3,226,439 United States Patent Office Patented Dec. 28, 1965 E. 2 tion. Thereafter, the desired products are isolated by con 3,226,439 POLYHALOGENATED ALKYL MANES AND HY. Ventional means, e.g., by fractional distiliation as illus BRAZINES AND METHOD OF PRESPARATION trated in Example. Willian.J. Middleton, Willington, Del, assignor to E. H. Exampies of polyhalothioketones of Formula 2 which di Poat de Nemours and Coapany, Winnington, Del., 5 are useful in the above process are a corporation of Delaware octafluoro-2-butathione No Drawing. Fied Yan, 10, 1963, Ser. No. 250,501 S A4 Claigas. (C. 260-566) CF.--C F-CF3 This invention relates to new fluorinated, nitrogen-con O tetradecafluoro-4-heptathione taining organic compounds and to methods for their prep S aration. This application is a continuation-in-part of my co CF3-CF-C F-8-0 F-CF-CF3 assigned application Serial No. 134,815, filed August 30, hexafluoro-2-propathione 1961. S The compounds of this invention are of the formula: CF -8-0 F3 (1) 4H-heptafluoro-2-butathione S wherein R and R may be the same or different and 20 CF-C F-5-c F3 are halogen of atomic number 9-17 or haloalkyl of up to 6 carbons (i.e., 6 carbons or less) in which all halogens 1-chloroheptafluoro-3-butathione are of atomic number 9-17 (i.e., fluorine or chlorine); S and R is hydrogen, amino (-NH) or alkyl of up to 18 carbons. 25 and the like. The preferred compounds are those of the above for The above are known compounds, prepared as de mula wherein Rh and Rh each represent chlorine or scribed in U.S. 2,970,173 either by: fluorine, or perfluoroalkyl, chloroperfluoroalkyl or a-hy (1) Reaction of a secondary polyfluoroalkyl iodide of droperfluoroalkyl of up to 6 carbons; and R is hydrogen, at least three carbons in the alkyl group with a phos amino or alkyl of up to 7 carbons. 30 phorus polysulfide, e.g., P2S5 or PS3, in the liquid or The polyhaloalkylidene imines (RFH) are prepared by vapor state at elevated temperatures. reacting hydrazoic acid (HN) with a polyhalothioketone (2) Heating a polyfluoroketone with phosphorus pen of the formula: tasulfide for several hours at 200 to 300° C. under au (2) i togenous pressure. Rh-CF-C-CF-R (3) Reacting a secondary perfluoroalkanethiol with a wherein Rh and Rh are as defined above. hydrogen fluoride acceptor, e.g., sodium fluoride. As a practical matter, the reaction is carried out at a (4) Reacting sulfur with a perfluoroolefin of at least temperature between -50° C. and 0° C. followed by three carbon atoms at 400 to 650° C. Warming of the reaction mixture to a temperature be 40 (5) Thermal decomposition of selected polyfluorinated tween 20 C. and 100° C. This two-step procedure is a dithietanes at 450° to 700° C. safety measure employed to keep the exothermic reaction The compounds of Formula 1 wherein R is alkyl, i.e., under proper control when using elementary reaction the N-alkyl polyhaloalkylidene imines, are prepared by equipment not suitable for rigorous process conditions. a Second method which can also be used to prepare the Preferably, the acid and thioketone are contacted at a polyhaloalkylidene imines (R=H). This method com temperature between -20° C. and 0° C., and the reac prises two process steps which are, in part, schematically tion mixture is thereafter warmed to a temperature be represented as follows: tween 40 C. and 60° C. (A) The pressure at which the reaction is conducted is not O OE critical; and, therefore, it is most convenient to operate R-CF-C-CF-R -- NHalER --> B-CF-C-CF.-R. at ambient pressure. 50 NHR The hydrazoic acid and polyhalothioketone react in equimolar amounts, and therefore, these reactants are (B) OH preferably used in a 1:1 molar ratio. However, an ex R-CF-d-of-R - Rh-CF-C-CF3-R." - HO cess of either reactant can be employed at the expense of process efficiency. 55 NHR R Preferably the hydrazoic acid and polyhalothioketone wherein R, Rh and Rh' have the previously indicated are contacted in a mutual inert solvent. Any mutual sol meanings. Vent which is normally liquid and will not react with the In Step (A) the polyhaloketone is contacted with at reactants and products is satisfactory. Examples of suit 60 least one molar equivalent of ammonia (R=H) or pris able Solvents are chloroform, methylene chloride, di mary alkylamine (R-alkyl) at a temperature maintained methyl and diethyl ethers, tetrahydrofuran, cyclohexane, between -50 and 10° C. A normally liquid reaction etc. The amount of solvent, if any, is not critical and medium is preferably employed to assist in dissipating the it can equal or exceed the weight of reactants by many heat which is spontaneously generated when the reactants fold. are admixed. For optimum control of the reaction, it is To obtain optimum temperature control over the re preferred that all of the ammonia or primary alkylamine action, it is preferred to dissolve the hydrazoic acid in be added incrementally to a cold (-15° C. or less) solu the reaction medium, add the solution of acid to a reactor tion of polyhaloketone while the temperature of the re cooled, e.g., to -15° C. and then incrementally add all action mixture is maintained at or below -15° C. The the thioketone. After this addition is completed, the re desired product, i.e., the amino, hydroxy-substituted poly action mixture is warmed as described above until re haloalkane can be isolated, if desired, by conventional action is complete, as evidenced by cessation of gas evolu techniques. 3,226,439 3. Examples of polyhaloketones which can be employed in step (A) are perfluorodiethyl ketone, s-dichlorotetra (b) NH N-NH2 fluoroacetone, 1H,7H-dodecafluoroheptane-3-one, trichlo Deamination rotrifluoroacetone, perfluoroacetone, 1H,9H-hexadecafluo R-CF.--CF-Rs - Rh-CF-C-CF-Rh' rononane-5-one, 1, 16-dichloroperfluoropentadecane-8-one NH-NH and tetrachlorodifluoroacetone, all of which are known compounds. wherein Rh and Rh have their previously indicated mean Suitable amines (NHR) for step (A) are, e.g., methyl 1ngS. amine, butylamine, heptylamine, decylamine, dodecyla in step (a), a polyhaloalkylidene imine of this inven mine, tetradecylamine and octadecylamine, all of which O tion (R-H) is reacted with at least one molar equivalent are known compounds. of hydrazine at a temperature maintained between -50 In step (B), the intermediate from step (A), i.e., the and 10 C. For optimum control of the reaction, it is amino, hydroxy-substituted polyhaloalkane, is dehydrated preferred that all of the hydrazine be added incremental by warming a mixture of the intermediate, a dehydrating ly to a cold (-15° C. or less) solution of the polyhalo agent and an acid acceptor to at least its reflux tempera 15 alkylidene imine while the temperature of the reaction ture. The intermediate from step (A) can be employed mixture is maintained at or below -15° C. The amino, in this step either in its pure or crude form, i.e., the de hydrazino-substituted product can be isolated, if desired, hydrating agent and acid acceptor can be added directly by conventional techniques. to the porduct mixture from step (A). The desired imine In step (b), the amino, hydrazino-substituted interme can be removed from the product mixture either by per 20 diate from step (a) is de-aminated by heating it together mitting it to distill off during the dehydration step or by with a de-aminating agent to a temperature of 90 to 250 subsequently distilling the product mixture. The imine C. The de-aminating agent can be added directly to the may then be purified by fractional distillation. product mixture form step (a) or to the intermediate For optimum control of step (B), it is preferred that from that step after it has been isolated by conventional the dehydrating agent be incrementally added to the mix 25 techniques. ture of amino, hydroxy-substituted polyhaloalkane and The de-aminating agent can be any compound known acid acceptor and the resulting mixture then heated to to be useful in this capacity, e.g., the strong dehydrating reflux temperature, which will vary depending upon the agents mentioned above as being suitable for step (B) particular reactants employed and the nature of the added of the process for preparing the imines of this invention. reaction medium if any. 30 The preferred de-aminating agent is phosphorous pentox The dehydrating agent can be any compound known to ide. Although the amount of de-aminating agent is not be useful in this capacity, e.g., POCl3, POs, etc. Phos critical, best yields of polyhaloalkylhydrazone are ob phorous oxychloride (POCl3) is the preferred dehydrating tained when the molar ratio of de-aminated agent to in agent. termediate from step (a) is at least 1:1. Generally there Although it is not essential, the use of a liquid reaction 35 is no advantage in letting this ratio exceed 2:1. medium in steps (A) and (B) is preferred. The medium Although it is not essential, an inert normally liquid can either be a normally liquid tertiary amine, which func reaction medium is preferably employed in steps (a) tions both as a medium and as an acid acceptor, or it can and (b) to moderate the reaction. Suitable media are be any normally liquid medium which is inert to the re those mentioned above in connection with steps (A) and actants and products. Preferably the medium is a solvent 40 (B) of the process for preparing the polyhaloalkylidene for the reactants and products of steps (A) and (B).