3,274,258 United States Patent Office Patented Sept. 20, 1966 2 o, ox'-thiobis(2-n-heptyl-6-tert-butyl-p-cresol); 3,274,258 ox.c4'-thiobis 2-(3'-nonyl)-6-isopropyl-4-ethylphenol); HYDROXYBENZYL THOETHERS AND METHOD OF PREPARATION o,c'-thiobis(2-n-dodecyl-6-sec-butyl-p-cresol); Joseph D. Odenweiler, Birmingham, Mich., assignor to ox,c''-thiobis(2,6-di-tert-butyl-4-hydroxybenzyl); Ethyl Corporation, New York, N.Y., a corporation of 5 (3-isopropyl-5-tert-butyl-4-hydroxy-benzyl)-(3-ethyl-5- Virginia tert-butyl-4-hydroxybenzyl)-thio ether; No Drawing. Filed Sept. 1, 1960, Ser. No. 53,353 o,o'-thiobis(2-methyl-6-tert-butyl-4-(4'-hexylbenzyl)- 6 Ciains. (C. 260-609) phenol). The compounds of this invention are water insoluble, This invention deals with a novel class of compounds, O their preparation and their use as antioxidants. More white to yellow, crystalline solids. They are ashless, hy particularly, it relates to a novel and unusual class of sul drolytically stable and non-volatile, facilitating their in fur-containing substituted phenolic compounds, their prep corporation into a wide range of organic material. aration from the corresponding benzyl chlorides and the Although the compounds of this invention described in employment of these novel compounds as stabilizers and 5 the above formula, are those in which R5 and Rs are alkyl antioxidants for organic materials. radicals having from 1 to 12 carbon atoms, haloalkyl radi It is an object of this invention to provide a novel class cals having from 1 to 12 carbon atoms are also useful. of chemical compounds. A further object of this inven A preferred embodiment of this invention consists of tion is to provide a novel method for preparation of these compounds of the above formula wherein R5 and R6 are compounds. Another object is to provide novel composi 20 hydrogen. These compounds are preferred because of tions of matter comprising organic material stabilized their ease of preparation from readily available starting against oxidative deterioration. A specific object of this materials and greater antioxidant activity. Among the invention is to provide lubricating oil stabilized against compounds represented by this preferred embodiment are oxidative deterioration. Another specific object is to pro cy,c'-thiobis(2-isopropyl-6-(3'-nonyl)-p-cresol; vide leaded gasoline containing manganese compounds 25 o,o'-thiobis (2,6-di-tert-butyl-p-cresol); stabilized against oxidative deterioration. Other objects co'-thiobis 2-n-propyl-6-(2-octyl)-p-cresol; will become apparent from the following description of the o,a'-thiobis(2-sec-butyl-6-(4-dodecyl)-p-cresol; invention. (3-methyl-5-isopropyl-4-hydroxybenzyl)-(3-n-butyl-5- The above and other objects are accomplished by provi tert-butyl-4-hydroxybenzyl)thioether; sion of a compound having the formula: 30 (3-methyl-5-tert-butyl-4-hydroxybenzyl)-(3-n-propyl-5- dibutyl-4-hydroxybenzyl)thioether; (I) QH o,a'-thiobis(2-methyl-6-n-propyl-p-cresol); 3-(3'-hendecyl)-5-(2'-decyl)-4-hydroxybenzyl-(3- R- -R2 methyl-5-isoamyl-4-hydroxybenzyl)thioether; cx,o'-thiobis(2-ethyl-6-(3'-dodecyl)-p-cresol; 35 o,0'-thiobis(2-methyl-6-isopropyl-p-cresol); and o,a'-thiobis(2-methyl-6-tert-butyl-p-cresol). II--Rs The most particularly preferred compound of this in s vention is o.o.'-thiobis (2,6-di-tert-butyl-p-cresol) which is 40 a most Superior antioxidant for lubricating oils. H--Rs The compounds of this invention can be produced by a four step method which comprises reacting a compound of the formula: R8 - l. (II) OEI 45 OE wherein R1 and Rs are each independently selected alkyl radicals having from 1 to 12 carbon atoms, R2 and R4 are each independently selected alpha-branched alkyl radicals having from 3 to 12 carbon atoms and R5 and Rs are se 50 R-(-x lected from the group consisting of hydrogen, alkyl radi cals having from 1 to 12 carbon atoms and mononuclear wherein R1, Ra and R5 are as in Formula I, and X is a aryl radicals having from 6 to 12 carbon atoms. Thus, halogen, first with thio-urea, then chlorine, and then re the two phenolic radicals in the above formula may be ducing the resultant benzyl sulfonyl chloride with sulfuric the same or different. Examples of the compounds of this 5 5 acid and metallic zinc to the benzylthiol. This is then invention include reacted with a compound of the formula: o,o'-thiobis(2-sec-butyl-6-tert-butyl-p-cresol); (III) OH a’,ox4-thiobis(2-methyl-6-isopropyl-4-sec-butylphenol); R3- -R4 o,ox'-thiobis(2-ethyl-6-isoamyl-p-cresol); 60 c.,a?-thiobis(2-isopropyl-6-(2'-heptyl)-4-n-heptylphen ol); o,ox'-thiobis(2,6-diisopropyl-p-cresol); R6-C-X ox'o?-thiobis(2-n-butyl-6-(3'-nonyl)-4-n-dodecylphenol; H o, ox'-thiobis(2,6-di-tert-butyl-p-cresol); wherein R3, R4 and R6 are as in Formula I, and X is a a',A4'-thiobis 2-n-amyl-6-(3'-dodecyl)-4-n-butylphenol); halogen, to yield compounds of Formula I. 3,274,258 3 4. The above reactions can be illustrated by the following cated above except the reaction of the benzylthiol with general equations: benzyl halide. In this latter reaction the use of pyridine or tertiary amines is preferred. These solvents enhance OH OEI the reaction rate by absorbing hydrogen halide, one of the R1 R2 - R R2 5 Ieaction products. -- 1. thiourea -- H2SO4 -- Zn -A The following example illustrates the compounds of this 2. Cl2 invention and their preparation according to the method outlined above. d Example 1 R.--x R.--soci O To a reaction vessel equipped with cooling and heating H H means, a stirrer, a thermometer, a water cooled condenser OE OH OH and sintered disperson tube, is added 254 parts of 3,5-di tert-butyl-4-hydroxybenzyl chloride, 76 parts of thiourea R R2 R3 R R1- R and 600 parts of isopropyl alcohol. The temperature is -- -3 5 raised and the reaction mixture is allowed to reflux for 30 minutes. The reaction vessel is allowed to cool and 1000 parts of water are added. The mixture is cooled R.--SH Ri- -X HC-R is to about 0° C. A source of anhydrous chlorine gas is H H s attached to the sintered tube and chlorine gas is passed H-C-R6 20 into the solution, maintaining the temperature between 0 to 10 C. until formation of the insoluble benzylsulfonyl chloride is complete (about one hour). The benzyl Sulfonyl chloride is separated by filtration and 63.2 parts R3- -R4 of it are added to 140 parts of 95 percent H2SO4 and 425 parts of ice in the reaction vessel described above. (bH To this is added 72 parts of zinc dust, while maintaining In the above reactions the halide preferred is chlorine the temperature below 0° C. The mixture is stirred for but other halogens of atomic weight greater than 17 may one hour, during which time the temperature rises to re also be used. Chlorine is preferred because of its cost flux. After cooling, the 3,5-di-tert-butyl-4-hydroxybenzyl effectiveness and high reactivity. 30 thiol thus formed is extracted with ethyl ether. The ether The preparation of certain preferred reactants of For is evaporated off by heating to give the benzylthiol in good mulas II and III is disclosed in an application filed con yield. In a reaction vessel equipped with cooling and currently with the present application entitled, “Organic heating means, a thermometer and stirrer, 25.2 parts of Aromatic Compounds,' the inventor being Joseph D. the above benzylthiol is added to a solution of 25.5 parts Odenweller. They can be prepared by reacting a suitable 35 of 3,5-di-tert-butyl-4-hydroxybenzyl chloride in 200 parts 2,6-dialkylphenol with an aldehyde having from 1 to 13 of pyridine, maintaining the temperature at about 20° C. carbon atoms and concentrated hydrogen halide. Thus, After the addition, the solution is warmed to 50° C. for 2,6-di-tert-butyl-4-hydroxybenzyl chloride can be pre 15 minutes and then cooled to about 20° C. Two hun pared by reacting 2,6-di-tert-butylphenol with formalde dred parts of water are then added to the reaction mixture hyde and 35 percent hydrochloric acid. 40 and a,cz'-thiobis (2,6-di-tert-butyl-p-cresol) is filtered off. The temperatures employed in practicing this invention It is purified by recrystallization from isooctane and found vary from -20° C. to the reflux temperature of the high to have a melting point of 141 to 143° C. Upon sulfur est boiling solvent, about 305 C., at reaction times of analysis 6.87 percent sulfur is found. Calculated sulfur from a few minutes to one week or more to give a good for CaoH46O2S is 6.81 percent. yield of product. 45 Example 2 In the reaction of the benzylsulfonyl halide, a preferred temperature range is from about 20° C. to about 150° C. Fifty-five parts of 3-methyl-5-(3'-dodecyl)-a-ethyl-4- The reaction proceeds at a sufficiently rapid rate in this hydroxybenzyl chloride, 14 parts of thiourea and 130 parts temperature range to give a good yield of product in a of dioxane are mixed in a reaction vessel equipped with reasonable time with a minimum of undesirable side re 50 cooling and heating means, a thermometer, a stirrer, a actions.