United States Patent (19) (11) 4,172,115 Hulme (45) Oct
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United States Patent (19) (11) 4,172,115 Hulme (45) Oct. 23, 1979 (54) PREPARATION AND USE OF SULFUR 56 References Cited TETRACHELORIDE DERVATIVES OF THE FORMULA (SA3+.MX- U.S.S. PAPATEN T DO CUMENTS ,923,094 8/1933 Jenness ................................. 423/467 (75) Inventor: Roger Hulme, Somerville, N.J. 2,992,0732,883,267 4/19597/1961 TullockMuetterties ....... .......................... ... 42.3/469423/469 3,000,694 9/1961 Smith et al. .......................... 423/467 73) Assignee: Exxon Research & Engineering Co., 3,054,661 9/1962 Muetterties .......................... 423/469 Florham Park, N.J. 3,848,064. 1 1/1974 Becher et al. ........................ 423/469 (21) Appl. No.: 929,285 FOREIGNG PATENTT DOCUMENTSD MENT 805860 12A1958 United Kingdom ...................., 423/469 22 Filed: Jul. 31, 1978 Primary Examiner-O. R. Vertiz Assistant Examiner-Gary P. Straub Related U.S. Application Data Attorney, , Agent, or Firm-JFirm-John W. DitstSler 63 Continuation-in-part of Ser. No. 807,522, Jun. 17, 1977, 57 ABSTRACT abandoned, which is a continuation-in-part of Ser. No. Sulfur tetrachloride derivatives are prepared by react 628,590, Nov. 4, 1975, abandoned. ing suitable sulfur-containing compounds in hydrogen fluoride with a gas containing molecular chlorine in the 51) Int. Cl. ....................... C01B 17/45; CO1B 17/00 presence of one or more acidic halides. Such derivatives 52) U.S. Cl. .................................... 423/276; 423/292; can be used to remove water from its solutions in hydro 423/300; 423/462; 423/466; 423/468 gen fluoride. 58) Field of Search ................... 423/467, 469, 561 R, 423/564, 511; 423/468,292, 276, 300, 462, 466 18 Claims, No Drawings 4,172,115 1 2 ride, said sulfur tetrachloride derivatives react with PREPARATION AND USE OF SULFUR water in either system to produce gaseous thionyl fluo TETRACHELORIDE DERVATIVES OF THE ride (SOF2) and HCl. Thus, use of compounds prepared FORMULA (SA3+.MX-1-) according to the present invention enables the removal of water from a solution containing water and hydrogen CROSS-REFERENCE TO RELATED fluoride, including solutions comprising water, hydro APPLICATIONS gen fluoride and the aforementioned acidic halides. This is a continuation-in-part of application Ser. No. In an analogous manner, the addition of water and of 807,522 filed June 17, 1977 which is a continuation-in a gas containing molecular chlorine to a mixture com part of application Ser, No. 628,590 filed Nov. 4, 1975, 10 prising suitable sulfur-containing compounds and hy both applications now abandoned. drogen fluoride can be used to remove the sulfur in said BACKGROUND OF THE INVENTION sulfur-containing compounds from said mixture as gase ous SOF2. Also the addition of chlorine to a mixture 1. Field of the Invention comprising water and suitable sulfur-containing com The present invention relates to a new method for 15 pounds, whether or not in the presence of the above synthesizing sulfur tetrachloride derivatives. More spe mentioned acidic halides, serves to reduce the concen cifically, sulfur tetrachloride derivatives may be synthe tration of the water and of the sulfur compounds simul sized from suitable sulfur-containing compounds by taneously. reacting same in hydrogen fluoride with a gas contain ing molecular chlorine in the presence of one or more 20 DETAILED DESCRIPTION OF THE acidic halides. INVENTION 2. Description of the Prior Art Sulfur tetrachloride is an unstable material that de The acidic halides used in the present invention are of composes at about -30 C. Stable derivatives of SCl4 the formula MX where M is an element selected from may be prepared by chlorinating sulfur compounds in 25 the group consisting of tantalum, niobium, titanium, the presence of a Lewis acid such as aluminum chloride. zirconium, hafnium, phosphorus, arsenic, antimony, In this way have been prepared SCl3 AlCl4; boron or mixtures thereof, X is a halogen, n is the SC13+SbCl6-; and SCl3+ AsF6. The reaction be atomic ratio of halogen to M and varies from 3-5 (see tween chlorine, sulfur-containing compounds and a Olah, G. A. Friedel-Crafts Chemistry, John Wiley & Lewis acid in the presence of hydrogen fluoride has 30 Sons, pp. 215-216, New York, 1973). Preferred acidic been described as a method for preparing sulfur hexaflu halides are tantalum halides, niobium halides or mix oride (see U.S. Pat. No. 3,054,661). It is therefore sur tures thereof. For the purposes of this invention, X will prising that I have found it possible to prepare deriva be considered to be a single halogen (i.e., fluorine, chlo tives of sulfur tetrachloride in the form of salts of com rine, bromine and iodine) even though it should be plex fluoroacids in hydrogen fluoride solution. Indeed, 35 understood that X could refer to a mixed halogen such none of the prior art teaches or suggests a method of that MX could be, for example, TaF4C1. Specific exam synthesizing sulfur tetrachloride derivatives by contact ples of useful acidic fluorides include antimony penta ing suitable sulfur-containing compounds with a gas fluoride, tantalum pentafluoride, niobium pentafluoride, containing molecular chlorine in the presence of one or titanium tetrafluoride, boron trifluoride, arsenic penta more acidic halides and hydrogen fluoride. 40 fluoride, mixtures thereof and the like. Tantalum penta fluoride, niobium pentafluoride or mixtures thereof are SUMMARY OF THE INVENTION preferred acidic fluorides. Such acidic halides can be Now, in accordance with the present invention, a used as such or formed in situ from the element by method has been found for synthesizing sulfur tetra reaction with the chlorine and hydrogen fluoride. chloride derivatives by contacting suitable sulfur-sup 45 The sulfur can be employed either in elemental or in plying reagents with hydrogen fluoride and with a gas combined form. Thus, the reaction mixture can com containing molecular chlorine at a temperature above prise, in addition to hydrogen fluoride, and one or more about -50 C., said contacting being done in the pres acidic halides, sulfur and chlorine as the separate ele ence of one or more acidic halides of the formula MX ments: or sulfur dichloride (SCl2), or a sulfane or sul where M is an element selected from the group consist 50 fanes (compounds of the formula H2S, where y ranges ing of tantalum, niobium, titanium, zirconium, hafnium, from 1-6 such as are described in Cotton, F. A. and phosphorus, arsenic, antimony, boron or mixtures Wilkinson, G. Advanced Inorganic Chemistry-A Con thereof, X is a halogen, n is the atomic ratio of halogen prehensive Study, 3rd Ed. N.Y. Interscience Publishers, to M and varies from 3-5. The acidic halides may also New York, 1972), or disulfurdichloride (S2Cl2) or sulfur be generated in situ from the metal or non-metallic 55 bromide, or mixtures thereof, each with additional chlo parent. Suitable sulfur-containing compounds include rine. The chlorine content of the gas is not critical and elemental sulfur, the sulfanes, the lower sulfur halides may range between 1 and 100 mole %, but is preferably (e.g. S2Cl2, SCl2) and metal sulfides. When the reactants between 10 and 100 mole % and most preferably be are contacted accordingly, there results a gas phase tween 50 and 100 mole %. comprising predominantly hydrogen chloride and a While not wishing to be bound by any particular liquid phase from which sulfur tetrachloride derivatives theory, it is believed that the above-identified sulfur can be recovered. Preferably, the contacting will occur compounds react with chlorine to form unstable sulfur under substantially anhydrous conditions. tetrachloride (SCl4) which then reacts with one or more In another embodiment of the present invention, it acidic halides to form compounds containing the cation has been found that whereas the sulfur tetrachloride 65 SCl3 or derivatives thereof, having the general form derivatives are surprisingly stable towards solvolysis by SA3.MX 1 where A is fluorine, chlorine or mix anhydrous hydrogen fluoride or solutions of the afore tures thereof and X may be partially or totally replaced mentioned acidic halides in anhydrous hydrogen fluo by fluorine. At temperatures of 100° C. or less and for 4, 172,115 3 4 reaction times of less than ten and preferably less than However, in the interest of efficient utilization of the five minutes, the SCl3+ cation will be formed preferen sulfur, it is recommended to have the chlorine and the tially. Typically, as deduced from the chloride analysis, sulfur present in the system (separately or combined) in the purity of the SCl3 salts formed in this way exceeds such amounts that the atom ratio of chlorine to sulfur is 90%. However, at temperatures greater than 100 C, at least 1:1, preferably at least 3:1 and still more prefera and longer reaction times, the chlorine may be increas bly at least 4:1. At least 0.5, preferably 1.0 mole, of ingly replaced by fluorine to form cations of the type acidic halide should be present per mole of sulfur. If the SFCl2 + and SF2Cl and eventually be totally replaced acidic halide is generated in situ from the element, then by fluorine to form the SF3+ cation. Thus the term chlorine is required in an amount sufficient to raise the derivatives of sulfur tetrachloride as used herein is O element to the appropriate oxidation state, i.e., the oxi meant to include the cations SCl3, SCl2Fh, SF2Clt dation state whose halides correspond to those de and SF3 +. scribed above. Although the mechanism of the reaction is not known It is preferred but by no means critical that the reac with certainty, it appears that the stoichiometry of the tion be conducted under substantially anhydrous condi process using the above-mentioned sets of reactants can 15 tions; i.e., less than 1 wt.% water, to prevent or mini be represented by the following equations, wherein ES mize the formation of such compounds as thionyl fluo denotes a metal sulfide with v ranging from 0.5 to 3, the ride due to the hydrolysis of sulfur tetrachloride deriva acidic halide is an acidic fluoride (MF) or is generated tives in HF.