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United States Patent Office Patented May 20, 1958

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United States Patent Office Patented May 20, 1958 2,835,652 United States Patent Office Patented May 20, 1958 1. 2 In a typical embodiment of this invention, ethylphos 2,835,652 phonyl diisocyanate, having the formula ORGANIC PHOSPHORUS CONTAINNG C.H. (NCO) SOCYANATES AND POLYMERS O Alfred C. Haven, Jr., Hancocks Bridge, N.J., assignor to is formed by reacting together ethylphosphonyl dichlo E. I. du Pont de Nemours and Company, Wilmington, ride and silver cyanate. The reaction is preferably car Del, a corporation of Delaware ried out in an organic solvent which is free from active No Drawing. Application April 16, 1954 hydrogen atoms. Serial No. 423,838 10 The compounds of this invention are usually colorless liquids boiling from 10 to 20° C. higher than the cor 13 Claims. (C. 260-47) responding chlorides from which they are prepared. They react readily with water. When reacted with alco This invention relates to a new class of phosphorus hols or phenols they form urethanes which are ordinarily containing organic isocyanates, a process for their prepa 15 crystalline products. ration, and new polymeric addition products formed Useful polymeric addition products are obtained by from these compounds. More particularly it relates to reacting together the phosphorus-containing organic di organic compounds in which isocyanate radicals are at isocyanates of this invention with organic compounds tached directly to phosphorus. containing a plurality of atoms to which are attached As a result of the ease with which the isocyanate 20 active hydrogen atoms. The term “active hydrogen group reacts with compounds containing active hydro atoms' refers to hydrogens which, because of their po gen atoms such as are present in hydroxyl, sulfhydryl, sition in the molecule, display activity according to the carboxyl, amino and imino groups, organic isocyanates Zerewitinoff test as described in J. Am. Chem. Soc. 49, are useful in a wide variety of chemical reactions and 3181 (1927). Thus a useful polymeric adduct is formed industrial applications. The reactions of isocyanates 25 by reacting together ethylphosphonyl diisocyanate and with such active hydrogen containing compounds have hydroquinone. As compared with similar products ob been utilized in the manufacture of synthetic fibers, tained from diisocyanates which do not contain the phos elastomers, adhesives, and rigid and elastic foams. Or phorus atom, these products are characterized by re ganic compounds containing phosphorus also have valu sistance to burning. able properties. Phosphorus compounds are useful as 30 The organic radical in the compounds of this inven fire retardants, corrosion inhibitors, extreme pressure tion may be a hydrocarbo radical, i. e., contain only lubricants, and as combustion modifiers. carbon and hydrogen atoms, or it may be a halohydro In pending applications Serial Nos. 252,811 and 252,812 carbo, a nitrohydrocarbo or a hydrocarboxy radical. of Kvalnes et al., filed October 23, 1951, now U. S. Useful compounds in which the organic radical is a Patents 2,691,566 and 2,691,567, respectively, there are 35 hydrocarbo radical include those in which the radical described isocyanate dimers containing phosphorus atoms. is alkyl, such as methyl, ethyl, isopropyl, amyl, decy, These products do not contain free isocyanate groups or octadecyl; aryl, such as phenyl, tolyl, xylyl, diphenyl and in every case the phosphorus is separated from the or naphthyl; aralkyl, such as benzyl or phenylethyl; and isocyanate dimer by intervening atoms. cycloalkyl, such as cyclopenity, methylcyclopentyl, ethyl It is an object of this invention to provide a new class 40 cyclohexyl, or dimethylcyclohexyl. Examples of useful of organic compounds in which isocyanate radicals are compounds in which the organic radical is a halohy attached directly to phosphorus. A further object is drocarbo radical include those in which the radical is to provide a process by which such compounds may chlormethyl, chlorethyl, bromethyl, fluorethyl, chlor be obtained. A further object is the provision of a phenyl, chlorbenzyl, chlorimethylcyclohexyl and chlor useful class of polymeric addition products containing cyclohexyl. The organic radical may also be a nitro-. phosphorus. Further objects will appear from the de hydrocarbo radical such as nitroethyl, nitrophenyl or tailed description of this invention which follows. nitrocyclohexyl, or a hydrocarboxy radical such as meth According to the present invention, compounds having oxy, ethoxy, isopropoxy, phenoxy, benzyloxy, phenyl the formula ethoxy or cyclohexyloxy. (NCO) (3-) 50 The compounds of this invention contain either one R-P or two isocyanate groups and are either phosphonyi or Y O phosphine derivatives depending on whether or not an in which R is an organic radical from the class consisting oxygen atom is attached to the phosphorus. Thus of hydrocarbo, halohydrocarbo, nitrohydrocarbo and hy 55 C.H. (NC O)2 drocarboxy radicals, n is an integer from 1 to 2, and x O is an integer from 0 to 1, are obtained by reacting to gether a compound having the formula isethyldiisocyanatophosphine. ethylphosphonyl diisocyanate while CHP (NCO) is Cl(3-) The organic phosphorus isocyanates of this invention R-P 60 are readily prepared by mixing the corresponding or Y ganic phosphorus chloride with a metal cyanate at room O temperature or at only moderately elevated temperature. in which R, in and v have the significance above de It is convenient to carry out the reaction in the presence scribed with a metal cyanate. The metal chloride is . of an organic solvent, although this is not necessary. formed as a by-product. 65 The solvent should not contain active hydrogen atoms 2,835,652 3. 4 which will react with isocyanates. Hydrocarbons, ethers, Another portion of the distillate is added to an excess nitriles, nitrohydrocarbons and the like make suitable of anhydrous methanol. A vigorous exothermic reaction solvents. Materials such as alcohols are unsuitable since takes place without the evolution of gas, but no solid the isocyanates will react with the hydroxyl groups to forms. The methanol is removed by evaporation and an form urethanes. When polar solvents such as nitro oil is recovered which crystallizes from ether as a white benzene are used, the reaction takes place rapidly and solid melting at 138-143° C. On recrystallization from cooling is normally required to control the reaction. a mixture of methanol and anhydrous ether crystalline, The reaction rate may also be controlled by adding one white rosettes are obtained, melting at 142-144° C. This of the reactants gradually or in small portions. With bis-methylurethane derivative shows the following analy non-polar solvents, the reaction is more sluggish and it 10 sis: is sometimes necessary to heat the mixture to drive the reaction to completion within a reasonable time. Any metal cyanate may be employed in the preparation Calc. for of these compounds, but silver cyanate and potassium CH3NOP Found cyanate are preferred because of their ready availability. '' -- - T. Lead cyanate is also satisfactory. When the reaction is Percent Percent 32.1 . 32.2 carried out in the presence of a solvent, the metal chlo 5.84 - 5.93 ride usually separates as a solid and is readily filtered 12.5 12.3 off. The solvent may then be evaporated to recover the organic phosphorus isocyanate. The preparation of the compounds of this invention If instead of ethylphosphonyl dichloride there is used and their use in the formation of polymeric products are an equivalent amount of ethyl dichlorophosphine, the shown in the following examples in which parts are by resultant product is ethyldiisocyanatophosphine, weight. CHP(NCO)2 Example 1 25 which has similar reactivity. Into a vessel equipped with an agitator and a reflux condenser are placed 200 parts of acetonitrile (previously Example 2 dried and freed from acetamide by distilling from phos phorus pentoxide) and 72.75 parts of powdered silver Into a vessel fitted with a reflux condenser are placed cyanate. The mass is heated to about 75 C. while agi 30 480 parts of dry benzene and 150 parts of powdered silver tating and 35 parts of ethylphosphony dichloride are cyanate. There are added 73.5 parts of ethylphosphonyl added slowly and uniformly over a period of about 15 dichloride. The mass is heated at reflux (about 80 C.). minutes. The reaction is quite fast and vigorous and the for nine hours. The suspension is filtered, the benzene solvent refluxes, the temperature being about 80 C. distilled from the filtrate under reduced pressure and the After all the ethylphosphonyl dichloride is added, stirring 3 5 ethylphosphony diisocyanate is distilled off at 69° C. under reflux is continued for one hour. The mass is under a pressure of 1.5 mm. cooled somewhat and the suspended silver chloride is Example 3 filtered off. The acetonitrile is then distilled off under Into a vessel equipped with a reflux condenser are vacuum. The residue is distilled at 0.65-1.0 mm. pres 40 placed 200 parts of acetonitrile (distilled from phos sure and a single fraction boiling at 61-65 C. is ob phorus pentoxide), 40.5 parts of powdered potassium tained. The distillate is a clear, water-white liquid which cyanate, and 37 parts of ethylphosphonyl dichloride. reacts vigorouly with water, evolving carbon dioxide ac The mixture is heated under reflux for 20 hours. The cording to the typical reaction of isocyanates. The non mass is cooled, the solid is filtered off, and the solvent is. volatile residue does not distill at 300 C, at 2 mm. distilled off. On distillation at 1 mm. pressure, unreacted. pressure. It is a viscous liquid which also evolves car ethylphosphony dichloride distills off first about 38-40 bon dioxide when mixed with water. C. and then ethylphosphonyl diisocyanate distills off at Analysis of the distillate is as follows: 65° C. Calc, for 50 Example 4 C.H. NCO) Found Into a vessel equipped for agitation are placed 160 parts O of acetonitrile (distilled over phosphorus pentoxide) and 60 parts of silver cyanate.
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