US2865956A

US2865956A - Preparation of basic polyvalent metal salts of organic acids

Info

Publication number: US2865956A
Application number: US510502A
Authority: US
Inventors: Ellis Glyn; Hartley James; Moseley John Campbell
Original assignee: Shell Development Co
Current assignee: Shell Development Co
Priority date: 1954-09-27
Filing date: 1955-05-23
Publication date: 1958-12-23
Anticipated expiration: 1975-12-23
Also published as: FR1136852A; GB786167A; DE1086701B

Description

PREPARATION OF BASIC PO Stats Paton-1.:

LYVALENT METAL SALTS OF ORGANIC ACIDS Glyn Ellis, Rhntldlan,

assignors to Shell Development N. i

No Drawing. Application Serial No. 510,50

Rhyl, James Hartley, ral, and John Campbell Moseley,

Whitby, Wir- Liverpooi, England, Company, New York,

., a corporation of Delaware May 23, 1955 Claims priority, application Great Britain September 27, 1954 11 Claims. (Cl. 26

This invention relates to a method for preparaing basic polyvalent metal salts of oil-soluble organic acids,

particularly of oil-soluble petroleum naphthenic acids and alkyl-substituted sulfonic acids, salicylic acids.

More specifically, this invention relates to the prepara- I tion of mineral oil solutions of highly basic alkaline earth metal petroleum sulfonates, naphthenates and alkylsubstituted salicylates.

It is well known that when a metal salt of an oil-soluble organic acid is the acid, the mere use of an exc tains an amount prepared by the direct neutralization of ss of that theoretically required to replace the acidic hydrogen atoms of the acid.

These so-called basic salts have many uses, one of the detergents, improving compositions of which excess metal appears to be base used to neutralize imparts to the lubricating commonly known as the The alkaline reserve of a lubricating oil composition is an important factor in the effectiveness of the oil during operation, for

apparently the excess base neutralizes sulfur and other acids formed during combustion of the fuel, reducing corrosion of the motor and decreasing wear of piston rings and cylinders. salts is usually defined as the excess of metal in the basic salts over that quantity of metal whichwould be present in the normal (nonbasic) salts alone.

Thus a mixture of 0% basicity would denote a mixture containing the metal only in the form of the normal salt and a mixture content of metal in a by weight, and if the content of m If the particular mixture is (a) percent etal the mixture would have if it were present only as the normal salt is (b) percent by Weight then the basicit y of the mixture is erally, the proposed neutralization of the oil soluble or excess of the neutralizing agent.

processes have involved the direct ganic acid with a large However, it has been found that there is a definite limit to the amount of basicity which may be imported proposed methods, and none of t into these salts by the he proposals has been those in which the alkyl 'phatic carboxylic acids, such as composition during storage.

The process of the invention may be used to prepare highly basic' polyvalent metal salts of such acids, as, for example, the cyclic sulfur acids and carboxylicacids and the corresponding thio analogs. The process is particularly useful in the preparation of the highly basic salts of petroleum sulfonic acids, alkly-substituted salicyclic acids and naphthenic acids.

The sulfur acids include the sulfonic acids, sulfamic acids, sulfinic acids, thiosulfonic acids, and the like. A particularly desirable group of these acids are the sulfonic acids, which term includes the aliphatic-substituted cyclic. sulfonic acids in which the aliphatic substituent(s) contain a total of at least 12 carbon atoms, such as the alkylaryl sulfonic acids, alkylcycloaliphatic sulfonic acids, and alkyl-heterocyclic sulfonic acids, and aliphatic sultonic acids in which the aliphatic radical contains at least 12 carbon atoms. Specific examples of oil-soluble sulfonic acids include: petroleum sulfonic'acids; petrolatum sulfonic acids; monoand polywax substituted naphthalene sulfonic acids, substituted sulwonic acids such as cetyl-chlorobenzene sulfonic acids, cetylphenolnaphthalene sulfonic acids, substituted sulfonic acids such at petroleum naphthene sulfonic acids, cetyl-cyclopentyl sulfonic acids, monoand poly-wax substituted cyclo-hexyl sulfonic acids and the like.

The term, petroleum sulfonic acids, is intended to cover all sulfonic acids which are derived directly from petroleum products.

The carboxylic acids include the cyclic types, such as those containing a benzenoid structure, and an oil-solubilizing radical or radicals, such as alkyl radicals con taining a total of at least about 12 carbon atoms. The cyclic type of carboxylic acids also includes cycloalithe petroleum naphthenic acids, cetylcyclohexane carboxylic acids, dilauryl decahydronaphthalene carboxylic acids, di-octylcyclopentane carboxylic acids, etc. The thio-carboxylic acids-i. e., such acids as mentioned above in which one or both of the oxygen atoms of the carboxylic acid group are replaced by sulfurare also included.

A particularly desirable class of these carboxylic acids comprises thevalkl-substituted salicylic acids, especially groups are each long-chain alkyl groups. The most desirable class of these acids comprises those which have been which has been al'kylated with straight chain hydrocarbons with from about 8 to about 26, and preferably, with from 'about 10 to about 22 carbon atoms. Alkyl-substituted salicylic acids of the kinds prepared by the processes disclosed in copending application Serial Number The salts prepared by this methodderived from benzene or phenol with an alkali metal base, and then converting the alkali metal salt to the polyvalent metal salt by the metathetical reaction of the alkali metal salt with a polyvalent metal salt or base. The neutralization and/or metathesis reactionmaybe carried out ,using a solution of the oil soluble acid or alkali metal salt. in a mineral oil. If desired, the polyvalent metal salt may be prepared in situ in the reaction mixture which is to be used in reacting the polyvalent metal salt with-the polyvalent metal carbonate. In "such case,' the acld itself is used as the raw material, a polyvalent metal basebeing 'used to prepare meant. 'This aspect, of the process of the inventionwill be described inmore detail hereinafter.

'As the polyvalent metal base there may be used any basic compound of a polyvalent metal-by which is meant any compound of the polyvalent metal which is capable of neutralizing the oil-soluble organic'acid. Most suitable are the polyvalent metal oxides, hydroxides and salts of the rnetalwith a weak acid, such as the carbonate. -As the polyvalentmetal salt there my vbe used any water soluble salt'of the polyvalent metal with a strong mineral acid. The salts of the polyvalent metal with the hydrohalic acids-the metal halides-are preferred. Of this group, the chlorides are preferred, since they are most widely available and least expensive.

The polyvalent metal may be any alkaline earth metal-i. e., strontium, calcium and barium.

The reaction of the polyvalent metal salt and the polyvalent metal carbonate formed in situ is carried out in the presence of any monohydric lower aliphatic alcohol. Preferably, the alcohol used boils below about 140 C. A preferred class of the monohydric lower aliphatic alcohols, comprises'the alkanolscontainin g from 1 to about 6 carbon atoms. Examples of this class include methanol, ethanol, 1- and Z-propanols, n, secand tert-butyl alcohol, and the various C and C -alcohols, both straightand branched-chain in configuration. *It is preferred that the alcohol be substantially water-miscible, and complete water-miscibility is desirable.

Thepolyvalent metal salt may be directly reacted with the polyvalent metal carbonate, or a solution of the salt may be used. Preferably, fable solvent. Preferably, character, and readily fluid at the reaction temperatures used. Such hydrocarbons as benzene, toluene or xylene the salt-is dissolved in a suitthis solvent ishydrocarbon in are quite suitable, as are mixtures of oneor more of these compounds. Gasoline fractions are also suitable, as are mineral oil fractions generally, provided their viscosity is not too high. Where the product ofthe reaction is to be a solution of the highly basic polyvalent metal salt to be used as an additive for lubricating oil compositions, the solvent should be compatible with the base fluid of the composition contemplated. Lubricating oil fractions having a viscosity of from about 100 to about 400 seconds Saybolt Universal at 38 C. aresuitable. Alternatively, where a volatile solvent, such as xylene or a gasoline fraction, isused, the solvent may be removed at the end of the reaction and replaced with the mineral oil, to provide a mineral oil concentrate of the highly basic polyvalent metal salt of the acid for use in lubricating oilcompositions.

Where a solution of the polyvalent metal salt is used, care should be taken to use sufficient solvent to assure a readily fluid solution. In general, it is preferred that the salt'bedissolved in at least an equal weight of solvent, and it is preferred that it. be dissolved in from ture in any convenient manner.

carbon dioxide from exceeding 4 about one and one-half to about six times its weight of solvent.

The amount of the alcohol used should constitute at least five percent by weight of the organic acid, or alkali metal salt thereof, charged, and it is preferred that several times this amountfrorn about 10% to about 75 by weight of the organicacid or alkali metal saltbe used. In some cases, a weight of alcohol equal to the weight of acid or alkali metal salt may be desirable. it will seldom be necessary to use more than about twice as much alcohol as acid or alkali metal salt (by weight).

The polyvalent metal carbonate is formed in situ by passing carbon dioxide into the reaction mixture containing free polyvalent metal base. Thus, where the polyvalent metal salt of the acid is used as the raw material, polyvalent metal base is added and carbon dioxide passed into the mixture; where the aciditself is the raw material, polyvalent metal base is added in an amount sufficient to provide an excess of base over the amount theoretically required to neutralize the acid. In any case, the amount of base added should. be sufficient to provide at least two equivalents of free base in the reaction mixture per equivalent of acid charged. It is desirable that the excess of base be so chosen with respect to the amount of carbon dioxide to be charged that an excess of base remains after carbonation is complete. In general, there should be a residual excess of base equivalent to at least about 5% by weight of the excess of base originally charged. For economic reasons, the residual excess of base should not exceed about 15% by weight of the excess of base originally charged.

The carbon dioxide may be added to the reaction mix- Forexarnple, the carbon dioxide may be bubbled through the mixture, or by injecting the reaction mixture into an atmosphere of carbon dioxide. .It, is preferred that the carbon dioxide be injected into the strongly agitated reactionv mixture below the surface thereof, and that the reaction be conducted in a closed reactor, so that the reaction is also conducted in an atmosphere of carbon dioxide.

It has been found that, for a reaction mixture. containing a certain excess of polyvalent metal base, as carbon dioxide is introduced into the reactionmixture the basicity of the product gradually increases;;-then, as the'introduction of carbon dioxide continues, the basicity of the product suddenly begins to decrease. It has also been found that the stability of the product-Abe resistance of the product to precipitation of -the,;excess base during storage-begins to rapidly decline at this sarnepoint. This phenomenon occurs while-there isstill free polyvalent metalbase present in the mixture. This phenomenon, for which applicants at present have no sound explanation, is termed overcarbonation.

Several methods have been devised for phenomenon:

(a) The amount ofthe alcohol affects it; the use of larger proportions of the alcohol to the polyvalent metal salt substantially reduces the danger of overcarbonation. Use of proportions of the alcohol within the preferred range heretofore stated virtually precludes overcarbonation.

(b) Control of the amount of polyvalent metal base used and the amount (fraction) of that base reacted with carbon dioxide, so that a residual excess of base exists, also reduces the hazard of overcarbonation. This factor has been discussed previously.

(0) The rate of carbon dioxide addition, and the speed with which the bulk of the reaction mixture is contacted with the carbon dioxide also affect the possibility of over carbonation. It should be noted that overcarbonation may be a local as well as a general effect, so that the basicity of the product may be substantially reduced by allowing local overcarbonation to occur. Such may be prevented primarily by preventing the local amount of the local amount .of base,

preventing this and by providing locally a suificient amount of the alcohol. Effective dispersal of the gaseous and liquid components of the reaction mixture and correlation of the carbon dioxide addition rate with the degree of such dispersion is essential. Danger of local overcarbo-nation is also reduced by diluting the carbon dioxide with an inert gas. such as nitrogen, or air, or water vapor.

(d) It has also been found that the presence of substantial amounts of water in the reaction zone increases the danger of overcarbonation. Therefore, it is desirable that the reaction mixture be substantially anhydrous. The effect of the water on overcarbonaticn, has, however, been found to be much less where a large proportion of the alcohol is used. In the case where the weight ratio of the alcohol to the polyvalent metal salt-lies at about 50%-from about 35% to about 65%by weight of the organic acid or salt charged an amount of water amounting to as much as 15% by weight of the reaction mixture may be present without danger of overcarbo-nation. The proportion of water in the reaction mixture should, therefore, be maintained below this limit, where high alcohol/ polvvalent' metal salt weight ratios exist. Where the wei ht ratio is substantially below about 50%i. e., below about 25% the amount of water permissible is correspondingly lower, preferab y not more than about 2 to about percent by weight of the reaction mixture.

The reaction temoerature should not exceed about 70 C., and the attainment of reasonable reaction ratesrequires that temperatures of at least 20 C. be used. It is preferred that the reaction temperature lie between about 50 C. and about 70 C. If the temperature exceeds this limiting value, the rate of carbon dioxide absorption becomes so low that unfeasibly low reaction rates result. 7

Although the reaction may be carried sure above atmosrheric pressure, it has necessary to employ pressures above about five pounds per square inche, gauge. In most cases, operation at sub tantially atmospheric pressure is satisfactory.

The reaction time is not a critical factor in the process of the invention. In general, a reaction of at least /2 hour is required but it seldom exceeds about 4-5 hours. In most cases a reaction time of from about /2 hour to about 2 hours will be required.

The reaction mixture at the end of the reaction contains the highly basic polyvalent metal salt, some free polyvalent metal carbonate, some unreacted polyvalent metal base, the alcohol, posibly some water, hydrocarbon diluent (if such were used) and possibly other inorganic salts. The metal carbonate, metal base and other inor ganic salts are present in the solid form, and may be removed by centrifuging or filtering the reaction mixture. The alcohol and the water can be removed by distillation. A final filtration may be used to remove any traces of solid matter. Where a volatile hydrocarbon diluent was used, this. too maybe removed by distillation.

The process of the invention may be operated in a batch manner, or it may be operated in a cyclic, including continuous, manner. When the process is operated in a cyclic manner, the sludge obtained by filtration of .the reaction mixture, which sludge comprises primarily polyvalent metal carbonate and polyvalent metal base, may be used to neutralize the organic acid, or to metathetical- 1y replace the alkali metal from the salt thereof.

The followng examples are offered as illustrations of specific applications of the process of the invention:

out at any preseen found un- Example I A mixture of highly basic calcium alkyl salicylates (C C monoand di-alkyl salicylates) was prepared using a reaction vessel fitted with a stirrer, a refiux' condenser and means for bubbling carbon dioxide through the reaction mixture.

At the commencement of the process 1500 parts by weight of a 70% solution of alkyl salicylic acids in xylene (C C monoand di-alkyl salicylic acids containing reaction vessel was also provided with means amass some unreacted alkyl phenol and having an acid value about mg. KOH/g.) were placed in the reaction vessel, together with 5%, by weight of the acid solution, of methanol and 200 parts, by weight (i. e., four equivalents) of calcium hydroxide. The resulting mixture was then heated to C. with vigorous stirring (l500 2000 R. P. M.) and maintained at that temperature for /2 hour, whereupon carbon dioxide was bubbled through the reaction mixture, which was maintained at 60 C. and stirred vigorously throughout.

The reaction fmixture was then centifuged to remove any unreacted calcium hydroxide and any calcium carbonate produced during the course of the reaction and not utilized in producing the highly basic product, and the resulting liquid was distilled to remove the methanol, the water produced in the course of the reaction and some of the xylene. The remaining xylene solution was clarified by filtration and a quantity of spindle oil was then added to the clarified solution and the xylene removed therefrom by distillation leaving a concentrated spindle oil solution of the highly basic calcium alkyl salicylates.

The resulting mineral oil concentrate was used as additive for lubricating oils with which it was found to have excellent blend stability. Blend stability may also be determined by diluting a sample of the xylene solution with about 25 parts by volume of pentane. Blend stable material gives a completely clear and bright solution in this test. The highly basic calcium alkyl salicylates produced in the foregoing process yielded a pentane-diluted solution which was clear and bright when observations were made at the end of nine weeks.

The highly basic of about 226%; 3.87 and its total base and acid contents being 1.19 milliequivalents per gram respectively.

Example -II The process of Example I was repeated using 10%, by weight of the acid solution, of methanol and a reaction temperature of 60 C.; other conditions remaining substantially the same.

A highly basic product having a basicity of about 266% and a total base and acids content of 3.85 and 1.05 milli-equivalents per gram respectively was obtained. The resulting mineral oil concentrate had excellent blend stability with lubricating oils, the pentane-diluted solu tion being clear and bright when observations were made at the end of nine weeks.

- Example III A mixture of highly basic calcium alkyl salicylates (C C monoby a continuous process using two reaction vessels each fitted'with a stirrer and a reflux condenser and connected in series with an intermediate surge vessel. The second for bubbling carbon dioxide through the reaction mixture therein.

A slurry comprising a solution in xylene of C C monoand 'di-alkyl salicylic acids containing some unreacted alkyl phenol, 5% (by weight of the acid solution) of methanol and four equivalents of calcium hydroxide was charged into the first reaction vessel in which the temperature of the slurried reaction mixture was raised to 60 C. and maintained at that temperature for /2 hour, with constant vigorous stirring. The resulting mixture, which contained basic calcium alkyl salicylates of about 50% basicity, was then passed to the surge vessel from which it was fed continuously into the second reaction vessel in which the highly basic product was produced, in accordance with the invention, by forming calcium lcarbonate in situ in the reaction mixture by bubbling .in carbon dioxide with constant vigorous stirring. The feed rate of the reacton mixture from the surge vessel to the second reaction vessel was 0.35 volume per second and carbon dioxide was bubbled through at-therate of 6.9

gvolumcs per second, the reaction mixture being mainproduct was found to have a basicity and di-alkyl salicylates) was prepared in the manner described in was withdrawn con- Ex mplelV The continuous process of Example llll was repeated using by weight of the acid solution, of methanol and a reaction temperature of 60-65 C.. in both reaction vessels. The reaction mixture wasted from the surge vessel to the second reaction vessel at the rate of 0.5! volume per second and carbon dioxide was fed thereto at the rate of 8.3 volumes per second.

A highly basic product having a basicity of about 202% was obtained. The reaction mixture was worked up Example I to give a mineral.

oil concentratehavingexcellent blend stability with lubrieating oils.

The various highly basic calcium alkyl salicylates produced in accordance with theforegoing Examples I to IV were subjected to engine performance tests as additives for Cardon HVI 170 base lubricating oil. (Cardon HVI 170 oil is a Duosol extracted lubricating fraction of about 100 viscosity index and having a viscosity of 170 second Redwood No. l at 140 F.) Good results were obtained in the Gardner engine piston-cleanliness test (comparable to CRC Designation L1545.), the Fowler ring sticking test the Chevrolet L-4test (CRC Designation L-4-545) and the Petter engine LABA test (CRC L3545). In addition, these highly basic calcium alkyl salicylates were found to have excellent compatability and blend stability at 100 C. with a number of different lubricating oils, both in the absence and in the presence of other additives, such as octyl formol and Anglamol 304, a crankcase oil corrosion and oxidation inhibitor manufactured by The Lubrizol Corporation.

Example V A mixture of highly basic calcium alkyl salicylates (C -C monoand di-alkyl salicylates) was prepared using a reaction vessel fitted with a stirrer, a reflux condenser and a means of circulating a mixture of carbon dioxide and air through the reaction mixture.

At the commencement of the process 1,000 parts by weight of a 70% solution of alkylsalicylic acids (C -C monoand di-alkyl salicylic acids containing some unreacted alkyl phenol and having an acid value of 57 mg. KOH/ g.) in xylene were placed in the reaction vessel together with 10%, by weight of the acid solution, of methanolfi. e., 100 parts by weight) and 532 parts by weight of calcium hydroxide (i. e., 14 equivalents per equivalent of alkyl salicylic acids). The resulting mixture was stirred for minutes during which the temperature rose to 30 C. A mixture oi air and carbon dioxide containing (by volume) of carbon dioxide was then circulated through the reaction mixture, at the rate of about 300 liters/hour, the reaction mixture being vigorously stirred (1800 R. P. M.) and carbon dioxide being added to the cycling gas at the same rate as carbon dioxide was absorbed by the reaction mixture. The absorption was continued for 34 minutes during which time the reaction mixture absorbed 67 liters of carbon dioxide and its temperature rose from 30 C. to C. The mixture was then stirred for 2.4 hours before diluting with xylene and centrifuging to remove the unreacted solids. The resulting liquid was distilled to remove the methanol, the water produced in the reaction and some of the xylene. The remaining xylene solution was filtered and the xylene removed by'dis tillation leaving the highly basic calcium alkylsalicylates.

The highly basic product was found to have a basicity ell) of about 512%; its total base and acid contents being 5.12 and 0.836 milliequivalent per gram respectively.

Example VI The process of Example V was repeated using 575 parts by weight of the acid solution, 517 parts by weight of methanol, 58 parts of water and 88 parts of calcium hydroxide (4 equivalents per equivalent of alkyl salicylic acids). The reaction mixture was first stirred for 30 minutes during which time the temperature rose to 25 C, whereupon a 20% carbon dioxide/air mixture was circulated through the reaction mixture at the rate of 600 litres/hour for 16 minutes. During this period 12 litres of carbon dioxide were absorbed and the temperature of the reaction mixture rose to 32 C. The reaction mixture was stirred for a further 24 hours and the unreacted solids removed by centrifuging. The remaining liquid separated into two phases and the lower xylene phase containing the highly basic calcium alkylsalicylates was distilled to remove methancl, water and some xylene. The remaining xylene solution was filtered, a quantity of spindle oil was added and the remaining xylene was then removed leaving a concentrated spindle oil solution of highly basic calcium alkyl salicylates having a bascity of 226%.

Example VII The process of Example V was repeated using 971 parts by weight of the acid solution, 97 parts by weight of methanol and 151 parts by weight of calcium hydroxide (4 equivalents per equivalent of alkyl salicylic acids). The reaction mixture was heated to 50 C. and stirred at this temperature for 5 minutes. A 20% by volume carbon dioxide/air mixture was circulated through the reaction mixture at the rate of 600 liters/hour for 43 minutes. During this period the mixture absorbed 20 litres of carbon dioxide. The reaction mixture was stirred for 24 hours and the resulting highly basic calcium alkylsalicylates were obtained in the manner described in Example V. The product had a bascity of 222%.

Example VIII The process of Example V was repeated using a 35% solution in xylene of C -C monodi-alkyl salicylic acids having an acid value of about 30 mg. KOl-I/g. 1105 parts by weight of acid solution, 57.5 parts by weight of methanol and 87.5 parts by weight of calcium hydroxide (4 equivalents per equivalent of alkyl salicylic acids) were mixed together for 30 minutes. A 20% by volume carbon dioxide/air mixture was then circulated through the reaction mixture for 20 minutes during which time l2.2 litres of carbon dioxide were absorbed. The reaction mixture was then stirred for 24 hours and the highly basic calcium alkyl salicylates, which were obtained in the manner described in Example V, had a bascity of 185%.

The process of the present invention is also equally applicable to the preparation of other oil-soluble highly basic polyvalent metal salts of for example naphthenic acids and petroleum sulfonic acids, i. e., sulfonic acids or mixtures thereof which are derived directly from petroleum products, as is illustrated by the following examples:

Example IX 3.3 kilograms of naphthenic acids (acid value mg./KOH per gram) dissolved in 7.6 gallons of xylene were mixed with a slurry comprising 5.92 kilograms of calcium hydroxide and 7 kilograms of methanol in the reaction vessel used in Example 1. After mixing with continuous high speed stirring for 1 hour at 60 C., the system was fiushed free from air and about 40 cubic feet of carbon dioxide was bubbled through the reaction mixture over a period of 4 hours. The temperatre during the carbon dioxide treatment was 35- 40 The resulting reaction product was then filtered at cel filter aid to remove aeeaese room temperature through a filter pre-coated with Clarsuspended solids and the clear filtrite was then added to a light hydrocarbon oil base and the methanol and xylene were removed by distillation, together with the water formed during the reaction, to give a solution of highly basic calcium naphthenates in oil. The basicity of the product was about 1000%.

Example X 66 parts by weight of naphthenic acids (acid value 170 mg. K'OH/g.) dissolved in 600 parts by weight of xylene were mixed with a slurry comprising 72.7 parts of barium oxide and 70 parts of methanol in a reaction vessel as described in Example I. After mixing with continuous high speed stirring for 2 hours the system was flushed free from air and 0.323 cubic foot of carbon dioxide at 100 cm. Hg pressure and 20 C. was bubbled through the reaction mixture during a period of 12 minutes. The temperature during the carbon dioxide treatment was about 30 C.

The resulting reaction product was then filtered at room temperature through a filter precoated with Clarcel filter aid to remove suspended solids and the resulting xylene solution of highly basic barium naphthenates was found to have a basicity of 252% Example XI A mineral oil solution of highly basic calcium petroleum sulfonates was prepared from the acid oil obtained by sulfonating Cardon 65 (a solvent refined lubricating oil having a viscosity of about 65 seconds Redwood l at 140 F. and a viscosity index of about 95), the acid oil having an acid value of 21.5 mg./KOH per gram and a sulfonic acid content of 12.5% by weight.

The acid oil was neutralized with excess calcium hydroxide at 45 C., the calcium hydroxide being added in the form of a slurry with 99% methanol so as to yield a mixture containing 5 equivalents (based on the sulfonic acids content of the acid oil) of free calcium hydroxide and by weight of the acid oil, of methanol. Altogether 5.5% of calcium hydroxide by weight of the acid oil was added.

The resulting mixture was then stirred vigorously (3000 R. P. M.) at 40-42 time carbon dioxide was bubbled through the mixture, about 1.8% of carbon dioxide, by weight of the acid oil (75% equivalent based on the free calcium hydroxide) being absorbed. The reaction product yielded on filtration a 12.5% mineral oil solution of basic calcium petroleum sulfonates which was of good color and had a viscosity of 94 centistokes at 100 F. It had an alkalinity of 34 mg./KOH per gram, a sulfated ash con tent of 6.2% and a control ratio of 5.5.

The term, control ratio is defined as follows:

Alkalinity (mg. KOH/e'ram cf concentrate) Control ratlo Percent sulfate a. h

In the above expression, and as used throughout the present specification, the terms alkalinity and mean total base number, determined by electrometric titration according to American Society for Testing Ma terials, Designation D664-49. By this test, metal hydroxides, such as calcium hydroxide, and salts of metals with weak acids, such as calcium carbonate, have equal alkalinity on a mole-for-mole basis. Sulfate ash is determined by first igniting the sample until only ash and carbon remain, then heating with sulfuric acid at 260 C. until all of the carbon is oxidized, cooling, and reheating with sulfuric acid, and then igniting to 415 C. This test, the ofiicial name of which is Sulfated Residue," is detailed in American Society for Testing Materials, Designation D874-47T.

in this specification, the terms neutral salt, basic salt and highly basic salt have been used. These C. for 1 hour during which basicity at least 18 carbon atoms terms are intended to have the meaning set out for these terms in United States Patent No. 2,585,520, issued February 12, 1952, to Paul Van Ess and Hulbert Sipple. Briefly, the neutral salt, is the salt represented by the formula M(R),,, wherein M represents the metal, R represents the acid residue and x represents the valence of the metal. Thus, the neutral salts are those wherein all of the valences of the metal are satisfied by acid residues. The basic salts are those represented by the formula: M(OH),,(R) wherein M, and R have the meaning above and a+b= the valence of the metal. In these salts, one or more .but less than all of valences of the metal are satisfied by hydroxyl radicals, the remaining valence(s) by acid residues. The highly basic salts are those in which the basicity is greater than the basicity of the basic salts, the excess basicity being present in the form of the free base, or as a complex of the base with the sulfonate.

It will be noted that in the highly basic salts prepared according to this invention, the excess base is present primarily in the form of the metal carbonate, and not in the form of the metal hydroxide. These salts thus are essentially neutral in solutio-ni. e., they have a pH not substantially above 7.0yet are capable of neutralizing substantially larger amounts of acids than are the basic salts available heretofore. Highly basic salts of this kind are highly desirable for many applications where the pH of the salt must not vary substantially from 7.0, as where the salt is added to lubricant compositions containing other additives which may not tolerate a pH above about 7.0.

We claim as our invention:

1. A process for preparing an oil soluble highly basic metal salt of an organic acid, said process comprising reacting, as the only chemically reactive organic material, an oil soluble organic acid compound selected from the class consisting of (l) cyclic sulfur acids containing at least 18 carbon atoms per molecule, (2) cyclic carboxylic acids containing at least 17 carbon atoms per molecule and (3) salts of those acids with alkali metals and with alkaline earth metals, in the presence of at least 5% of the weight of said organic acid compound of a lower alkalol, with an alkaline earth metal carbonate formed in situ, by the reaction of carbon dioxide and an alkaline earth metal base, at least a part of said base being in the free state, thereafter removing said alkanol and any water present in the resulting mixture.

2. A process for preparing an oil soluble highly basic metal salt of an organic acid, said process comprising reacting, as the only chemically reactive organic material, an oil soluble organic acid compound selected from the class consisting of (l) cyclic sulfur acids containing per molecule, (2) cyclic carboxylic acids containing at least 17 carbon atoms per molecule and (3) salts of those acids with alkali metals and with alkaline earth metals, said oil soluble organic acid compound being in solution in a hydrocarbon oil, in the presence of at least 5% by weight of said organic acid compound of a lower alkanol, with an alkaline earth metal carbonate formed in situ by the reaction of carbon dioxide and an alkaline earth metal base, at least a portion of said metal base being in the free state, and thereafter removing said alkanol and any water present in the resulting mixture.

3. A process according to claim 2 wherein the amount of carbon dioxide reacted is less than the amount theoretically required to convert the free alkaline earth metal base to the corresponding alkaline earth metal carbonate.

4. A process for preparing an oil soluble highly basic metal salt of an alkyd-substituted salicylic acid, said process comprising mixing a hydrocarbon oil solution containing as the only chemically reactive material an oil soluble alkaline earth metal salt of an alkyl-substituted salicylic acid in which each alkyl group contains at least eight carbon atoms, with at least 5% of the weight of the said salt of a lower alkanol, and with an alkaline earth metal base,

all

'carbon dioxideto the resulting mixture'and thereafter removing said alkanoland any water present in the resulting mixture.

5. A process according to claim 4 wherein the alkaline earth metal salt of the alkyl-substituted salicylic acid is formed in situ by reaction of the alkyl-substituted salicylic acid and an all aline earth metal base.

6. A process for preparing an oil soluble highly basic metal salt of petroleum sulfonic acid, said process comprising mixing a hydrocarbon oil solution containing me only chemically reactive material an oil soluble alkaline earth metal salt of a petroleum sulfonic acid with at least 5% of the weight of the said salt of a lower alkanol, and with an alkaline earth metal base, at least 'a part of said base being in the free state, adding carbon dioxide to the resulting mixture and thereafter removing said alkanol and any water present in the resulting mixture.

7. A process according to claim Gwherein the alkaline.

earth metal salt of the petroleum sulfonic acid is formed in situ by reaction of the petroleum sulfonic acid and an alkaline earth metal base.

8. A process according to claim 6 wherein the am unt of carbon dioxide reacted is less than the amount theoretically required to convert the free alkaline earth metal base to the corresponding alkaline earth metal carbonate.

9. A process according to claim 6 wherein thealkal-ine earth metal salt of the petroleum sulfonic acid is formed in situ by reaction of an alkali metal-salt of the petroleum sulfonic acid and an alkaline earth metal base.

10. A process for preparing an oil soluble highlybasic metal salt of a naphthenic acid, said process comprising mixing a hydrocarbon oil solution containing as the only chemically reactive material an oil soluble alkaline earth metal salt of a naphthenic acid with at least 5% of the weight of the said salt of a lower alkanol, and with an alkaline earth metal base, at least'a part of-said base being in the free state, adding carbon-dioxide to the resulting mixture and-thereafter removing said alkanol and any water present in the resulting mixture.

11. A process according to claim 6 wherein the'alkaline earth metal salt of the naphthenic acid is formed in situ by reaction of the naphthenic acid and an alkaline earth metal base.

References Cited in the file of this patent UNITED STATES PATENTS 2,304,230 Archibald et al Dec. 8, 1942 2,617,049 Asseff et a1 Nov. 4, 1952 2,695,910 Asseff et a1 Nov. 30, 1954 2,767,209 Asseft et a1. Oct. 16, 1956 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent N0. 2 55653956 December 23 1958 Glyn Ellis et a1.

It is hereby certified that error appears in the above numbered petent requiring correction and that the said Letters Patent should read as corrected below.

Celumn 2 line 34, for "sulwonic" read sulfonic line 36 strike out "nephthaleme sulfcnic acids, substituted sulfcni'c acids" and insert instead suifcmc acids and the like; cyclcaliphatic sul'icnic acids line 37, for "such. sat" such as Signed and sealed this thdeysi June 1961,

SEAL Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents Notice of Adverse Decision in Interference In Interference No. 91,510 involving Patent No. 2,865,956, G. Ellis, J. Hartley and J. G. Moseley, Preparation of basic polyvalent metal salts of organic acids, final judgment adverse to the patentees Was rendered Feb. 20, 1963, as to claims 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[Oyficz'al Gazette April 30, 1.963.]

Claims

1. A PROCESS FOR PREPARING AN OIL SOLUBLE HIGHLY BASIC METAL SALT OF AN ORGANIC ACID, SAID PROCESS COMPRISING REACTING, AS THE ONLY CHEMICALLY REACTIVE ORGANIC MATERIAL, AN OIL SOLUBLE ORGANIC ACID COMPOUND SELECTED FROM THE CLASS CONSISTING OF (1) CYCLIC SULFUR ACIDS CONTAINING AT LEAST 18 CARBON ATOMS PER MOLECULE, (2) CUCLIC CARBOXYLIC ACIDS CONTAINING AT LEAST 17 CARBON ATOMS PER MOLECULE AND (3) SALTS OF THOSE ACIDS WITH ALKALI METALS AND WITH ALKALINE EARTH METALS, IN THE PRESENCE OF AT LEAST 5% OF THE WEIGHTG OF SAID ORGANIC ACID COMPOUND OF A LOWER ALKALOL, WITH AN ALKALINE EARTH METAL CARBONATE FORMED IN SITU, BY THE REACTION OF CARBON DIOXIDE AND AN ALKALINE EARTH METAL BASE, AT LEAST A PART OF SAID BASE BEING IN THE FREE STATE, THEREAFTER REMOVING SAID ALKANOL AND ANY WATER PRESENT IN THE RESULTING MIXTURE.