Patented Oct. 8, 1946 2,408,785

UNITED STATES PATENT OFFICE 2,408,785 METHOD OF PRODUCTION OF ANHYDROUS MONOFUOROPOSPORCACD Willy Lange, Cincinnati, Ohio, assignor, by direct and mesne assignments, to Ozark Chemical Company, Tulsa, Okla., a corporation of Dela Ware No Drawing. Application June 28, 1944, Serial No. 542,603 18 Claims. (CI. 23-139) 1. 2 In an application for United States Letters A further object is to provide a method of pro Patent, Serial No. 478,838, filed March 11, 1943 by ducing the said acid either alone or in conjunction Ralph Livingston and me, jointly, anhydrous with anhydrous diffuorophosphoric acid (HPO2F) monofluorophosphoric acid (H2PO3F) and a which, after separation from the monofluoro method of producing it from anhydrous hydro phosphoric acid, forms a valuble by-product. fluoric acid and water-free metaphosphoric acid A still further object is the provision of a are described and claimed, but the production of method of the character aforesaid which is capa metaphosphoric acid exactly corresponding to the ble of performance in such manner that none of formula HPO3 and free from its dehydration the difluorophosphoric acid, Substantially equal products for use in that method is accomplished O quantities of both acids Or, between these tWO only with a certain amount of difficulty. Thus a extremes, any desired percentage of difluorophOS method for the production of monofluorophos phoric acid with relation to the monofluorophos phoric acid not requiring the use of the somewhat phoric acid may be produced. difficultly preparable metaphosphoric acid offers Other objects, advantages and novel features, advantages over that disclosed in the said appli 5 steps and operations comprehended by or inci cation. dent to the invention are hereinafter more par Moreover anhydrous difluorophosphoric acid ticularly pointed out or will be apparent from (HPO2F2) would be of distinct commercial value the following description. if available to industry, but while a dilute aqueous This application is a continuation-in-part of Solution of this acid has been known for some 20 my applications for United States Letters Patent, time the solution cannot be concentrated with Serial Nos. 503,420 and 503,421, filed September out complete hydrolysis of the acid. The anhy 22, 1943, in which, respectively, I described and drous form of this acid obtained as a by-product claimed a method of preparing substantially equal in the high temperature reaction between cal parts of monofluorophosphoric acid and difluoro cium fluoride and phosphorus pentcxide has also phosphoric acid through the reaction of phos been described in literature in recent years but phorus pentoxide with anhydrous hydrofluoric the quantities of the acid obtainable in this way acid and subsequent distillation of the product are so small that the process is of no interest as resulting therefrom, and a method of preparing a possible commercial source of anhydrous diflu monofluorophosphoric acid by a generally corre orophosphoric acid. 30 sponding reaction of phosphorus pentoxide and Earlier in the literature it has been pointed aqueous hydrofluoric acid of about 69% concen out that in reacting a 40% aqueous hydrofluoric tration without production of an appreciable acid Solution and phosphoruspentoxide, the aque amount of the difluorophosphoric acid. ous solution of a mixture of orthophosphoric acid . The present invention therefore comprehends and mono-, di- and hexafluorophosphoric (HPFs) production either of monofluorophosphoric acid acids is obtained, the Solution also containing free or substantially free of difluorophosphoric unreacted hydrofluoric acid. But when an at acid or of monofluorophosphoric acid in conjunc tempt is made to concentrate this solution the tion with difluorophosphoric acid in any desired fluorophosphoric acids decompose with the re ratio up to Substantially equal quantities of each sult that it likewise is of no industrial value. by reaction of phosphorus pentoxide with hydro It is therefore a primary object of the present fluoric acid of from about 69%-100% HF con invention to provide a method adapted for use centration, so that by suitable selection of the in a commercial way to produce anhydrous mono degree of concentration and amount of the hy fluorophosphoric acid (H2PO3F) through the use drofluoric acid, the method may be operated to of phosphorus pentoxide (POs), a readily obtain supply either the monofluorophosphoric acid able material, and hydrofluoric acid (HF) of suit alone or the monofluorophosphoric and the diflu able concentration. orophosphoric acids in a predetermined ratio 2,408,785 3.d 4. with consequent avoidance of production of an resulting parts by weight of acid or acids which excess of difluorophosphoric acid in order to meet commercial demand for the monofluorophos in accordance with the invention are obtained: phoric acid. Parts by weight Theorctical yields in More specifically, I have discovered that the 5 Songs: value of of hydrilloric parts by weight reaction product obtained at low temperatures in drofluoric X in cities the violent reaction of phosphorus pentoxide with tEf by weight of Monofluoro- PEO hydrofluoric acid of between about 69% and 100% pe if phosphorus phosphoric E. oric inclusive HF concentration and in a predeter pentoxide acid pnoacid mined ratio is a liquid in which all three fluoro 68.97 0.00 40.84 140.84 0.00 phosphoric acids (namely, mono-, di- and hexa 69.00 0.001074 40. S5 40.77 0.08 fluorophosphoric acids) and a fluorine-free phos 70.00 0.03226 40, 89 38.57 2.32 71.00 0.06350 40, 93 36.37 4.56 phoric acid are present as can be shown by 2.00 0.09483 40.98 134.17 6.8 analytical methods described in the literature, 73.00 (). 1262 41.02 131.96 9.06 7400 0.1577 41.07 29.74 1.33 but this liquid as such cannot be used for COm 75.00 0, 1892 41. I 127.52 13.59 mercial purposes So far as I am aware. However, 76.00 0.2208 41.16 125.29 5.87 77.00 0.2524 41. 20 23.07 18. 13 if it be subjected to heat under conditions Such 8.00 0.2852 4.25 20.76 20, 49 that none of the gaseous reaction products are 79,00 0.359 4.29 8.60 22.69 S0.00 0.3478 41.34 16.35 24, 99 allowed to escape, a succession of complicated 81.00 0,3797 41.38 4. 27.27 intermediate reactions takes place, not presently 20 82.00 0.418 41, 43 ll1.85 29.58 83.00 0.4438 447 109.59 31, 88 known in detail, the end-product of which has a 8400 0.4760 4.52 107.32 34.20 simple composition and is of definite commercial 85.00 0.5082 4, 56 05, O6 36.50 86.00 0.5405 4, 6 102.78 38.83 interest, said end-product being in accordance 87.00 0.5728 . 41.65 100, 50 41, 5 With the percentage concentration and relative 88.00 0.6053 41.70 98.22 43. 48 89.00 0.6378 42.74 95.93 45.81 quantity of the hydrofluoric acid employed either 25 90.00 0.6703 4.79 93. 64 48.5 Substantially pure monofluorophosphoric acid or 91.00 0.7030 4.84 91.34 50, 50 92.00 0.7357 4.88 89.03 52.85 a mixture of the monofluorophosphoric and diflu 93.00 0.7685 41.93 86. 55.20 orophosphoric acids which may be readily sep 94.00 0.8013 41.97 84.41 57.56 95.00 0.8342 42,02 S2.0 59.92 arated by distillation, preferably under vacuum, 96.00 0.8673 42,06 79.77 62.30 the difluorophosphoric acid passing off as the 30 97.00 0.9003 42. 77. 44 64.67 98.00 0.9335 42.16 75. 67.05 distillate and the monofluorophosphoric acid re 99.00 0.9667 42, 20 72.76 69. 44 maining as the distillation residue, the yield of 100.00 .0000 42.25 70. 42 7.83 crude difluorophosphoric acid approaching the theoretical value. Then if an analytically pure It will be apparent from this table that When material is desired the crude difluorophosphoric 35 operating with hydrofluoric acid of 68.97% con acid may be re-distilled under vacuum; the resid centration no difiuorophosphoric acid is produced; ual monofluorophosphoric acid of the first distill that when operating with hydrofluoric acid of lation is of a technical grade and cannot be puri substantially 100% concentration approximately fied by further distillation. equal quantities of monofluorophosphoric and di The reaction between the phosphorus pent 40 fluorophosphoric acids are produced and that Oxide and hydrofluoric acid of about 69% to 100% between these two extremes progressively greater inclusive HF concentration to which reference amounts of the difluorophosphoric acid are pro has been made proceeds in accordance with the duced as the concentration of the hydrofluoric general equation acid increases. 45 The temperature at which the reaction is per formed may vary from very low ones to those exceeding the boiling point of hydrofluoric acid of 100% concentration but at temperatures exceed in which X has any value in the range from 0 to 1 ing the boiling point of low boiling reaction prod inclusive, and in the practice of the invention lucts, the reaction should be carried out in a closed care should be taken that during the reaction system, with or without pressure, in order to avoid the phosphorus pentoxide, hydrogen fluoride and losses of hydrofluoric acid and of gaseous reaction Water, if any, always meet in the ratio of 1 mole products, the presence of which are necessary P2O5: (2--X) moles HF: (1-X) mole H2O in to secure an end-product consisting essentially which X has any value between 0 and 1 inclu 55 of monofluorophosphoric acid or of monofluoro Sive. By bearing this condition in mind one phosphoric and difluorophosphoric acids. Skilled in the art can readily calculate the quan For attainment of optimum results and prod itty of hydrofluoric acid of a given HF concen ucts of essential purity the proportions of ingre tration between about 69% and 100% inclusive dients employed when operating with hydro which should be used with a certain quantity of 60 fluoric acid of any given HF concentration with phosphorus pentoxide in order to obtain the best in the ranges specified must be carefully followed results, as well as the necessary concentration in accordance with the foregoing table, as de and quantity of the hydrofluoric acid required if partures therefrom may result in production of it be desired to produce both monofluorophos impure difluorophosphoric acid distillates and/or phoric and difluorophosphoric acids in a desired 65 fluorine-free phosphoric acid instead of distilla ratio. tion residues consisting only of monofluorophos However, to minimize the necessity for such phoric acid, and it is of utmost importance that calculations and to facilitate the practice of ny none of the products incident to the reaction be invention, I have Set out in the following table 70 tween the phosphorus pentoxide and hydrofluoric the parts by weight of hydrofluoric acid of various acid be permitted to escape from the reaction ves HF concentrations between about 69% and 100% sel. To this end the reaction may be carried out inclusive which should be used with 100 parts in a closed vessel of suitable type, or a vessel hav by weight of phosphorus pentoxide, the value of ing a reflux condenser associated therewith X in the said equation in terms of moles and the 75 whereby all gases and vapors developed during 2,408,785 5 6 s the reaction are returned by condensation or, in 150 C. only slight pressure being developed dur fact, by any means suitable for attainment o ing this operation. The resulting reaction prod the desired end. uct is anhydrous monofluorophosphoric acid In the practice of the invention the reaction of which exhibits all analytical data and identifying the phosphorus pentoxide and the hydrofluoric characteristics described in said application, Ses acid may be effected in various ways. Thus the rial No. 478,838. It cannot be purified by dis phosphorus pentoxide may be added in small por tillation. tions, applying agitation, to liquid hydrofluoric Eacample 2-142 parts by weight of phosphorus acid maintained at such low temperature that pentoxide are placed in a closed, jacketed, stain the reaction products, gaseous at room tempera 10 less steel mixer having two constantly rotating ture, remain dissolved in the liquid reaction prod curved blades, and oil is circulated through the uct at ordinary pressure. Or, if preferred, hydro jacket. After the mixer has been evacuated aque fluoric acid may be passed into a closed, evacuate ouis hydrofluoric acid of about 69% HF is run into ed, rotating cylindrical and suitably cooled con the mixer, later applying pressure, and by cooling tainer holding the phosphorus pentoxide so that 5 the circulating oil and regulating the rate of in hydrogen fluoride and low boiling reaction prod troduction of the acid a temperature of about 180 ucts are condensed, or the hydrofluoric acid may C. is maintained in the mixer. After 58 parts be passed into a closed, evacuated container hold by weight of the acid have been introduced the ing the phosphorus pentoxide, applying pressure, reaction product is allowed to slowly cool down or the phosphorus pentoxide with air as the car 20 to room temperature during a period of approxi rier gas may be blown into a stream of evaporated mately 3 hours. The final product again is an hydrofluoric acid in such manner that the phos hydrous monofluorophosphoric acid. phorus pentoxide and hydrogen fluoride always Since in these examples hydrofluoric acid of a meet in a ratio of 1 mol PaOs: (2--X) moles concentration of about 69% His employed, the F: (1-X) mole HaO, if any, where X has any 25 value of X in the general equation is 0 and it is value in the range from 0 to 1 inclusive and all thus simplified to POs--2HF--HaO=2OF, no reaction products are Conserved. difluorophosphoric acid being produced. If a reaction temperature of lower than about At this point it may be observed that an aque 150 C. has been utilized, it is generally necessary ous hydrofluoric acid of approximately 69% BF to keep the reaction product in a closed container 30 concentration contains the acid and Water in a at an elevated temperature for a time sufficient ratio of 2 moles HF:1 mole HaO, thus conforming to enable the above mentioned intermediate re to the general equation when X equals O. actions to come to completion, the rate of these The following are illustrative of the practice reactions depending upon the temperature. The of the method where a more concentrated aqueous time and temperature of this treatment may vary 35 hydrofluoric acid is used: w although generally a temperature of from about acample 3-58.5 parts by weight of aqueous hy 90° C. to 150° C. and a time of from 2 to 12 hours drofluoric acid of 77.43% HF are placed in a plati is required. It will be understood, however, that nun bottle and cooled with a mixture of solid car the time and temperature just mentioned are by bon dioxide and alcohol and 142 parts by weight way of example only and not by way of limita 40 of phosphorus pentoxide are added in small por tion since other times and temperatures may be tions under agitation so that the temperature of employed with equal facility and, further, that the liquid does not rise substantially. The phos if the reaction of the phosphorus pentoxide with phoruspentoxide reacts vigorously with the aque the hydrofluoric acid has taken place attempera ous hydrofluoric acid and dissolves quickly, and ture above about 150° C. usually no after treat after all the phosphorus pentoxide has been added ment as just described is necessary since the to the acid a clear liquid is obtained. The bottle intermediate reactions may have already taken is then closed and heated for 10 hours at 100 C. place to greater or lesser extent. Only slight pressure being developed during this - It will be appreciated that the excess of water Operation. The resulting reaction product is a . in hydrofluoric acids of less than about 69% His 50 mixture of monofluorophosphoric acid and difluo inimical to success of the method and attainment rophosphoric acid and is subjected to distillation of the desired ends since when such acids are at a pressure of 50 mm. of mercury to separate the used the monofluorophosphoric acid produced is acids, the temperature of the batch being slowly associated with fluorine-free phosphoric acid raised to 150 C. but not higher. The vapors of which cannot be separated from it. difluorophosphoric acid evolved during the distill The following are illustrative of different Ways lation are condensed by passing through a con of practising the method of the invention in ac denser cooled with brine of -20° C. and a yield cordance with the general equation of 176.2 parts by weight of monofluorophosphoric acid is obtained and 24.2 parts of crude difluoro 60 phosphoric acid. To further purify it, the difluo rophosphoric acid may be re-distilled at a pres in which X has any value in the range from 0 to 1 sure of 200 mm. of mercury at which pressure it inclusive: boils at about 70° C. It will be noted that in the Eacample 1.-58 parts by weight of aqueous reaction the components are used in the ratio of hydrofluoric acid of about 69% HF are placed in 65 mole POs: (2-X) moles HF: (1-X) mole H.O. a platinum bottle and cooled with a mixture of Eacample 4-59.0 parts by weight of aqueous solid carbon dioxide and alcohol and 142 parts hydrofluoric acid of 84.95% HF are combined with by weight of phosphorus pentoxide are added in 142 parts by weight of phosphorus pentoxide in small portions under agitation so that the tem the manner described in Example 3 and the re perature of the liquid does not rise substantially. 70 action product subjected to like treatment and The phosphorus pentoxide reacts vigorously with subsequent distillation to separate the difluoro the aqueous hydrofluoric acid and dissolves quick phosphoric acid from the monofluorophosphoric ly and after all the phosphoruspentoxide has been acid. A yield of 150.9 parts by weight of the added to the acid a clear liquid is obtained. The latter and 50.5 parts of the former is obtained bottle is then closed and heated for ten hours at 75 and it will be noted that the components are supe 2,408,785 7 8 plied in the same ratio as in Example 3 but with pressure. After 60 parts by weight of the fluoride X accorded a different value. have been introduced, the mixer inlet valve is Eacample 5-59.5 parts by weight of aqueous closed and the mixer warmed up slowly to a hydrofluoric acid of 91.78% HF are combined final temperature of 90° C. and maintained there with 142 parts by weight of phosphorus pentoxide 5 for 5 hours. The reaction product after distill and the resultant product again treated as in lation in the manner described in Example 6 Example 3. Components are thus supplied in affords a yield of 96 parts by weight of crude di the same ratio as in Examples 3 and 4 though fluorophosphoric acid and a distillation residue again with a suitably different value for X, but of 14 parts by weight of monofluorophosphoric because of the higher concentration of the hy O acid. drofluoric acid a yield of 1283 parts by weight Eacample 8-142 parts by weight of phosphorus of monofluorophosphoric acid and 73.9 parts of pentoxide are placed in a mixer similar to that difluorophosphoric acid is obtained after the dis described in Example 7 and oil is circulated tillation step. through its jacket. After the mixer has been In the three last examples the value of X in 15 evacuated anhydrous hydrogen fluoride is passed the general equation is intermediate between 0 into it applying pressure. By suitable cooling of and , having the lowest value in Eample 3 and the circulating oil and regulation of the rate of progressively higher values in the others. introduction of the hydrogen fluoride into the The following are illustrative of the practice mixer, a temperature of about 150° C. is main of the method where hydrofluoric acid of a con 20 tained in the latter. After 60 parts by weight centration of 100% HF is utilized, i. e., the an of the fluoride have been introduced, the mixer hydrous form of the acid, and as under these inlet valve is closed and the reaction product al conditions the value of X in the general equa lowed to slowly cool down to room temperature tion is 1, it is correspondingly simplified to for a period of approximately three hours. By 25 like distillation of this product, a yield of 91 parts by Weight of difluorophosphoric acid and 109 and in each instance a yield approximating the parts of monofluorophOSphoric acid is obtained. theoretical yield of monofiuorophosphoric and di All the foregoing examples numbered 1 to 8 fiuorophosphoric acids respectively as set forth inclusive are given by way of illustration only in the foregoing table is obtained. 30 and not in any restrictive or limiting sense since Eacample 6-60 parts by weight of anhydrous it will be understood from the foregCling descrip. hydrogen fluoride are placed in a platinum bot tion of the invention that So long as phosphorus tle and cooled to the temperature of a mixture pentoxide and the proper quantity of hydroflu of solid carbon dioxide and alcohol. 142 parts oric acid of suitable HF concentration are mixed by Weight of phosphorus pentoxide are then add 35 in the ratio of 1 mole P2O5: (2--X) moles ed in small portions under agitation, so that the HF: (1-X) mole H2O where X has any value in temperature of the liquid does not rise appre the range from 0 to 1 inclusive, with after treat ciably. It will be noted that in the reaction the ment by heating the reaction product in a closed components are used in the ratio of 1 mole container or its equivalent if the reaction has PaOs: 3 moles HF. The phosphorus pentoxide re 40 not gone to completion according to the equation acts vigorously with the hydrogen fluoride and dissolves quickly and after all of it has been add ed to the acid a clear liquid is obtained. The bot tle is then closed and heated for 8 hours at 85 in which X has any value in the range from 0 C., only slight pressure being developed during to 1 inclusive, many other ways may be em this operation. The resulting reaction product is ployed for combining and subsequently treating a mixture of difluorophoSphoric and monofluoro the initially supplied components in order to con phosphoric acids and is subjected to distillation form to special requirements of the equipment at a pressure of 50 mm. of mercury to separate being utilized, the form in which the phosphorus the former from the latter, the temperature of pentoxide is most readily available and the like. -the batch being slowly raised to 150° C. but not The reaction vessels may be those customarily higher. The vapors of difluorophosphoric acid utilized for similar or analogous operations and evolved during the distillation are condensed by thus may be of the usual mixer or rotating drum passing through a condenser cooled with a brine types, while the distillation apparatus may be of of -20° C. and a yield of 97 parts by weight of any desired construction suitable for the purpose. crude difluorophosphoric acid is obtained and The equipment may be made from stainless steel 103 parts of crude monofluorophosphoric acid. or other corrosion resistant material or may be To further purify it the difluorophosphoric acid plated therewith and, according to the conditions may be re-distilled as in Example 3. This puri of the reaction, ordinary or pressure vessels may fied product when analyzed by analytical meth be used. The practice of the invention therefore ods established in the literature is found to con (60 does not require specially constructed apparatus tain P 30.6%; F 37.0% as against the calculated and as Substantially pure phosphorus pentoxide values respectively of P 30.4% and F37.2%. The and hydrofluoric acid may be obtained without monofluorophosphoric acid is obtained as a dis difficulty in the open market the invention readily tillation residue and is found to contain when lends itself to commercial usage. likewise suitably analyzed P 30.7% F 20.1% as It will now be apparent that practice of the against the calculated values respectively of P method may be readily adjusted from time to 31.7% and F. 19.0%. time to conform to market demand for the acids Example 7-142 parts by weight of phosphorus or for other reasons without change in the equip pentoxide are placed in a closed jacketed stain 70 ment employed. Thus, for example, if during a less steel mixer having two constantly rotating Certain period the Said demand approximates 7 curved blades and cooled with a brine of -20 tons of the monofluorophosphoric acid to 3 tons C. circulating through the jacket. The mixer is of the difluorophosphoric acid, the method may then evacuated and anhydrous hydrogen fluoride be operated to produce both acids in approxi slowly passed into it, in the latest stage applying 75 mately that ratio, or should demand for the di 2,408,785 9 s O fluorophosphoric acid become negligible it may and desire to protect by Letters Patent of the be operated to produce the monofluorophosphoric United States: acid alone, a feature of the invention which is 1. In a method of producing anhydrous mono obviously of great importance to manufacturers fluorophosphoric acid, the steps of mixing phOS of these acids. Thus my invention for the first phorus pentoxide and hydrofluoric acid of any time, as far as I am aware, makes possible the HF concentration between about 69% and 100% production of anhydrous monofluorophosphoric inclusive according to the equation acid, as well as anhydrous difluorophosphoric acid suitable for industrial purposes, from readily available materials in a convenient and commer 10 cially practical way. in which X has any value in the range from 0 to 1 Concerning some of the properties of these inclusive, and maintaining the mixture in the acids, it may be mentioned that anhydrous mono presence of heat and under conditions prevent fluorophosphoric acid H2POF exhibits to a de ing the escape of any products of the reaction cided degree some of the chemical properties of 15 until the latter goes to completion according to concentrated sulfuric acid without showing any said equation. oxidizing action and anhydrous difluorophos 2. In a method of producing anhydrous mono phoric acid HPOF, resembles to some extent fluorophosphoric acid, the steps of mixing phos anhydrous perchloric acid without any oxidizing phorus pentoxide and hydrofluoric acid of any or explosive properties. In addition to having a 20 HF concentration between about 69% and 100% number of properties of a non-oxidizing "pseudo inclusive according to the equation sulfuric' acid H2PO3F and a non-explosive, non oxidizing “pseudo-perchloric" acid HPOF, both acids are derivatives of hydrogen fluoride as well in which X has any value in the range from 0 to 1 as of Orthophosphoric acid, and they combine in 25 inclusive, and heating while preventing escape a convenient form the reactivities of both an of the reaction products until the reaction has hydrous Orthophosphoric acid and anhydrous gone to completion according to said equation. hydrogen fluoride for a number of reactions. 3. In a method of producing anhydrous mono The salts of both monofluorophosphoric and fluorophosphoric acid, the steps of mixing phos difluorophosphoric acids have been described in 30 phorus pentoxide and hydrofluoric acid of any the literature. They may be produced now on a HF concentration from about 69% to 100% in commercial scale by passing calculated quantities clusive in the ratio of 1 mole PaOs: (2--X) moles of the anhydrous acids in a thin stream into HF (1-X) mole H2O where 2 has any value in aqueous solutions of alkali bases or aqueous Sus the range from 0 to 1 inclusive, and then heating pensions of non-alkali bases undergoing stirring the product in a closed vessel at a temperature and kept at a low temperature, and then by not exceeding about 150', C. until the reaction evaporating the water in good vacuo at a low has gone to completion according to the equation temperature to avoid hydrolysis. Or dry amines, like anhydrous ammonia, methylamine, aniline, pyridine, are reacted in the theoretically required 40 quantities with the strongly cooled acids. Of in which X represents any number between 0 and special interest are the andline salts, which may 1 inclusive. be transformed into the diazonium compounds 4. The method of producing anhydrous mono which, in turn, when heated in the absence of fluorophosphoric acid which includes the steps water, will form the corresponding aryl fluoro 45 of mixing phosphorus pentoxide and a hydroflu phosphates with loss of their nitrogen. The anhydrous fluorophosphoric acids may be oric acid of concentration exceeding 69% HF used as catalysts for polymerization, condensa substantially according to the equation tion and alkylation reactions, especially for com bining such compounds as isoalkanes and olefines 50 or isoolefines. Esters may be prepared by re in which X has any value in the range from 0 to 1 acting olefinic or acetylenic compounds with the inclusive, maintaining the mixture in a closed anhydrous acids in the presence of catalysts, or container at a temperature sufficient to cause by reacting alcohols or ethers with the anhydrous the reaction to go to completion according to acids. Of special interest are the esters of mono 55 said equation and thereby form a resultant prod fluorophosphoric acid. Their similarity with the uct containing monofluorophosphoric and di corresponding Sulfuric acid derivatives is far fluorophosphoric acids, and then separating the reaching. The long-chain monoalkyi- (and iso difluorophosphoric acid in vapor form from the alkyl) monofluorophosphoric acid salts, such as monofluorophosphoric acid by distillation. sodium laury monofluorophosphate, are surface- 60 5. The method of producing anhydrous mono active agents. Monoethyl-monofluorophosphoric fluorophosphoric acid which includes the steps acid, obtained e. g. by reacting the anhydrous acid of mixing phosphorus pentoxide and a hydroflu with ethylene, forms diethyl monofluorophos oric acid of a concentration of from 69% to 100% phate in a reaction corresponding to that of inclusive HF in the ratio of 1 mole P.Os: (2+x) monoethyl sulfuric acid which, when heated, moles HF: (1-X) mole H2O in which X has any forms diethyl sulfate. value from 0 up to and including 1, maintaining Due to their non-oxidizing nature, both said the ingredients in a closed vessel until comple fluorophosphoric acids may be used as anhydrous tion of the reaction among them substantially acids in the non-oxidizing refining of oils and the to according to the equation like, while other uses in addition to those just suggested may be readily devised and other compounds may be prepared from them by those skilled in the art. in which X has any value in the range from 0 to 1 Having thus described my invention, I claim 75 inclusive to thereby form a resultant product 2,408,785 11 12 containing monofluorophosphoric and difluoro 12. That step in a method of producing anhy phosphoric acids, and then separating said acids drous monofluorophosphoric acid which com by distillation. prises mixing phosphoruspentoxide and an aque 6. The method of producing anhydrous mono ous hydrofluoric acid of about 69% Hin a man fluorophosphoric acid which comprises combining 5 ner to prevent loss of reaction components or re phosphorus pentoxide and hydrofluoric acid of action products. HF concentration exceeding 69% substantially 13. The method of producing anhydrous mono according to the equation fluorophosphoric acid which comprises mixing phosphorus pentoxide and an aqueous hydro 0 fluoric acid of about 69% HF in the ratio of 1. mole P2O5:2 moles BF:1 mole H2O, and then in which X has any value in the range from 0 to 1 maintaining the mixture in a closed vessel until inclusive, maintaining the reaction products in the reaction has gone to completion according to a closed vessel at a temperature and for a time the equation P20s--2HF--HaOs2H2PO3F. sufficient to cause the reaction to go to comple 15 14. The method of producing anhydrous mono tion according to said equation, and then Sepair fluorophosphoric acid which comprises mixing rating the monofluorophosphoric and difluoro phOSphorus pentoxide and an aqueous hydro phosphoric acids in the resultant product by dis fluoric acid of about 69% HF in the ratio of 1 tillation. mole P2O5:2 moles BF:1 mole H2O, and then 7. The method of producing anhydrous mono 20 heating the product in a closed vessel at a tem fluorophosphoric acid which comprises mixing perature not exceeding about 150° C. until the phosphorus pentoxide and hydrofluoric acid of reaction has gone to completion according to the about 69% HF in the ratio of 1 mole P2O5:2 moles equation P2O5-2HF--HaO=2H2POF. HF:1 mole H2O, and then maintaining the reac 15. The method of producing anhydrous di tion product in a closed vessel at a temperature 25 fluorophosphoric and monofluorophosphoric and for a time sufficient to cause the reaction to acids which comprises mixing phosphorus pent go to completion according to the equation oxide and anhydrous hydrofluoric acid and '...in P2O5--2HF--H2O-2H2PO3F. taining the resultant product in a closed vessel 8. In a method of producing anhydrous mono until the reaction has gone to completion sub fluorophosphoric acid, the steps of mixing phos stantially according to the equation phorus pentoxide and hydrofluoric acid of any 30 HF concentration from about 69% to 100% in PaOs--3HF=HPOF--HaPOF clusive in the ratio of 1 mole P2O5: (2--X) moles 16. The method of producing anhydrous di HF: (1-X) mole H2O in which X has any value fluorophosphoric and monofluorophosphoric acids in the range from 0 to 1 inclusive, and then main which comprises mixing phosphorus pentoxide taining the reaction products in a closed vessel and anhydrous hydrofluoric acid, maintaining the at a temperature and for a time sufficient to cause resultant mixture in a closed vessel until the re the reaction to go to completion according to the action has gone to completion, Substantially ac equation cording to the equation 40

in which X represents any value in said range. and then separating the two acids in the result 9. In a method of producing anhydrous mono ant product by distillation. fluorophosphoric acid, the steps of mixing phos 17. The method of producing anhydrous di phorus pentoxide and hydrofluoric acid in the fluorophosphoric and monofluorophosphoric acids ratio of 1 mole P2O5: (2--X) moles HF: (1-X) which comprises mixing phosphorus pentoxide mole H2O in which X has any value in the range and anhydrous hydrofluoric acid, maintaining from 0 to 1 inclusive, and maintaining the reac the resultant mixture in a closed vessel to there tion products in a closed vessel to prevent loss 50 by prevent the escape of reaction products until thereof until the reaction has gone to completion the reaction has gone to completion substantially according to the equation according to the equation then distilling the resultant product to separate in which X represents any value in said range. the difluorophosphoric acid in vapor form from 10. The method of producing anhydrous mono the residual monofluorophosphoric acid, and fluorophosphoric acid in conjunction with anhy condensing the vapor. drous difluorophosphoric acid which comprises 18. The method of simultaneously producing mixing phosphorus pentoxide and anhydrous hy anhydrous difluorophosphoric and monofluoro drofluoric acid substantially in the ratio of 1. 60 phosphoric acids which includes the steps of mix mole P2O5:3 moles HF, and then maintaining the ing phosphorus pentoxide and anhydrous hydro reaction products in a closed vessel at a tempera fluoric acid in the ratio of 1 mole:3 moles, pre ture and for a time sufficient to cause the reac venting the escape of reaction products from the tion to go to completion according to the equa mixture until the reaction has gone to completion tion P2O5-3HF-H2PO3F--HPO2F2. Substantially according to the equation 11. The method of producing anhydrous mono fluorophosphoric acid which comprises mixing phosphorus pentoxide and an aqueous hydro and then separating the difluorophosphoric acid fluoric acid of about 69% HF and maintaining in vapor form from the residual monofluorophos the mixture in a closed vessel until the reaction phoric acid by distillation. has gone to completion according to the equa WLLY ANGE. tion P2O5--2HF--H2O=2H2PO3F.