US2527335A - Alkyl dibenzothiophene sulfonic acid - Google Patents

Description

Patented Oct. 24, 1950 2,527,335

Frederick P. Richter and Everett W. Full'cr, Woodbury, N. J., assignors to Socony-Vacuum Oil Company, Incorporated, a corporation'of New York I No Drawing. Original application June 24, 1947," Serial No. 756,812. Divided and this application August 20, 1948, Serial No. 45,426

. V l I This invention relates to alkylated dibenzothiophene sulfonic 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 sufficient to improve the properties thereof of one 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 alkyl halide in the presence of a Friedel-Crafts type catalyst to produce alkylated dibenzothiophenes.

'It has further been discovered that the alkyl dibenzothiophene produced as described above can be sulfonated by contact with a suitable sulfonating agent, such as chlorosulfonic acid, concentrated sulfuric acid, oleumfand the-like.

Still further, ithas been discovered that metal salts of the alkylated dibenzothiophene sulfonic acid, produced as a'result of the aforesaid reaction, can be prepared upon contacting said acid with an inorganic'salt or hydroxide of the desired metal. It'has been further found that certain of said metal salts, notably those of the alkali and the alkaline earth metals, are useful as mineral oil additives and, moreparticularly, are effective as detergents in motor lubricating oils. j

The compositions'ocf this invention are pre pared by using as a starting material substan tially pure dibenzothiophene or a crude product which contains a major proportion of dibenzo thiophene. This starting material is alkylated in accordance with the present invention by bringing the same into contact'with an alkyl halide and a Friedel-C-rafts catalyst, preferably in'the presence of an inert organic solvent such as Stoddards solvent.

The orientation of the alkyl group in dibenzothiophene has not been established with certainty. Indications are, however, that when only one hydrogen in each molecule of dibenzo thiophene is replaced by an alkyl radical, the entering alkyl group occupies. the 2- or33-position and that when two hydrogens are replaced with alkyl groups, the entering radicals occupy the 2- and 8 -positionsor the 3-. and '7-positions.

The orientation, however, does not appear to be of too great significance in'the practical syn-- thesis of oil additive compositions prepared from the dibenzothiophenes so alkylated.

.The initial ratio of alkyl halide to diben zothiophene can 'be varied over widelirnits and.

'7 Claims. 7 (01. 260329) the degree of alkylation thus controlled to yield m ono-, 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 alkyldibenzothiophene, while product is practically nil; while at temperatures above about 85 0., a tar formation becomes predominant; causing a substantial decrease in theyield of desired product. Accordingly, the temperature range of from about 20 C. to about 85 0. appears to be a critical factor in the successfulalkylation of dibenzothiophene. Particular preference is accorded to temperatures in the range of from about C. to about 0., since under these conditions the reaction was found to proceed at a faster rate, and consequently as apractical matter, to yield a greater amount of alkylated dibenzothiophene per unit time as compared with lower temperatures in the operable range. a

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 c0ndensa-.,

as-well as economical reasons, the use of alkyl' halides of hydrocarbons in the paraffin wax range having from about 20 to about 30 carbon atoms represents a preferred embodiment of this invention. Such alkyl halides having molecular weights in' excess of about 250 and having more than about 20 carbon atoms in their molecules are well known. Chlorinated wax may be 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 5 and about15 per cent chlorine.

The alkylated dibenzothiophenes described R will represent an alkyl radical in the paraflin wax range having a chain of 20 to 30 carbon atoms, and R, will likewise represent a hydrogen atom or an alkyl radical in the paraffin wax having'a chain of 20 to 30 carbon atoms.

The metal alkyldibenzothiophene sulfonates described above have been found to be particularly useful in lubricating compositions where 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 C. and about 30 C. Upon final addition of the sulfonating agent, the mixture is suit ably heated under reflux for a period to insure complete reaction. The solvent employed may then be recovered by distillation. The residue obtained from said distillation is an alkyldibenzothiophene sulfonic acid. I

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 methods with an inorganic halide of the desired metal.

The temperature at which the metal salt of alkyldibenzothiophene sulfonic acid is prepared will generally be in the range 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 where R is an alkyl radical, R is selected from the group consisting of hydrogen and an alkyl radical and M is one equivalent of a metal. More specifically, where the metal salts are intended for use as additives in petroleum oils, M will represent an alkali or an alkaline-earth metal and 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 productswhich are sufliciently soluble in oil may be marketed in the form of oil con centrates, in which the percentage of the new products is greatly in excess of that which is desired in the final lubricating composition, for example, quantities up to about per cent'by weight.

Further details and advantages of this invention will be apparent from the following illustrative examples: 7

Example 1 Petroleum wax of A. S. T. M. melting point of 125 F. was chlorinated by introducing chlorine gas at about 100 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 C. The temperature was allowed to gradually rise during the addition of the chlorowax to -85 C., in which range it was held during the alkylation. The mixtur was agitated for a period of 4 /2 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 C. to hasten the separation of the mixture into organic and aqueous layers. After said separation was -effected,'the mixture was cooled and the aqueous layer was drawn off anddiscarded. The remaining organic layer'was washed with water, filtered, and the solvent distilled off under vacuum. The 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 per cent.

Two hundred parts by weight of the diwaxdibenzothiophene as prepared above were dissolved nating'agent was complete, the mixture was amazes heated under reflux for a period 012% hours to complete the reaction. The chloroform was then recovered by distillation and the residue was identified as a diwaxdibenzothiophene'sulfonic acid having a neutralization number of 81, the theoretical neutralization number being 82.

Example 2 The diwaxdibenzothiophene sulfonic acid as prepared in Example 1 was diluted with 400parts by weight of an SAE 30 grade solvent-refined jpe troleum oil and 9''! parts by weight of barium hydroxide octahydrate were added. The resulting mixture was held vat-a temperature of 85 C. for a period of 1 hour, raised gradually to 100 C. for 1 hour and finally increased to 150 0., where it was held until all of the waterin the reaction mixture had been removed. This required maintaining the reaction mixture at the temperature of 150 C. for an additional hour. During this operation a steady stream of dry nitrogen gas was passed through the mixturein order to facilitate the removal of the water. The resulting hot oil solution was then filtered through Hi-Flo (a clay of the activated montmorillonite type represented by the ideal formula:

wherein n is an integer). The filtrate obtained from said filtration consisted of a petroleum oil solution of barium diwaxdibenzothiophene sulfonate 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 l was reacted with magnesium hydroxide, in the same manner as described under Example 2, for the preparation of the barium salt. The resulting product was an oil solution of the magnesium salt of diwaxdibenzothiophene sulfonic acid. It analyzed to give 1.1 per cent magnesium, the calculated magnesium content being 1.0 per cent.

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 eflicient 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 passing therethrough. 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 2,381,377. *The following blends were prepared:

A. Oil plus 0.75 per cent antoxidant.

B. Oil plus 0.75 per cent antioxidant plus 5 per cent of the above described barium diwaxdibenzothiophene sulfonate.

C. Oil plus 0.75 per cent antioxidant plus 2 per cent of the above described magnesium "diwax- (libenzo'thi'ophene' sulfonate. V a

D. Oil plusl).'75 per cent antioxidant plus 2 per c'ent'of the above described sodium diwaxdi- .benzothiophene sulfonate.

Cleanliness Rating 20 60 Hrs. Hrs. Hrs.

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.

This application is a division of our copending application, Serial No. 756,812, filed June 24, 1947.

We claim:

1. As a new composition of matter, an alkyl dibenzothiophene sulfonic acid.

2. As a new composition of matter, a compound having the general formula:

where R is an alkyl radical, R is selected from the group consisting of hydrogen and analkyl radical and M is a metal.

3. As a new composition of matter, a compound having the general formula:

RLUU R where R. is an alkyl radical, R is selected from the group consisting of hydrogen and an alkyl radical and M is a metal selected from the group consisting of the alkali and alkaline earth metals.

where R. and R are alkylrradicals having between about 2 0 and about 30 carbon atoms. I

6; As anew composition of matter, a .compound having th'general formula:

where R and R are alkyl radicals having between about 20 and about carbon atoms. 7. As a new composition of matter, a compoun having the general formula:

era

where R and R are alkyl radicals having between about 20 and about 30 carbon atoms.

'FREDERICK P. RICHTER. I

EVERETT W. FULLER. 7

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES-PATENTS I Number Name "Date 2,438,955 Tryon Apr. 6, 1948

Claims (1)

1. AS A NEW COMPOSITION OF MATTER, AN ALKYL DIBENZOTHIOPHENE SULFONIC ACID.