2,336,622 United States Patent Office Faiented Vay 27, 1958 2 substantially all of the hydrogen chioride is removed therefrom. With respect to the reactants usei in this process, the 2,336,622 phosgene car be preformed or it can be formed in situ PREPARATION OF CARBONY, FIUOR);E from carbon monoxide and chlorine which, as is weli Charles W. Tullock, Winnington, Dei., assig or its E. H. known, combine readily at elevated temperature to give iil Pont de Nemours and Conpany, Wii Saiigioia, Bei, phosgene. When this is done, the carbon monoxide is a corporation of Delaware preferably, though not necessarily, used in excess over the amount calculated to react with the chlorine. Simi No Drawing. Appication February 13, 1955 :) larly, the hydrogen fluoride can be used preformed, as the Seria No. 489,294 substantially anhydrous material, or if desired, it can be prepared in situ by employing approximately equivalent 10 Claims. (C. 260-544) amounts of a strong, substantially anhydrous acid such as sulfuric acid or hydrogen chloride and of an alkaline or This invention relates to a new process for preparing alkaline earth metal fluoride, such as Sodium or calcium fluorine-containing organic compounds. in particular, it fuoride. This embodiment is not preferred, however, be relates to a new process for preparing carbonyl fluoride. cause of the additional difficulties encountered in mixing It has recently been discovered that valuable fluorocar the reactants and in separating the reaction product from bons, including tetrafluoroethylene, can be synthesized in solid by-products. Another method of forming both very good yields by reacting carbonyl fluoride with car d phosgene and hydrogen fluoride in situ involves reacting bon at high temperatures, for exampie, by bringing car together formaldehyde, chlorine and a metal fluoride, bonyl fluoride in contact with the carbon electrodes of e.g., calcium fluoride. The reactions taking place are an electric arc. This discovery is disclosed and caimed presumably H2CO--2Cl2-> COCl.--2HCl and in application Ser. No. 420,472, filed on April 1, 1954, by M. W. Farlow and E. L. Muetterties and issued May Regardless of whether the phosgene and hydrogen fluo 24, 1955, as U. S. Patent 2,709,189. ride are used preformed or are formed in situ, it is de Adequate commercial exploitation of this discovery sirable that there be in the reaction mixture at lease one would of course be furthered by economical syntheses of Inole of hydrogen fluoride per mole of phosgene, in order carbonyl fluoride in an acceptable state of purity, and to obtain satisfactory yields of carbonyi fuoride. Since in particular, free from hydrogen chloride. Such a the formation of carbonyl fluoride requires two moles of synthesis has heretofore been lacking. Carbonyl fluoride hydrogen fluoride per mole of phosgene, it is generally has been prepared by reaction of silver II fluoride with preferred to use the reactants in approximately those pro carbon monoxide Rufi et al., Z. anorg. allgem. Chem. poritions, or to use a small to moderate excess of hydro 221, 154 (1934) and, as a mixture with many other gen fluoride, e. g., to use up to three moles hydrogen products, by direct fluorination of acetone Fukuhara et fluoride per mole of phosgene. al., J. Am. Chem. Soc. 63, 788 (1941)). A much more The rate of the reaction between phosgene and hydro practical method involving the reaction of hydrogen fluo gen fluoride is almost negligible below 50° C., and the ride with phosgene has been reported, first by Simons reaction should therefore be carried out above that tem et al., who obtained chiefly carbonyl fluorochloride J. 40 perature. While the reaction rate is already much in Am. Chem. Soc. 68, 1672 (1946), then by Xwasnik creased at temperatures in the neighborhood of 100° C., FIAT Review of German Science 1939-1946, inorganic it is much preferred from a practical standpoint to use Chemistry I, p. 242 (1948)). However, even this atter temperatures of at least 150° C. The temperature can method has little practical utility since the reports indi be as high as the decomposition point of the reactants but cate that these workers were unable to separate the car it is not desirable to exceed 700° C. and preferably about bonyl fluoride from the hydrogen chloride formed in the 500 C. when carbonyl fluoride is the desired main prod reaction. The reason for this is that the two compounds lict because the yields of carbonyl fluoride decrease when have practically the same boiling points, -83.1 and this temperature is approached and other products form -83.7 C., respectively. Moreover, the usual absorbents in increasing amounts, as discussed below. The preferred for hydrogen chloride react with, and destroy, carbonyi temperature range is that between 150 and 400° C., and fiuoride. still more preferably 150-300° C. This invention has as an object a process for the prep The reaction is most conveniently carried out at atmos aration of carbonyl fluoride, CCF. A further object is pheric pressure, for example, in a tubular reactor which a process providing carbonyl fluoride essentially free from may be packed with contact materials such as active deleterious contaminants. Another object is the provision carbon or calcium fluoride powder or pellets, although of a process for preparing fluorochlorocarbons. A still this is not essential since satisfactory, although lower, further object is a process for preparing fluorochloro conversions to carbonyl fluoride are obtained in the methanes. Still another object is a process for preparing absence of such materials. However, the use of active carbonyl fluoride from carbonyl chlorofluoride. Other ob carbon, which acts as a reaction catalyst, is preferred since jects will appear hereinafter. 60 it leads to high conversions at relatively low temperatures. The present invention is to a process wherein phosgene in atmospheric pressure operation, a gaseous mixture in is reacted with at least a molar equivalent of hydrogen the proper proportions of hydrogen fluoride and phosgene, fluoride, HF, at a temperature of at least 50° C. and the or of hydrogen fluoride, carbon monoxide and chlorine is reaction product with or without a preliminary separation passed through the reactor heated to the desired tempera therefrom of unreacted phosgene and/or hydrogen fluo tre. The contact time is not very critical since appre ride is brought into contact with a stoichiometric amount, ciable conversions are observed even at very short contact based on the hydrogen chloride in the reaction product times, e.g., 5 seconds. Good results are obtained at con and on any hydrogen fluoride there present, of an inor tact times in the range of 15-60 seconds, although much ganic material inert to carbonyl fluoride but reactive wit longer contact times can be used, e.g., 5 minutes or more. hydrogen chloride to form stable products, said inorganic ; ; The effluent gas is treated as described below to remove material being maintained in contact with the reaction the hydrogen chloride formed, and also any unreacted product at a temperature at least as high as 0° C. until hydrogen fluoride. 2,836,622 . . . . . es. . 4 . Another satisfactory mode of operating consists in car fluoromethane. The carbonyl fluoride is readily separated rying out the reaction in sealed, corrosion-resistant pres from the mixture by fractional distillation as shown be sure vessels, and preferably at the autogenous pressure low. Under the same conditions, but in the presence of developed by the reactants at the operating temperature. a small amount, 1-5%, by weight, of calcium fluoride, a If desired, additional pressure provided by a non-interfer similar disproportionation takes place except that a higher ing gas such as nitrogen or carbon monoxide can be ap amount of chlorofluoromethanes (CCIF, and CFCI) is plied. In particular, carbon monoxide can be introduced found in the product. Thus, it is apparent that the car into the reaction vessel to any desired degree of initial bonyl chlorofluoride can be largely converted into valuable pressure, for example between 10 and 800 atmospheres, products. . . especially when the phosgene is synthesized in situ from its O if it were not for the presence of hydrogen chloride, components, chlorine and carbon monoxide. However, the separation of carbonyl fluoride from the other com no substantial advantage appears to result from using ponents of the crude. reaction product would offer no carbon monoxide much in excess over the amount re special difficulty. Fractionation in a low temperature quired to form phosgene. Within the preferred tempera still accomplishes this separation. Even carbon dioxide, ture range of 150-400 C., the reaction time in pressure 5 which sublimes at -78° C., can be to a large extent sep vessels can be quite short, Substantial yields are ob arated from carbonyl fluoride (P. B. -83.1° C.) owing tained with a reaction time as short as 10-30 minutes, to the fact that it appears to form a constant boiling mix especially when a catalyst such as active carbon is used. . ture with carbonyl fluoride and concentrates in the first It is not necessary to use reaction times exceeding three fraction of this compound distilling over. In any event, hours, and in fact it is undesirable to do so in the higher 20 carbon dioxide is formed only in small amounts and does temperature ranges, e. g., 400-500 C., since the yield not normally interfere with the reactions of carbonyl of carbonyl fluoride appears to decrease as a consequence. fluoride, especially its reaction with carbon at high tem Active carbon, that is, very finely divided, porous peratures, e.g., 1500 C. or higher as in the carbon arc, carbon having a total surface area of at least 20 square to give tetrafluoroethylene. meters per gram IHassler, "Active Carbon, Chemical 25 Hydrogen chloride, however, which boils at -83.7 C, Publishing Co. (1951), p. 127], is a desirable catalyst for cannot be separated from carbonyl fluoride by distillation the reaction of phosgene with hydrogen fluoride. Higher and it is undesirable as an impurity. The synthesis of conversions to carbonyl fluoride can be obtained when carbonyl fluoride from phosgene and hydrogen fluoride this catalyst is used than without it, particularly in the is impractical unless the by-product hydrogen chloride lower temperature range, e.g., 150-250° C. Good re 30 can be removed. Aqueous acid absorbent systems cannot sults are obtained by using between 1% and 20% of active be employed nor can numerous materials capable of ab carbon, based on the weight of the phosgene present in sorbing hydrogen chloride, e.g., calcium oxide, soda lime, static systems under pressure. When operating contin aluminum oxide, potassium acetate, boric anhydride, acetic uously, at atmospheric pressure, the gaseous reactant mix anhydride, and pyridine. Anhydrous alkaline agents such ture is simply passed through a bed of active carbon main 35 as disodium hydrogen phosphate were found not to re tained at reaction temperature. The catalyst can be re move hydrogen chloride. ... used a number of times without purification. The principal carbon-fluorine compound obtained by Agents which have been found capable of absorbing the reaction of hydrogen fluoride with phosgene is car hydrogen chloride without reacting with carbonyl fluoride bonyl fluoride, COF. The crude reaction product nor 40 or carbonyl chlorofluoride are the alkali metal fluorides, mally contains variable amounts of unreacted starting used in anhydrous form, sulfur trioxide, and phosphorus materials, and the hydrogen chloride formed in the re pentoxide. These agents also remove hydrogen fluoride action. In addition, some carbonyl chlorofluoride, from the reaction product, which is another advantage, CCFC), is formed, generally in relatively small amounts although a less important one since hydrogen fluoride unless the initial moie ratio of hydrogen fluoride to phos can be separated from carbonyl fluoride by distillation. gene is substantially less than 2:1. Carbon dioxide is With the anhydrous alkali metal fluorides, e.g., sodium present in the reaction product, generally in small amounts. fluoride, hydrogen chloride reacts with formation of In the higher range of reaction temperature, e.g., above sodium chloride and sodium acid fluoride, according to about 400° C., other carbon-fluorine compounds are the equation HCI-4-2NaF->NaCl-NaF.H.F. From this formed in increasing amounts. These are the chloro it will be seen that it is necessary to use two moles of fluoromethanes, and particularly chlorotrifluoromethane sodium fluoride per mole of hydrogen chloride. The and dichlorodifiuoromethane. Carbon tetrafluoride and use of lesser amounts of sodium fluoride results in in trichlorofluoromethane also appear in minor amounts. complete removal of the hydrogen chloride. In prac These compounds while minor in amount can be recov tical operation it is desirable to trap out most or all of ered as by-products. The copending application of Don 5 the excess hydrogen fluoride, if any, from the reaction ald D. Coffman and Charles W. Tullock, Serial No. gases. The gases are then analyzed, preferably by infra 489,296, filed of even date herewith, now U. S. Patent red technique, for hydrogen fluoride and hydrogen chlo 2,757,213, issued July 31, 1956, discloses a process for ride content and treated with at least the amount of the preparation of carbon tetrafluoride and chlorofluoro sodium fluoride stoichiometrically equivalent to the hy methanes by reacting hydrogen fluoride with phosgene and 60 drogen fluoride and hydrogen chloride according to the carbon at temperatures of 600° C. and above. equations: Carbonyl chlorofluoride, which is formed in appreciable HC1--2NaF->NaCl--NaHF amounts in the reaction, can readily be converted in sub and stantial yields to carbonyl fluoride, thus increasing the yield of the latter. This is done simply by heating car 65 HF--NaF->NaHF, bonyl chlorofluoride at a temperature in the range of When the hydrogen fluoride and the phosgene are used 400-600° C., preferably in a sealed vessel under the auto in substantially equivalent amounts (2 moles hydrogen genous pressure developed, under which conditions dis fluoride per mole of phosgene) it is only necessary to proportionation of the carbonyl chlorofluoride occurs. use sodium fluoride in amount equivalent to the hydrogen For example, when a sample of substantially pure car chloride theoretically formed (2 moles sodium fluoride bonyl chlorofluoride is heated in a corrosion resistant bomb per mole hydrogen chloride, that is, 4 moles sodium fluo at 500° C. for two hours, the resulting gaseous product ride per mole of phosgene) since this will be sufficient to is found by infrared analysis to contain, on a molar basis, absorb all the hydrogen chloride formed and any un 50% carbonyl fluoride, 35% carbonyl chlorofluoride, reacted hydrogen fluoride. 10% phosgene, 3% carbon dioxide and 2% dichlorodi 75 Potassium fluoride reacts similarly, except that in this 2,886,823 5 case somewhat smaller amounts may be permissible liquid nitrogen and admitting into it the crude gaseous since potassium acid fluorides containing higher than reacton mixture or the same after trapping out, by means molar amounts of hydrogen fluoride can form, such as of low temperature (-15 C.) trap, most of the hydro KF.2HF and KF.3HF. Even so, however, it is recom gen fluoride in the reaction gases, the reaction gases be mended to use two moles of potassium fluoride per mole 5 ing preferably but not necessarily cooled down to or in of hydrogen chloride formed, and one mole per mole the neighborhood of room temperature. If carbon mon of excess hydrogen fluoride to insure complete absorption. oxide is present in the reaction mixture, which is nor Sulfur trioxide (sulfuric anhydride, SO3) removes hy mally the case when the initial carbonyl-containing re actant is a mixture of carbon monoxide and chlorine, drogen chloride completely with formation of chlorosul () rather than preformed phosgene, it can be separated by fonic acid, CISOH. Only one mole of sulfur trioxide pumping it of under reduced pressure from the cylinder per mole of hydrogen chloride and one moie per mole of (cooled in liquid nitrogen) containing the sodium fluo excess hydrogen fluoride are used to insure complete ab ride and the reaction mixture. The cylinder is then Sorption. There is no detectable reaction between car closed, allowed to warm up to room temperature and bonyl fluoride and sulfur trioxide at room temperature, maintained at that temperature until absorption of the even after several days contact. However, when the l; hydrogen chloride is substantially complete. It is diffi phosgene/hydrogen fluoride reaction product is treated cult to state precisely the minimum length of time need with Sulfur trioxide, it is found to contain somewhat ed for this removal since it depends on variables such as more carbon dioxide than upon treatment with sodium the relative proportions of reactants and the pressure fluoride. However, additional formation of carbon di developed in the absorption vessel. In general, a contact oxide can be minimized by using only a short contact time of at least 10 minutes, preferably at least one-half time between Sulfur trioxide and the reaction product, hour after the reactants have reached room temperature since sulfur trioxide reacts rapidly with hydrogen chlo is desirable. However, a very accurate test of the sub ride and hydrogen fluoride. stantial completion of the hydrogen chloride removal is Phosphorus pentoxide (phosphoric anhydride, PO5) available through infrared spectroscopic analysis of the also removes hydrogen chloride completely with forma reaction mixture. tion of phosphorus oxychloride and metaphosphoric acid Sometimes the above described treatment does not re according to the equation move the last traces of hydrogen chloride from the reac tion mixture. In such cases a second, similar treatment There is no detectable reaction between phosphorus with another portion of sodium fluoride, e. g., one pentoxide and carbonyl fluoride. Any hydrogen fluoride quarter to one-half the amount used in the first treat present in the reaction product is also absorbed with ment, completes the purification. formation of phosphorus oxyfluoride. While the latter A similar procedure is used when sulfur trioxide or is a gas, it can be readily separated from carbonyl fluoride phosphorus pentoxide is used as the hydrogen chloride by fractional distilation since it boils at -40° C. 3. 5 absorbent. With these absorbents the period of contact The hydrogen chloride absorbents discussed above all can be even shorter, e. g., from five minutes to one-half convert hydrogen chloride to stable products having boil hour. One mole of sulfur trioxide is required per mole ing points widely different from that of carbonyl fluoride. of hydrogen halide (HCl or HF) present in the reaction With the alkali metal fluorides, solid alkali metal halides a. product, and with phosphorus penioxide two-thirds of a are obtained; with sulfur trioxide, the product is chloro mole is required per mole of hydrogen halide. Sulfonic acid, B. P. 150 C.; and with phosphorus pent Other procedures can be used for removing hydrogen oxide, it is phosphorus oxychloride, B. P. i07 C. All chloride from the reaction product. For example, the these products are therefore readily separable from car crude gaseous mixture can be passed continuously bonyl fluoride. through tubes or towers containing the absorbent ma In all cases, the reaction whereby hydrogen chloride is terial, with recycling if necessary. Also, the crude re absorbed appears to proceed very slowly at temperatures action product can be subjected to a preliminary frac below about 0° C. It is therefore recommended to bring tionation to remove the easily separable components, and the reaction product and the absorbent material in con the non-separable mixture of carbonyl fluoride and hy tact at temperatures above about 0° C. When the mix drogen chloride can then be purified by treatment with ture reaches or slightly exceeds that temperature, a mildly the absorbent material. exothermic reaction takes place between the absorbent The gaseous reaction product remaining after this puri and the hydrogen chloride, which generally raises the fication is transferred to a cooled, evacuated storage cyl temperature to 40-60 C. Experiments have shown that, inder where it can be kept for future use. If desired, at an initial temperature in the range 0-20 C. the re this product can be further enriched in carbonyl fluoride action between the hydrogen chloride and the absorbent by Thefractionation process is in illustrated low temperature, by the examples high pressure given still.be is substantially complete in a short time, between 5 and low either in descriptive or in tabular form. In the 25 minutes, depending on the absorbent. Contact be examples carried out in closed systems, the reactants tween the reaction product and the absorbent can, of were heated at the specified temperature and for the course, be maintained for much longer periods of time. specified time in a bomb of 140 ml. capacity lined with When sulfur trioxide is used, however, some of the a corrosion-resistant nickel-iron-molybdenum alloy. At phosgene present, if any, may be converted to sulfuryl the completion of the heating period, the reactants were chloride and carbon dioxide on prolonged contact. There usually allowed to cool in the reaction bomb overnight is no harm in using temperatures substantially in excess and then bled into an evacuated, cooled cylinder con of that attained in the spontaneous exothermic reaction. taining the hydrogen chloride absorbent. In some cases For example, contact temperatures of 150° C. or higher (e. g., Examples 2, 3, 4, 6, 7, 10) the crude reaction can be used, although there is no advantage in doing so. mixture was bled hot from the bomb. If any carbon A convexlient irc.cedure for reihoving the hydrogen Inonoxide was present, either as unreacted starting ma-. chloride and excess or unreacted hydrogen fluoride from terial or as pressuring gas, it was removed by pumping the crude product consists in transferring the gaseous the cylinder cooled in liquid nitrogen down to about reaction mixture to a cylinder containing from 2 to 2.5 0.1 mm. pressure. The remaining product was left in moles of sodium fluoride per mole of hydrogen chloride, contact with the absorbent material in the cylinder at and one mole of sodium fluoride per mole of hydrogen room temperature for periods of time ranging from fluoride in the gases treated. This is done by evacuating about 2 to about 16 hours. When the absorbent ma-. the cylinder containing the sodium fluoride, cooling it in 75 terial was silhydrous sodium fluoride (Examples 1-14, 2,836,622 7 8 16-19), there was used from 2 to 3 moles of it per gen chloride and hydrogen fluoride, were again collected mole of hydrogen chloride theoretically formed. The separately and their composition was determined by in is last traces of hydrogen chloride were in most cases re frared analysis. The percent conversion to carbonyl moved by transferring the remaining gas to a second fluoride in these examples is based on the hydrogen fluo evacuated and cooled cylinder containing somewhat 5 ride and chlorine initially weighed into the storage cyl more than two moles of anhydrous sodium fluoride per inder, no correction being made for the small but ap mole of hydrogen chloride in the gases treated. When preciable fraction of these reactants which did not ac the absorbent material was sulfur trioxide (Example 15), tually pass through the reaction tube, or for the amount there was used 1.25 moles of it per mole of hydrogen which was converted to carbonyl chlorofluoride or car chloride theoretically formed, and the second treatment 10 bonyl chloride. - ...... ------was omitted. When the absorbent material was phos Following the removal of hydrogen chloride and hy phorus, pentoxide (Example 26) there was used 0.83 drogen fluoride, the product gas was in all cases analyzed mole of it per mole of hydrogen chloride theoretically by infrared spectroscopy. The infrared reference stand formed and the second treatment was also omitted. ard was a sample of carbonyl fluoride prepared from car In the examples carried out in a continuous flow syst. bon monoxide and silver II fluoride according to the tem at atmospheric pressure using hydrogen fluoride and procedure of Ruff et al., Z. anorg. allgem. Chem. 221, phosgene as the reactants (Examples 20-26), the reactor 154 (1934) which sample was shown to be 97% pure was a nickel tube, one inch inside diameter, and 29 by mass spectrograph analysis. A redistilled sample of inches long, of which a 13-inch length was heated in an carbonyl chlorofluoride, prepared from phosgene and electric furnace. The tube either did not contain any antimony trifluoride according to the procedure of contact material (Example 23) or was packed within Emeleus et al., J. Chem. Soc. 1948, 2183, served as the its heated portion with active carbon (Examples 20-22) carbonyl chlorofluoride. standard. In most cases, the or with calcium fluoride pellets (Examples 24, 25). reaction product contained very small amounts of silicon Prior to reaction, the contact materials were heated for tetrafluoride, presumably resulting from hydrolysis of several hours in a slow stream of helium to remove water carbonyl fluoride by traces of water present in the infra and trapped gases. The same contact material was used red analysis cell and reaction of the resultant HF with for a number of successive runs. The reactants were the glass of the cell. Infrared analysis is sufficiently weighed separately, then mixed in a cylinder and the accurate for the purposes of this invention although reactant mixture was bled through the reactor at a pre chlorine, which was present in small amounts in many determined bubble rate, together with a slow stream of 30 of the runs, as shown by bubbling the product through helium to prevent possible backsurges of air into the aqueous potassium iodide does not have an infrared ab-, apparatus. The reactor temperature was determined with sorption band and carbon dioxide is somewhat difficult a thermocouple. After passage through the reactor, the to determine accurately in the presence of the carbonyl effluent gas was led through two copper traps cooled in car halides. However, neither of these difficulties vitiates bon dioxide/acetone, then through two glass traps cooled the analyses to an appreciable degree. In some cases in liquid nitrogen. The products collected in the liquid the products were also analyzed by mass spectrography nitrogen traps and in the carbon dioxide/acetone traps and results were in very good agreement. - were, in the case of Examples 20-25, collected separate The product compositions given in the examples are ly in stainless steel cylinders containing 60 g. of sodium based in most cases on infrared analysis of the first sam fluoride. After remaining in contact with the sodium ple of gas bled from the storage cylinder. When the fluoride for approximately 24 hours, the products were analysis was carried out on the last portions of gas mix again collected separately. When phosphorus pentoxide tures rich in carbonyl fluoride, there was no difference in was used as the absorbent material (Example 26) the the percentages of this product present in both samples, collecting procedure was slightly different, as described from which it was concluded that no significant fractiona in that example. The percent conversion of phosgene tion occurred in such products. Some fractionation to carbonyl fluoride is based in all cases on the amount probably occurred in samples poorer in carbonyl fluoride, of phosgene with which the run was started, no correc e.g., containing 35-50% of this component. tion being made for the phosgene which remained un reacted or which was converted to carbonyl chloroflu EXAMPLE I oride. 50 A bomb of 140 ml. capacity lined with a corrosion re When the reactants in the continuous flow, atmos sistant nickel-iron-molybdenum alloy was charged with pheric pressure reaction were hydrogen fluoride, carbon 20 g. ( 1.0 mole) of anhydrous commercial hydrogen flu monoxide and chlorine (Examples 27-29) the same tubu oride and 49.5 g. (0.5 mole) of phosgene. The bomb lar reactor was used. In all cases, the reactor was was heated at a temperature of 150-152 C. for 3 hours packed, within its heated portion, with active carbon. 5 s under the autogenous pressure developed by the reactants The chlorine and the hydrogen fluoride were weighed and the reaction products at that temperature. At the in approximately 2:1 molar ratio into a stainless steel completion of the heating period the reactants were al cylinder, which was warmed at 50-60° C. during the lowed to cool in the bomb overnight and were then bled entire run. The carbon monoxide was metered into the into an evacuated, cooled cylinder containing 80 g. (1.9 reaction tube at a rate sufficient to have at least a 1:1 60 moles) of anhydrous sodium fluoride. The cylinder was molar ratio of it with respect to chlorine. The three cooled further by immersion in liquid nitrogen and evac reactants entered the reaction tube at the same point. uated down to 0.1 mm. pressure to remove any carbon After passage through the reactor, the effluent gas was monoxide present in the reaction product. The cylinder first led through copper traps cooled in an ice/ethanol was allowed to warm up to room temperature and the bath whose temperature was between -13 and - 17° C. reaction product was left in contact with the sodium The material collected in these traps appeared to be fluoride for approximately 24 hours. The gaseous prod solely hydrogen fluoride since it was completely absorbed uct was then transferred to a second evacuated cooled by sodium fluoride. The gas passed next through a glass cylinder containing 40 g. (0.95 mole) of anhydrous so trap cooled in a carbon dioxide/acetone mixture, then dium fluoride and again left in contact with the sodium through two glass traps cooled in liquid nitrogen. The fluoride at room temperature for about 16 hours. Finally, products condensed in the liquid nitrogen traps and in the residual gaseous product was transferred to an evac the carbon dioxide acetone traps were collected separate uated cylinder cooled in liquid nitrogen. There was thus ly in stainless steel cylinders containing 80 g. of sodium obtained 33 g. of product which was shown by infrared fluoride. After remaining in contact with the sodium analysis to contain no detectable amount of hydrogen fluoride for 24 hours, the products, now free of hydro 75 chloride. It contained, on a molar basis, 40% carbonyl 2,836,622 9 O fluoride, 15% carbonyl chlorofluoride, 40% phosgene oxide and chlorine. In all of these examples, the and 5% carbon dioxide. The conversion to carbonyl hydrogen chloride and unreacted hydrogen fluoride, if fluoride was 33%. Carbonyi fluoride of 95% purity can any, were removed from the reaction product with an be obtained by distillation of this material through a low hydrous sodium fluoride as already described. In some test, high pressure still. f 5 of these runs (Examples 10, 11) a phenomenon not ob which Eye"E. S Fire, 1 of able I below, served when using preformed phosgene was noted. This glVeS the de se Seveeveral examplesle carried out was a temperature "flash,” occurring in the runs carried in closed systems under varying conditions of tempera- t i the 300-400 C which tarily i ture,Example pressure 1. In and all casestime, thesubstantially reactants. aswere described preformed in Ccreased 1 tiethe temperature3 U- 50-100°range, yhtenC as wellmomentarily as the pres in phosgene and hydrogen fluoride, and anhydrous sodium sure. This "flash' was not observed in runs carried out fluoride was used to remove the hydrogen chloride. below 300 C. Table I PREPARATION OF CARBONYL FLUORIDES FROM PHOSCENE AND HYDRO GEN CELORIDE Weight reaction Composition of product reaction Percent ExaInple Reactants (moles) Temp., time Pressure (atm.) Weight NaF and time movalafter re- of product(moles Sionconver'- to Cogol, percent) COF (grams)
OF t 0 g. (24 hrs.) 885. 1------0.510HF------COCl2------}150-1529 C., 3 hours ------Autog------1standpassic.(8 pass 80 g. (2 days).S.--- 38.5 3874) - - - 33 2 - 2------g Eof...I. II. ho-ite C., 3 hours 140 (autog)...S.E, SSY---- } 32.0 88:'85 65 9.7 g. activated charcoal.----- y w saw a ------2nd pass 40 g. ( day).--- 88:3) - COF (30) 200 C.,., 0.25-0.50hU.25-U.5U ------Autll.09.------(5.2nd pass pass 80 40 g.g. (3(1 day).-----days). -- } 42.0 COClCOFC (50)(10 t32 885).2 0------1st pass 80 g. (3 days) --- COFC (15)-- ko-is C., 0.25-0.50 hr----. 185 (autog)---E, pass 40 g. (1 day).---- } 30.5 23.9) - - - - - 66 OEF t pass 80 g. (4 days) E2, - 5------V COCl)------300 C., 3hrs------310 (autog)---iss6.ii.51st pass 80 g. ayS) - ... } 30.2 387,0. - - - - 67 2 - - 6 EEsof, 300° C., 0.25-0.50hr 800 1st pass 80 g. (1 day).---- } 35.6 888). 61 ------Öo (866 an is V saw we ------2nd pass 40 g. (1 day).--- 88.35).2) ------COFs (75)----- 7 1.0 HF------400° C., 0.25-0.30 hr as autog). Gas.33i: 3.08:56: 7 -- a-- - - - 0.5 OOCl)------, 0.25-0.30 hr------345 (autog)---issio.ii.5 837,9.2 ------
Table II below gives details on another series of ex It will be seen from Table that the conversions to amples in sealed systems in which phosgene was pre carbonyl fluoride were in general higher than those ob pared in situ, by using as reactants carbon mon- 45 tained using preformed phosgene. Table II PREPARATION OF CARBONYL FLUORIDES FROM CARBON MONOXIDE, CHLORINE AND HYDRO GEN FLUORIDE Weight productreaction Composition Percent Example Reactants (moles) Temp., time Fiveal Weight NaF and time afterOWa. E. ofproduc E" SIOSY to of CO (noles per- COF (grams)cliff cent)
or C., 3hrs------stpaSS 84 g. (4 days).-----days) 882;- - - -- 71 800 KEEI) 30.4 33,7).2 ------
1stt pass 105105g. g. (4 days)aSS)---- 88.8.- - - - 86 ho C., 3 hrs------800 { paSS 40 g. (1 day).----- } 24.4 38.9) - - - -
listt pass 105105g. g. (3 days)ayS)-...-- 38.2 -- - - 76 { pass 40 g. (1 day).---- } 28.8 33, - - - - ass-3. C., .56-75 hr------570-630 25)------COF2 (75)----- { paSS 84 g. (1 day).------} 32.5 COFC) (5)-- 3 so as C., 9.6 hrs------750-840 2nd pass 40 g. (1 day).----- 33 2,0):
list pass 80 g. (4 days) (56 (50). 39 ko-no C., 3 hrs------720-800 { st passpass 8Ug. 40 g. (1 day).-----ayS)----- } 31. (5) ( bear C., 0.25-0.50 hr------260-300 {EE::::::st pass 80 g. (4 days)----- 26.0 56 here C., 1 hr------300-30 (a1st paSS pass 80 40 g. g. (3 (1 days)----. day).----- } 28.5 53 2,836,622 - EXAMPLE 1.5 - - ent. The sulfuric acid and hydrogen chloride used in This example describes the preparation of carbonyl three of these examples were, of course, anhydrous. - Table III . . . . PREPARATION OF CARBONYL FLUORIDES FROM PHOSGENE AND HYDROGEN FLUORDE MADE INSITU Weight productreaction Composition.- . . . Percent- Example Reactants Temp., time Pressure Weight NaF. and time after of reaction - conversion (moles) (atn.) removal product to COF, . of CO, (moles percent) HC1,(grams) HF
0.50 CaF2------1st pass 80 g. (1 day) --- i6------0.50 COC2---- 200° C., 3 hrs------Autog--- W------30.5 COC88%). (20). About 5 HaSO4------no. 3. pass 40 g. (1 day).---- } CO (20)------SO ()--- COF. (20 3:0.25 SF::::::::::::::::::::Cla------1stS pass 80 g.2. (1 day)8y)------88E3.2 - - - - 17------3.236). III ------500° C., 3 hrs------600 (i. pass 40 g. (3 days)----- } 14, 5.66, ti).I. 5. CO (pressured to 600 atm.).--- CCF (5)-- ?O.3 CaF2------s 68EC0).888.I. 0.3Cl2------1st pass 80 g. (day).------18------E. fiso, ------or C.. i hr------800 { pass 40 g. (1 day).----- } 19.2 83; SO) -----17. CO (pressured to 800 atm So, (5) - COF2 (20)-
0.35 SF: . . . . .m. ------wran was us us . 83ESS) 19.------0.350.70 Cla------(iii.6 (as paraformaide- 499-504. C., 2 hrs.------Autog-...- 80 g., 1 pass (3 days).------23.556 (20)------17. hyde). CF3CI (5)---- CCF (5)-- fluoride by a procedure essentially similar to that of Ex- 30 EXAMPLE 2.0 amples 8-14, but using sulfur trioxide rather than sodium fluoride as the hydrogen chloride absorbent. This and the following tabulated examples describe A bomb of 140 ml. capacity lined with a corrosion re-. runs carried out at atmospheric pressure in a continuous sistant nickel-iron-molybdenum alloy was charged with flow system. ------The reactor was a nickel tube, one inch inside di 20 g. (1.0 mole) of anhydrous commercial hydrogen 35 ameter and 29 inches long, of which a 13-inch length was fluoride and 35.5 g. (0.5 mole) of chlorine. Sufficient heated in an electric furnace. The tube was partly filled carbon monoxide was injected in the bomb to give a with activated carbon which occupied a volume of 117 pressure of 800 atm. at 400° C. The bomb was heated ml. in the heated portion of the tube. Prior to reaction, at 392-400° C. for 1.25 hours and allowed to cool over this carbon packing was heated at 700-800° C. for 16 night. The gaseous reaction product was then bled into 40 hours in a slow stream of helium to remove water and a 300 ml. cylinder cooled in liquid nitrogen and con trapped gases. w - taining 100 g. (1.25 moles) of sulfur trioxide. The ex Into a stainless steel cylinder containing 16.5 g (0.825 cess carbon monoxide was removed from the reaction mole) of anhydrous commercial hydrogen fluoride was product by evacuating the cylinder down to a pressure distilled 36 g. (0.364 mole) of phosgene. The cylinder of 1.6 mm. of mercury. The cylinder was then warmed 45 was connected to the reactor through a copper Y tube, up to room temperature for 30 minutes, again cooled the other branch of which was connected to a helium con in liquid nitrogen and evacuated to 0.1 mm. of mercury. . tainer. The cylinder containing the reactants was placed It was then again warmed to room temperature and held in a water bath at 40-50° C. and the reactants were bled there for 2 hours with intermittent shaking. After this. out at a predetermined bubble rate, accompanied by a operation the cylinder was cooled to -12 C. and the 50 slow stream of helium to prevent backsurges. The other residual gaseous product was distilled into another cylin end of the reactor was connected to a train of receivers der cooled in liquid nitrogen. The weight of the ab-. consisting of two copper traps cooled in carbon dioxide/ sorbent remaining in the first cylinder had increased to acetone followed by two glass traps cooled in liquid 130.6 g. There was obtained 29.2 g of product which nitrogen. - was shown by infrared analysis to be entirely free from 55 The reactor was heated to 195-200 C. and the re hydrogen chloride and to contain, on a molar basis, 60% actants were passed through it over a period of 1.07 carbonyl fluoride, 30% carbonyl chlorofluoride, 5% car hours. The products condensed in the carbon dioxide/ bon dioxide and 1% dichlorodifluoromethane. The con acetone and in the liquid nitrogen traps were collected version to carbonyl fluoride was 50%. separately in two stainless steel cylinders each contain Table II below summarizes several examples in sealed 60 ing 60 g. of anhydrous fluoride. After remaining in con systems in which one or both of the reactants, vis., tact with the sodium fluoride for approximately 24 hours, hydrogen fluoride and phosgene, were prepared in situ the products were again collected separately. The ma directly in the reaction vessel from other reactants terial in the liquid nitrogen traps weighed 26.9. g. before capable of forming them under the reaction conditions. contact with the sodium fluoride and 13.3 g after; the These specific embodiments of the invention are entirely 65 material in the carbon dioxide/acetone traps weighed operable, but they are not preferred because of the me 20.7 g. before contact with the sodium fluoride and chanical difficulties already mentioned and because the 9.5 g. after. Both residual materials were subjected to conversions to carbonyl fluoride obtained thereby are in infrared analysis, which showed that they contained no general lower than those obtained by employing phos detectable amount of hydrogen chloride. The product gene, or a carbon monoxide/chlorine mixture, and hydro 70 from the liquid nitrogen traps contained, on a molar gen fluoride. v basis, 90% carbonyl fluoride, 2% carbonyl chlorofluo In the examples of Table III, as in the previous ex ride, 1% phosgene, 3% carbon dioxide and 1% silicon amples, the crude reaction product was treated with an tetrafluoride. The product from the carbon dioxide/ absorbent material (anhydrous sodium fluoride) to re acetone traps contained, on a molar basis, 80% carbonyl move the hydrogen chloride and hydrogen fluoride pres fluoride, 4% carbonyl chlorofluoride, 4% phosgene, 4% 2,836,623 3 carbon dioxide and 1% silicon tetrafluoride. The con gene and 18 g. (0.90 moie) of anhydrous commercial hy version to carbonyl fluoride was calculated to be 84%. drogen fluoride. This cylinder was warmed in a water Carbonyl fluoride of high purity can be obtained by dis bath at 43-45 C. during this entire run and the reactant tillation of these products through a low temperature, mixture, together with a slow stream of helium as a car high pressure still. rier, was passed through the reactor tube heated at 200 C. The above example is Example 20 of Table IV below, over a period of 1.27 hours. There was left in the cyl which also summarizes several other examples in which inder 3.5 g. of the reactant mixture at the end of the run. the reaction was carried out in a continuous flow system At the exit and of the iiii.2 tiere was a train of receivers at atmospheric pressure under similar conditions. In Ex consisting of two copper traps cooled to -15 to -17 C. amples 20, 21, and 22, the reactor was packed with active 0 in an ice/ethanol inixture, then a glass trap cooled in a carbon; in Example 23 no contact material was used, and carbon dioxide/acetoine mixture, and finally two glass in Examples 24 and 25 the reactor was packed with cal traps cooled in liquid nitrogen. At the end of the run, cium fluoride peliefs. in these last two examples the ma the material condensed in the ice/ethanol traps amounted terial collected in the carbon dioxide/acetone traps was to 2.5 g. This was solely unreacted hydrogen fluoride, as not analyzed. In all cases, the crude reaction product shown by the fact that it was completely absorbed by an prior to infrared analysis was treated with sufficient so hydrous sodiura fluoride. The material condensed in the dium fluoride to remove the hydrogen chloride formed carbon dioxide/acetone trap (20.5 g.) was transferred in and any unreacted hydrogen fluoride. These runs were the usual manner to a cylinder containing 80 g. of sodium all carried out using phosgene and hydrogen fluoride as fluoride. After remaining in contact with the sodium the reactants. The reaction times refer to the time it took 20 fluoride for four days at room temperature, the residual for all the reactants to be passed from the storage cylin gaseous product (16.0 g.) was found by infrared analysis der to and through the reactor. to be free from hydrogen chloride and to contain, on a in Table IV, the columns headed I, II, II, and V show, molar basis, 5% carbonyl fluoride, 15% carbonyl chloro respectively: I, the weight of reaction product collected fuoride, 2% carbon dioxide, and 75% phosgene. in the liquid nitrogen traps; I, the weight of the same 2 5 The material condensed in the liquid nitrogen traps product after treatment with sodium fluoride; I, the (29.0 g) was transferred to a stainless steel cylinder con weight of reaction product collected in the carbon diox taining 97 g. (0.68 rinole) of phosphorus pentoxide. Ap ide/acetone traps; TV, the weight of the same product after proximately 15-20 minutes after the outside Surface of treatment with sodium fluoride. Products I and V were this cylinder appeared to be at room temperature, an exo subjected to infrared analysis and their composition is 30 thermic reaction took place whereby the cylinder warmed given in the table. up to about 40-45 C., then cooled off again. Contact b Table IV PREPARATION OF CARBONY, FLUORIDES FROM PHOSGENEANDIYDROGEN FLUORDEATATMOSPERIC PRESSURE; Weight reaction product (g) Composition of reaction product Percent Reactants Wit. Na and (moles percent) COWer Example (noles) Temp., time time Liquidtraps N. CO2facetonetraps sionCOF to
II IW I w COF2 (90).------COF2 (80).---
20------0.825 IF------195-2009 C..., i.07.0 hrs.----- 60 g. (242 hrs.)----S. 26.923. 13.3 20.7 9.5 S3ESS).------83ESS):2 :)----- 84 0.364 COCl. g 88): -- CO2 (4)------SiF4 (1).--- - SiF4 (1).------COF2 (85). - COFa (15)-----
21------1.00V ---EIF ------286-290 C.,. . 1.50hr. U.S.----- 60 g. (2424 hrs.)----hrs.) -- 35.2 6.5 26.26.7 14.0-888.S2- 88S8 5 { COCla------s g CO2 - CO2 (i) ------SiF4 (3).--- -- SiF4 (1).------COF2 (90).------. COF2 (60).----- 22 {83. HF------384-402 C., 1.33 hrs.----- 60 g. (24 hrs.) --- 30.2 13.5 25.8 12.0 88S95. - 67 ------0.425 COCl.------CO, (2) SiF4 (1) 0.775 HF------...-HF 83.3 (5)- 2 5 23------(8:5 COCl.------}495-506 C., (1.23 hrs). 60 g. (3 days).... 10.3 3, 7 ||37,022.2 RSS------SiF4COC (1)------(60)--- 88Faga).III80e).------24------0.900 HF------95-497 O C., (1 hr.) ------60 g. (24 hrs.). 24.6 11.4 ------COCl2 (trace).------33 (836. i4 SiFA88, (1)-- ree 882,1)--- 25------(8:SEO.0.750 FIF------III. 3704711°d C., (1 hr.)--...- 60 g. (24 hrs.)- 19.0 12. 0------89, race) 42 SiF4 (0.5)------
EXAMPLE 26 6 between the reaction product and the phosphorus pentox ide was continued for 16 hours at room temperature. The This example illustrates the use of phosphoruspentoxide residual gaseous product (13.0 g.) was then found by in as the hydrogen chloride absorbent. frared analysis to be entirely free from hydrogen chloride A hollow graphite tube of 0.75 inch inside diameter was packed with high purity acetylene black for about 9 inches and to contain, on a molar basis, 80% carbonyl fluoride, of its length and placed inside the nickel tube used in Ex 70 15% carbonyl chlorošiuoride, 5% carbon dioxide, less amples 20-25. Prior to reaction, the tube containing the than 1% phosgene, about 1% silicon tetrafluoride, and a acetylene black was heated at 800 C. in a slow stream of trace of phosphorus oxyfluoride. The weight increase of helium for about 16 hours. the phosphorus pentoxide was 16 g. The conversion of Following the procedure of Example 20, a stainless steel phosgene to carbonyl fluoride was 37%. cylinder was charged with 40.5 g. (0.41 mole) of phos- 75 Table W below summarizes three other examples car 2,836,622 - 5 16 ried out in a continuous flow system at atmospheric EXAMPLE 32 pressure essentially by the procedure of Example 26, but using as reactants hydrogen fluoride, carbon mon A mixture of 0.5 mole of hydrogen fluoride, 0.5 mole oxide and chlorine rather than hydrogen fluoride and of phosgene and 0.01 mole (0.84 g.) of aluminum tri preformed phosgene and using sodium fluoride as the 5 fluoride was heated in a bomb at 500 C. for two hours. hydrogen chloride absorbent. The heated zone of the under autogenous pressure. The gaseous reaction prod reaction tube was packed with active - carbon. The duct weighed 46.0 g., from which the hydrogen chloride. columns headed I, II, II, IV and V show, respectively: can be removed by sodium fluoride treatment, leaving the I, the weight of reaction products collected in the liquid carbonyl fluoride in the reaction product. It can also nitrogen traps; II, the weight of the same product after 0. be scrubbed with 40% aqueous potassium hydroxide to treatment with sodium fluoride; III, the weight of re remove all the acidic and hydrolyzable components, leav action product collected in the carbon dioxide/acetone ing only the alkali-unreactive products. The residual traps; IV, the weight of the same product after treat inert gas (12.6 g.) contained, on a molar basis and after ment with sodium fluoride; and, V, the weight of reaction alkali scrubbing 5% carbon tetrachloride, 75% chlorotri product collected in the ice/ethanol trap. This last prod 5 fluoromethane, 20% dichlorodifluoromethane and 1% uct was unreacted hydrogen fluoride. Products i and trichlorofluoromethane. - IV were subjected to infrared anaylsis and their compo When this experiment was repeated except that the sition is given in the table. Unreacted chlorine was de aluminum fluoride catalyst was omitted, there was ob-, tected qualitatively in the reaction product through its tained 40.5 g. of crude gaseous product which, after scrub reaction with aqueous potassium iodide. It is not de- 20 bing with aqueous potassium hydroxide, left 6.8 g. of inert tected by infrared analysis. gas. This contained, on a molar basis, 10% chlorotri. Table V PREPARATION OF CARBONYL FLUORIDE FROM HF, CO AND CLAT ATMOSPEERIC PRESSURE Weight reaction product (g.) Composition of reaction prod- Percent Reactants - - Liq. N. Colacetone Icel uct (noles percent) COWer Example (noles) Temp., time - traps traps ac. sion to traps COF
II III-IV V II IV
... 1.25 HF------gao - - - - - 88.888)...COC (35. ---- . 27------0, 62 Cla------142-154 C., 2.0 hrs------41 19 - 3. 23 5.5 CO3 (5)------32 0.89 CO------SiFi (trace).---
- - - - Oil------883). 28------0.950.48 Cla------F------. 199-214 0. C., 1.0 hrs-----, 36 17.5 14 1 4 COCl.CO (5) (2) are - 4. 0.48 CO------SF4S32 (1). 2------...... ------COF (65). COF (10)--...- 0.95 HF------COFC) (5)---- COFCi (15)-- 29------g Cl2------as so C., 1.87 hrs----- 35 14 14 9 6 33:39) - 393 (0): 32
|0.79 00. - SF (8). SiF4(1)------
When the reaction is conducted in the higher tem 50 fluoromethane, 75% dichlorodifluoromethane, 15% tri perature range, in the neighborhood of 500 C. the for chlorofluoromethane and traces of carbon tetrafluorid mation of carbonyl fluoride is accompanied by the for ... and carbon tetrachloride. . . . mation of chlorofluoromethanes. The particular object The product obtained by reacting phosgene with hy of Examples 30, 31, and 32 below was the determination drogen fluoride and removing the hydrogen chloride and of the formation of chlorofluoromethanes. . . 55 hydrogen fluoride according to the foregoing description EXAMPLE 30 can be further enriched in carbonyl fluoride by fractionar A mixture of 1.5 moles of hydrogen fluoride and 0.37 tion at low temperature and elevated pressure, for ex mole of phosgene was heated in a corrosion-resistant ample through a Monel metal column, 45 inches high and bomb at 500 C. for three hours under autogenous pres 1.75 inches internal diameter, packed with small stainless sure. The gaseous reaction product (65.5 g.) contained, 60 steel rings. The still is designed, like all low temperature on a molar basis, 20% CCF, 10% COFC, 10% CO2, pressure stills, to distill at constant temperatures and cuts 5% chlorotrifluoromethane and some SiF (from unre acted HF by action on the glass of the infrared analyzer). are made as the pressure changes. The still head was sur The remainder was chlorine and hydrogen chioride. The rounded by coils through which acetone cooled in a hydrogen chloride can be removed by the sodium fluoride 65 carbon dioxide/acetone bath was circulated. There is treatment as above. - thus obtained a product consisting essentially of carbonyl EXAMPLE 31 fluoride, with small amounts of carbon dioxide. For A mixture of 1.0 mole of hydrogen fluoride, 0.5 mole illustrative purposes, details of a typical fractionation of phosgene and 0.008 mole (2.3 g.) of antimony penta 70 are given below. chloride was treated as above. The gaseous reaction The products of six syntheses carried out under a variety product (47 g.) contained, on a molar basis, 30% CORF2, of conditions from carbon monoxide, chlorine and hy 15% COFC, 10% CO2, 10% chlorotrifluoromethane, drogen fluoride were composited after removal of excess 1% dichlorodifluoromethane, 2% carbon tetrafluoride carbon monoxide and of hydrogen chloride and hydrogen and some. SiF. - - 5 fluoride as described above. The six individual products 2,886,622 17 18 had the following compositions, as determined by infra formed in the phosgene-hydrogen fluoride reaction is red analysis: absorbed. 2. The process for the preparation of carbonyl fluoride, COF, wherein phosgene is reacted with at least one Product Weight Composition (moles percent) mole, per mole of phosgene, of hydrogen fluoride at a (g.) temperature of at least 50 C., the reaction product is brought into contact at temperatures above about.0 C. l------28 COF, (70); COFC) (5); COCl2(10); CO2(3). 2 (Ex.8)- 27 COF(80); COFC (5); COCla(7); CO2(3). with at least a stoichiometer amount, based on the hydro 3 (Ex.9)-- 21 COF(90); COFC) (3); COCl3(1); CO2(5) gen chloride and hydrogen fluoride in the reaction prod 4 (Ex. 11) 29 COF(75); COFC) (5); COCl2(10); CO(5). 5 (Ex. 12). 30.5 COF(50); COFC (5); COCla(40); CO2(5). O uct, of an alkali metal fluoride and the contact is main 6------30.6 COF,(40); COFC) (5); COCl3(5); CO(5). tained until substantially ail of the hydrogen chloride (Remainder chiefly chlorine) is absorbed from the reaction product. 3. The process for the preparation of carbonyl fluoride, COF2, wherein phosgene is reacted with at least one Distillation of the composite gave the following frac 5 mole, per mole of phosgene, of hydrogen fluoride at a tions, boiling at the indicated temperatures and pres temperature of at least 50 C., the reaction product sures and having the indicated compositions by infrared is brought into contact at temperatures above about 0° C. analysis: with at least a stoichiometric amount, based on the hydrogen chloride and hydrogen fluoride in the reac Frac B. P. ( C.) Pressure Weight Composition (noles 20 tion product, of sodium fluoride and the contact is main tion (b.fsq. in.) (g.) percent) tained until substantially all of the hydrogen chloride is absorbed from the reaction product. COF (70). 4. The process for the preparation of carbonyl fluoride, 32 to 33.7- 8. CO2 (15). SiF4 (0.5). COF2, wherein phosgene is reacted with at least one mole, 40 to 40.5-- 6.4 Not analyzed. 25 per mole of phosgene, of hydrogen fluoride at a temper COF2 (90). 32.5 to 39 22.8 CO2 (5). ature of at least 50 C., the reaction product is brought SiF4 (0.5). into contact at temperatures above about 0° C. with at 23 to 33.2 - 36.0 CO2 (1). least a stoichiometric amount, based on the hydrogen SiF (0.5). chloride and hydrogen fluoride in the reaction product, COF (90). CO2 (2). 30 of Sulfur trioxide and the contact is maintained until sub -60 to -62.------18 to 25.5. 4.6 COFC (0.5). SiF4 (0.5). stantially all of the hydrogen chloride is absorbed from Losses------. 0.0 the reaction product. COF2(1). 5. The process for the preparation of carbonylfluoride, COFC1 (40). Undistilled reside- 6.2 COC (25). COF2, wherein phosgene is reacted with at least one CO2 (0.5). 35 mole, per mole of phosgene, of hydrogen fluoride at a Renainder chlorine. temperature of at least 50 C., the reaction product is brought into contact at temperatures above about 0° C. This invention provides an efficient and economical with at least a stoichiometric amount, based on the method of preparing, in good conversions and from hydrogen chloride and hydrogen fluoride in the reaction readily available starting materials, carbonyl fluoride free 40 product, of phosphorus pentoxide and the contact is from hydrogen chloride and suitable for such uses as maintained until substantially all of the hydrogen chloride the preparation of tetrafluoroethylene by reaction of car is absorbed from the reaction product. bonyl fluoride with carbon at temperatures of 1500 C. 6. The process for the preparation of carbonyl fluoride, and above, e. g., in the carbon arc, the products of COF2, wherein phosgene is reacted with at least one the reaction preferably being suddenly and completely 45 mole, per mole of phosgene, of hydrogen fluoride, at a quenched. A most useful embodiment of the process temperature of 150-300° C. at atmospheric pressure in is that wherein phosgene and hydrogen fuoride are re the presence of active carbon; the reaction product is acted at a temperature of 150-300 C. at atmospheric brought into contact at temperatures above about 0° C. pressure in the presence of active carbon, and the hydro with at least a stoichiometric amount, based on the hydro gen chloride formed is removed from the crude reaction 50 gen chloride and hydrogen fluoride in the reaction prod product by treatment with anhydrous sodium fluoride. uct, of sodium fluoride; and the reaction products are The foregoing detailed description has been given for maintained in contact with the sodium fluoride until clearness of understanding only and no unnecessary limi substantially all of the hydrogen chloride formed in the tations are to be understood therefrom. The invention phosgene-hydrogen fluoride reaction is absorbed. is not limited to the exact details shown and described 55 7. The process of claim 1 wherein the carbonyl chloro for obvious modifications will ccur to those skilled in fluoride formed in the reaction is isolated and heated the art. at 400-600 C. and the resultant carbonyl fluoride iso The embodiments of the invention in which an ex lated. clusive property or privilege is claimed are defined as 8. The process wherein carbonyl chlorofluoride is dis follows: 60 proportionated by heating at 400-600° C. and the re 1. The process for the preparation of carbonyl fluoride, Sultant carbonyl fluoride isolated. COF2, wherein phosgene is reacted with at least one 9. The process which comprises contacting, at a tem mole, per mole of phosgene, of hydrogen fluoride at a perature of above about 0° C., a mixture of carbonyl temperature of at least 50 C.; the reaction product, fluoride and hydrogen chloride with an inorganic chem containing carbonyl fiucride and hydrogen chloride, is 65 ical compound of the group consisting of alkali metal brought into contact at temperatures above about 0° C. fluorides, Sulfur trioxide and phosphorous pentoxide, said with at least a stoichiometric amount, based on the hydro compound being unreactive with carbonyl fluoride but gen chloride and residual hydrogen fluoride therein, of reactive with hydrogen chloride to form stable prod an inorganic chemical compound of the group consist ucts, the naolar ratio of the inorganic compound to hydro ing of alkali metal fluorides, sulfur trioxide and phos 70 gen chloride being at least stoichiometric, to react hydro phorus pentoxide, said compound being unreactive with gen chloride with the inorganic compound and thereby carbonyl fluoride but reactive with hydrogen chloride remove the hydrogen chloride from the carbonyl fluoride. to form stable products; and the reaction products are 10. In a process yielding carbonyl fluoride which yields maintained in contact with said inorganic chemical con hydrogen chloride in mixture therewith, the step of con pound until substantially all of the hydrogen chloride 5 tacting, at a temperature of above about 0° C., said 3,836,622 g 20 :mixture, with an inorganic chemical compounds of the - r References Cited in the file of this patents. . . . . group consisting of alkali metal fluorides, Sulfur trioxide UNITED STATES PATENTS . . . . . and phosphorus pentoxide, said compound being unre active with: carbonyl fluoride but reactive with hydro- 2,526,776 Smith et al. ------Oct. 24, 1950 ofgen the chloride inorganic to formcompound stable toproducts, hydrogen the chloride molar beingratio 5 OTHERw REFERENCES ------m at least stoichiometric, to react hydrogen chloride with Kwasnik, Fiat Review of German Science, 1939-1946, the inorganic compound and thereby remove the hydro- Inorganic Chemistry I, p. 242 (1948). Y gen chloride from the carbonyl fluoride. Simons et al., J. A. C. S., vol. 68 p. 1672-3 (1946).