3,397,244 United States Patent Office Patented Aug. 13, 1968

2 aryl halide or alkaryl halide with an alkali metal sulfide in a polar organic reaction medium. In that process, a 3,397,244 Solution of an alkali metal sulfide, such as Na2S, is formed PROCESS FOR PRODUCTION OF DARYLAND in a polar organic solvent medium, such as N-methyl-2- DI(ALKARYL) SULFDES pyrrollidone. These solutions set up to gelatinous masses Rector P. Louthan, Bartlesville, Okla., assignor to Philips at temperatures below 130° C. This makes such process Petroleum Company, a corporation of Delaware Steps as the charging of the reactor very difficult, and No Drawing. Filed Sept. 9, 1964, Ser. No. 395,292 line plugging can be encountered. 12 Claims. (CI. 260-609) I have now found that, by using an alkali metal bisul O fide in lieu of or in addition to the alkali metal sulfide of This invention relates to the production of diaryl sul said application, the tendency to produce gelatinous fides, di(alkaryl) sulfidies and aryl alkaryl sulfides. In masses at temperatures below 130° C. is reduced or elim one of its aspects, the invention relates to the production inated. Use of the bisulfide alone is now preferred. of a diaryl or a di(alkaryl) sulfide by reacting an aryl The process of the present invention is applicable to halide or an alkaryl halide in a polar organic compound 5 the operation and materials disclosed or within the scope solvent at an elevated temperature with an alkali metal of said application for patent, bisulfide. In another of its aspects, the invention relates It is an object of this invention to provide a new and to such a reaction wherein the reactants, alkali metal improved process for the production of diaryl sulfides hydroxide and hydrogen sulfide which form the alkali and/or di(alkaryl) sulfides. It is a further object of this metal bisulfide, are supplied to the reaction Zone. In an 20 invention to provide a new process for the production of other of its aspects, the invention relates to the reaction said Sulfides in a one-step reaction, employing inexpensive of an aryl halide and/or alkaryl halide with an alkali starting materials. It is a further object of the invention metal bisulfide at an elevated temperature in a polar to prepare the said sulfides in the substantial absence of organic compound in a closed vessel under autogenous water. It is a still further object of the invention to pro pressure. In a still further aspect of the invention, it re 25 vide a process for the production of the said sulfides lates to such a reaction as here described wherein, in prep avoiding tedious and expensive operations heretofore re aration for the reaction, the alkali metal bisulfide is dis quired. It is a still further object of the invention to pro solved in the polar organic solvent at room temperature. vide a new and improved process for the production of A wide variety of diary sulfide and di(alkaryl) sulfides diaryl sulfides and/or di(alkaryl) sulfides and aryl alkaryl are known, some of which have wide utility. However, 30 Sulfides employing an alkali metal bisulfide which dis the processes currently available for preparing these com solves in the polar organic reaction medium employed at pounds are so tedious and expensive that the price of ordinary temperatures without forming a gelatinous these compounds has remained relatively high, thus pre maSS. venting real commercial development. For example, di Other aspects, objects and the several advantages of phenyl sulfide has been prepared by the reaction of 35 the invention are apparent from a study of this disclosure benzenediazonium chloride with the sodium mercaptide and the appended claims. of thiophenol. Another method which has been used for According to the present invention, there is provided a the preparation of this compound is the pyrolysis of the process for the production of at least one diary sulfide, lead mercaptide of thiophenol. Diaryl sulfides and di di(alkaryl) sulfide, and/or aryl alkaryl sulfide by a re (alkaryl) sulfides are useful as intermediates for the prep 40 action of aryl monohalide and/or alkaryl monohalide aration of insecticides, as plasticizers, high boiling sol with an alkali metal bisulfide in a reaction medium con vents and the like. sisting essentially of a polar organic compound, said These sulfides are useful as high boiling solvents, heat polar organic compound being a substantial solvent for exchange fluids, hydraulic fluids, and as intermediates the reactants and being essentially stable at the reaction for the production of sulfoxides and sulfones which, them 5 conditions which generally include an elevated tempera selves, have utility in such fields as insecticides and high ture, the range of temperature presently considered ap boiling solvents. For example, diphenyl sulfide has a plicable being from about 125° C. to about 450° C. melting point of -21.5 C. and a boiling point at at The reaction according to which the invention can be mospheric pressure 296° C. This wide fluid range, coupled said to be effected is illustrated by the equation with its very high boiling point, makes this compound 50 particularly suitable for use as a heat transfer medium. Diphenyl sulfone, prepared by the peroxide oxidation of diphenyl sulfide, is useful as an insecticide. Physical prop erties of other diaryl sulfides and di(alkaryl) sulfides are wherein each R is selected from the group consisting of given in “Organic Chemistry of Bivalent Sulfur,” Reid, 55 aryl and alkaryl radicals containing from 6 to 18 carbon vol. 2, Chemical Publishing Company Incorporated, New atoms, inclusive, each X is a halogen selected from the York (1960), pages 117-123. A relatively simple, eco group consisting of chlorine, bromine, fluorine and iodine, nomical process for the preparation of these sulfides would and M is an alkali metal selected from the group con find ready acceptance by the industry. sisting of sodium, potassium, lithium, rubidium and It is disclosed in copending application Serial No. 60 cesium. At present, it is preferred that X be chlorine or 326,389 of H. W. Hill and James T. Edmonds, filed Nov. bromine and M be sodium or potassium. Mixtures of re 27, 1963, now Patent 3,322,834, issued May 30, 1967, actants of any group can be used and are within the scope that diary sulfides and di(alkaryl) sulfides and aryl of the invention. alkaryl sulfides can be prepared by the reaction of an Some examples of compounds of the formula RX which 3,397,244 3 4 can be employed as reactants in the process of this inven ventional techniques can be utilized for recovering the tion are: -- M diaryl sulfides, di(alkaryl) sulfides, aryl alkaryl sulfides chlorobenzene and/or mixtures thereof. At the completion of the re 4-chlorotoluene action, the reaction mixture is generally cooled from the 5 reaction temperature, filtered to remove alkali metal bromobenzene halide, and then treated by such processes as distillation, 1-chloro-3-ethylbenzene crystallization, extraction and the like for the recovery of 1-fluoro-3-isopropylbenzene the sulfide product. 1-iodo-2-methyl-4-ethylbenzene As a further advantage of this invention, it has been 1-bromo-2,4-diethylbenzene discovered that alkali metal bisulfides are soluble in cer 1-chloro-3,4,5,6-tetramethylbenzene O tain polar organic solvents at room temperature. For 1-chloronaphthalene example, sodium bisulfide exhibits an inverse solubility 4-chlorobiphenyl in N-methyl-2-pyrrolidone. For example, a free-flowing 2-bromobiphenyl solution of sodium bisulfide is obtained at room tempera 1-chloro-4-dodecylbenzene ture with 1 mol of sodium bisulfide in 1 liter of N-methyl 1-bromo-2,4,6-tri-n-butylbenzene 2-pyrrolidone. Thus, if one prefers to form the sodium 4-bromo-p-terphenyl bisulfide or other alkali metal bisulfide outside of the 6-n-octyl-1-chloronaphthalene reaction zone in which this compound is to be reacted and the like, including mixtures thereof. with an aryl halide, it is relatively easy to charge such a The alkali metal bisulfides which are employed in the 20 free-flowing solution. This solubility at atmospheric tem process of this invention are the bisulfides of sodium, peratures simplifies the charging procedures and also potassium, lithium, rubidium and cesium. These bisulfides eliminates the problem of line plugging encountered with can be charged to the reaction Zone as the bisulfide, or solutions of alkali metal sulfides, such as Na2S in the they can be formed directly in the reaction zone by the same solvent, N-methyl-2-pyrrolidone. reaction of hydrogen sulfide with an alkali metal hy 25 It can be seen from the discussion and example herein droxide, such as NaOH. Formation of the alkali metal that the process of this invention provides a relatively bisulfide in situ by reaction of an alkali metal hydroxide simple, economic process for the production of diaryl and HS is effected at a mol ratio generally not exceeding sulfides, di(alkaryl) sulfides, aryl alkaryl sulfides and/or 1:1 HS:alkali metal hydroxide. Higher amounts of alkali mixtures thereof. Typical sulfides which can be prepared metal hydroxide lead to formation of alkali metal sulfides. 30 by the process of this invention include: The formation of the alkali metal bisulfide in the reac diphenyl sulfide tion zone can be carried out in the presence or absence of di(4-methylphenyl) sulfide an aryl halide or alkaryl halide of the formula RX. di(3-ethylphenyl) sulfide Polar organic compounds which can be employed as di (2-methyl-4-isopropylphenyl) sulfide reaction media in the process of this invention are those di (2,4-diethylphenyl) sulfide in which the aryl halides, alkaryl halides and the alkali dinaphthyl sulfide metal hydroxide and hydrogen sulfide are used in lieu of phenyl 4-methylphenyl sulfide the alkali metal bisulfide. Representative examples of suit di(2-ethyl-4-n-decylphenyl) sulfide able classes of compounds include amides, lactans, Sul phenyl naphthyl sulfide fones and the like. Specific examples of Such compounds 40 di(4-biphenylyl) sulfide C di(4-p,p'-terphenylyl) sulfide N-methyl-2-pyrrolidone 4-biphenylyl phenyl sulfide. pyrrollidone The following specific example is illustrative of the ad caprolactam vantages of the process of the invention which is generally N-ethylcaprolactam applicable as herein stated. sulfolane dimethylacetamide EXAMPLE tetramethylurea A run was carried out in which chlorobenzene and hexamethylphosphoramide sodium bisulfide were reacted in N-methyl-2-pyrrollidone N,N'-ethylenedipyrrollidone to form diphenyl sulfide according to the process of this and the like. invention. The process of this invention is carried out by contact In this run, H2S gas in excess of 2.0 mols was passed ing the above-defined reactants in at least one polar slowly into a stirred slurry of NaOH (2.0 mols) in 2200 solvent at a temperature of from about 125 C. to about ml. of N-methyl-2-pyrrollidone while heating slowly to 450° C., preferably from 175° C. to 350° C. The mol reflux. The heating was continued until all of the sodium ratios of RX reactant to MSH reactant will generally range hydroxide pellets had disappeared. During this heating, from about 0.5:1 to about 5:1, and preferably will range about 250 ml. of water and N-methyl-2-pyrrollidone were from 1:1 to 3:1. Larger amounts of RX reactants can be taken overhead. After the first 35 ml. came overhead, employed, if desired, and unreacted RX compound can a white solid began to precipitate. The slurry of the white be recovered and recycled to the reaction zone. The pres 60 Solid in N-methyl-2-pyrrollidone was allowed to stand sure in the reaction zone will generally be autogenous, overnight at room temperature, and the next morning it and, at the reaction temperature specified, this pressure Was noted that all of the solid had gone into solution. On can run as high as 1000 p.s. i. or greater, depending upon heating to 120° C., the solid began to precipitate again, the chosen reactants and polar solvent. Reaction times but redissolved on cooling. The cooled solution which was will depend upon the chosen reaction temperature, and essentially anhydrous since it had been freed of water, can range from 10 minutes to 50 hours. As in the case of was charged to a 1-gallon, stirred stainless steel auto most reactions, the longer reaction times will be required clave, and heated to 260° C. Two mols of chlorobenzene at the lower temperatures, and vice versa. Were then pumped into the autoclave over about a 40 The amount of polar organic solvent present in the 70 minute period, and the material in the reactor was main reaction zone can vary over a wide range, but will gen tained at 260 C. for 2 hours and then heated at 300° C. erally range from about 100 to 2500 ml. per mol of MSH for 2 additional hours. reactant, Following the reaction time, the reactor contents were The reaction can be carried out batchwise or as a con cooled, diluted with about 4 liters of water and extracted tinuous operation. At the completion of the reaction, con with about 2 liters of ether. After separating the phases, 3,397,244 5 6 the ether extract phase was washed with water and heated sulfide by reacting at least one of an aryl halide and an to 80° C. to strip off the ether. The remaining material alkaryl halide with an alkali meta bisulfide in a reaction was then distilled to obtain a 96 mol percent ultimate medium comprising a polar organic compound which is a yield of diphenyl sulfide, based on a 90.2 percent conver Substantial solvent for the reactants and which is stable sion of the chlorobenzene in this run. at the reaction conditions which include an elevated tem The procedure above exemplified, using chlorobenzene, perature, the reaction taking place being as follows: hydrogen sulfide, and sodium hydroxide, will yield analogous results when the other alkali metal bisulfides and halogenated compounds as herein disclosed are em ployed. The example shows that, when the slurry of white wherein each R is a member selected from the group con solid in N-methyl-2-pyrrollidone was allowed to stand over O sisting of aryland alkaryl radicals containing from 6 to 18 night at room temperature, it disappeared into solution. carbon atoms, inclusive, X is a halogen selected from the Further, that on heating the solid began again to pre group consisting of chlorine, bromine, fluorine and iodine, cipitate. This solid was, of course, the sodium bisulfide and M is an alkali metal selected from the group consist which had been produced by the reaction of the hydrogen ing of sodium, potassium, lithium, rubidium and cesium, sulfide with the sodium hydroxide in the N-methyl-2- 15 said reaction medium being selected from pyrrollidone. N-methyl-2-pyrrolidone Reasonable variation and modification are possible pyrrollidone within the scope of the foregoing disclosure and the ap caprolactam pended claims to the invention the essence of which is 20 N-ethylcaprolactam that a process for the preparation of at least one of a sulfolane diaryl sulfide, a di(alkaryl) sulfide and an aryl alkyaryl dimethylacetamide sulfide has been provided, the process comprising reacting tetramethylurea at least one of an aryl halide and an alkyaryl halide with hexamethylphosphoramide an alkali metal bisulfide in a polar organic compound 25 N,N'-ethylenedipyrrollidone reaction medium at an elevated temperature, the alkali metal bisulfide being supplied, as such, to the reaction the ratio of said halide to said bisulfide being in the ap Zone dissolved in the solvent or prepared in situ by a re proximate range of 0.5:1-5:1. action substantially as set forth and herein described. 4. A process according to claim 3 wherein the solvent I claim: 30 is N-methyl-2-pyrrolidone and the mass to be reacted is 1. A process for the preparation of at least one of a freed from water. diaryl sulfide, a di(alkyaryl) sulfide and an aryl alkyaryl 5. A process for the preparation of at least one of a sulfide by reacting at an elevated temperature at least one diaryl sulfide, a di(alkaryl) sulfide and aryl alkaryl sulfide of an aryl halide and an alkaryl halide with an alkali by reacting at an elevated temperature at least one of an metal bisulfide in a polar organic compound reaction me 35 aryl halide and an alkaryl halide with an alkali metal bisul dium which is a substantial solvent for the reactants and fide in a reaction medium comprising a polar organic com which is essentially stable at the reaction conditions and pound which is a substantial solvent for the reactants then recovering a sulfide thus formed from the reaction and which is essentially stable at the reaction conditions mass thus obtained, said reaction medium being selected wherein prior to the reaction the mass to be reacted is from 40 freed from water, said reaction medium being selected N-methyl-2-pyrrollidone from pyrrollidone N-methyl-2-pyrrolidone caprolactam pyrrolidone N-ethylcaprolactam caprolactam sulfolane N-ethylcaprolactam dimethylacetamide sulfolane tetramethylurea dimethylacetamide hexamethylphosphoramide tetramethylurea N,N'-ethylenedipyrrollidone hexamethylphosphoramide N,N'-ethylenedipyrrollidone the ratio of said halide to said bisulfide being in the ap proximate range 0.5:1-5:1. the ratio of said halide to said bisulfide being in the ap 2. A process for the production of at least one of a proximate range 0.5:1-5:1. diaryl sulfide, a di(alkaryl) sulfide and an aryl alkaryl sul 6. A process for the production of at least one of a fide by reacting at an elevated temperature at least one of 55 diaryl sulfide, a di (alkaryl) sulfide and aryl alkaryl sulfide an aryl halide and an alkaryl halide and alkali metal bi by a reaction at a temperature of the range of from about sulfide in a reaction medium comprising a polar organic 125 C. to about 450° C. of at least one of an aryl halide compound which is a substantial solvent for the reactants and an alkaryl halide with an alkali metal bisulfide in a and which is stable at the reaction conditions and then polar organic compound reaction medium which is a sub recovering the sulfide thus formed from the reaction mass 60 stantial solvent for the reactants and which is essentially thus obtained, said reaction medium being selected from stable at the reaction conditions, said reaction being con N-methyl-2-pyrrollidone ducted under substantially anhydrous conditions, said re pyrrolidone action medium being selected from caprolactam. N-methyl-2-pyrrolidone N-ethylcaprolactam 65 pyrrolidone sulfolane caprolactam dimethylacetamide N-ethylcaprolactam tetramethylurea sulfolane hexamethylphosphoramide dimethylacetamide N,N'-ethylenedipyrrolidone 70 tetramethylurea hexamethylphosphoramide the ratio of said halide to said bisulfide being in the ap proximate range 1:1-3:1. N,N'-ethylenedipyrrolidone 3. A process for the preparation of at least one of a the ratio of said halide to said bisulfide being in the ap diaryl sulfide, a di(alkaryl) sulfide, and an aryl alkaryl proximate range 0.5:1-5:1. 3,397,244 7 7. A process for the preparation of at least one of a metal bisulfide in a polar organic compound reaction me diary sulfide, a di(alkaryl) sulfide and an aryl alkaryl dium selected from sulfide by reacting at least one of an aryl halide and an N-methyl-2-pyrrolidone alkaryl halide with an alkali metal bisulfide formed in situ pyrrollidone in a polar organic compound which is a substantial solvent caprolactam for the reactants and which is essentially stable at the re N-ethylcaprolactam action conditions by reacting therein hydrogen sulfide and sulfolane an alkali metal hydroxide, the reaction with the alkali dimethylacetamide metal bisulfide being effected at an elevated temperature tetramethylurea and a sulfide thus formed being recovered from the reac hexamethylphosphoramide tion mass thus obtained, said reaction medium being O N,N'-ethylenedipyrrollidone selected from 11. A process for the preparation of at least one of a N-methyl-2-pyrrolidone diary sulfide, a di(alkaryl) sulfide, and an aryl alkaryl pyrrollidone sulfide which comprises reacting at least one of an aryl caprolactam 5 halide and an alkaryl halide with an alkali metal bisulfide N-ethylcaprolactam in a reaction medium comprising a polar organic com sulfolane pound which is a solvent for the reactants selected from dimethylacetamide N-methyl-2-pyrrollidone tetramethylurea pyrrolidone hexamethylphosphoramide 20 caprolactam N,N'-ethylenedipyrrollidone N-ethylcaprolactam sulfolane the ratio of said halide to said bisulfide being in the ap dimethylacetamide proximate range 0.5:1-5:1. tetramethylurea 8. A process involving steps as follows: forming a solu hexamethylphosphoramide tion of an alkali metal bisulfide in a polar organic com N,N'-ethylenedipyrrollidone pound reaction medium at a temperature below about and which medium is stable at the reaction conditions 130° C., admixing said solution with at least one of an which include an elevated temperature in the approxi aryl halide and an alkaryl halide, then reacting said bisul 30 fide and said halide at an elevated temperature, and then mate range 175-350° C., the reaction taking place being recovering a sulfide thus formed from the reaction mass as follows: thus obtained, said compound being a Substantial solvent for the reactants and being essentially stable at the reac wherein each R is a member selected from the group con tion conditions under which said sulfide is formed, said sisting of aryl and alkaryl radicals containing from 6 to 18 reaction medium being selected from carbon atoms, inclusive, X is a halogen selected from the N-methyl-2-pyrrolidone group consisting of chlorine, bromine, fluorine and iodine, pyrrollidone and M is an alkali metal selected from the group consist caprolactam ing of sodium, potassium, lithium, rubidium and cesium N-ethylcaprolactam 40 the ratio of said halide being in the approximate range sulfoane 1:1-3:1. dimethylacetamide 12. A process for the production of at least one of a tetramethylurea diaryl sulfide, a di(alkaryl) sulfide and aryl alkaryl sul hexamethylphosphoramide fide which comprises a reaction at a temperature in the range of from about 125° C. to about 450° C. of at least N,N'-ethylenedipyrrollidone one of an aryl halide and an alkaryl halide with an alkali the ratio of said halide to said bisulfide being in the ap metal bisulfide in a polar organic compound reaction me proximate range 0.5:1-5:1. dium which is a substantial solvent for the reactants and 9. A process for the preparation of at least one of a which is essentially stable at the reaction conditions, said diary sulfide, a di(alkaryl) sulfide and an aryl alkaryl reaction being conducted under substantially anhydrous sulfide by reacting at an elevated temperature at least one conditions, said medium being selected from of an aryl halide and an alkaryl halide with an alkali metal N-methyl-2-pyrrollidone bisulfide in a polar organic compound reaction medium pyrrollidone selected from caprolactam 55 N-ethylcaprolactam. N-methyl-2-pyrrolidone sulfolane pyrrollidone dimethylacetamide caprolactam tetramethylurea N-ethylcaprolactam hexamethylphosphoramide sulfolane 60 N,N'-ethylenedipyrrollidone dimethylacetamide the ratio of said halide to said bisulfide being in the ap tetramethylurea proximate range 0.5:1-5: . hexamethylphosphoramide N,N'-ethylenedipyrrolidone References Cited FOREIGN PATENTS said medium being a substantial solvent for the reactants and being essentially stable at the reaction conditions 553,518 2/1958 Canada. under which said sulfide is formed, then recovering a sul OTHER REFERENCES fide thus formed from the reaction mass thus obtained Houben-Weyl: Methoden der Organischen Chemie, vol. the ratio of said halide to said bisulfide being in the ap 9, pp. 7 and 98 (1955). proximate range 0.5:1-5:1. Ephraim: Inorganic Chemistry, 4th edition, p. 524, 10. A process for the preparation of at least one of a diaryl sulfide, a di(alkaryl) sulfide and an aryl alkaryl (1947). sulfide by reacting at an elevated temperature at least one CHARLES B. PARKER, Primary Examiner. of an aryl halide and an alkaryl halide with an alkali 75 D. R. PHILLIPS, Assistant Examiner.