Patent GB-967131-A (GB)
Title: Process for the preparation of phosphorus-containing isocyanates
IPC: C07F9/46
Filed: 1962-01-10
Abstract: Phosphorus triisocyanate P(NCO)3 is obtained by reacting isocyanic acid and a phosphorus trihalide in the liquid phase at a temperature of from - 85 DEG  to 150 DEG  C. in the presence of one or more of one or both nitrogen compounds of the formula (R1)2N.CO.R2 and (R3)(R4)N(R5) in which R1 is a monovalent hydrocarbon radical which may be substituted, and R2, R3, R4 and R5 are hydrogen atoms or hydrocarbon radicals which may be substituted, one or two of R3, R4 and R5 being a monovalent aromatic hydrocarbon radical which may be substituted and not more than one of R3, R4 and R5 being a hydrogen atom.  When any of R1 to R5 is a substituted radical said substituent is a non-interfering substituent, e.g. an ester group or nitro group. The radicals R1 to R5 may be alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, or aralkyl, which may be substituted and the preferred nitrogen compounds are dimethyl acetamide, diphenylamine and dimethylaniline.  The reaction may be carried out in an inert solvent, e.g. diethyl ether, benzene, toluene, xylene, methyl chloride, or acetonitrile. The amount of nitrogen compound present may suitably be from 0.5 to 3.0 moles. and preferably from 0.8 to 1.5 moles. per mole. of isocyanic acid.  Examples are given in which phosphorus triisocyanate is obtained by reacting phosphorus trichloride with isocyanic acid in the presence of toluene and of dimethylacetamide and dimethylaniline respectively.ALSO:A phosphorus-containing isocyanate RyP-(NCO)z in which R is a monovalent hydrocarbon, alkoxy, or aryloxy radical which may be substituted, y is 0, 1 or 2 and z is an integer from 1 to 3 inclusive, the sum of y and z being 3, is obtained by reacting together in the liquid phase isocyanic acid and a phosphorus-containing halide RyPXz in which X is halogen and R,y and z are as defined above at from-85 to 150 DEG C. in the presence of one or more of one or both nitrogen compounds of the formula: (R1)2N. Co.R2 and (R3)(R4)N(R5) in which R1 is a monovalent hydrocarbon radical which may be substituted, R2 is hydrogen or a hydrocarbon radical which may be substituted and R3, R4 and R5 are hydrogen atoms or hydrocarbon radicals which may be substituted, one or two or R3, R4 and R5 being a monovalent aromatic hydrocarbon radical which may be substituted and not more than one of R3, R4 and R5 being a hydrogen atom. When any of R or R1 to R5 is a substituted radical said substituent is a noninterfering substituent.  The reaction may be carried out in the presence of an inert solvent, e.g. diethyl ether, benzene, toluene, xylene, methyl chloride or acetonitrile and preferred reaction temperatures are between -40 DEG C. and 20 DEG C. The amount of nitrogen-containing compound present may suitably be from 0.5 to 3.0 moles and preferably from 0.8 to 1.5 moles per mole of isocyanic acid. It is advantageous to use gaseous isocyanic acid formed directly from the pyrolysis of cyanuric acid-and it is preferred to add the nitrogen-containing compound slowly to a mixture of isocyanic acid and the phosphorus halide compound or to add the isocyanic acid slowly to a mixture of the nitrogen-containing compound and phosphorus halide compound. The R radicals in the above formulae may be the same or different and may be alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, aralkyl, alkaryl, alkoxy, or aryloxy and may be substituted by a non-interfering substituent such as halo, e.g. chloro, bromo, fluoro, iodo or sulphonic radical. The radicals R1 to R5 may be alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, or aralkyl which may be substituted, e.g. with an ester group or nitro group. The preferred nitrogen-containing compounds are dimethyl acetamide, diphenylamine and dimethyl aniline. Examples are given for the production of phosphorus triisocyanate (see Division C1), methoxy diisocyanates phosphine and phenyldiisocyanato phosphine.  Other products specified include diphenyl isocyanato phosphine, 2,4-dichlorophenyl diisocyanato phosphine and 2,4-dinitrophenyl diisocyanato phosphine. The products may be converted to urethanes and ureas by reaction with alcohols and amines respectively and are useful in the preparation of sealants, coatings, and flame-retardant polymeric resins and cellulosic material.