3,49,165 United States Patent Office Patented Sept. 5, 1964 2 In practice, however, it is desirable to use the tetra 3,49,165 flucrohydrazine in slight excess in order to insure com NDFLUOROAMNO-SUBSTITUTED HYDRA ZINES AND THER PREEPARATION plete utilization of the R-NFN-R compound. The George N. Sausen, Wilmington, Del, assignor to E. E. du excess tetrafluorohydrazine is removed from the reac Point de Neriors and Company, Wilmington, Dei, a 5 tion mixture after completion of the reaction and may corporation of Delaware be reused, if desired. No Drawing. Fied May 2, 1962, Ser. No. 9,756 The polyfluoroazoalkane intermediates, i.e. 6 (Clairas. (C. 260-583) This invention relates to, and has as its principal objects O compounds, as a class, are know compounds. Thus, hexa provision of, novel and useful compositions of matter fluoroazomethane, CF-NFN-CF (R and R' in the and the preparation of the same. formula R-NFN-R, are both CF) can be prepared The compositions of this invention are defined by the by the reaction of cyanogen chloride or iodide with such formula highly reactive fluorides as iodine pentafluoride (Ruff 5 et al., Ber. 73, 724 (1940)) or silver bifluoride (Glemser RN-NFR et al., Ger. 1,005,792), or by heating at a temperature of NF at least 150 C. a cyanogen halide, such as, the chloride, in which R and R' may be the same or different and are bromide, or iodide, with a fluoride of an alkali metal of perfluoroalkyl, co-hydroperfluoroalkyl, or co-chloroper atomic number 11 to 19, as disclosed and claimed in fluoroalkyl of up to 19 carbon atoms. 20 U.S. 2,912,429. The compounds of this invention are obtained by sub The higher polyfluoroazoalkanes are obtained by main jecting a mixture of tetrafluorohydrazine, NFA, and an taining in contact at a temperature of 25 to 250° C. (1) aZo compound of the formula R-N-N-R', in which a polyfluoronitrile, (2) a halogen of atomic number of R and R are as already defined, to a source of chemical 17 to 35, and (3) a fluoride of a metal of Group I hav energy at a temperature up to 50° C. 25 ing an atomic number from 11 through 55 until the desired In practice, the mixture of tetrafluorohydrazine and polyfluoroazoalkane has been formed. The reaction R-NFN--R' compound is passed through a zone illumi which takes place may be represented by the following nated with ultraviolet light, e.g., a mercury vapor lamp, equation (see, e.g., Example I of U.S. Patent 3,057,849). and the condensible products are collected in traps cooled to a temperature which can be as low as -95 C., e.g., 30 through the use of toluene slush as a cooling means. The irradiation is carried out at temperatures of up to The nitrile R-CN used in the above process can be --50 C., but usually in the range of 20 to 30° C., for either a perfluoronitrile, an co-chloroperfluoronitrile, or an periods of time which can be as short as one to two co-hydroperfluoronitrile. These nitriles are prepared from minutes or can extend up to several hours, depending 35 corresponding polyfluorocarboxylic acids, which are con upon the size of the sample being irradiated and the verted by conventional methods to the amides, and then efficiency of the light source. dehydrated to the nitriles with phosphoric anhydride. The Although it is desirable to carry out the reaction in polyfluorocarboxylic acids, their salts, and amides are vessels made of nickel or copper or alloys of these metals, known compounds. Thus, U.S. 2,559,629 describes the the reaction can be conveniently carried out in quartz 40 acids H(CFCF)COOH, U.S. 2,646,449 describes the glass equipment, especially in laboratory-scale prepara preparation of amides H(CF)CONH2, and U.S. tions. 2,567,011 describes the perfluorocarboxylic acids, their As used herein, ultraviolet light refers to light sources amides, and nitriles and co-chloroperfluorocarboxylic acids of wave lengths in the range of 2500 to 4000 A. can be made by the methods described by M. W. Buxton in general, it is desirable that the light source be as et al., J. Chem. Soc., 1954, 366. close as possible to the mixture of tetrafluorohydrazine The halogen can be of commercial quality. and R-NFN-R compound. This can be accomplished The fluoride of the Group I metal of atomic number by placing the lamp immediately adjacent to a transparent 11 to 55 is a fluoride of one of the metals sodium, potas wall of the reaction vessel, or in a suitable well projecting sium, copper, rubidium, silver, and cesium. The fluorides into the reaction space, or by passing the reaction mixture of potassium, cesium, silver, and mercury are preferred through a tube which is exposed to ultraviolet light. 50 because of their greater activity. As a source of ultraviolet light there can be used any Usually, the reaction which leads to the formation of of the commercially available lamps which are high in the tw-hydropolyfuoroazcalkane, co-chloropolyfluoroazo ultraviolet light output. Generally speaking, mercury alkane, or polyfluoroazoalkane is carried out under essen vapor lamps are preferred because they provide a rela tially anhydrous conditions. tively intense source of ultraviolet light. Many lamps. 55 The relative proportions of the three reactants is criti of this type are available and include low and high pres cal only to the extent that it is desirable to utilize as much Sure lamps with various types of envelopes. The most of the polyfluoronitrile as possible. For this reason, there preferred types are those with quartz envelopes because is generally used at least one mole, preferably at least Such envelopes permit higher transmission of ultraviolet two moles, of the metallic fluoride per mole of polyfluoro light. 6) nitrile. The chlorine is usually used in a molar ratio to The reaction between the tetrafluorohydrazine and . polyfluoronitrile of 0.5:1 to 2.5:1. R-N=N-R' compound can be carried out in the vapor The polyfluoroazoalkanes are yellow-green liquids char or liquid phase under pressures which are usually autog acterized by good heat-stability and resistance to hy eOS drolysis by 10% aqueous sodium hydroxide solution up The tetrafluorohydrazine and R-N-N-R' compound 65 to at least 100° C. react in equimolar amounts to produce the compounds Exemplary co-hydroperfluoroazoalkanes, w-chloroper of this invention, in accord with the following schematic fluoroazoalkanes, and perfluoroazoalkanes are azoper representation: fluoromethane, azoperfluoroethane, azoperfluoropropane, aZOperfluorobutane, azoperfluorooctane, azo(a)-hydroper 2NF 4 - 2B-N=N-R - 2R-N-NFR -- NF 70 fluoropropane), azo (co-hydroperfluoropentane), azo (per NF fluoroisobutane), azo(a)-hydroperfluorononane), azo (per

3,149,165 3 4. fluorodecane), azo (co-hydroperfluorotridecane), azo (cy prepared as above, is useful as a polymerization catalyst. chloroperfluoropropane), azo (co-chloroperfluorooctadec This use is illustrated below: ane), azo (co-chloroperfluorododecane), and the like. A 38' x 6' platinum tube was charged with 0.34 g. of The new compositions of this invention are useful as ethylene and 19 mg. of purified 2-difluoroamino-3-fluoro catalysts for the polymerization of ethylenically unsatu 2,3-diazahexafluorobutane, CFN(NF)NFCF, and the rated compounds and as energy-rich sources in propulsion tube was sealed and heated under 1,000 atmospheres ex systems. ternal pressure at 40 for one hour, at 70° for two hours, The examples which follow illustrate but do not limit and at 100 for two hours. A small amount of white, this invention. Chromatographic analyses were run on acetone-insoluble polyethylene was obtained together with a 6' x 0.25' column packed with a diatomaceous earth O a dark, acetone-soluble oil. No trace of polymer was treated with the ethyl ester of perhalooctanoic acid so as obtained from a control run in the absence of added to deposit 20% by weight of the ester on the support. initiator. The column was held at 0° C., using helium as a carrier EXAMPLE gas at a flow rate of 60 cc./min, measured at the outlet. 5 A 400-cc. quartz reactor was evacuated and charged EXAMPLE I with 1.63 g. of decafluoroazoethane, A 150-cc. quartz reactor was evacuated and charged with 0.47 g. of hexafluoroazomethane and 0.30 g. of tetra fluorohydrazine, NFA. The mixture was irradiated with and 0.64 g. of tetrafluorohydrazine, N.F. The mixture a low-pressure mercury-resonance lamp at 25 C. for 1.25 20 Was irradiated with a low-pressure mercury-resonance hours. Two such runs were combined and the product lamp at 25 C. for 0.57 hour. The tube was cooled to gases were transferred to a cylinder cooled in liquid nitro -80 C. and volatile products were removed to a pres gen. The by-product, elemental nitrogen, was removed Sure of 1-2 mm. of mercury. The residual yellow liquid by evacuation to leave 1.5 g. of crude product. This amounted to 1.53 g. Gas-chromatographic analysis of this crude product was further purified by distillation from 25 crude product showed it to consist of a mixture analyzing a toluene slush bath (-95 C.) to leave 1.0 g. of residue. 16% 3-difluoroamino-4-fluoro-3,4-diazadecafluorohexane, Gas-chromatographic analysis of this residue showed it C2F5N (NF2)NFC2F5, 81% CaFN=NCF, and traces of to contain 67% of 2-difluoroamino-3-fluoro-2,3-diazo a few impurities. hexafluorobutane, CFN(NF)NFCF, 22% The mixture containing 3-difluoroamino-4-fluoro-3,4- 30 diazadecafluorohexane, and various amounts of NF and NFA. 2-Difluoro amino-3-fluoro-2,3-diazahexafluorobutane, NF, f prepared as above, is useful as a polymerization catalyst. of >99% purity was obtained as a colorless gas, B.P. This use is illustrated below: 19 C., by gas-chromatographic separation of the partially An 80-cc. "Hastalloy” C-lined shaker tube was charged purified residue. with i0 g. of tetrafluoroethylene, 30 g. of hexafluoropro The fluorine nuclear magnetic resonance spectrum of pylene dimer solvent, and 150 mg. of the the purified material was obtained at -62 C. and showed four unsplit peaks at -5325 c.p.s., --840 c.p.s., -1-3650 40 c.p.s., and --4270 c.p.s. in area ratios of 2/1/3/3 in agree mixture, and the tube was shaken at ambient temperature ment with the proposed structure (56.4 mc., fluorotri (21-27 C.) for five hours. A total of 5.9 g. (59%) of chloromethane reference=0). Low temperature (-46 white, solid, polytetrafluoroethylene was separated from to -80 C.) infrared analysis of the product showed the solvent. Decafluoroazoethane itself is not a polym major absorption bands at 7.65-8.2u, (C-F), 9.85u, erization initiator at 25 in the absence of light. 10.2u, 10.8 and 11.5u (N-F) and 13.75u. Mass spec 45 Table I Summarizes a series of experiments carried out trometric analysis of the product showed positive ion frag following the procedure of Example I. In the table, the ments expected from a mixture of CFN=NCF and left column lists the polyfluoroazoalkanes used in place Naf indicating that the product, CFN (NF)NFCF, was of the hexafluoroazomethane of Example I and the right decomposed to starting materials in the spectrometer. column the products obtained. Table I

Polyfluoroazoalkane Product

F3C-CF-CF3-CF-Ne-N-CF3-CF3------F3C-CF-CF-C. F-N-N-cf F-CF3 NF 3,4-aZOperfluorooctane------5-difluoroamino-6-fluoro-5,6-diazaperfluorooctane. HCF-(CE)g-N=N-(CF)g-CFI.------EICF2(C F)-N-N-(CF–CF.E. NF, F. AZO(a)-hydroper?iuOrodecane).------1,22-dihydro-1-difluoroamino-12-fluoro-1,12 diazaperfluorodocosane. ClCF (CF)8-N-N-(CF2)3CF.C.------C-CFCF-NNE N-(CP)-cF.C.F Azo(a)-chloroperfluorononane).------120-dichloro-10-difluoroamino-1-fluoro-10,11diazaperfluoroeicosane.

The 2 - difluoroamino-3-fluoro-2,3-diazahexafluoro Since obvious modifications and equivalents in the in butane, vention will be evident to those skilled in the chemical FC-N-N-CF3 arts, I propose to be bound solely by the appended claims. NF, F. 75 The embodiments of the invention in which an ex 3,149,165 5 6 clusive property or privilege is claimed are defined as wherein R and R' are selected from the group consisting follows: of perfluoroalkyl, co-hydroperfluoroalkyl and w-chloroper 1. A compound of the formula fluoroalkyl of up to 19 carbons, in the presence of ultra violet light at a temperature of up to about 50 C. 5. The process which comprises reacting tetrafluorohy drazine and hexafluoroazomethane in the presence of wherein R and R are selected from the group consisting ultraviolet light at a temperature of up to about 50 C. of perfluoroalkyl, co-hydroperfluoroalkyl and co-chloro 6. The process which comprises reacting tetrafluoro perfluoroalkyl of up to 19 carbons. hydrazine and decafluoroazoethane in the presence of 2. 2-difluoroamino-3-fluoro-2,3-diazahexafluorobutane. 0. ultraviolet light at a tempertaure of up to about 50 C. 3. 3-difluoroamino-4-fluoro-3,4-diazadecafluorohexane. 4. The process which comprises reacting tetrafluoro No references cited. hydrazine and a compound of the formula R-N=N-R',