United States Patent 119] 1111 3,869,540 Hardy, Sr. [451 Mar. 4, 1975

[541 MONTMORILLONITE CLAY CATALYSTS 3,179,489 4/1965 Becke ...... 423/300 FOR THE PRODUCTION OF 3.365347 1/1968 Lund ...... , 252/450 X 3,379,510 4/1968 .luszka ...... 423/300 PHOSPHONITRILIC CHLORIDE 3.407.047 10/1968 Paddock at 111...... 423/302 [75] Inventor: Donald Hardy, Sr., Yardley, Pa. 3,575,693 4/1971 Emsley et a1...... 423/300 1731 Assigneei FMC Corporation, New York, N-Y- 3,677,7203,691,099 9/19727 1972 MaYou; (1 t'l...... 1 ...... 423252/450 300 [22] Filed: May 25, 1973 A 1. N .: 64 Primarr~ E.\'am1'ner~—Oscar R. Vertiz [21] ' pp 0 ~3 ,057 Assistant Examiner-Brian E. Hearn

. [52] U.S. Cl...... 423/300, 423/302 [51] Int. Cl ...... Colb 25/10 [57] ABSTRACT {58] Field of Search ...... 423/300, 302; 203/6, 8, . . . .. 703/41. 757/450 A process for producing polymeric phosphonltrlllc ' "- '- chlorides by reacting phosphorus pentachloride with U6] References Cited ammonium chloride in the presence of acid-treated UNITED STATES PATENTS Montmorlllomte clay catalyst. 3,029.78} 4/1962 Suwycr ct 211...... 252/450 X 4 Claims, N0 Drawings 3,869,540 1 2 MONTMORILLONITE CLAY CATALYSTS FOR ?ne particle size ammonium chloride makes it very de THE PRODUCTION OF PHOSPHONITRILIC sirable to use commerical grade ammonium chloride CHLORIDE having a mesh size greater than 200 (US. Standard Sieve Series — ASTM E-l 1-61); generally, 60 to 200 This invention relates to an improved process for the 5 mesh material is used in commercial processes. Ammo manufacture of phosphonitrilic chlorides by catalyzing nium chloride having mesh sizes larger than 60 is not the reaction of ammonium chloride with phosphorus generally used because of the long reaction times re pentachloride to produce phosphonitrilic chlorides quired. containing substantial amounts of trimeric and tetra The reactant phosphorus pentachloride is prepared meric cyclic phosphonitrilic chlorides. by the conventional process of the chlorination of Phosphazenes are ring or chain compounds which phosphorus trichloride in a nonaqueous solvent. The contain alternating phosphorus and nitrogen atoms in small amounts of nonreacted phosphorus trichloride or the skeleton, with two substituents on each phosphorus possibly phosphorus oxychloride are not harmful to the atoms. Phosphonitrilic chlorides are phosphazenes in main reaction. which at least one substituent is chlorine. Cyclic tri Simply heating mixtures of ammonium chloride and mers are conventionally called cyclotriphosphazenes; phosphorus pentachloride produces phosphonitrilic cyclic tetramers are cyclotetraphosphazenes and high chloride and large amounts of generally undesired oily polymers are called polyphosphazenes. Hexachlorocy polymers. The reaction is, therefore, generally carried clotriphosphazene, (PNCl2)3 is a key intermediate in out by the controlled addition of phosphorus penta the synthesis of many phosphazene derivatives. This 20 chloride to a stirred suspension of‘ ammonium chloride product is manufactured on a commercial scale in the in an inert solvent. It is well known that the preferred United States, United Kingdom, and Germany. solvents for this reaction are chlorinated hydrocarbon The synthesis of phosphazenes involves the reaction solvents such as monochlorobenzene, tetrachloro of phosphorus pentachloride with ammonium chloride ethane, dichlorobenzene and the like. Preferably, the in a solvent such as tetrachloroethane or chloroben 25 ammonium chloride is present in the hydrocarbon sol zene. The products of this reaction include the cyclic vent in an amount of not more than 400 to 500 grams trimer and tetramer, polymeric cyclic phosphazenes per liter of solvent. and a series of polymeric linear species which are “end Large proportions of cyclic polymer are produced capped," for example, by the elements of phosphorus when a molar excess of ammonium chloride is main pentachloride or l-lCl. Under favorable conditions, the 30 tained in the reaction mixture. When a high proportion trimer and tetramer may constitute as much as“90% of of cyclic material is desired, the molar excess of ammo the reaction products. It is well known in the art that nium chloride is 10 to 25 mole percenLWhen the the reaction comprising heating phosphorus pentachlo molar ratio of ammonium chloride to phosphorus pen ride and ammonium chloride in a solvent such as tetra tachloride is one to one, or less, large amounts of linear chloroethane and monochlorobenzene at re?ux tem 35 polymer are formed. Acid-treated Montmorillonite peratures is catalyzed by anhydrous metallic salts clay catalyst catalyzes the formation of either high lin which form coordination complexes with ammonia. ear or high cyclic phosphonitrilic chlorides. Phospho Such use of aluminum chloride, magnesium chloride, rus pentachloride can be added to the reactions in zinc chloride and the like is described in U.S._Pat. No. many ways; however, it is usually added slowly as a 50 3,407,047 issued to Paddock et al Oct. 22, 1968, and 40 to 60 percent solution in the solvent of choice in order US. Pat. No. 3,462,247 issued to Paddock et al Aug. to obtain a high proportion of cyclic polymers. 19, 1969. it is also well known that different catalysts The acid-treated Montmorillonite clay catalyst is have different effects on reactions, and it is always de used in a proportion of at least 1 gram per mole of sirable to find new catalysts to catalyze the reaction of phosphorus pentachloride, and preferably 3 to 15 ammonium chloride with phosphorus pentachloride. 45 grams per mole of phosphorus pentachloride. Larger In accordance with the present invention, there is amounts of catalyst, 50 grams or more per mole of provided a process in which an acid-treated Montmo~ phosphorus pentachloride can be used, but no appre rillonite clay is the catalyst used in the preparation of ciable advantages are obtained, and it is commercially phosphonitrilic chloride by the reaction of ammonium 50 undesirable to use such large amounts of catalyst. chloride with phosphorus pentachloride in an inert sol The reaction of ammonium chloride with phosphorus vent. Since U.S. Pat. Nos. 3,407,047 and 3,462,247 to pentachloride is generally run in the presence of an Paddock and Searle emphasize the use of anhydrous inert solvent. Solvents of choice have boiling points metallic salts capable of forming coordination com within the desired temperature range for carrying out plexes with ammonium, it is surprising that acid-treated 55 the reaction. The reaction may be run without the sol— Montmorillonite clays, which are hydrated salt mix vent; however, handling of the reaction product is diffi tures, would be suitable catalysts for the reaction of cult. Halogenated solvents are preferred for diluting phosphorus pentachloride with ammonium chloride in the reaction mixture. Particularly preferred are mono an inert solvent. chlorobenzene, dichlorobenzene and tetrachloro Fine particle size ammonium chloride (5 to 15 mi 60 ethane. Standard chemical processing equipment is crons in size) or ammonia gas may be used as the nitro~ used in the process of this invention. gen source. Fine particle size ammonium chloride or The process of the present invention is carried out at ammonia do not require the presence of the catalyst to an elevated temperature, preferably between about react with phosphorus pentachloride at suitable reac 100° C and the boiling point of the solvent under the tion rates in producing phosphonitrilic chlorides. It is conditions of the reaction. It is often convenient, but not always desirable to use ammonia gas, and the ?ne not necessary to carry out the reaction at the boiling particle size ammonium chloride (5 to 15 microns in point of the solvent under re?ux. Temperatures of l 80° size) is difficult to produce. The cost of preparing the C or above can be used, but these high temperatures 3,869,540 3 4 result in the formation of considerable amounts of cyclic to linear polymers was measured by the selective polymeric phosphonitrilic chlorides. Preferably, the re partitioning of the cyclic polymer into hexane. The action is carried out at temperatures between 125° and amount of reactants, the time required to feed the 160° C. A reaction temperature substantially higher phosphorus pentachloride, the total reaction time, the than 160° C is not favorable, since losses due to the dis- 5 ratio of catalyst to moles of phosphorus pentachloride,

sociationI I of PCls to PCI;; ande chlorine gasI becomeu sig-' the p ercent of theor y of hydro g en chloride g as evolved nlficant. The solvent of choice should boil suf?c1ently and the cyclic-linear ratio of the phosphonitrilic chlo low that, when removed from the crude phosphonitrilic ride‘product §e_se_tmf_or_th_in Table]. V in

TABLE I

Grams Acid Mont Total moril Reac- ,lonite . % of Moles of PCI:, tion per Theory Cyclic Reactants Fed. Time Mole HCI Lmear Ex. PC]; NH4Cl Hrs. Hrs. PCl5 Off Ratio 1 25 3014 21 22 12.0 93 88:12 2 25 30.4 20.5 23 3.2 96 98.5115 3 25 30.4 20.5 24 3.2 96 95:5 4 25 30.4 27 37 No 90 65:35 catalyst

chloride p roduct, undesirable polymerization does not EXAMPLE B — HIGH-LINEAR POLYMER

occur- _ . , _ , , 25 A solution of 688 grams (5.0 moles) of phosphorus The Pfessul'e at which the macho" 'S'camed OR“ 15 trichloride in 688 grams of monochlorobenzene was not Critical, 50 long as’a _tempel'ature m the desnjed placed in a 5-liter ?ask equipped with a stirrer, ther range 15 used, and the eilmlnatlon of hydrogen Chlorlde mometer, the chlorine inlet and a Dry Ice condensor. reaction by-products 1s not retarded. Most conve- Chlorine gas was gradually added to this solution (355 niently the reaction is carried out at atmospheric pres- 30 grams or 5.0 moles of chlorine) to make 1040 grams sure. The addition rate of phosphorus pentachloride (5.0 moles) of phosphorus pentachloride. The chlorine has a pronounced effect on the course of the reaction. addition _WaS Carried Out in 90 minutes, during Which Slow addition favors the formation of the cyclic poly- the reaction temperature gfaduauif ‘056 to 1 17° C due mers, whereas charging all of the phosphorus penta- to the heatof the exotherm1c react1on. The phoosphorus chloride results in high yields of an oily linear polymer 35 pentachloride solution was 69016‘! to 5Q to 60 C’ and fraction. The reaction is continued until the evolution £12138 19g FZZE.‘.,“Z°,£ZL°3IZZ1.338313%“??? of hydrogen chloride gas has ceased. The react1on t1me (5 0 moles‘) of commercial ammonium chloride gveina generally varies between about 6 t9 about 25 hqurs' period of l5 minutes. The reaction temperature was . The followmg.examples further illustrate the mven' raised to re?ux over a period of about 1 hours, and the tlon- A" proportlons afe by_ we'ght m the examples_an_d 4O reaction progress was followed as in Example A. The throughout the spec1f1cat1on unless otherwise 1nd1- reaction was completed in 21 hours with a recovery of cated- 95% of the hydrogen chloride theoretically expected. EXAMPLE A — HIGH CYCUC CONTENT A control experiment using no catalyst was run; it A series of three runs using the Montmorillonite cata- 45 :22: 2 h3g2; ffiggglleitii?'gngzzcgioonf ?ygggszglghclig: lyst and a control using no catalyst were run accordmg ride ’e“lo‘l’ved ‘ to the following procedure. The results are given in _ ' _ _ Table L ' As will be apparent to those skilled 1n the art, numer Monochlombenzene’ 3,465 grams’ was added to a 22 ous modi?cations and variations‘ of the embodiments liter ?ask equipped with a stirrer, thermometer, jacket- 50 tggsggilrt?dglz?gi“ti/‘Sgtaenlgici?ewgégogtoiigirémfogz’nm ed-addition funnel and a re?ux condenser. To the claims P g monochlorobenzene 1,624 grams (30.36 moles) tech- ' _ _ _ nical commercial ammonium chloride (50 to 200 What ‘3 cla‘med ‘51 _ ‘ . _ mesh) and a catalytic amount of acid-treated Montmo- 1' procfiss for {he produfitlon of PhPSPhOmmIIC rillonite clay was added. The level of catalyst used var- 55 Chlondes which conslsts essentially of heatfng Ph°§Ph° ied from 80 to 300 grams on a dry weight basis. rustpelmgchlonde W'Lh ammomum .chlorlde having a the gradual addmon 9f 51270to grams (2,509 moles), ence of at least 1 gram of acid-treatedis‘: Montmorillonite phosphorus pentachlorlde, as a 60% solut1on 1n mono- clay for each grammole of PCIS charged to the reac_ chlorobenzene was begun. The rate of phosphorus pen- 60 tion mixtum tachloride introduction was adjusted so that the addi~ 2 The process of daim l in which-3 to 15 grams of tion was completed in about 20 hours. Introduction of ,' _ _ , phosphorus pentachloride to the control run required ?ggij'tgzitgegmh?giglg?ggggshs?g pgllfliéc?ggit are 27 ours. - ‘ - - ' The reaction rate was monitored by “Rating the 65 3. The process of dam 1 1n WhlCh the react1on tem evolved hydrogen chloride. The reaction mixture was perature is between 125° and 180° C. 4. The process of claim 1 in which the solvent is se then filtered to remove the excess ammonium chloride lected from the group consisting of monochloroben and catalyst. A portion of the filtrate was vacuum dis zene, dichlorobenzene and tetrachloroethane. tilled to remove the monochlorobenzene. The ratio of * * it it it