US3007868A - Light-color, oil-soluble alkaline earth metal sulfonates - Google Patents

Description

3,007,868 Patented Nov. 7, 1961 nice 3,007,868 LIGHT-COLOR, OIL-SOLUBLE ALKALINE EARTH METAL SULFONATES Marshall B. Eck, Media, and Ralph I. Gottshall, Roslyn, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed May 19, 1959, Ser. No. 814,348 19 Claims. (Cl. 25233) This invention relates to light-color, fully oil-soluble, substantially water-insoluble alkaline earth metal sulfonates and their production. More particularly, the invention relates to light-color alkaline earth metal sulfonates that are suitable for use as lubricating oil additives.

Light-color alkaline earth metal sulfonates, obtained without bleaching, and without metathesis, and that are fully compatible with lubricating oil stocks, including high viscosity index lubricating oil stocks, have long been desired in concentrated form for use as lubricant additives. As is known, oil-soluble sulfonates have valuable detergent, rust inhibiting and other properties, when employed in compounded lubricants. The oil-soluble alkaline earth metal sulfonates heretofore produced without bleaching and without metathesis have been substantially darker than many lubricating oil stocks used in the preparation of compounded lubricants. Such sulfonates therefore have tended to impart an unduly dark color to lubricating oils compounded therewith. The dark color of sulfonates of this general class produced by previously known methods is due primarily to the products, such as sulfates, sulfones and the like, of side-reactions during the sulfonaticn procms. These side-products ordinarily have a deleterious effect on the performance characteristics of the sulfonic acid salts. Light-color sulfonates are therefore desired not only for their superior appearance, but also because of the general correlation between color and quality.

Light-color sulfonates obtained without bleaching are normally superior to those obtained by bleaching because of the tendency of the latter to darken on standing, and because in many cases the bleaching process does not remove the dark-color impurities but merely masks them. Moreover, the use of some bleaching agents is disadvantageous in that such use involves introducing foreign materials into the sulfonates, which materials are difiicult to remove completely and which adversely affect the performance characteristics of the sulfonates and the lubricants in which they are employed.

In addition to avoiding bleaching, it is desirable to produce alkaline earth metal sulfonates directly without the necessity of metathesis of inorganic alkaline earth metal salts with other sulfonates. Where alkaline earth metal sulfonates are prepared by metathesis, for example, with alkali metal sulfonates, the metathesis reaction does not proceed to completion, and unreacted alkali metal sulfonates are present in the final product. These materials possess substantial afiinity for water and lead to difiiculties due to hazing, foaming, emulsibility, insufiicient oil-solubility and the like. Moreover, the use of the metathesis procedure instead of direct neutralization normally results in the presence of appreciable amounts of inorganic salts, for example, halides, in the final sulfonate product which salts are objectionable in lubricating oils.

The production of directly neutralized, unbleached,

light-color, fully oil-soluble alkaline earth sulfonates presents especially difiicult problems. For example,

reasonably light-color alkali metal sulfonates can be prepared by direct neutralization of a dark-color sulfonated or sour oil with an alkali metal base, and by selectively extracting the thus-produced sulfonates from the dark-color neutralized oil with a suitable solvent. Light-color alkaline earth metal sulfonates cannot be produced in this fashion, since these sulfonates cannot be selectively extracted from oil. Moreover, the sulfonates described herein are to be sharply distinguished from the low molecular weight, water-soluble sulfonates of the type used as cleansing detergents, which can be produced in very light colors with little special care. The difficulty in producing light-color sulfonates, free from deleterious, dark-color impurities, increases rapidly with increasing molecular weight.

For purposes of lubricating oil manufacture it is important that the ASTM Union color of the sulfonate addition agents be sufficiently light in color that, when diluted to a concentration suitable for addition to the oil, their color will not exceed about 3.5, and preferably about 3.0, so as to the usable in a wide variety of lubricating oils, including very light-color, high viscosity index stocks, without discoloring the same.

We have found that fully oil-soluble, unusually lightcolor alkaline earth metal sulfonates can be produced in concentrated form without the use of a bleaching agent and by direct neutralization without metathesis by the novel process disclosed herein. In accordance with the process of our invention a sulfur trioxide-containing sulfonating agent is admixed with a sulfonatable hydrocarbon material that has a relatively homogeneous composition and an ASTM Union color of no more than about 3, said sulfonatable hydrocarbon material being selected from the group consisting of (a) alkylbenzenes that contain at least 30 carbon atoms and that have at least one unsubstituted carbon atom in the aromatic nucleus, and (b) petroleum distillate oils that have an average molecular weight of about 275 to about 450, a viscosity of about 50 to 250 S.U.S. at F., a viscosity index of at least about 85, a Conradson carbon residue of no more than 0.05, and that are relatively free from predominantly aromatic constituents. The proportions of the sulfonating agent and the sulfonatable hydrocarbon material are such that the mol ratio of the sulfur trioxide and the sulfonatable portion of the hydrocarbon material is greater than 1:1 and sutficient to maintain the reaction mixture in anhydrous condition. The admixing of the sulfonating agent and the hydrocarbon material is effected at a rate not much greater than that at which the sulfur trioxide is removed from the reaction and such that the over-all temperature of the reaction mixture is maintained between 65 F. and F. Exceptionally good results from the standpoint of color and product performance are obtained when the sulfonation temperature is maintained in the range of 65 F. to 83 F. Without substantial lapse of time thereafter, acid sludge is separated from the sulfonated oil, the total time lapse from the completion of the admixing of sulfonating agent and the hydro carbon material to the separation of acid sludge from sour oil not exceeding about one hour. Sulfonic acids are then separated from the sulfonated sour oil by admixing the latter with an oil-immiscible, selective solvent for oil-soluble sulfonic acids, and separating the solvent phase from the oil phase. The separated sulfonic acids are quickly neutralized with a basic, inorganic alkaline earth metal compound. Fully oil-soluble, light-color =alkaline earth metal sulfonates are recovered from the neutralized sulfonates by dissolving them in an organic, oilmiscible, essentially nonpolar, selective solvent therefor. The present invention includes the foregoing procedure, subcombinations thereof and the light-color sulfonates produced by such procedures.

We have found the selection of the sulfonatable hydrocarbon material to be of great importance in this invention. The hydrocarbon material should have a relatively high average molecular weight and an ASTM ing oil stocks.

Union color of no more than about 3.0 in order to insure a good yield of light-color sulfonates that will be fully' compatible when added to high viscosity index lubricat- However, the average molecular weight of the hydrocarbon materialshould not be too great as poor yields and less effective sulfonates will result. Nor should the average molecular weights referred to reflect too broad a range of extremes, as the presence of substantial proportions of relatively low molecular weight constituents will ordinarily lead to compatibility and emulsibility difficulties when the sulfonates are blended with lubricating oil stocks. Best results will therefore be obtained when the material is substantially homogeneous in molecular composition, i.e., when the major proportion of the components possesses molecular weights within 100, preferably within 50, of the average. A light color in the sulfonatable material is important, since the ultimate sulfonate will be no lighter than the sulfonatable stock.

We have found that natural sultonates, that is, those produced from naturally occuring hydrocarbons, selected as described herein, produce especially outstanding sulfonates, particularly from the compatibility standpoint. A limited selection of synthetic oils can also be used, but sulfonates obtained from natural oils are usually markedly superior as lubricating oil additives.

Light lubricating oil distillates of certain carefully selected kinds contain suitable sulfonatable hydrocarbons for the purposes of this invention. The exact nature of such distillates is of utmost importance to this invention. In general, the chemical composition of suitable lubricating distillates will reflect high paraflinic and naphthenic hydrocarbon content and relatively low aromatic hydrocarbon content. Good results are obtained when the ratio of paraffinic and nap-hthenic components to aromatic components is between about to l and about to 1. However, aside from the over-all type of compounds present in such oils, the nature of the individual hydrocarbon molecules present in the oils is also important. We have found that in order to produce alkaline earth metal sulfonates that are fully compatible with lubricating oils including high viscosity index oils, the lubricating distillates must be composed principally of hydrocarbon molecules of the kind that exhibit a high viscosity index and a low carbon residue. Insofar as the aromatic molecules contained in the oil are concerned, such molecules will be of a type that are preferentially soluble (in the presence of conventional solvents for aromatics in lubricating oils) in thehigh viscosity index paraffinic and naphthenic components. These aromatic molecules are believed to be those having large aliphatic substituent groups and small aromatic rings, that is, those in which the aliphatic characteristics are predominant. Lubricating oils having the desired characteristics can be derived from paraflinic or Pennsylvania type crude oils, and from mixed base or Mid-Continent-type crudes. cating distillates derived from Coastal or asphaltic type crudes possess too great a concentration of low viscosity index materials to be of value in this invention. In this connectiomsulfonation of a lubricating distillate derived from a Coastal crude and having an average molecular weight of 405, but a viscosity index of 56, according to the procedure disclosed herein, produced'a dark-color sulfonate in relatively low yield. 7

In order to reduce to a minimum the content of predominantly aromatic hydrocarbons, that is, those in which the aromatic characteristics tend to predominate over the aliphatic characteristics, it will generally be necessary, except possibly in the case of extremely paraflinic oils, to solventtreat or acid-treat the oils, preferably the former,

. according to conventional petroleum lubricating oil refining procedure, before sulfonation of such oilsI Thus, as is known, solvent treatment of a lubricating distillate with conventional solvents, such as phenol, furfural, dichloroethyl ether, mixed solvents, such as sulfur dioxidebenzene, or double solvents, such as propane-cresylic We have found that lubriacid, tend to separate the more aromatic and asphaltic hydrocarbon components, which are characterized by a relatively low viscosity index and relatively high carbon residue, from the more paraflinic and naphthenichydrocarbon components, which are characterized by a higher viscosity index and a lower carbon residue. In the case of highly paraflinic distillates a mild acid treatment with, say, 93 percent sulfuric acid, can be used to remove the small proportion of. low viscosity index materials that are present. It will be understood that the aromatic constituents which remain in the oil after solvent treatment will be made up primarily of complex molecules wherein the preponderant or most influential portion thereof is paraffinic or naphthenic. In contrast, the aromatic constituents that are removed from the oil by solvent treatment will be made up of molecules wherein the aromatic portion constitutes the more influential portion.

Lubricating oil distillat-es that have an average molecular weight of about 275 to about 450, that have a viscosity of about 50 to 25 0 Saybolt Universal seconds at 100 F., that are relatively free from predominantly aromatic components, that have a viscosity index of at least about 85, that have an ASTM Union color of 3.0 or less, and that have a carbon residue of not more than about 0.05, preferably 0.04, and more'preferably 0.03, are suitable for the purposes of this invention. The use of distillate oils is important for two reasons. First, the use of a distillate oil, particularly one of not too bro-ad a boiling range, assures an oil having a relatively homogeneous molecular weight composition, since chemically analogous hydrocarbon components having about the same number of carbon 'atoms and the same molecular weight normally tend to boil at about the same temperature. The use of light (low viscosity) distillate oils in this invention is also important in that such oils normally contain a relatively high proportion of the higher viscosity index components. Light distillate oils having an average molecular weight of about 275 to about 450, preferably about 300 to about 420, and a viscosity of about 50 to about 250, preferably 200' to 250, Saybolt Universal seconds at 100 F., can be used to advantage. Oils having lower avenage molecular weights than 275 and lower viscosities than 50 Saybolt Universal seconds at 100 F. will ordinarily produce alkaline earth metal sulfonates that are not fully compatible with high viscosity index oils, especially in the presence of water. The use of lubricating distillates that have viscosities of more than about 250 Saybolt Universal seconds at 100 F., and higher average molecular weights than 450 is undesirable since such oils ordinarily are present only in the higher boiling cuts which, being closer in chemical composition to residual oils, contain sufficient low viscosity index, high carbon residue components, even after solvent treatment, asto render the oils unsuitable for the purposes of this invention. By way of emphasis it can be noted that when the herein disclosed procedure was employed 7 in connection with an oil having an average molecular weight of 498 and a viscosity of 403 Saybolt Universal seconds at 100 F., the yield of calcium sulfonates was 34 percent less and the'color was 100 percent darker than in the case of a calcium sulfonate produced from an oil having an average moleculargweight of 413 and a viscosityof 207 Saybolt Universal seconds at 100 F.

We have found that light lubricating distillates of the character described herein that have a viscosity index of at least and preferably at least 95, and a Conradson carbon residue of not more than 0.05, can be used to advantage. On the other hand an oil having a viscosity index of 56 and a carbon residue of 0.04, and another having aviscosity index of 99 and a carbon residue of 0.08, produced unsatisfactory. sulfonates, when treated according to the procedure of this invention. j

Although aromatic hydrocarbons are in ,general unsuitable for the purposes of this invention, we have found that a limited class of these hydrocarbons can be used to produce sulfonates of the kind contemplated herein.

class includes aliphatic hydrocarbon-substituted benzenes that are preferentially soluble, or miscible, with high viscosity index oils. Suitable aromatic hydrocarbons are generally those that have high molecular weights and that are predominantly aliphatic. More particularly, such hydrocarbons should contain about 30 or more carbon atoms per molecule, with no more than 6 of said carbon atoms being in in aromatic ring. Such hydrocarbons can be employed in the form of mixtures, so long as the former constitute a substantial proportion. In the case of such mixtures, the average molecular weight of the mixtures may vary from about 360 to about 450. By way of example, oil-soluble polyalkylbenzenes within the described molecular weight range and having at least one and preferably at least 3 unsubstituted carbon atoms in the aromatic nucleus can be used. Polydodecylbenzene, such as found in the distillation bottoms obtained from the distillation of dodecylbenzene is an example of such a material. Normally, best results will be obtained by fractionating the distillation bottoms product to obtain only the long-chain alkylbenzene material, prior to sulfonation. By way of example, good results have been obtained with a polydodecylbenzene containing a relatively high proportion of di-dodecylbenzene and having an average molecular weight of about 397, marketed under the name Indoil.

In all cases where sulfonation is carried out in a batch operation, and sometimes in instances involving continuous sulfonation, it will be advantageous for the sulfonatable hydrocarbon material to be diluted with, say, about 30 to 100 percent by volume of the hydrocarbon material of an inert, nonviscous solvent for said hydrocarbon material, before the sulfonatable hydrocarbon materials of this invention are admixed with a sulfonating agent. The diluent serves as a means of dissipating local heat of reaction at the place of initial contact between the sulfonating agent and the sulfonatable hydrocarbon, and also as a means of facilitating sludge separation. When the diluent is vaporized during the sulfonation reaction it also serves as a temperature control by removing heat of reaction. In a batch operation, less than 30 percent diluent will ordinarily result in a dark-color final sulfonate, while substantially greater than 100 percent diluent normally causes an undue restriction in yields. Any diluent that is completely miscible with the hydrocarbon material and that vwll not be appreciably attacked by the sulfonating agent, or that will not otherwise enter into the reaction under the conditions of the sulfonation, can be used. Excellent results have been obtained with heptane and pentane. Hexane, octane, propane and butane are examples of other inert diluents that can be used. The use of a closed vessel and elevated pressure will ordinarily be necessary with the lower boiling diluen'ts.

The nature of the sulfon-ating agent is important in this invention. The sulfonating agent must be one that contains sulfur trioxide that Will be available for sulfonation at the reaction conditions. Thus, oleum containing 15 to 30 percent iactive sulfur trioxide can be used, and excellent results have in fact been obtained with 20 percent oleum, that is, oleum containing 20 percent active sulfur trioxide. The use of oleum containing less than 15 percent active sulfur trioxide is undesirable, since the rate of sulfonation in relation to that of side reactions, such as sulfiation, sulfone formation, etc, is reduced to a degree that color darkening will occur. The use of oleum containing more than about 30 percent active sulfur trioxide is also undesirable in that the instantaneous contact temperature, or local reaction temperature, at the interface between the sulfonating agent and the sulfonatable hydrocarbon material, as distinguished from the over-all temperature of the reaction mixture, will tend to be so great, due to the more vigorous reaction, that side reactions and color darkening of the final product vw'll result. Sulfur trioxide in vapor phase, or stabilized, liquid sulfonating compositions containing the same, such as Sultan can also be used in this invention. These materials can be diluted dowvn to the desired concentration, say, 5 to percent, for example 7 percent, 10 percent, or the like, by the use of an inert diluent gas, vapor or liquid.

The proportion of sulfonating agent to sulfonatable material is highly important in this invention. We have found that the amount of sulfonating agent must be such that the mol ratio of active trioxide to the sulfonatable portion of the hydrocarbon material must be in excess of 1:1 and also sutficient to maintain the reaction mixture in anhydrous condition. This means that sufilcient excess sulfur trioxide must be added to take up whatever water of reaction is formed by sulfonationwith sulfuric acid. Thus, by way of example, when using 20 percent oleum as a sulfonating agent, and a solvent treated Mid-Continent lubricating distillate having a sulfonatable portion comprising about 20 percent of the total material present, one should employ the oleum in a weight ratio with the oil of at least 1:4, which corresponds to a mol ratio of sulfur trioxide to sulfonatable material of about 1.3 1, and preferably in a weight ratio of at least about 1:2. At the same 7 time, when the sulfonation reaction has reached substantial equilibrium under the reaction conditions described herein, there should be an excess of unreacted, active sulfur trioxide in the acid sludge. When using 20 percent oleum and a polydodecylbenzene, which is considered essentially percent sulfonatable, a weight ratio of at least about 1:1, which corresponds to a mol ratio of sulfur trioxide to polyd'odecylbenzene of about 1.1:1, should be used. Again, the ratio will have been reached when sulfonation has reached substantial equilibrium and when there is unreacted, active sulfur trioxide in the acid sludge.

The herein disclosed minimum proportion of the sulfo nating agent is important in the invention, since it insures that sulfonation, i.e., formation of sulfonic acids of the type RSO H involving a direct carbon-sulfur linkage, will predominate and side reactions will be minimized. To some extent this is effected by the relatively rapid rate of sulfonation with sulfur trioxide. However, the minimum proportion of sulfonating agent employed also insures sulfonation under anhydrous conditions. Anhydrous conditions are important, since the presence of aqueous acid tends to promote sulfation.

The presence of excess, unreacted active sulfur trioxide in the acid sludge is also important since when such excess is present at the reaction conditions employed by us, any dark-color impurities, such as sulfates and sulfones, will tend to be preferentially dissolved or retained in the acid sludge phase rather than in the sour oil phase. Although it is important for the reasons indicated that sufficient sulfonating agent be employed to provide an excess of sulfur trioxide in the acid sludge, too great an excess of the sulfonating agent should not be employed, as an extremely large excess may result in side reactions between the sulfonating agent and the acid sludge, oxidation, charring or the like, any or all of which may result in turn in poorer quality and darker-color sulfonates. Normally, good results will be obtained when the sulfonating agent is employed in a proportion such that the sulfur trioxidezsulfonatable material mol ratio does not exceed about 5:1, preferably 3:1.

We have found that the maximum temperature in the sulfonation reaction mixture, including both the over-all reaction mixture temperature and the local reaction temperature at the points of admixture of reactants, is highly influential as regards the quality and yield of the final sulfonate. These temperatures are controlled primarily by the rate and method of addition of the sulfonating agent to the sulfonatable material. However, it will be understood that the agitation of the reactants and independent cooling means, the effect of which will be substan tially constant, also contribute to the maintenance of proper temperatures. Initially, it is essential that the sulfonating agent be admixed with the sulfonatablehydrocarbon material at a rate such that the over-all temperature of the reaction mixture will be maintained between 65 F. and 120 F. We have found that especially desirable sulfonates are produced when the sulfonation temperature is maintained in the range of about 65 to 83 F., as even a small increase in the reaction temperature above 83 F. will produce a disproportionate darkening in the color of the final product and will reduce the effectiveness thereof. In this connection, a series of comparable experimental runs were carried out at various reaction temperatures, and the final sulfonates were diluted to a 33 percent concentration with a water-white mineral oil, and the color of the resultant concentrate was noted. The results of several representative runs from this series are summarized in the table below:

1 Color corrected to same sludge separation conditions as runs 1, 2 and 3.

In FIGURE 1, the color of the various sulfonate concentrations is plotted against sulfonation temperatures. From the resultant curve the disproportionate color darkening that results from exceeding the 83 F. temperature limit will be evident. On the other hand, the over-all temperature of the reaction mixture should not be permitted to be maintained below 65 F., since an undue reduction in yield will he suffered under such conditions. To obtain satisfactory yields along with superior color and performance, the sulfonation temperature should be maintained at about 75 to 80 F., but greater yields are obtained at temperatures ranging up to 120 F. at some sacrifice in color and performance.

Not only is it important that the over-all temperature of the reaction mixture should not exceed 120 F. and preferably 83 F. but also it is important that unduly high local reaction temperatures be avoided in the reaction mixture :at the place of admixture of reactants. The local reaction temperature in the reaction mixture also should not exceed 120 F., and preferably 83 F. This can be accomplished by continuously introducing the sulfonating agent into the hydrocarbon material at a substantially uniform rate not substantially greater than the rate at which the sulfonating agent, particularly the sulfur trioxide, is quickly consumed, said rate also being controlled so as to maintain the over-all temperature of the reaction mixture at a predetermined level, preferably about 75 to 80 F., employing at the same timeefficient agitation of the reaction mixture during the addition of the sulfonating agent in order that the localized heat of reaction may be dissipated through the entire reaction mixture as quickly as possible. When the sulfur trioxidecontaining sulfonating agent is admixed with the oil, sulfonation with sulfur trioxide takes place rapidly on contact, until the sulfur trioxide is substantially consumed. In order to obtain very light-color sulfonates, the sulfonating agent should not be added at a rate greatly in excess of the rate at which the active sulfur tiioxide is consumed. Preferably, the sulfonating agent will be added at about the same rate at which sulfur trioxide is consurned. In this way a small excess of sulfur trioxide, sufficient to maintain anhydrous condition, can be maintained, without contacting any portion of the oil or sulfonic acids with large excesses of sulfonating agent. The restriction of the local reaction temperature to the'desire-d level will be obtained when the over-allreaction temperature, having'been allowed to reach the desired level, shows no tendency to increase with further addition 7 5 such increased rates."

cated range are preferred, but where a very low rate of admixture is employed, care should be taken to prevent the total reaction time and sludge contact time from exseeding about two hours. All other things being equal,

where the proportion of sulfonatable material in the reaction mixture is relatively lower, as in the case of a lubricating distillate, a rate of addition in the upper portion of the range can be used, In continuous operations the average reactant proportions at the zone of admixture should correspond approximately to the proportions in which the reactants are employed, and the rate of admixture in such zone will be not much greater than the rate at which the sulfur trioxide is removed as such from the reaction. One effect of continuous admixture of reactants at a substantially uniform rate, aside from temperature control, is to contact each portion of the sulfonatable material with about the same proportion of sulfonating agent. In this way local acceleration of the reaction resulting from unduly large localized ratios of sulfonating agent to sulfonatable material, and from the resulting localized runaway temperatures, will be avoided.

It is import-ant that the substantially continuous addition of sulfonating'agent at a substantially uniform rate as employed in our process be distinguished from the addition of the sulfonating agent to the sulfonatable material in one or more dumpsfwherein unduly high localized ratios of sulfonating agent to sulfonatable material and unduly high local reaction temperatures, are produced. The use of dumps of sulfonating agent invariably results in a dark-color final product.

Because of the extreme exothermic nature of the sulfonation reaction is is normally advantageous actually to remove heat from the reaction mixture in addition to controlling its rate of evolution and in addition to dissipating it over the entire reaction mixture. This can be done by the use of external cooling means. As previously indicated when the diluent is a low boiling material it can serve by evaporation as a refrigerant for the reaction mixture. It is also possible to carry out the admixture of sulfonating agent and hydrocarbon material in a jacketed cylindrical reactor provided with agitating cylindrical blades (marketed under the name Votator by the Girdler Corporation, Louisville, Kentucky) that are designed to continuously scrape the inside surface of the reactor during rotation. The continuous scraping of the inside surface of the cylindrical reactor by the agitator blades provides rapid and intimate mixing of the hydrocarbon material with upwardly graduated proportions of the sulfonating agent, rapid dissipation of local reaction heat through thereaction mixture, and at the same time provides good transfer of heat from the sulfonation reaction through the wall of the cylindrical reactor to a heat transfer medium'circulated through the aforesaid jacket. In batch operations the temperature of the reaction mixture can be advantageously controlled by the use of crushed Dry Ice. This material acts not only as -a refrigerant but the vaporized carbon dioxide produced during sublimation serves to strip sulfur dioxide from the reaction mixture, thereby also aiding in the prevention of side reactions.

Although the rate of admixture of reactants ordinarily should be continuous and substantially uniform, the rate of admixture can be increased somewhat as the reaction proceeds in view of the buffering effect of the sulfonic acids, and the resultant; reduction in the rate at which 1 sulfur trioxid'e is consumed, and the invention includes alkyl- When addition of the sulfonating agent to the hydrocarbon materi-al is complete it is important that the acid sludge be separated from contact with the sour oil as quickly as possible. To this end digestion of the reaction mixture and settling of sludge for any substantial period must be avoided. We have found that good results are produced when the total time lapse after addition of the sulfonating agent to the hydrocarbon material is complete, until separation of the acid sludge from the sour oil, is not more than one hour. Separation of acid sludge from sour oil within 30 minutes after completion of the sulfonation reaction is preferred, and excellent results have been obtained when separation has been effected Within about minutes. We have found that the period immediately following sulfonation is extremely important from the standpoint of quality and color in the final product and that during this period even a small increase in the time of contact between acid sludge and sour oil Will result in a disproportionate sacrifice in the color and quality of the ultimate sulfonate produced from the sour oil.

In this connection a series of comparable experimental runs were carried out permitting the acid sludge to remain in contact with the sour oil for various periods of time. The sulfonates produced from each run were diluted with a water-white mineral oil to a 33 percent concentration and the color of the resultant solution was noted. The results of several representative runs in this series are summarized in the following table:

1 Color corrected to same sulfonation temperature as runs 1 and 3.

In FIGURE 2, the color of the various sulfonate concentrates is plotted against time elapsed before sludge separation. From this curve it will be seen that contact of acid sludge and sour oil for a period up to about one hour, and preferably not more than 30 minutes, will permit production of a very light-color alkaline earth metal sulfonate, but if appreciably more than one hour of contact of acid sludge and sour oil is permitted a substantial sacrifice in the color of the final alkaline earth metal sulfonate will be suffered. It should be noted that the continuous, substantially uniform admixture of sulfonating agent according to this invention not only is important in controlling the sulfonation temperature and reactant proportions, but also in that such addition minimizes, within the limits disclosed, the total time period over which sour oil is in contact with acid sludge.

In view of the normal increase in viscosity of the reaction mixture as the sulfonation reaction proceeds, and in view of the possible loss of solvent during sulfonation, it is often desirable as an aid in accelerating separation of sludge from sour oil to dilute, or further dilute if this has already been done, the reaction mixture with an inert diluent of the kind previously mentioned.

In accordance with this invention, the acid sludge must be quickly separated from the sour oil. To this end, rapid separation can be effected in any convenient manner, for example, by suction filtering, using, if desired, a commercial filter such as Celite or Filtrol. These filter aids appear to exert a sludge-coagulating effect. Acid sludge also can be separated rapidly by centrifuging, and for continuous operation, centrifugal sludge separation is preferred.

After separation of sour oil from acid sludge the former is stripped of sulfur oxide, if any is present, preferably with an inert gas such as nitrogen. The same oil is then treated by admixing therewith at least 30 percent by volume, preferably 30 to percent by volume, for example 50 percent by volume, of an oil-immiscible, selective solvent, including mixtures, for oil-soluble sulfonic acids. Examples of such solvents are aqueous, low molecular weight alcohols, such as normal propyl alcohol, isopropyl alcohol, ethyl alcohol, ethylene gycol or the like. wherein the volume ratio of water to alcohol is between 1:1 and 3:1, with a ratio of 1:1 being preferred. Although aqueous alcohols, particularly isopropyl alcohol, are preferred for economic reasons, any water-miscible oxygen-containing organic solvent for the oil-soluble sulfonic acids can be used. When the solvent is oil-immiscible per se, it need not contain water nor be miscible therewith. Acetone and diacetone are examples of solvents other than alcohols that are suitable for use in this invention. When the solvent used is aqueous, the solvent and water need not be premixed but can be separately added.

After thorough admixture of the solvent with sour oil, the solvent phase, containing oil-soluble sulfonic acids, is separated, for example, by decanting. 'Ihe sulfonic acids are neutralized in the solvent phase with a basic inorganic alkaline earth metal compound such as hydroxides, oxides, and/or carbonates of alkaline earth metals such as barium, calcium or strontium. Calcium hydroxide and barium oxide are the preferred neutralizing agents for economic reasons, and excellent results have been obtained therewith. The sulfonic acids can be heated to a temperature below the boiling point of the solvent in order to accelerate complete neutralization.

It is important that the sulfonic acids be neutralized as quickly as possible and without appreciable lapse of time, preferably Within about one hour, following extraction from the sour oil, since the sulfonic acids and/or possibly some substances admixed therewith appear to be relatively unstable in the presence of the selective solvent, prior to neutralization. The quantity of the basic inorganic alkaline earth metal compound employed is preferably somewhat in excess of the quantity theoretically required to neutralize the sulfonic acids, which theoretical quantity can be calculated from the neutralization value of these acids. Sufficient basic material will normally have been added when the reaction mixture, after filtration, tests basic to alkacid indicator paper. However, more can be added if basic alkaline earth metal sulfonates are dwired rather than normal alkaline earth metal sulfonates.

After neutralization is complete the neutralized mixture is filtered to remove solid matter, i.e., alkaline earth metal sulfates, unreacted base, etc., and the mixture is advantageously heated to remove the oil-miscible portion of the solvent, if any, prior to further treatment. Although the majority of the preferentially Water-soluble sulfonic acids are separated from the sulfonated reaction product in the acid sludge, some of these materials and/or sulfonic acids having borderline solubility between oil and Water will be found in the sour oil and may be extracted therefrom with the solvent. In order to insure separation of fully oil-soluble alkaline earth metal sulfonates that will be fully compatible with high viscosity index lubricating oils, that is, those having a viscosity index of 85, 100 or higher, it is important that the sulfonates of the preferentially water-soluble sulfonic acids and of the sulfonic acids having borderline oil-solubility, if any are present, be eliminated from the final product to the greatest extent possible. When the solvent per se is an aqueous solvent and it is not removed from the aqueous sulfonates prior to extraction with a nonpolar solvent, as hereinafter described, the oil-miscible portion of the solvent tends to act as a mutual solvent for the water and the nonpolar solvent, whereby rela- 11 tively low molecular weight sulfonates are carried over in the water to the final product. As indicated, this difficulty is avoided by removal of the oil-miscible portion of the solvent from the aqueous sulfonates, prior to extraction thereof with the nonpolar solvent.

After removal of the solvent from the neutralized sulfonates, the latter are extracted or taken up with an oilmisciole, nonpolar solvent, preferably a low-boiling, aromatic hydrocarbon, such as benzene, toluene or the like, but other oil-miscible solvents can be used. For example, lower boiling halogenated hydrocarbons such as trichloroethylene and carbon tetrachloride can be used. Normally about 50 percent to about 200 percent by volume of the nonpolar solvent, based on the volume of aqueous sulfonic acids, will be sufiicient, but other proportions, smaller and larger, can be used. This extraction can be carried out in single or multiple stage. In order to facilitate blending with lubricating oils the nonpolar solvent solution can be advantageously mixed with a light, preferably water-white, lubricating distillate in an amount sufficient to produce the desired viscosity and blending characteristics in the final concentrate, and the nonpolar solvent and any residual water can be removed by distillation.

The invention can be further understood by reference to the following specific embodiments.

Example I High molecular weight, fully oil-soluble, light-color alkaline earth metal sulfonates are produced in accordance with this invention using an unfiltered, solvent-refined lubricating distillate having a viscosity of about 200 Saybolt Universal seconds at 100 F., derived from a Mid-Continent petroleum crude oil, as the sulfonatable hydrocarbon material. A sample of this distillate was previously determined by exhaustive sulfonation to contain approximately 20 percent sulfonatable material. A typical sample of the distillate had the following inspections:

Gravity, API 19.1 Viscosity, SUS/ 100 F 211 Viscosity index 109 Carbon residue (Conradson) 0.02 Hydrocarbon analysis, percent:

Paraffinic 64 Naphthenic 29 Aromatic rings 7 Color, ASTM Union 2.75 Average molecular weight 413 To 2640 grams (3000 ml.) of the foregoing lubricating distillate there is added an equal volume of heptane as a diluent. Approximately 670 ml. (1200 g.) of oleum containing 20 percent active sulfur trioxide (20 percent oleum) is added to the diluted lubricating distillate at an average rate of about 40 ml. per minute. Crushed Dry Ice is added to the reaction mixture during the course of the reaction so that some is always present. The over-all temperature of the reaction mixture is maintained at 75:5" F. during addition of the oleum. After addition of the oleum to the reaction mixture is completed, about one-half hour, the mixture is allowed to digest for about 20 minutes or less. Additional heptane is added to facilitate settling of sludge from the mixture and the mixture is allowed to stand for about 30 minutes or less. Supernatant liquid is decanted from the partly settled sludge and filtered under suction using a filter aid. The filtered sour oil is then blown with nitrogen to remove traces of sulfur dioxide therefrom. The filtered, stripped sour oil is then diluted first with about one-half its volume of isopropanol and then the mixture is diluted with onethird its volume of water. After thorough admixture of the aqueous alcohol and sour oil the aqueous alcohol phase, containing extracted sulfonic acids, is decanted' from the unsulfonated oil. Calcium hydroxide is then added to the aqueous alcohol sulfonic acids extract until the material tests basic to alkacid indicator paper, after filtration to remove excess, suspended lime. The quantity of calcium hydroxide required is several times greater than the theoretical amount as calculated from the neutralization value of the sour oil. The temperature is held at 160 F. during neutralization. After neutralization is complete the neutralized mixture is filtered toremove solids. The filtered, neutralized sulfonates are then heated to a temperature of 200 P. so as to boil off the isopropyl alcohol. Following this step about an equal volume of benzene is added for the purpose of extracting the high molecular weight, fully oil-soluble sulfonates from the lower molecular weight sulfonates that have a substantial affinity for water. The benzene containing the high molecular weight, fully oil-soluble sulfonates is separated from the aqueous phase and the benzene is driven ofi by heating to a temperature of 235 F. The resultant product is then diluted with a sufiicient amount of a water-white, low viscosity mineral lubricating oil to produce a 33 weight percent sulfonate concentrate. A typical sample of this concentrate has the following inspections:

Color, ASTM Union 3 minus Ash, sulfated residue, percent 6.6

Example 11 Fully oil-soluble, light-color alkaline earth metal sulfonates are prepared using a synthetic sulfonatable hydrocarbon material comprising a polydodecylbenzene (marketed by the Indoil Chemical Company) and having the following inspections:

ASTM distillation, percent at 10 mm.:

I.B.P. -c 325 560 Color, ASTM 1.75 Bromine No 0.7 Viscosity, SUV, sec.:

210 46.1 Pour, F. 10 Aniline point, F 144.5 Refractive index, 11 1.4891 Average molecular weight 397 Five thousand grams of the polydodecylbenzene is diluted with an equal volume of pentane, and 2900 ml. (approx. 5350 g.) of oleum containing 20 percent sulfur trioxide are added to the diluted mixture at an average rate of about 39 ml. per minute. Drylce in an amount sufficient to maintain the reaction mixture between 65 F. and 75 F. is added during the course of the sulfonation reaction. After additionof the oleum is complete the reaction mixture is allowed to digest for about 20 minutes. 'Additional pentane is then added to facilitate sludge separation, and the mixture is allowed to stand for about 30 minutes, following which supernatant liquid is decanted from the sludge and filtered under suction. The sour oil is then stripped with nitrogen to remove sulfur dioxide. The sour oil is next diluted with about 50 percent by volume of isopropyl alcohol and then with:

In this embodiment, the

one-third by volume of Water. alcohol, oil-soluble sulfonic acids and pentane separate from the water phase, which contains low molecular weight sulfonic acids. The aqueous phase is removed from the alcoholic sulfonic acids and discarded. The alcoholic sulfonic acids are heated to Fnand cal cium hydroxide is added thereto until, after filtration, the mixture tests basic to alkacid indicator paper. The neutralized mixture is then filtered to remove solids, and the reaction mass is heated to 200 F. to drive off the isopropyl alcohol and lower boiling materials. A viscous liquid remains. Benzene in about an equal volume is then admixed with the sulfonates toextract the fully oilsoluble, high molecular weight sulfonates from lower molecular weight sulfonates. The benzene phase is then diluted with a water-white mineral lubricating oil in an amount sufiicient to produce a 33 weight percent sulfonate concentration, in the final concentrate, and the mixture is heated to 220 F. to remove benzene. A typical sample of the 33 percent concentrate has the following inspections:

Color, ASTM Union 3 pH, glass-calomel electrodes 7.2 Ash, sulfated residue, percent 6.0

Example III To 8,000 grams of a lubricating distillate of the kind described in Example I there was added about 9,200 ml. of heptane as a diluent. To this mixture there was added over a peroid of about 45 minutes 4,000 g. fuming sulfuric acid (20 percent oleum) at an average rate of about 40 ml. per minute. In order to control the temperature of the reaction mixture, crushed Dry Ice was added to the reaction mixture throughout the course of the reaction so that some amount was always present. The over-all temperature of the reaction mixture was maintained in this way at about 751-5 F. during addition of the oleum. The mixture was then allowed to digest for about minutes. Heptane in the amount of 1,000 ml. was added and the thus-diluted mixture was allowed to stand for about minutes. Diluted sour oil was decanted from the partly settled sludge and filtered. The filtered sour oil was blown with nitrogen to remove sulfur dioxide. Sulfonic acids were extracted from the sour oil by admixture with the latter of isopropyl alcohol in the amount of about percent by volume of the sour oil and by then adding thereto a volume of Water equal to that of the alcohol. The aqueous alcohol phase, containing extracted sulfonic acids, was then separated from the heptane-oil phase. Barium hydroxide octahydrate was then added to the aqueous alcoholic extract in molar excess (1100 g., 3.5 mols), and the mixture was heated to 160 F. The neutralized mixture was then filtered to remove unreacted barium hydroxide. The product tested basic to alkacid indicator paper (color change at pH 8.0). To this mixture was added an equal volume of percent benzene (technical grade). The mixture was then agitated for 15 minutes and allowed to settle. The upper layer (benzene and alcohol) was decanted and the solvents were distilled off at a maximum temperature of 225 F. The resultant product was diluted with sufiicient water-white lubricating oil having a viscosity of about 50 SUS/ F. to produce a 20 weight percent barium petroleum sulfonate concentrate in the oil. The 20 percent oil concentrate had the following inspections:

Color, ASTM Union 2.5 pH, glass-calomel electrodes 8.2 Barium, percent by weight 8.28

Example IV A light-color barium sulfonate concentrate was prepared essentially identically with the procedure described in Example III, except that the sulfonation temperature was maintained principally in the range of to F., 90 F. and the maximum temperature of treatment being about F. The 20 percent barium sulfonate solution in Oil prepared in accordance with the procedure of this example had the following inspections:

Color, ASTM Union 3.5 pH, glass-calomel electrodes 8.4 Barium, percent by weight 2.08

In the practice of this invention, iron salts are to be avoided in the final sulfonates because of the color produced thereby. To this end, glass, stainless steel or other inert apparatus is used throughout.

The foregoing embodiments are illustrative only. Good results can also be obtained by the substitution in the foregoing examples of other charge stocks within the scope of this invention, for example, an acid-treated lubricating oil distillate derived from an Ordovician (parafiinic) crude oil having an average molecular weight of about 320, a carbon residue of about 0.01, a viscosity index of about 95, and ASTM Union color of 1.25, and a hydrocarbon analysis of 14.0 percent aromatic rings and the balance parafiinic and naphthenic materials, by substitution of sulfur trioxide diluted with an inert diluent for the oleum, by substitution of barium and strontium oxides and hydroxides for the calcium hydroxide, and by variation of the sulfonation-sludge separation, and neutralization conditions within the limits disclosed herein.

For the purposes of this invention, it is important that the charge stocks, reaction conditions and treating steps all be adhered to, as all of these coact and modify one another to produce exceptionally light-color, oil-soluble sulfonates of unusual purity. Thus, in a series of runs carried out to investigate the individual effects of sulfonation temperature control and rapid sludge separation, it was found that the color improvement in the sulfonate (calcium sulfonate, 33 percent concentrate in water-white oil) produced where both factors were controlled according to the preferred manner of this invention was greater than would be expected from the improvements obtainable by controlling either factor individually in accordance with the preferred manner of this invention. The data from these runs are summarized in the table below:

From the foregoing results it will be seen that a color improvement of 1.75 units is obtained when both factors are controlled according to this invention, as compared with a color improvement of only 0.75 when only the sludge separating time is so controlled, and only 0.50 when only the sulfonation temperature is so controlled.

The sulfonates indicated in the foregoing Table C were prepared by extraction of directly-neutralized sulfonic acids that in turn were extracted from the sour oil, as fully disclosed elsewhere herein. Although sulfonates prepared in this fashion are of unusually light color and possess exceptional properties from a performance standpoint, especially as regards compatibility and Water-sensitivity, it will be understood that a similar disproportionate change in color can be obtained by the subcombination of proper temperature control and rapid sludge separation in combination wtih other extraction and neutralization procedures. Examples of other neutralization and extraction procedures include neutralization of the unextracted sour oil with alkali metal hydroxide, extraction of the oil-soluble material, and metathesis with alkaline earth metal salt, or, extraction of the highmolecular weight sulfonic acids from the sour oil, followed by neutralization with alkali metal hydroxide and metathesis with an alkaline earth metal salt.

By way of demonstrating the superior performance characteristics of sulfonates prepared in accordance with the herein disclosed invention a test sample of the 20 percent barium sulfonate concentrate prepared as described in Example III was prepared by dilution with sufficient water-white lubricating oil having a viscosity of about 50 SUS/ 100 F. to provide a barium content of 0.035 percent by weight. This test sample was then subjected to the ASTM D-665 Procedure B rust inhibiting test. Briefly, in accordance the procedure of this test a prepolished cylindrical steel specimen is immensed in a stirred mixture of 300 ml. test oil and 30 ml. synthetic sea water maintained at a temperature of 140 F. At the conclusion of the test the steel test specimens are examined for rust Without magnification under normal light.

For purposes of comparison there was also subjected to the same test procedure a test sample, hereinafter referred to as Test Oil B, prepared by diluting a 20 percent barium sul fonate solution in oil, prepared by a diiferent method, with a suflicient amount of the previously mentioned water-white lubricating oil to provide a barium content of 0.035 percent by weight. The 20 percent barium sulfonate solution employed in this test sample was prepared by treating 8,000 mi. of solvent-extracted, 500 SUS/ 100 F. lubricatingdistillate derived from a Coastabtype crude oil, with two dumps of 600 each (a total of 15 percent by volume) of fuming sulfuric acid (20 percent oleum), the temperature during sulfonation being maintained at about 158 F. (70 C.). After each dump, substantial separation by settling was allowed to take place, and the sour oil was removed from sludge by decanting. The sour oil was then diluted with an approximately equal volume of neutral oil. To the diluted sour oil there was added a commercial filter aid (JM Hyfio) in the proportion of 0.5 g./ 100 ml. The mixture was agitated for about 15 minutes at room temperature. The resulting mixture was then filtered. The filtered, diluted sou-r oil was blown with air to remove S The remaining sour oil mixture was extracted with 2000 ml. of a 50 percent aqueous alcohol mixture. To the alcoholic sulfonic acids was added a sufiicient amount of a water-white lubricating oil having a viscosity of about 50 SUS/ 100 F. to produce a 20 percent by weight barium sulfonate concentrate after removal of the alcohol. The mixture was then heated to 50 C. and a molar excess (650 g.) of barium hydnoxide octahydrate was added thereto. The temperature was then raised fro 75 C. with stirring. The stirring was then stopped and the oil layer was allowed to separate. The oil layer was decanted and filtered. The pH of this product was 7.9, the ASTM Union color was 7.5, and the barium content was 4.81 percent by weight. Y

The results of the tests described above were as follows:

' TABLE D ASTM D-66554, Proc. B, nine days, rust rating percent Example Hi Test Sample Trace 1) Test Sample B 27 From the foregoing test results it will be seen that the novel, light-color sulfonates prepared in accordance with the herein described process possess unique rust inhibiting characteristics.

The novel alkaline earth metal sulfonates produced in and are fully compatible with high viscosity index lubricating oils. They are exceptionally free from impurities such as sulfates, bleaching residues, alkali metals, and sulfonates having substantial affinity for water, such as lower molecular weight sulfonates or predominantly aromatic sulfonates. As disclosed, they possess distinctly superior rust inhibiting characteristic. On account of these propenties and in view of their carbon and sludge suspending properties and other valuable properties, the sulfonates of this invention form excellent motor oil additives. They can also be used in gasolines, distillate fuel oils, such as furnace oils, dieselfuels and the like, cutting oils, flushing oil's, turbine oils, and various hydrocarbon base coating and/or cleaning compositions.

Many variations of the invention as specifically dis closed herein will suggest themselves to, those skilled in accordance with this invention are uniformly light-color 16 the art. Such variations can obviously be practiced without departing from the spirit or scope of this invention. Accordingly, we do not intend to be limited to the embodiments described, but only by the scope of the v appended claims.

This application is a continuation-in-part of application Serial No. 589,692, filed June 6, 1956, and now abandoned.

We claim:

1. A process for preparing light-color oil-soluble sulfonates, comprising admixing a sulfur trioxide-containing sulfonating agent with a sulfonatable hydrocarbon material that has a relatively homogeneous composition and an ASTM Union color of no more than about 3, said sulfonatable hydrocarbon material being selected from the group consisting of (a) alkylbenzenes containing at least 30 carbon atoms and having at least one unsubstituted carbon atom in the aromatic nucleus, and (b) petroleum distillate 'oils having an average molecular weight of about. 275 to about 450, a viscosity of about 50 to 2.50 S.U.S. at F., a viscosity index of at least about 85, a carbon residue of not more than 0.05 and that are relatively free fromfpredorninantly aromatic constituents, the proportions of the sulfonating agent and the hydrocarbon material being such that the mol ratio of the sulfur trioxide and the sulfontatable portion of the hydrocarbon material is greater than 1:1 and sufficient to maintain the reaction mixture in anhydrous condition, the admixing of said sulfonating agent and said hydrocarbon material being effected at a rate not substantially greater than that at which the sulfur trioxide portion of the sulfonating agent is consumed, and such that the over-all temperature of the reaction mixture is maintained between 65 F. and F., and without appreciable time lapse after addition of the sulfonating agent to the hydrocarbon material is complete, separating acid sludge from the sour oil, the time lapse from the completion of the admixing of sulfonating agent and hydrocarbon material to the separation of acid sludge from sour oil not exceeding about one hour, separating sulfonic acids from sour oil by admixing the latter with an oil-immiscible, selective solvent for the oil-soluble sulfonic acids, separating the solvent phase from the oil phase, quickly neutralizing the separated sulfonic acids with a basic, inorganic, alkaline earth metal compound, and recovering fully oil-soluble alkaline earth metal sulfonates from the neutralized sulfonates by dissolving them in an oil-miscible, organic, nonpolar solvent therefor. l

2. A process for preparing light-color oil-soluble sulfonates, comprising admixing a sulfur trioxide-containing sulfonating agent with a sulfonatable hydrocarbon material that has a relatively homogeneous composition and an ASTM Union color of no more than about 3, said sulfonatable hydrocarbon material being selected from the group consisting of (a) alkylbenzenes containing at least 30 carbon atoms and having at least one unsubstituted carbon atom in the aromatic nucleus, and (b) petroleum distillate oils having an average molecular weight of about 275 to about 450, a viscosity of about 50 to 250 S.U.S. at 100 F., a viscosity index of at least about 85, a carbon residue of not more than 0.05 and that are relatively free from predominantly aromatic constituents, the proportions of the sulfonating agent and the hydrocarbon material being such that the mol ratio of the sulfur trioxide and the sulfonatable pornon of the hydrocarbon material is greater than 1:1 and sufficient to maintain the reaction mixture in anhydrous condition, the admixing of said sulfonating agent and said hydrocarbon material being effected at a rate not substantially greater than that at which the sulfur trioxide portion'of the sulfonating agent is consumed, and such that the over-all temperature of the reaction mixture is maintained between 65 F. and 83 F., and without appreciable time lapse after addition of the sulfonatmg agent to the hydrocarbon material is complete, separating acid sludge from the sour oil, the time lapse from the completion of the admixing of sulfonating agent and hydrocarbon material to the separation of acid sludge from sour oil not exceeding about one hour, separating sulfonic acids from sour oil by admix'mg the latter with an oil-immiscible, selective solvent for the oil-soluble sulfonic acids, separating the solvent phase from the oil phase, quickly neutralizing the separated sulfonic acids with a basic, inorganic, alkaline earth metal compound, and recovering fully oil-soluble alkaline earth metal sulfonates from the neutralized sulfonates by dissolving them in an oil-miscible, organic, nonpolar solvent therefor.

3. The process of claim 2 wherein the sulfonatable hydrocarbon material is an alkylbenzene containing at least 30 carbon atoms and having at least one unsubstituted carbon atom in the aromatic nucleus.

4. The process of claim 2 wherein the sulfonatable hydrocarbon material is a petroleum distillate oil having an average molecular Weight of about 275 to about 450, a viscosity of about 50 to about 250 S.U.S. at 100 F., a viscosity index of at least about 85, a carbon residue of not more than 0.05, and that is relatively free from aromatic constituents.

5. The process of claim 2 wherein the basic inorganic alkaline earth metal compound is calcium hydroxide.

'6. The process of claim 2 wherein the basic inorganic alkaline earth metal compound is barium oxide.

7. The process of claim 2 wherein the basic inorganic alkaline earth metal compound is barium hydroxide.

8. The process of claim 2 wherein the basic inorganic alkaline earth metal is strontium.

9. A process for preparing light-color oil soluble sulfonates, comprising admixing a sulfur trioxide-containing sulfonating agent with a sulfonatable hydrocarbon material that has a relatively homogeneous composition and an ASTM Union color of no more than about 3, said sulfonatable hydrocarbon material being selected from the group consisting of (a) alkylbenzenes containing at least 30 cmbon atoms and having at least one unsubstituted carbon atom in the aromatic nucleus, and (b) petroleum distillate oils having an average molecular weight of about 275 to about 450, a viscosity of about 50 to 250 S,U.S. at 100 F., a viscosity index of at least about 85, a carbon residue of not more than 0.05, and that are relatively free from predominantly aromatic constituents, the proportions of the sulfonating agent and the hydrocarbon material being such that the mol ratio of the sulfur trioxide and the sulfonatable portion of the hydrocarbon material is greater than 1:1 and sufircient to maintain the reaction mixture in anhydrous condition, the admixing of said sulfonating agent and said hydrocarbon material being effected continuously at a substantially uniform rate such that the over-all temperature of the reaction mixture is maintained between 65 F. and 83 F. and such that the local reaction temperature does not significantly exceed 83 F., and without appreciable time lapse after addition of the sulfonating agent to the hydrocarbon material is complete, separating acid sludge from the sour oil, the time lapse from the completion of the admixing of sulfonating agent and hydrocarbon material to the separation of acid sludge from sour oil not exceeding about one hour, separating sulfon-ic acids from sour oil by admixing the latter with an oil-immiscible, selective solvent for the oil-soluble sulfonic acids, separating the solvent phase from the oil phase, quickly neutralizing the separated sulfonic acids with a basic, inorganic, alkaline earth metal compound, and recovering fully oil-soluble alkaline earth metal sulfonates from the neutralized sulfonates by dissolving them in an oil-miscible, organic, nonpolar solvent therefor.

10. A process for preparing light-color oil-soluble sulfonates, comprising admixing a sulfur trioxide-containing 'su'lfonating agent with a sulfonatable hydrocarbon material that has a relatively homogeneous composition and an ASTM Union color of no more than about 3, said sulfonatable hydrocarbon material being selected from the group consisting of (a) alkylbenzenes containing at least 30 carbon atoms and having at least one unsubstituted carbon atom in the aromatic nucleus, and (b) petroleum distillate oils having an average molecular weight of about 275 to about 450, a viscosity of about 50 to 250 S.U.S. at 100 'F., a viscosity index of at least about 85, a carbon residue of not more than 0.05, and that are relatively free from predominantly aromatic constituents, the proportions of the sulfonating agent and the hydrocarbon material being such that the mol ratio of the sulfur trioxide and the sulfonatable portion of the hydrocarbon material is greater than 1:1 and sulficient to maintain the reaction mixture in anhydrous condition and to provide an excess of unreacted sulfur trioxide in the acid sludge after sulfonation has reached substantial equilibrium, the admixing of said sulfonating agent and said hydrocarbon material being eifected continuously at a substantially uniform rate not substantially greater than the rate at which the sulfur trioxide portion of the sulfonating agent is consumed and such that the over-all temperature of the reaction mixture is maintained between 65 Rand 83 F. and without appreciable time lapse after addition of the su'lfonating agent to the hydrocarbon material is complete, separating acid sludge from the sour oil, the time lapse from the completion of the admixing of sulfonating agent and hydrocarbon material to the separation of acid sludge from sour oil not exceeding about one hour, separating sulfonic acids from sour oil by admixing the latter with an oil-immiscible, selective solvent for the oil-soluble sulfonic acids, separating the solvent phase from the oil phase, quickly neutralizing the separated sulfonic acids with a basic, inorganic, alkaline earth metal compound, and recovering fully oilsoluble alkaline earth metal sulfonates from the neutralized sulfonates by dissolving them in an oil-miscible, organic, ncnpolar solvent therefor.

11. A process for preparing light-color oil-soluble sulfonates, comprising admixing oleum containing about 15 to 30 percent active sulfur trioxide with a sulfonatable, solvent-treated petroleum distillate oil having an average molecular weight of about 300 to about 420, a viscosity of about 200 to 250 S.-U.S. at 100 R, a viscosity index of at least about 95, a carbon residue of not more than 0.04, and that is relatively free from predominantly aromatic constituents, the proportions of the oleum and the petroleum distillate oil being such that the mol ratio of the sulfur trioxide and the sulfonatable portion of the petroleum distillate oil is between about 1:1 and 5:1 and sufiicient to maintain the reaction mixture in anhydrous condition, the admixing of said oleum and said petroleum distillate oil being eifected continuously at a substantially uniform rate not substantially greater than the rate at which the sulfur trioxide portion of the sulfonating agent is consumed and such that the over-all temperature of the reaction mixture is maintained between about 70 and F., and such that the local reaction temperature does not exceed about 83 F., and without appreciable time lapse after addition of the oleum to the petroleum distillate oil is complete, separating acid sludge from the sour oil, the time lapse from the completion of the admixing of the oleum and the petroleum distillate oil to the separation of acid sludge from sour oil not exceeding about one-half hour, separating sulfonic acids from sour oil by admixing the latter with a total of about 30 to percent by volume of isopropyl alcohol and water in a 1:1 to 1:3 ratio, separating the alcohol phase from the oil phase, quickly neutralizing the separated sulfonic acids with calcium hydroxide, removing solids and alcohol from the neutralized mixture, recovering fully oil-soluble calcium sulfonates from the neutralized sulfonates by preferential dissolution in an oilmiscib'le, organic, nonpolar solvent therefor, and admixing with the thus-obtained solution a mineral oil of lubricating viscosity, and removing said nonpolar solvent an average molecular weight of about 27 to about 450, a

viscosity of about 50 to-250 S.U.S. at 100 as viscosity index of at least about 85, a carbon residue of not more than 0.05 and that are relatively free from predominantly aromatic constituents, the proportions of the sulfonating agent and the hydrocarbon material being such that the mol ratio of the sulfur trioxide and the sulfonatable portion' of the hydrocarbon material is greater than 1:1 and sufficient to maintain the reaction mixture in anhydrous condition, the admixing of said sulfonating agent and said hydrocarbon material being eifected at a, rate not substantially greater than that at which the sulfur trioxide fportion of the sulfonating agent is consumed, and such that 450, a viscosity of about 50 to 250 S.U.S. at 100 F., a viscosity index of at least'about 85, a carbon residue of not more than 0.05 and that are relatively free from predominantly aromatic constituents, the proportions of the 's'ulfonating agent and the hydrocarbon material being such that the mol ratio of the sulfur trioxide and the sulfonatable portion of the hydrocarbon material is greater than 1:1 and suflicient to maintain the reaction mixture in anhydrous condition, the admixing of said sulfonating agent and said hydrocarbon material being effected at a' rate not substantially greater than that at which the sulfur trioxide portion of the sulfonating agent is consumed, and such that the over-all temperature of the reaction mixture is maintained between 65 Fuand 120 F., and without appreciable time lapse after addition of the sulfonating agent to the hydrocarbon material is complete, separating acid sludge from the sour oil, the time lapse from the completion of the admixing of sulfonating agent and hydrocarbon material to the separation of acid sludge'from sour oil not exceeding about one hour.

1 3. A process for preparing sulfonic acids suitable for the preparation of light-color oil-soluble sulfonates, comprising admixing a sulfur trioxide-containing sulfonating agent with a sulfonatable hydrocarbon material that has a relatively homogeneous composition and an ASTM Union color of no more than about 3, said sulfonatable hydrocarbon material being selected from the group consisting of (a) alkylbenzenes containing at least '30 carbon atoms and having at least one unsubstituted carbon atom in the aromatic nucleus, and (b) petroleum distillate oils having the over-alltemperature of the reaction mixture is main:

tained between -F. and 83 F., and without appreciable time lapse after-addition of the-sulfonating agent tothe hydrocarbon material is complete, separating acid sludge from the sour oil, the time lapse from thecompletion of the admixing of sulfonating agent and'hydrocarbon material to the sep'arationof acid'slildge from sour oil not exceeding about one hour.

7 14-. The product produced in accordance with'the processofc1aim1.-" ,7

15. The product produced in accordance with the V ess of claim 3. s T' t 16. The product produced in accordance with the process of claim 4. a

17. The product produced in accordance with the process ofclaim'i;

18. The product produced in accordance with the process of claim 7. 1 r I 19. The product produced in accordance with the process of claim 8.

References Cited in the file of this patent V UNITED STATES PATENTS 7 2,442,915 Berger et a1. Q June 8; 1948 2,532,997 Cohen ,Dec. 5, 1950 1 2,815,370 Hutchings et a1. Dec. 3, 1957 2,816,076 Neville et al Dec. 10, 1957 V FOREIGN PATENTS 709,587 Great Britain May 26, 1954

Claims (2)

1. A PROCESS FOR PREPARING LIGHT-COLOR OIL-SOLUBLE SULFONATES, COMPRISING ADMIXING A SULFUR TRIOXIDE-CONTAINING SULFONATING AGENT WITH A SULFONATABLE HYDROCARBON MATERIAL THAT HAS A RELATIVELY HOMOGENEOUS COMPOSITION AND AN ASTM UNION COLOR OF NO MORE THAN ABOUT 3, SAID SULFONATABLE HYDROCARBON MATERIAL BEING SELECTED FROM THE GROUP CONSISTING OF (A) ALKYLBENZENES CONTAINING AT LEAST 30 CARBON ATOMS AND HAVING AT LEAST ONE UNSUBSTITUTED CARBON ATOM IN THE AROMATIC NUCLEUS, AND (B) PETROLEUM DISTILLATE OILS HAVING AN AVERAGE MOLECULAR WEIGHT OF ABOUT 275 TO ABOUT 450, A VISCOSITY OF ABOUT 50 TO 250 S.U.S. AT 100*F., A VISCOSITY OF ABOUT ABOUT 85, A CARBON RESIDUE OF NOT MORE THAN 0.05 AND THAT ARE RELATIVELY FREE FROM PREDOMINANTLY AROMATIC CONSTITUENTS, THE PROPORTIONS OF THE SULFONATING AGENT AND THE HYDROCARBON MATERIAL BEING SUCH THAT THE MOL RATIO OF THE SULFUR TRIOXIDE AND THE SULFONATABLE PORTION OF THE HYDROCARBON MATERIAL IS GREATER THAN 1:1 AND SUFFICIENT TO MAINTAIN THE REACTION MIXTURE IN ANHYDROUS CONDITION, THE ADMIXING OF SAID SULFONATING AGENT AND SAID HYDROCARBON MATERIAL BEING EFFECTED AT A RATE NOT SUBSTANTIALLY GREATER THAN THAT AT WHICH THE SULFUR TRIOXIDE PORTION OF THE SULFONATING AGENT IS CONSUMED, AND SUCH THAT THE OVER-ALL TEMPERATURE OF THE REACTION MIXTURE IS MAINTAINED BETWEEN 65*F. AND 120*F., AND WITHOUT APPRECIABLE TIME LAPSE AFTER ADDITION OF THE SULFONATING AGENT TO THE HYDROCARBON MATERIAL IS COMPLETE, SEPARATING ACID SLUDGE FROM THE SOUR OIL, THE TIME LAPSE FROM THE COMPLETION OF THE ADMIXING OF SULFONATING AGENT AND HYDROCARBON MATERIAL TO THE SEPARATION OF ACID SLUDGE FROM SOUR OIL NOT EXCEEDING ABOUT ONE HOUR, SEPARATING SULFONIC ACIDS FROM SOUR OIL BY ADMIXING THE LATTER WITH AN OIL-IMMISCIBLE, SELECTIVE SOLVENT FOR THE OIL-SOLUBLE SULFONIC ACIDS, SEPARATING THE SOLVENT PHASE FROM THE OIL PHASE, QUICKLY NEUTRALIZING THE SEPARATED SULFONIC ACIDS WITH A BASIC, INORGANIC, ALKALINE EARTH METAL COMPOUND, AND RECOVERING FULLY OIL-SOLUBLE ALKALINE EARTH METAL SULFONATES FROM THE NEUTRALIZED SULFONATES BY DISSOLVING THEM IN AN OIL-MISCIBLE, ORGANIC, NONPOLAR SOLVENT THEREFOR.

14. THE PRODUCT PRODUCED IN ACCORDANCE WITH THE PROCESS OF CLAIM 1.

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