US2769836A - Process for preparing oil-soluble sulfonic acids - Google Patents

Description

United States Patent PROCESS FOR PREPARING OIL-SOLUBLE SULFONIC ACIDS Everett E. Gilbert, Flushing, and Benjamin Veldhuis, Al-

bertson, N. Y., assignors to Allied Chemical & Dye Corpioration, New York, N. Y., a corporation of New Yor No Drawing. Application March 18, 1953, Serial No. 343,228

9 Claims. (Cl. 260504) This invention relates to a process for preparing oilsoluble sulfonic acids and more particularly to a process for preparing such acids from hitherto substantially valueless waste materials.

Oil-soluble sulfonic acids are useful in the preparation of rust-proofing formulations, as emulsifiers, as diesel engine lubricant additives and the like, and the demand for such oil-soluble sulfonic acids and sulfonates has increased steadily in recent years.

Oil-soluble sulfonic acids have been prepared in the past as byproducts in processes for the production of mineral white oils. In certain of these processes, an appropriate distillate or residual fraction of an aromaticcontaining petroleum oil is first purified by a light sulfuric acid treatment or by solvent extraction by conventional methods using such solvents as nitrobenzene, liquid sulfur dioxide, furfural, dichlorodiethylether, phenol, etc. The purified fraction so obtained is then sulfonated in one or more steps or dumps using 20% oleum, sulfur trioxide or other appropriate sulfonating agent. This process sulfonates the aromatic and unsaturated constituents of the oil fraction. Upon settling, the acid-oil mixture stratifies into two layers, one containing residual sulfuric acid together with sludge and green acids, i. e., Water-soluble hydrocarbon sulfonic acids, the other layer comprising oil containing dissolved oil-soluble sulfonic acids. The oilsoluble sulfonic acids are usually extracted from the oil layer with solvents such as alcohols. The yield of oil soluble sulfonic acids obtained by this process is extremely low, usually from about to about 10% based on the weight of the raifinate sulfonated.

As the demand for the oil-soluble sulfonic acids increased beyond the small quantity available as a by-prodnot in the production of mineral white oils as described above, additional quantities of sulfonates were produced as primary products of these petroleum oils without the concomitant formation of white oil.

It has long been recognized that the solvent extracts obtained in refining various petroleum fractions using nitrobenzene, liquid sulfur dioxide, furfural, dichlorodiethylether, etc., might be source materials for sulfonic acids, since they were known to contain high percentages of aromatic hydrocarbons. Various types of extracts have been available varying in characteristics with the character of the oil purified. These included extracts from the manufacture of kerosene, light lubricating oils, heavy lubricating oils, residual lubricants (bright stocks) etc. The extracts obtained in the above operations differ widely in viscosity, molecular weight, boiling range, and other physical properties.

Extracts obtained by solvent extraction from light distillates and low viscosity lubricating oil stocks have found use in the preparation of hydrocarbon sulfonic acids and sulfonates which are water-soluble and which possess surface-active properties which render them useful as detergents.

Processes for utilizing extracts from solvent refining of intermediate viscosity lubricating oil stocks, for example, stocks having viscosities up to about seconds Saybolt Universal viscosity (SUS), at 210 F. have been proposed for the preparation of oil-soluble sulfonic acids. Such procedures involve step-wise sulfonation of such intermediate viscosity extracts, with removal of sludge between steps, or the preparation of distillates or extracts of such extracts and sulfcnation of the raflinates from these operations to produce oil-soluble sulfonic acids or mixtures of oil and water-soluble sulfonic acids. These processes have not proven practical due to excessive sludge formation, poo-r yields of desired oil-soluble product, high labor costs due to the plurality of steps involved and the extra costs involved in refining the extract before sulfonation.

Attempts to utilize the extremely high viscosity extracts, i. e., those having viscosities as high as about SUS at 210 F., have taken a direction similar to that utilized in treating the medium viscosity extracts, but without even the partial success achieved with the medium viscosity extracts, since such operations fail to reduce sludge formation on sulfonation sufliciently to make such sulfonations commercially practicable.

We have now found that oil-soluble sulfonic acids suitable for use in the preparation of lubricant additives, rustproofing compositions, emulsifiers for agricultural sprays, ingredients of cutting oils, as fat-splitting agents and the like, may be prepared with minimal sludge formation by direct, single-step sulfonation with sulfur trioxide gas, in the presence of an inert liquid chlorinated hydrocarbon or nitrated aromatic hydrocarbon, of crude high viscosity aromatic-containing petroleum extracts having Saybolt Universal viscosities (SUS) at 210 F. of at least about 100 seconds.

Thus, in accordance with our process, crude extracts of the character described may readily be sulfonated with formation of minimal quantities of sludge varying from virtually none to minor amounts which in no Way interfere mechanically with the operation of the process in such respects as agitation, pumping, etc. The absence of sludge formation in sulfonations with sulfur trioxide of extracts of this character is quite unexpected, as sulfonation of even much lower viscosity extracts using S03 has heretofore been found to result in the formation of completely intractable sludges.

In carrying out the process according to our invention, suitable extracts are selected having the specified high viscosity, for example, heavy neutral extracts and bright stock extracts resulting from the solvent refining of heavy lubricating oil stocks and the like with the usual refining solvents such as, for example, liquid sulfur dioxide, nitrobenzene, furfural, dichloro-diethylether, phenol, etc.

The viscous extract is mixed with a suitable inert liquid selected, as specified hereinafter, not only for its ability to reduce the viscosity of the resulting mixture of extract and liquid to a sufficiently fluid state to permit ready agitation at the sulfonation temperatures, but also for its ability to homogenize all the components of the extract and substantially to inhibit separation of the sludge com,- ponents as well as to dissolve the unreacted sulfonatable hydrocarbons and their resulting sulfonation products. The extract-inert liquid mixture is then subjectedv to sulfonation with sulfur trioxide gas used either alone, or

Patented Nov. 6, 1956 preferably, diluted with an inert gas such as nitrogen or air, until the sulfonation reaction is complete. The oilsoluble sulfonic acids thus produced may then be recovered by any suitable means, for example, by volatilizing the inert liquid in the presence of steam. The residue may then be mixed with a water immiscible solvent for the oil-soluble sulfonic acids, such .as petroleum ether, and, if desired, additional water is added whereupon the mixture stratifies into an oil layer, containing the 'oilsoluble sulfonic acids and a water layer.

We have found that in general, yields of oil-soluble sulfonic acids will amount to between about 30% .and about 70% based on the weight of the extract sulfonated, using extracts of the character specified.

Our process is adapted for carrying out sulfonation of the crude high viscosity extracts of virgin heavy lubrieating oil stocks, utilizing the total of such extracts without prior treatment or purification thereof either by distillation, extraction, sludge removal or other treatment. Our process is adapted to utilize extracts of this character having viscosities of at least about 100 SUS at 210 F. and is particularly adapted for the sulfonation of extremely high viscosity extracts having viscosities up to 3500 SUS at 210 F. or higher and in general stocks having viscosities between about 150 and about 500 SUS at 210 F. are preferred.

The inert organic liquids which may be used as a medium for carrying out the sulfonation reaction may be any nitro or chloro aromatic or chloro aliphatic hydroor halohydro-carbons which are liquids at the sulfonation temperatures and especially those having from 1 to 5 carbon atoms inclusive and from 1 to 4 chlorine atoms. Illustrative of such suitable organic liquids are nitrobenzene, monochlorobenzene, nitrotoluene, orthodichlorobenzene, ethylenedichloride (1,2-dichloroethane), 1,1-dichloroethane, l,l,2,2 tetrachloroethane, 1,1,1 trich'loroethane, tetrachloroethylene (1,1,2,2-tetrachloroethene), methylene chloride (dichloromethane), chloroform, carbon tetrachloride, trichloromonofiuoromethane, 1,2-dichloropropane, l-chlorobutane, the mono and dichloropentanes, liquid mixtures of chlorinated naphthalenes, and-mixtures of "any of the above.

If the original extraction liquid was one of the suitable sulfonation liquids named above, it need not be removed from the extract, but may be used as the sulfonation liquid, supplemented, if necessary, with additional quantities of the same or a difierent liquid of the character described. Since nitrobenzene is commonly used as an extractant for heavy lubricating oils to produce extracts of a character utilizable in our process, this liquid is one of our preferred sulfonation liquids in such cases. Another especially valuable sulfonation liquid is ethylene dichloride because of its cheapness and its favorable boiling point (83.5 C.) which is high enough to prevent undue losses by volatilization and yet low enough to be very readily removable, as by steam distillation, after completion of the sulfonation reaction.

The quantity of inert liquid used is not critical but should be suflicient to bring the viscosity of the resulting mixture to a suitably low level to permit easy agitation and to dissolve or homogenize the hard sludge which forms upon sulfonation of the extracts. As small a quantity as will suffice for these two purposes is preferably used, as the inert liquid must be removed for final recovery of the sulfonic acids.

Difierent quantities of the different liquids will be needed, depending on the sludge forming character of the extract material to be sulfonated. In general, quantities of liquid equal to at least about by weight based on the weight of the extract, preferably quantities between about 50% and about 150% on the same basis are used. For certain extracts which yield unusually heavy sludges on sulfonation, somewhat larger proportions of liquid diluent may be necessary for example up to about 500% based on the weight of the extract. Such dilutions produce reaction media which maintain mobilities of the general character of water or similar low viscosity liquids, during sulfonation and are virtually free from sludge.

Sulfonation is carried out by sulfur trioxide gas, which may be obtained from any suitable source, for example, as sulfuric acid plant converter gas, stripped from oleum, or vaporized from stabilized liquid sulfur trioxide (Sulfan). The S03 gas may be used alone, but preferably should be diluted with inert gas such as nitrogen or air to reduce charring and decomposition.

Sulfonation temperatures may vary over a wide range, but preferably should be maintained between about 10 C. and about C.

The time required to complete the sulfonation reaction in batch operations will vary somewhat with the fluidity of the reaction mixture, the strength of the S03 gas stream, and the intimacy of contact of the $03 with the sulfonatable components of the extract. In any event, sulfonation is quite rapid and, with adequate agitation, will usually be complete in a period between about 5 minutes and about 70 minutes. In continuous operation, residence times required will be even smaller.

Recovery of the resulting oil-soluble sulfonic acids may be effected in any suitable manner, for example, by removal of the inert liquid as by volatilization, followed by extraction of the residue with a water-immiscible solvent for the sulfonic acids, aided, if desired, by prior addition of water or steam to cause separation of the crude material into water and oil layers and recovery of oil-soluble sulfonic acids from the oil layer. When the sulfonation mass contains inert liquids which have relatively low boiling points, steam distillation provides a convenient method for volatilizing the inert liquid, and leaves suffi'cient quantity of water in the residue to form a layer containing the water-soluble impurities upon addition of a water-immiscible solvent for the oil-soluble sulfonic acids.

The sulfonic acids are readily converted to their salts such as the alkali metal, alkaline earth metal and other metallic salts, and are useful in these salt forms for many purposes. The alkaline earth metal salts, especially the barium and calcium salts are useful as lubricating oil additives, in rust-proofing compositions etc. The alkali metal salts, such as the sodium salts are often prepared as an intermediate step to the preparation of other metallic salts, and may be merchandised in such form. Our invention therefore contemplates the metallic salts of the sulfonic acids as well as the acids themselves.

The following specific examples will further illustrate the invention. Parts are by weight except as otherwise noted.

Example 1 491 parts of an extract having a 338 SUS viscosity at 210 F., and molecular weight of 490, obtained by furfural extraction of a propane deasphalted mid-continent vacuum residuum, was placed in a reaction vessel equipped for agitation, and 250 parts of nitrobenzene were added thereto yielding a homogeneous solution with the extract. Sulfur trioxide vapor diluted with dry air to form a mixture containing approximately 35% by volume of S03 was introduced into the mixture during a period of 15 minutes at a temperature ranging from 42 C. to 53 C., using an external cooling bath, until 70 parts by weight of S03 had been added. The mixture remained homogeneous throughout the reaction period, and agitation was in no way impeded by the development of sludge or high viscosity. The sulfonated mixture was freed from nitrobenzene by steam distillation and the resulting mixture was found to contain oil-soluble sulfonic acids equal to a 49% yield, based on sulfur trioxide used, or 51% based on the crude extract, as calculated on the basis of the molecular weight of the crude given above, and of'the sodium salt as 592.

The sulfonic acids were extracted from the mixture with petroleum ether, to which was then added 150 parts each of water and isopropyl alcohol. This solution was neutralized with solid barium hydroxide, and vacuum dried to produce the barium salt of the sulfonic acids.

Example 2 1000 parts of an extract, having a 111 SUS viscosity at 210 F. (obtained by furfural extraction of a raw vacuum-distilled heavy neutral lubricant fraction of midcontinent origin and having a SUS at 210 F. of 60) was placed in a reaction vessel equipped for agitation, and 600 parts of ethylene dichloride added thereto yielding a homogeneous solution with the extract. Sulfur trioxide vapor diluted with dry air was introduced into the mixture during a period of 16 minutes at a temperature ranging from 33 C. to 42 C., using an external cooling bath, until 100 parts by weight of S03 had been added. The mixture remained homogeneous throughout the reaction period, and agitation was in no way impeded by the development of sludge or high viscosity. After removal of the ethylene dichloride by steaming, the mixture was treated with petroleum ether, yielding an oil layer and a water layer. The oil layer was titrated and found to contain 50% of oil-soluble sulfonic acids based on sulfur trioxide used, according to the equation The sulfonic acids were then converted to their sodium salts by diluting the oil layer with 150 parts each of water and isopropyl alcohol, and neutralizing the mixture with caustic soda solution. The mixture was then vacuum dried, the sodium salts isolated in a yield of 29% by weight based on the original extract.

Examples 3 to 8 Additional tests were carried out according to the procedure described in Examples 1 and 2. The quantities and character of the extracts and the inert sulfonation liquids, together with the results obtained, are listed in Table I below which also includes the data of Examples 1 and 2. In Example 3, ethylene dichloride was used as the extractant for the oil-soluble sulfonate. In no case was any difiiculty experienced with sludge during the sul- Examples 1 0-22 Example No.

Insert Liquid Nitrotoluene.

1,1-dichloroethane. 1,1,2,2-tetrachloroethane. 1,1,1-trichloroethaue.

tetrachloroethylene (1,1,2,2-tetrachloroethene) methylene chloride (dichloromethane). chloroform (trichloromethane) carbontetrachloride (tetrachloromethane) trichloromonofluoromethane. 1,1-diehloropropane.

l-chlorobutane.

secondary amyl chloride (2-chloro-pentane). amylene dichloride (dichloropentane).

In all cases the mixtures remained homogeneous and fluid throughout the sulfonation reaction period, and agitation was in no way impeded by development of sludge or high viscosity.

While the above describes the preferred embodiments of the invention it will be understood that departures may be made therefrom within the scope of the specification and claims.

We claim:

1. A process for preparing oil-soluble sulfonic acids which comprises contacting with sulfur trioxide gas, in a single step, as temperatures between about 10 C. and about 70 C., an aromatic petroleum extract having a Saybolt Universal viscosity at 210 F. of at least about 100 seconds, in the presence of at least about 25% by weight of an inert liquid selected from the group consisting of chloroalkanes, chlorofiuoroalkanes, chlorinated mononuclear and binuclear aromatic hydrocarbons, and nitromononuclear aromatic hydrocarbons whereby a sulfonation product free from troublesome sludge is obtained.

2. The process of claim 1 wherein the extract is a crude extract resulting from the solvent refining of a virgin heavy lubricating oil stock.

fonatlon. 3. The process of claim 2 wherein the extract has a TABLE I Extract Solvent Example Sulfur Temp. Time Yield Number Trioxide (C.) (Min.) (Per- YP SUS at ype (Parts) (Parts) cent) 210 F. (Parts) 1 Mid-Continent Bright Stock... 338 491 Nitrobeuzene 250 70 42-53 15 49 2 Mid-Continent Heavy Neutral- 111 1000 Ethylene Dichloride 600 100 33-42 16 50 3. West Coast... 450 491 Nitrobeuzeue 200 89 40-67 17 35 4. ..-..d0 450 354 Ethylene Diehlonde 310 63 3255 13 46 5. Mid-Continent B ht Stoc 3, 300 496 Nltrobeuzene 234 80 3654 15 45 6. d0 3, 300 476 Ethylene Dichlorrde 307 80 26-55 17 38 7 Mid-Continent Heavy Neutral. 148 506 Nitrobeuzene 229 80 33-46 22 68 8 do 148 404 Chlorobenzene 305 64 33-50 12 48 Example 9.C0nversi0n of oil-soluble sulfonic acids to sodium salts 955 parts of the petroleum ether layer, containing oilsoluble sulfonic acids prepared according to Example 7 was neutralized with 187 parts of a 10% aqueous caustic soda solution in the presence of 150 parts of isopropyl alcohol. The resulting solution was freed of petroleum ether, isopropanol and water by heating in vacuo on a water bath to constant weight (425 parts). The final product sodium sulfonate dissolved readily in petroleum oils and in organic solvents such as xylene. The yield amounted to 54% as sodium sulfonates, based on the weight of the original extract as calculated from its molecular weight of 406.

Saybolt Universal viscosity at 210 F. of between about seconds and about 3500 seconds.

4. The process of claim 2 wherein the inert liquid is selected from the group consisting of nitro and chloro mononuclear aromatic hydrocarbons.

5. The process of claim 2 wherein the inert liquid is a chlorinated aliphatic hydrocarbon having from 1 to 5 carbon atoms inclusive and from 1 to 4 chlorine atoms.

6. The process of claim 2 wherein the inert liquid is nitrobenzene.

7. The process of claim 2 wherein the inert liquid is ethylene dichloride.

8. The process of claim 2 wherein the inert liquid is monochlorobenzene.

aveasse 9. A process for preparing oil-soluble sulfonic acids which comprises contacting with sulfur trioxide gas in a single step, at temperatures between about 10 C. and about 70 C. a crude aromatic petroleum extract resulting from the solvent refining of a virgin heavy lubricating oil stock, having a Saybolt Universal viscosity at 21-0 F. between about 100 seconds and about 3500 seconds, in the presence of between about 25% and about 500% by weight of an inert liquid selected from the group consisting of nitro and chloro mononuclear aromatic hydrocarbons and chloroalkanes whereby a sulfonation product free from troublesome sludge is obtained.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. A PROCESS FOR PREPARING OIL-SOLUBLE SULFONIC ACIDS WHICH COMPRISES CONTACTING WITH SULFUR TRIOXIDE GAS, IN A SINGLE STEP, AS TEMPERATURES BETWEEN ABOUT 10* C. AND ABOUT 70* C., AN AROMATIC PETROLEUM EXTRACT HAVING A SAYBOLT UNIVERSAL VISCOSITY AT 210* F. OF AT LEAST ABOUT 100 SECONDS, IN THE PRESENCE OF AT LEAST ABOUT 25% BY WEIGHT OF AN INERT LIQUID SELECTED FROM THE GROUP CONSISTING OF CHLOROALKANES, CHLOROFLUOROALKANES, CHLORINATED MONONUCLEAR AND BINUCLEAR AROMATIC HYDROCARBONS, AND NITROMONONUCLEAR AROMATIC HYDROCARBONS WHEREBY A SULFONATION PRODUCT FREE FROM TROUBLESOME SLUDGE IS OBTAINED.