be a chlorinated paraffin hydrocarbon of an indefinite composition such as chlorinated white spirit or chlorinated paraffin wax.  The term "chloroalkyl" includes polychlorinated methyl radicals but only includes higher radicals than methyl containing one chlorine atom. The process may be carried out by using the compound RCl and phosphorus trichloride in substantially equimolecular proportions a slight excess of the compound RCl being preferably used in the presence of at least one molecular proportion of aluminium chloride, but it is preferred to use two molecular proportions of aluminium chloride.  The preparation of the complex is preferably carried out at room temperature although heating may be necessary to complete the reaction.  When one or both of the reactants have a relatively high vapour pressure at room temperature the process may be carried out under pressure.  The hydrolysis is carried out in a controlled manner advantageously at low temperature, e.g. in the neighbourhood of 0 DEG C. or somewhat lower, the complex as such or dissolved or suspended in a suitable solvent such as methylene chloride being decomposed by the addition of water which may, if desired, be in the form of ice or an emulsion or solution in an inert solvent.  In an alternative method of hydrolysis the reaction conditions are selected so that the complex is in liquid form and is then hydrolysed by passing it through an aqueous zone, e.g. a layer of crushed ice, accompanied by a stream of heavy inert solvent which dissolves the hydrolysis product.  It is stated that further hydrolysing of the product may result in the formation of a phosphinic acid and finally of a phosphonic acid. In examples: (1) to (15) phosphorus trichloride is used with the following organic chlorides: (1) and (4) ethyl chloride to yield ethyl phosphonyl dichloride; (2) isopropyl chloride to yield isopropylphosphonyl dichloride; (3) and (5) methyl chloride to yield methylphosphonyl dichloride; (6) isobutyl chloride to yield tert.-butyl phosphonyl dichloride; (7) cetyl chloride (n-hexadecyl chloride) to yield sec.-hexadecyl phosphonyl dichloride; (8) chlorocyclohexane to yield cyclohexylphosphonyl dichloride; (9) benzyl chloride to yield phenylmethyl - phosphonyl dichloride; (10) allyl chloride to yield allyl phosphonyl dichloride; (11) chlorinated white spirit which yields longchain hydrocarbon phosphonyl dichlorides mixed with a small proportion of partially chlorinated hydrocarbon phosphonyl dichlorides; in a similar manner chlorcosane (a chlorinated paraffin wax) yields a viscous mixture of phosphonyl dichloride derivatives; (12) methylene chloride, to yield chloromethyl phosphonyl dichloride; (13) chloroform to yield dichloromethylphosphonyl dichloride; (14) carbon tetrachloride to yield trichloromethylphosphonyl dichloride; (15) ethylene dichloride to yield 1 chloroethyl-2-phosphonyl-dichloride.  In additional examples: (16) phosphorus ethoxy dichloride, aluminium chloride and n-propyl chloride are mixed at 0 DEG  C. and the mixture finally heated to 70-80 DEG  C. for one hour, and the product dissolved in methylene chloride and hydrolysed to isopropyl phosphonyl dichloride; (17) phosphorus isopropoxy dichloride, aluminium chloride, and tert-butyl chloride are warmed together at 60-70 DEG  C. for thirty minutes and the product dissolved in methylene chloride and hydrolysed with water to yield tert.-butyl phosphonyl dichloride: (18) diethyl ether, aluminium chloride and phosphorus trichloride are heated together for six hours at 70-80 DEG  C. and the product hydrolysed to give ethylphosphonyl dichloride; (19) di-(n-butyl ether), aluminium chloride and phosphorus trichloride are heated to 70-80 DEG  C. for thirty minutes and the product hydrolysed to sec.-butyl phosphonyl dichloride; (20) sym.-dichlorodiethyl ether is refluxed with phosphorus trichloride and aluminium chloride and the product hydrolysed to form 1-chloroethyl-2-phosphonyl dichloride; (21) the complex derived from ethyl chloride, aluminium chloride and phosphorus trichloride is dissolved in methylene chloride; cooled and then treated with absolute ethyl alcohol until reaction ceases and the solution then treated with a small amount of water to yield diethyl-ethyl-phosphonate. According to the Provisional Specification any halide R.Hal, wherein R is an alkyl or mono- or poly-halo alkyl radical or other suitable radical, may be used and combined with a trivalent phosphorus derivative of the formula P.R1R11Hal, wherein R1 and R11 denote halogen or any suitable aliphatic radical in the presence of any agent which will form a molecular complex with the reactants, anhydrous aluminium bromide being specified as well as anhydrous aluminium chloride.  It is also stated that the complex compound may be treated with an excess of water to yield a phosphonic acid.