US2527334A - Mineral lubricating oil containing alkali and alkaline earth metal salts of alkylated dibenzothiophene sulfonic acid - Google Patents

Description

Patented Oct. 24, 1950 MINER L LUBRICATING OIL CONTAINING A KALI AN ALKALI E EA H S LTS. ALKY ATED mBENZ PHENE SULFONIC ACID 7 Frederick P. Richter and Everett W. Fuller, Wood-'- bury, N. J., assigii'ors to socony-Vacuuiii pil Company, Incorporated, a corporation of New York .N Drawing. Application June 24, 1 4

1 7 Serial No. 756,812

This invention relates to alkylated dibenzothiophene sul-fonic acids, to metal salts thereof, and to a method for preparing the same. More particularly, the present invention is concerned with lubricating oil compositions improved by incorporating therein a small proportion su-fiicient to improve the properties thereof ofone or more of the aforesaid compounds.

In accordance with the present invention, it has been discovered that dibenzothiophene can be alkylated under certain conditions by contacting the same with an allryl halide in the presence of a Friedel-Crafts type catalyst to produce alky-lateddibenzothiophenes. a

It has further been discovered that the alkyl dibenzothiophene produced as described above can be sulfonated by contact with a suitable Still-2 fonating agent, such as chlorosulfonic acid, concentrated sulfuric acid, oleurn, and the like.

Still further, itv has been discovered that metal salts of the alkylated dibenzothiophene sul Qllic acid, produced as a result of the aforesaid reaction, can be prepared uponcontacting said acid with an inorganic salt or hydroxide of the desired metal. It has been further found thatcertain of said metal. salts,,notably those of the al;-

kali and the alkaline earth metals, are useful asmineral oil additives-and, more particularly, are efiective as detergents in motor lubricating oils.

The compositions of this invention are prepared by using as astarting material substantially pure dibenzothiophene or a crude product which contains. a major proportion of dibenzothiophene. This starting'material is alkylated in accordance with the present invention by bring.-

ing the same into contact with an; alkylhalide,

and a Friedel-Crafts catalyst, preferably in the presence of an inert organic solvent such as Stoddards solvent.

The orientation of the alkylxgroup in, dibenzothiophene has not been established: with certainty. Indicationszare, however, thatwhenonly one hydrogen in. each molecule ofv dibenzothio phene is replaced by analkyl radical, the en-. tering alkyl group occupies the 2- or 3-.position and that when twohydrogens are replaced with alkyl" groups, the entering radicalsoccupy the 25- and 8-positions'or the 3;- and '7-positions. The orientation, however, does not. appear to be, of too great. significance in the practical synthesis of: oil additive composition prepared from the dibenzothiophenes soalkylated'.

The. initial ratio of alkyl halide todibenzo thiophene can be varied. over wide limits. andt-he degree. of: alkylation thus controlled tov yield-- 8 Claims. (01. 252%?) h mono-, di-, and polyalkylated dibenzothiophenes.

Generally, however, a ratio of l to 3 gram atoms of halogen, as combined in the alkyl halide, per mole of dibenzothiophene has been found to be preferable. Alkylating agents of lower halogen content tend to result in a reduced yield of the desired alky-l dibenzothiophene, while those of higher halogen contents, as a general rule, giveno added advantages and result in undue con-i sumption of the alkyl halide. Monoand di-' alkyldib'enzothi-ophenes accordingly represent preferred embodiments of the invention.

It has been established, in accordance with this: invention, that the temperature at which alkylation of dibenzothiophene is efiected is a critical feature of the reaction. At temperatures below about 20 C., the alkylation reaction becomes sosluggish that the yield of desired product is prac-- tically nil; while at temperatures above about C., a tar formationbecomes predominant, causing a substantial decrease in the yield of desired product. Accordingly, the temperature range of from about 20 C; to about 85 C. appears to be a critical factor inthe successful alkylation of dibenzothiophene. Particular preference is accorded to temperatures in the range of from about 60 C. to about 85 C., since under these conditions the reaction was found to pro-- ceed at a faster rate, and consequently as a practical matter, to yield a greater amount of alkyl ated dibenzothiophene per unit time as compared with lower temperatures in the operable range.

The use of an inert organic solvent, while not absolutely necessary, has been found to be highly desirable in modifying the alkylation of dibenzothiophene, causing a substantial decrease in the formation of undesirable tar as the condensation reaction proceeds. Any of the commonly employed organic solvents which are inert under the conditions of reaction" may beemployed for this purpose. 7 Representative solvents include Stoddards solvent,,carbon disnlfide, and the like. In general, theprocessrjdescribed herein may be employed for the alkylation of dibenzothiophene with any alk-yl'halide, However, when the sulfonate metallic salts of the resulting alkylated dibenzothiophene are to be employed as oil ad; ditives, alkylhalides of suiii'cient carbon chain length to render the prepared compound soluble in petroleum oil are preferred. For this, as well as economical reasons, the-use of alkyl halides of hydrocarbons in theparaifin wax range having from about 20 to about 30 carbon atoms represents a preferred embodiment. of this invention. Such; alkyl halides.- havingzmolecular weights in excess of about 250 and having more than about 20 carbon atoms in their molecules are well known. Chlorinated wax maybe considered as a preferred example of such compounds and, in particular, those waxes in which the degree of chlorination has been so regulated that the final chlorinated wax generally contains between about and about 15 per cent'c'hlorine.

The alkylated dibenzothiophenes described above may, in accordance with this invention, be sulfonated by dissolving in a suitable solvent and adding thereto a sulfonating agent such as chlorosulfonic acid. Concentrated sulfuric acid, oleum, or the like may also be used for sulfonating and may be employed directly. The ratio of sulfonating agent to alkyldibenzothiophene may be varied over a wide range to yield products of various degrees of sulfonation. In general, however, a ratio of 1 to 2 moles of sulfonating agent per mole of alkyldibenzothiophene is preferred. The addition of sulfonating'agent to the solution of alkyldibenzothiophene usually is conducted at ordinary room temperatures, that is, between about 15 C. and about 30 C. Upon final addition of the sulfonating agent, the mixture is suitably heated under reflux for a period to insure complete reaction. The solvent employed may then be recovered by distillation. The residue obtained from saiddistillation is an alkyldibenzothiophene sulfonicacid.

- In order to prepare metallic salts thereof, the alkyldibenzothiophene sulfonic acid, as prepared above is dissolved in a suitable solvent, such as a refined petroleum oil, and the solution of sulfonic acid is converted to the desired metal salt by simple neutralization thereof with a metal hydroxide, carbonate or other alkaline inorganic salt of the metal. Alternatively, synthesis of the desired metal salt may be accomplished by metathesis of an alkali metal sulfonate prepared by one of the above mentioned methodswith an inorganic halide of the desired metal.

The temperature at which the metal salt of alkyldibenzothiophene sulfonic-acid is prepared will generally be in therange of from about 50 C. to about 200 C. and preferably between about 85 C. and about 150 C. -The reaction mixture is maintained at an elevated temperature in the above range until all of the water of reaction is removed. During this operation, it is desirable but not necessary to bubble an inert dry gas such as nitrogen through the mixture in order to hasten the removal of said water. The resulting mixture is then suitably filtered through a clarifying agent, such as .a filtering clay, to yield a petroleum oil solution of a metal alkyldibenzothiophene sulfonate.

The above described procedure may be employed in synthesizing any of the metal salts having the general formula:

. soar drogen atom or an alkyl radical in the paraffin wax having a chain ofto 30 carbon atoms.

The metal alkyldibenzothiophene sulfonates .described above have been found to be particularly useful in lubricating compositions where they behave as detergents in maintaining the cleanliness of an engine.

These materials may be incorporated in any lubricating composition ranging from gasoline and kerosene to heavy gear oil, petroleum wax, and petrolatum. They may also be used with similar lubricating compositions derived from other animal, mineral, or vegetable sources, or prepared synthetically. Such lubricating compositions may contain any other desired addition agent or combination of addition agents which may be added for the purpose of effecting the same improvement or other improvements in that composition. Ordinarily, the new compositions described above will be added to mineral oil fractions in amounts ranging from about 0.1 to about 5 per cent but may be added in amounts.- up to 10 per cent in some instances. Those; of,- the new products which are sufiiciently soluble in oil may be marketed in the form of oil concentrates, in which the percentage of the new products is greatly in excess of that which is desired in the finallubricating composition, for example, quantities up to about 50-per cent by weight.

Further details and advantages of this invention will be apparent from the following illustra'-' tive examples: 5:

Example 1 H Petroleum wax of A. S. T.' M. melting point of 125 F. was chlorinated by introducing chlorine gas at about F. until 12 per cent by weight of chlorine was adsorbed therein. 596.6 parts by weight of the chlorowax so obtained were slowly added to a mixture of 184 parts by weight of dibenzothiophene, 596.6 parts'by weight of Stoddard solvent, and 30 parts by weight of anhydrous aluminum chloride maintained at a temperature of 60C. The temperature was allowed togradually rise during the addition of the chlorowax to 75-85 C., in which range it was held during the alkylation. The mixture was agitated for aperiod of 4 hours in this temperature range; after which time the'active evolution of hydrogen chloride had practically ceased. To the cooled alkylation mixture; 500 volumes of 20 per cent aqueous hydrochloric acid were slowly added and the resulting'mixture was heated to a temperature of 100 C. to hasten the separation of the mixture into' organic and aqueous layersi' After said separation was efiected', the mixture was cooled and the aqueous. layer was drawn off and discarded. The remaining organic Iayer Was washed with water, filtered, and the-solvent distilled off under vacuum. x-Ihe dark green residue consisted of 706 parts by weight-of? a diwaxdibenzothiophene having a sulfur-content of 4.1 per cent, the calculated sulfur content being'4'.0

percent. 1 e l I Two hundred parts by Weight. of the diwaxdi benzothiophene as prepared above. were dissolved in 400 volumes of chloroform. Forty-one and two tenths parts by weight ofxchlorosulfonic'acid were addedd'ropwise to the, resulting solution at room temperature. When the-addition of sulfonating agent was complete,.the mixture washeatedunder reflux for a periodof 2 :hours to complete the reaction. The chloroform was their recovered by distillation and .theiresidue was identified: gasa .diwaxdibnzothiophene sulfonic acid having a neutralization number of :81, the theoretical neutralization number lbeing 82.

. Example 2' The diwaxdibenzothiophene sulfonic acid as prepared in Example 1 was diluted 'with 400 parts by weight of an SAE 30 grade solvent-refined petroleum oiland 9'7 parts by weight of barium hydroxide octahydrate were added. The result ing' mixture was held at a temperature-of 85 C; for a'period of 1 hour, raised gradually to 100 C. for 1 hour and finally increased to 150 C.. where it was held until all of the water in the reaction mixture had been removed. This required maintaining the reaction mixture at the temperature of 150 C. for an additional hour. Duringthis operation -a steady stream of -dry. nitrogen gas was passed "through the mixture inorder to facilitate the removal of the water. The resulting hot oilsolution was then filtered through Hi-Flo (a clay of the activated montmorillonite 'typ represented'by the ideal formula: 7 Ahsnomornz nmo wherein n is an integer). The filtrate obtained from said filtration consisted of a petroleum oil solution of barium diwaxdibenzothiophene sul-' fonate having a barium content of 4.1 per cent and a sulfur content of 2.6 per cent.

Example 3 The diwaxdibenzothiophene sulfonic acid prepared as in Example 1 was reacted with magnesium hydroxide, in the same manner as described Example 4 A mixture consisting of 230 grams of a diwaxdibenzothiophene sulfonic acid, 23 grams of sodium hydroxide dissolved in 200 c. c. of methanol and 400 grams of a solvent-refined SAE 30 grade motor oil was heated under reflux with efiicient stirring for 2 hours. The methanol and water of reaction were then removed by distillation with a steady stream of dry nitrogen gas passing through the mixture until the temperature reached 150 C. Final traces of methanol and water were removed by maintaining the temperature of the mixture at 150 C. with a current of dry nitrogen gas passingtherethrough. The resulting hot oil solution was passed through a filtering clay at a temperature of about 95-100 C. in order to remove unreacted sodium hydroxide and other insoluble impurities. The product so obtained consisted of 520 grams of a clear oil solution of sodium diwaxdibenzothiophene sulfonate containing 1.4 per cent sodium and 3.2 per cent sulfur.

The above described metallic salts are effective as detergents in motor lubricating oils, as is demonstrated by the following test: Blends were made in a SAE 30 grade solvent-refined motor oil containing 0.75 per cent by weight of an antioxidant additive, consisting of the reaction product of pinene and phosphorus pentasulfide similar to that described in Example 3 of U. S. Patent 2 381377., The ifollowin'g blends were prepared: A. Oil plus'0.'75 per centantioxidant. v B. 0ilp1us10.75 per cent antioxidant plus15'per cent of the 'above'described barium diwaxdibenzothiophenesulfonate. C.' Oil-plus 0.75 percent antioxidant plus 2 fp'er "enter the above described magnesium di wax'dibenz'othiophene sulfonate. D. Oil plus 0.75 per cent antioxidant plus 2'per cent of the abov described sodium"d'iwax Cleanliness Rating I l '20 Hrs. '60 Hrs. realms F Blend D 74 68 55 The above results show that the alkali and alkaline earth metal salts of diwaxdibenzothiophene sulfonic acid are effective additives in improving the characteristics of lubricating oils.

The above described lubricating compositions are, of course, merely illustrative of those contemplated by the present invention. Antioxidants other than the pinene-phosphorus pentasulfide reaction product may be used. Likewise, various other improving agents may be present in the oil blend, such as V. I. agents, pour point depressants, oiliness agents, and the like.

We claim:

1. A lubricating oil composition that comprises a mineral oil fraction and a small proportion sufficient to improve the detergent properties thereof of an alkaline earth metal salt of an alkylated dibenzothiophene sulfonic acid in which the sulfonic acid radical is attached directly to a benzene nucleus, said acid having an alkyl group of between about 20 and about 30 carbon atoms.

2. A lubricating oil composition that comprises a mineral oil fraction and a small proportion sufficient to improve the detergent properties thereof of an alkali metal salt of an alkylated dibenzothiophene sulfonic acid in which the sulfonic acid radical is attached directly to a benzene nucleus, said acid having an alkyl group of between about 20 and about 30 carbon atoms.

3. A lubricating oil composition that comprises a mineral oil fraction and a small proportion sufficient to improve the properties thereof of a compound selected from the group consisting of the alkali and alkaline earth metal salts of an alkylated dibenzothiophene sulfonic acid in which the sulfonic acid radical is attached directly to a benzene nucleus, said acid having an alkyl group of between about 20 and 30 carbon atoms.

4. A lubricating oil composition that comprises a mineral oil fraction and a small proportion sufiicient to improve the detergent properties thereof of a sodium salt of an alkylated dibenzothiophene sulfonic acid in which the sulfonic acldx'z'adlcal is attached' dirtljitd {Benzene nucleus, said acid having. ,an alkyl group of be; tween about 20 and about 30, carbn atoms; i 'i'f A lubricating oil composition that comprises a mineral oil fraction and a. small proportion sufi'icient to improve the detergent. properties thereof of -a' magnesium salt "of an alky lated dibe'nzothioph'enev sulfonic, acid inwhich'ltlie sulfonic acid radical is attached directly to, a ben- Zene nucleus, said acid having an alkyl'gr'oup of between about 20 and about 30 carbonatoms.

6. A lubricating oil composition that cornprlses a mineral'oil fraction and a small proportion suflicient to improve the detergent "properties thereof of a barium salt of an alkylated dibenzothiophene sulfonic acid in which the sulfonic' acid radical is attached directly'to a benzene nucleus; said acid having an alkyl group of between about 20 and about 30 carbon atoms. I 3

7. A lubricating oil composition thatcompr'ises a mineral oil fraction and between about-0.1 and and about 5 per cent by weight of a compoundslected from the group consisting of the alkali and alkaline earth metal salts of an alkylated dibenzothiophene sulfonic acid in which the sulfonic acid radical is attached directly to a benbetween about REFERENCES CITED The following references are of record in th file of'this patent:

' UNITED STATES PATENTS Number Name Date 1,471,150 Dziewonski Oct. 16, 1923 1,996,334 Hessle Apr. 2, 19 2,160,293 Shoemaker May 30, 1989 2,361,805 Wilson Oct. 31, 1944 McNab Apr. 15, 1947 Certificate of Correction Patent No. 2,527,334 October 24, 1950 FREDERICK P. RICHTER ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 64, before the Word properties insert detergent;

and that the said Letters Patent should be read as corrected "above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 8th day of May, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant C'ommz'ssz'oner of Patents.

Claims (1)

1. 6. A LUBRICATING OIL COMPOSITION THAT COMPRISES A MINERAL OIL FRACTION AND A SMALL PROPORTION SUFFICIENT TO IMPROVE THE DETERGENT PROPERTIES THEREOF OF A BARIUM SALT OF AN ALKYLATED DIBENZOTHIOPHENE SULFONIC ACID IN WHICH THE SULFONIC ACID RADICAL IS ATTACHED DIRECTLY TO A BENZENE NUCLEUS SAID ACID HAVING AN ALKYL GROUP OF BETWEEN ABOUT 20 AND ABOUT 30 CARBON ATOMS.