Patented Sept. 28, 1954 2,690,451 UNITED STATES PATENT OFFICE 2,690,451. METHOD FOR, PREPARATION OF SULFUR CONTANNG. ESTERS OF PEOSPHORIC ACED Everett E. Gilbert, Fushing, and Catherine J. McGough, Kew Gardeas, N. Y., assignors to Allied Chemica & Dye Corporation, New York, N. Y., a corporation of New York s No Drawing. Application September 28, 1951, 3. Serial No. 248,893 10 Claims. (C. 260-46) 2 This invention relates to new sulfur-contain amounts to prepare the novel sulfur-containing ing ester's of phosphoric acid and to the prepara phosphoric acid esters of the invention. tioi of Such compounds. High yields of the desired Sulfur-containing These new sulfur-containing phosphoric acid esters are obtained by carrying out the reaction esters conform to the general formula, 3. in the presence of an inert Solvent, preferably one lower boiling than the phosphoric acid ester O or esters produced. Suitable inert Solvents in RS-1 (or'), clude ethylene dichloride, ethyl ether, petroleum in which R, represents an alkyl, substituted alkyl ether, carbon tetrachloride, toluene and benzene. or cycloalkyl radical and R' represents an alkyl, When reaction is completed, lower boiling solvent Substituted alkyl, cycloalkyl or alkenyl radical, So used may be recovered for reuse by simple dis In the new compounds, typical examples of R, tiliation at atmospheric or lower preSSure. are methyl, ethyl, normal-butyl, tertiary-butyl, The reaction may be carried out at any ten petachloroethyl, triphenylmethyl and cyclohexyl, perature up to the decomposition point of the Typical examples of R.' are ethyl, butyl, beta reactants. Generally, the reaction is quite chloroethyl, methyl, allyl and cyclohexyl, Vigorous during the addition of the reactants, A sulfur-containing phosphoric acid ester of and cooling is desirable to retard the reaction. the general formula, given above may be prepared In other cases, gentle warming is required to according to certain aspects of the invention by initate reaction. reacting an organic phosphite of the general 20 As may be seen from the equation illustrating formula. the reaction of the organic phosphites with the Organic Sulfonyl chlorides, phosphoric acid esters in which R' has the meaning shown above, either of the general formula, With an Organic Sulfonyl chloride of the general formula 2 5 RSO3Cl. in which R has the meaning shown above, are produced during the course of the reaction. These or With an Organic Sulfenyl chloride of the gen phosphoric acid esters are well known articles of eral formula Commerce finding usage, for example, as Solvents RSC or plasticizers. Since heretofore, these esters in Which R, has the meaning shown above, and have not been produced by Such a reaction, their recovering Said Sulfur-containing phosphoric acid preparation constitutes another feature of Our ester. in Vention. The phosphoric acid esters may be The reaction between the organic phosphites Separated from other reaction products by any and the Organic Sulfonyl chlorides takes place in Suitable method Such as by Vacuum distillation accordance with the following equation: uSually at a temperature higher than employed for recovery of preferred lower boiling solvent. O AS is apparent froin the equation illustrating 3(RO)3P -- RSOC - RS-(or) + R’Cl -- 2(R'O)3PO the reaction of the Organic phosphites with the The reaction between the organic phosphites 40 Organic Sulfenyl chlorides, phosphoric acid esters and the Organic Sulfenyl chlorides is represented are not produced as by-products. Thus when the by the following equation: formation of by-product phosphoric acid esters is not desired, it may be preferred to produce the Sulfur-containing phosphoric acid esters (R'O)3P -- RSC1 - RS-P(OR)2 - R. Cl 45 characteristic of the invention by use of the Sull The lower trialkyl phosphites such as triethyl, fenyl chloride reaction. When a lower trialikyi tributyl and tri (beta-chloroethyl) phosphites are phosphite or other phosphite forming a rela preferred reactants, but other phosphites of the tively volatile organic chloride is employed in general formula, given above, including mixed reaction. With the Organic Sulfenyi chloride, re phOSphites containing different alkyl, substituted 50 COVery of product concentrated in Sulfur-contain alkyl, cycloalkyl or alkenyl radicals, may be effec ing phosphoric acid ester may be effected easily tively employed. and economically by Simple heating or distilla It is preferred that the organic phosphite and tion of the reaction mass at low temperature Organic Sulfonyl chloride or organic sulfenyl chlo Suitable for driving off such organic chloride and ride be employed in approximately stoichiometric 55 Solvent if present. 2,690,451. 3 4. The following examples are given for the pur Other aliphatic as well as cycloparaffinic Sul pose of illustrating the present invention, but are fonyl and sulfenyl chlorides may be used as re Parts are by weight. actants in the above examples including methyl, not intended to be limiting on the Scope thereof. ethyl and cyclohexylsulfonyl chlorides and Eacample 1-50 parts of triethyl phosphite Were methyl, beta-chloroethyl and triphenylmethylsul added slowly with stirring to a solution of 16 parts fenyl chlorides. Likewise, other organic phos of normal-butanesulfonyl chloride in 84 parts of phites, such as tributyl and tricyclohexyl phos ethyl ether, the temperature being maintained phites may be employed in the examples. below 30° C. The resulting Solution was heated Products of the type produced by the invention on a steam bath for 10 hours to complete the re 10 find valuable application for a number of pur action and to remove the ether solvent and the poses, including, but without limitation, as Sol ethyl chloride formed during the reaction. The Wents or plasticizers, and as intermediates for a, solution was then vacuum distilled to remove first Wide variety of mercaptains which are obtainable triethyl phosphate and then the Sulfur-contain directly by hydrolysis of the novel sulfur-con ing phosphoric acid ester having the formula. taining phosphoric acid esters characteristic of the invention. We claim: CHSP(OCH) 1. A method of preparing a Sulfur-containing The sulfur-containing phosphoric acid ester, a phosphoric acid ester of the general formula, colorless liquid distilling at 100° to 115° C. at 5 20 mm. mercury pressure, constituted 22 parts (97% of theory). In another run, normal-butanesulfonyl chlo in which R is a member of the group consisting ide Was reacted with tri (beta chloroethyl) phos of alkyl, Substituted alkyl and cycloalkyl radi phite. The beta-chloroethyl chloride formed dur Calls and R' is a member of the group consisting ing the reaction was removed by heating, leaV of alkyl, Substituted alkyl, cycloalkyl and aikenyl ing a product comprising tri (beta-chloroethyl) radicals, which includes the step of reacting an phosphate and the Sulfur-containing ester hav organic phosphite of the general formula. ing the formula, 30 in which R' is a member of the group consisting of alkyl, substituted alkyl, cycloalkyl and alkenyl Eacample 2-33.2 parts of triethyl phosphite radicals, with an organic chloride of the group were added dropwise with Stirring to a solution of consisting of organic sulfonyl chlorides of the 24.9 parts of tertiary-butanesulfenyl chloride in 35 general formula, 250 parts of carbon tetrachloride, the tempera RSO2C) ture being maintained below 25°C. The tertiary and Organic Sulfenyl chlorides of the general butanesulfenyl chloride was prepared by the formula nethod described in Industrial and Engineering RSC Chemistry, May 1950, page 919. The resulting 40 Solution was allowed to stand overnight at room in which R is a member of the group consisting temperature and was then heated at reflux for of alkyl, substituted alkyl and cycloalkyl radicals. approximately 6 hours to remove the carbon 2. A method of preparing a Sulfur-containing tetrachloride solvent and the ethyl chloride phosphoric acid ester of the general formula, formined during the reaction. The residue was 45 fractionated, and a product comprising the sul RS-P(OR') fur-containing phosphoric acid ester having the in which R, is a member of the group consisting formula, of alkyl, substituted alkyl and cycloalkyl radicais O and R' is a member of the group consisting of 50 CHSP (OCH5)2 alkyl, Substituted alkyl, cycloalkyl and alkenyl but containing no by-product triethyl phosphate radicals, which comprises reacting an organic Was removed. The sulfur-containing phosphoric phosphite of the general formula, acid ester, a colorless liquid, constituted 30 parts (66% of theory). 55 in which R' is a member of the group consisting Eacample 3-35 parts of triethyl phosphite of alkyl, Substituted alkyl, cycloalkyl and alkenyl were added dropwise with stirring to a solution radicals, with an Organic sulfonyl chloride of the of 24.9 parts of tertiary-butanesulfenyl chloride general formula in 200 parts of petroleum ether, the temperature RSOEC being maintained below 25° C. The tertiary 60 butaneSulfenyl chloride was prepared by the in which R, is a member of the group consisting of method described in Industrial and Engineering alkyl, substituted alkyl and cycloalkyl radicals. Chemistry, May 1950, page 919. The resulting 3. A method of preparing a sulfur-containing Solution was allowed to stand at room tempera phosphoric acid ester of the general formula, ture for 48 hours and was then refluxed for 3 65 hours to remove the petroleum ether solvent and the ethyl chloride formed during the reaction. RS-P(OR), The residue was fractionated, and a product in which R is a member of the group consisting Comprising the Sulfur-containing phosphoric acid of alkyl, substituted alkyl and cycloalkyl radicals and R' is a member of the group consisting of ester having the formula, alkyl, Substituted alkyl, cycloalkyl and alkenyl O radicals, which comprises reacting an organic CHSP (OCH) phOSphite of the general formula, Was obtained.