1 3,394,142 United States Patent 0 "ice Patented July 23, 1968

1 2 tetrazole which is isolated, e.g., by extraction with an 3,394,142 immiscible solvent and removal of the solvent. SUBSTITUTED TETRAZOLES AND The reaction is preferably carried out under autogenous ' PROCESS THEREFOR Robert J. Koshar, Lincoln Township, Washington County, pressure of the nitrile compound and liquid medium using Minn., assignor to Minnesota Mining and Manufac essentially anhydrous conditions. Atmospheric pressure turing Company, St. Paul, Minn., a corporation of may be used provided that the reaction vessel is equipped Delaware with a re?ux condenser to prevent the escape of the ni No Drawing. Filed Jan. 19, 1966, Ser. No. 522,806 trile used as starting material and the liquid medium. 10 ‘Claims. (Cl. 260—308) Although stoichiometric amounts of the nitrile compound and inorganic are preferably used to attain high This invention relates to a new class of ?uorine-con 10 yield and to simplify the isolation of the tetrazole and taining organic compounds and more particularly to a tetrazole salt, an excess of either of the reactants may di?uoraminopoly?uoroalkyltetrazoles, to salts thereof and be used. The reaction is carried out in substantially an to a process for the synthesis of these compounds. hydrous polar liquid solvent such as acetonitrile, dimeth It is known that compositions containing ylformamide, tetrahydrofuran and the like which dissolve ?uorine bonds, especially those containing di?uoramino at least a portion of the reactants. These can be termed (i.e., ——NF2) groups, are potent oxidizers which can pro inert organic solvents, by which is meant that they do vide useful energy when combined chemically with fuels not react destructively with the nitrile compound or re such as anhydrous hydrazine, especially when these mix sultant tetrazole salt. tures are con?ned in a chamber provided with a nozzle After completion of the initial reaction, any excess and ignited by means of a spark or ?ame. Compounds 20 nitrile is vented under reduced pressure. The resulting containing the tetrazole ring are ‘known, and certain of mixture is then ?ltered, if necessary, and evaporated to these are useful as ingredients of explosives because of dryness usually at less than 50° C. under reduced pres their high nitrogen content. sure yielding the corresponding tetrazole salt. This salt, It is an object of this invention to provide a novel which may contain some of the solvent used, is dissolved and useful class of ?uorine-containing heterocyclic ox 25 in water, acidi?ed with an inorganic acid such as sulfuric idants and methods for their synthesis. It is a further acid or hydrochloric acid ‘and extracted with an immisci object to provide a-di?uoraminopoly?uoroalkyltetrazoles ble solvent, for example , methylene chloride and‘ salts thereof, wherein the said alkyl is attached to and the like, and the extract then evaporated to yield the ring carbon of the tetrazole. Other objects will become the free tetrazole compound. Isolation of the free a apparent hereinafter. 30 di?uoraminopoly?uoroalkyltetrazole in high purity is best The novel a-di?uoraminopoly?uoroalkyltetrazoles of accomplished by chromatography such as liquid-solid this invention are represented by the general formula chromatography, e.g., using silica gel as the solid station ary phase. The above-mentioned nitrile compounds used as pre cursors to the tetrazole compounds of this invention can be prepared by methods described in our copending ap H 11 plication, Ser. No. 300,956, ?led Aug. 5, 1963. For ex ample, per?uoroguanidine, (FzNhbE-NF, which is ob wherein R is a monovalent or divalent radical selected tained by the reaction of nitrogenous compounds, such from the group consisting of ?uorine, di?uoramino, per 40 as ammeline, with elemental ?uorine, is reacted under flu'oroalkyl, per?uorocycloalkyl and per?uoroalkylene, R1 autogenous pressure with a molar excess of HCN in is a monovalent radical selected from the group consist acetonitrile using cyanide as catalyst to yield ing of ?uorine, di?uorarnino, pe'rfluoroalkyl and per?uoro per?uorocyanoformamidine, azaalkyl and n equals one or two; when n equals one, R and R1 taken together with the carbon atom to which 45 they are attached form a per?uoroalkylene ring; and the compound contains 2 to 18 carbon atoms. Direct ?uorination of the addition product of per?uoro It is to be understood that when R and R1 contain cyanoformamidine and ammonia under mild conditions, carbon-carbon linkages the carbon chain may be inter for example with 10 percent ?uorine in nitrogen at —30° rupted by heteroatoms such as oxygen or nitrogen and 50 C., yields tris(di?uoramino)acetonitrile, (F2N)3CCN, and the carbon chain may be branched and contain electro also 'bi-s(di?uoramino)?uoroacetonitrile, (F2N)2CFCN. negative substituents such as chloro, bromo, nitro and Likewise, using a somewhat similar procedure, the reac di?uoramino. tion of HCN with the poly?uoroalkyl?uorimino com These a-di?uoraminopoly?uoroalkyltetrazoles are pref pounds of the formulas RfCF=NF and (Rf)2C=NF erably obtained by the reaction of di?uoramino-contain 55 wherein Rf is a per?uoroalkyl or per?uorochloroalkyl, ing alkyl nitriles of the formula using as a catalyst, yields reaction prod ucts such as represented generally by the formulas

60 and (Rf)2C(CN)NFH, respectively. These can be ?uori nated directly or in the case of R,C(CN)=NF reacted wherein n, R and R1 are de?ned above, with inorganic with ammonia to form addition compounds which are such as for example , potassium azide, then ?uorinated under the abovementioned mild condi and aluminum azide in a stirred liquid tions to yield the starting nitrile compounds. Many of the medium at a temperature of about —20° to 150° C., to 65 poly?uoroalkyl?uorimino compounds described above form the correspondingly substituted tetrazole as a metal can be prepared by the method disclosed by R. A. Mitsch, salt. Acidi?cation of the salt yields the corresponding J. Am. Chem. Soc., 87, 328 (1965). 3,394,142 3 4 Illustrative compounds of the invention include the fol about 10.2 and 11.6 microns due mainly to the NF bonds lowing: of the tris(di?uoramino)methyl moiety. Sodium 5-tris(di?uoramino)methyltetrazole,

NN thus prepared is dissolved in 0.15 ml. of water and treated with 0.1 ml. of 37 percent aqueous HCl. The mixture v10 (2 liquid phases) is extracted with diethyl ether. The ex tracts are combined, dried over anhydrous calcium sulfate and evaporated to yield 5-tris(di?uoramino)methyltetra zole,

15

which is a viscous, acidic liquid soluble in ether and hav 20 ing a vapor pressure of less than about 2 mm. Hg at 25° C. Its ?uorine n.m.r. spectrum exhibits a peak at about —32.8¢ while its infrared spectrum shows strong absorp The a-di?uoraminopoly?uoroalkyltetrazoles are acidic tions in the region between 10.4 and 11.6 microns. compounds which are capable of forming a variety of Example 2 salts. These involve the tetrazole ring moiety. The cationic 25 portion of the salt can be metals such as sodium, potas 1,2-bis(di?uoramino)per?uoroethyl cyanide, sium, aluminum and other alkali and alkaline earth metals as well as cations derived from inorganic and organic F2NCF2CF(NF2)CN bases. The preparation of these tetrazole salts is accom is prepared in high yield by the reaction of excess tetra plished by the above described methods as well as those 30 ?uorohydrazine with per?uoroacrylonitrile under autoge methods known to the art for preparing salts of S-sub nous pressure at about 100° C. The product is isolated stituted tetrazoles. The free tetrazole compounds of this by gas-liquid chromatography at 25 ° C. using a column invention have appreciable acidity, their pKm range gen composed of 20 percent ‘by weight of a silicone rubber erally being between about 1 and 4. (available under the trade name LSX~3—0295), on acid The tetrazole compounds of this invention are oxidants 35 washed diatomaceous silica. which are especially useful as propellant oxidizers and ex The nitrile is caused is react with potassium azide by the plosive ingredients. All of the compounds oxidize potas procedure set forth in Example 1. In this way, 5-[1,2-bis sium iodide, for example in a solution of , di?uoramino)per?uoroethyl]tetrazole, water and acetonitrile, liberating iodine. Many of the N-—N compounds, especially those containing a high content of 40 % di?uoramino groups such as 5-tris(di?uoramino)methyl FzNCF2CF(NFz)C \N——N tetrazole, are shock-sensitive and readily release their en H ergy in the form of heat, light and gaseous products when impacted. The tetrazole salts, particularly the dry metal and the potassium salt of 5-[l,2-bis(di?uoramino)per ?uoroethyljtetrazole are obtained. salts, are especially explosive when impacted or sparked. 45 Since many of the compounds in the above-mentioned Example 3 process contain a high portion of difluoramino oxidant groups which can react violently with certain reducing 1,l-bis(di?uoramino)per?uorobutyl cyanide is pre agents or explode on impact, especially when highly puri pared by the reaction of per?uoro-l-azapentene-l, tied, a suitable barricade, and equipment such as heavy 50 CF3CF2CF2CF=NF, under anhydrous conditions with gauntlets and face shield should be provided for the op a molar excess of HCN at room temperature and under erator during all phases of their synthesis. autogenous pressure, using potassium cyanide as catalyst The following examples are given for illustrative pur and acetonitrile as a solvent, to yield the intermediate poses and are not intended to limit the described inven cyano?uorimino compound, CF3CF2CF2C(CN)=NF. The cyano?uorimino compound is treated with an equi tion. The ?uorine nuclear magnetic resonance (n.m.r.) 55 values are given as ¢ units which are relative to CFCls molar amount of ammonia in diethyl ether under es as the internal reference. All parts are by weight unless sentially anhydrous conditions at about -—60° C. The diethyl ether is removed in vacuo at about ~60° C. and otherwise speci?ed. the residual ammonia adduct is ?uorinated in acetonitrile Example 1 under mild conditions, using 10 percent elemental ?uorine 60 in nitrogen at —l3° to 0° C., thus producing the cyanide. A glass reaction vessel containing a polytetra?uoro (5 [1,1-bis(di?uoramino)per?uorobutyl]tetrazole, ethylene coated magnetic stirring bar and 0.3 millimole of sodium azide is evacuated, cooled to \-110° C. and then N—N charged by means of a vacuum manifold with 1 ml. (liquid % at 25° C.) of acetonitrile and 0.3 millimole of tris(di?uor 65 CF2CFzCFzC(NF2)2C\ N-N amino)acetonitrile. The reactor is closed, allowed to H warm to room temperatrue and then stirred at room tem perature for two hours and at 50° to 60° C. for one hour. and its sodium salt are prepared from 1,1-bis(di?uor Any unreacted tris(di?uoramino)acetonitrile is removed amino)per?uorobutyl cyanide and sodium azide, using under reduced pressure and the remaining solution is 70 the procedures described in Example 1. evaporated to give sodium 5-tris(di?uoramino)methyl Example 4 tetrazole, a white, ether insoluble, non-volatile, impact sensitive solid having a single ?uorine n.m.r. peak cen Employing the procedure of Example 1, bis(di?uor tered at about —31.8¢. Its infrared spectrum ‘(Nujol) ex amino)?uoroacetonitrile, (F2N)2CFCN, is reacted with hibits strong, broad absorptions in the region between sodium azide. 5- [dis ( di?uoramino ) ?uoromethyl ] tetrazole 3,394,142 5 6 and the sodium salt of 5-[bis(di?uoramino)lluoromethyl1 3. The sodium salt of a compound according to tetrazole are thus produced. claim 2. Example 5 4. The compound according to claim 1, wherein R is ?uorine and R1 is a di?uoraminodi?uoromethyl group. Employing the procedure of Example 1, 1,1-‘bis(di~ 5 5. The potassium salt of a compound according to ?uoramino)per?uoro-Z-azapropyl cyanide, claim 4. CF3NFC(NF2)2CN 6. The compound according to claim 1, wherein R1 is a di?uoramino group and R is the per?uoropropyl obtained from the ?uorimino compound, group. CF3NFC(NF2)=NF, 10 7. The sodium salt of a compound according to claim 6. a product of the direct ?uorination of ammeline, by pro 8. The compound according to claim 1, wherein R1 cedure similar to those described in Example 3, is caused is ?uorine and R is a di?uoramino group. to react with sodium azide to yield 5-[1,1-bis (di?uor 9. The sodium salt of a compound according to claim 8. amino ) per'?uoroZ-azapropyl] tetrazole, 10. The process for the production of substituted tet 15 razoles which comprises reacting an azide of the group consisting of sodium azide, potassium azide, ammonium azide, and aluminum azide and a nitrile of the formula N—N H and its sodium salt. 20 What is claimed is: it 1. A compound of the formula containing 2 to 18 carbon atoms, wherein R is a mono valent or divalent radical selected from ?uorine, di?uor l-Nlri /N—N amino, per?uoroalkyl, perfluorocycloalkyl or per?uoro R_-$_@/ 25 alkylene, R1 is a ?uorine, di?uoramino, per?uoroalkyl or per?uoroaza-alkyl radical and n is the number one or Lt. H n two and when n is one, R and R1 when taken together containing 2 to 18 carbon atoms, wherein R is a mono with the carbon atom to which they are attached form valent or divalent radical selected from ?uorine, di?uor a. per?uoroalkylene ring. amino, per?uoroalkyl, per?uorocycloalkyl or per?uoro 30 alkylene, R1 is a ?uorine, di?uoramino, per?uoroalkyl or References Cited per?uoroaza-alkyl radical and n is the number one or UNITED STATES PATENTS two and when n is one, R and R1 when taken together with the carbon atom to which they are attached ‘form 3,03 8,900 6/1962 Dess ______260—248 a per?uoroalkylene ring; and salts thereof with a metal. 3,215,709 11/1965 Logothetis ______260—349 2. The compound according to claim 1, wherein R and R1 are di?uoramino groups. ALTON D. ROLLINS, Primary Examiner. UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0. 3,394 ,142 July 23 , 1968 Robert J. Koshar

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below: Column 3, lines 11 to 14, the right-hand portion of the formula should appear as shown below: ' N ____N\ (iIFZ /N_ N--HN/ NF2I \NH——N

Column 4, line 61, "-13°"' should read -— ~30° - "S-[dis(fluoramino)" should read -- 5-[bis(diflu_ 5 line 75, oramino) -—. Signed and sealed this 10th day of February 1970. (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents