DE69213376T2 - Process for the preparation of overbased alkali metal salts - Google Patents

Abstract

The invention relates to a composition, comprising: at least one basic alkali metal salt of at least one hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl group is derived from a polyalkene having an M &cir& NOt n of at least 600, provided that when the organic compound is a sulfonic acid, the polyalkene has an M &cir& NOt n of at least 900; and provided that when the acidic organic compound is a mixture of acidic organic compounds containing a carboxylic acid and a sulfonic acid which has a hydrocarbyl group derived from a polyalkene having an M &cir& NOt n of less than 900, then the carboxylic acid comprises at least 10 % of the equivalents of the mixture.

Description

The invention relates to novel, overbased alkali metal salts of sulfonic acids, carboxylic acids, phenols or mixtures thereof.

Overbased alkali metal salts of many organic acids are well-known compounds and are useful in a number of applications, including lubricant compositions. The compounds are prepared by reacting an acidic material with a reaction mixture comprising basic metal compounds, an acidic organic compound, or salt, and an accelerant. The acidic material is generally carbon dioxide and the accelerators are usually lower alkyl alcohols, usually methanol, ethanol, or butanol, or lower alkyl acids.

In the overbasing process, the promoter improves the contact between the acidic material and the basic metal compound. An oil-soluble or dispersible form of the salt of the basic metal and the acidic material, usually a metal carbonate, is obtained. Methods for preparing these overbased compounds are well known.

CA-PS 1,055,700 relates to basic alkali sulfonate dispersions and processes. US-PS 4,326,972 relates to concentrates, lubricant compositions and processes for improving the fuel consumption of internal combustion engines. These compositions contain as essential components a special sulfurized composition and a basic alkali metal sulfonate. US-PS 4,904,401 relates to lubricating oil compositions. These compositions can contain a basic alkali metal salt of at least one sulfonic or carboxylic acid. US-PS 4,938,881 relates to lubricating oil compositions and concentrates. These compositions and concentrates contain at least one basic alkali metal salt of a sulfonic or carboxylic acid. US-PS 4,952,328 relates to lubricating oil compositions. These compositions contain from about 0.01 to about 2% by weight of at least one basic alkali metal salt of a sulfonic or carboxylic acid

It has been discovered that overbased alkali metal salts of high molecular weight acidic organic compounds can be prepared. One of the problems associated with working with high molecular weight material is the effective contacting of the acidic material to be overbased and the alkali metal compounds. In general, the low molecular weight, i.e. highly volatile, materials previously used are ineffective as accelerators for high molecular weight acidic organic compounds in providing the contact required to produce useful overbased compounds. Furthermore, the temperature used to overbase the high molecular weight acidic organic compounds usually exceeds the boiling point of the highly volatile accelerator. The high molecular weight alkali metal salts are useful in many applications, including lubricant applications. These compounds provide strongly basic components (alkali metal acidic material, usually alkali metal carbonate) together with high molecular weight solubilizing moieties.

According to a first aspect of the present invention, there is provided a process for producing basic alkali salts of acidic organic compounds comprising the steps:

(A) adding a portion of a basic alkali metal compound to a reaction mixture comprising a hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl moiety is derived from a polyalkene having a number average molecular weight of at least about 600, to form an alkali metal salt of the acidic compound, and removing free water from the reaction mixture and thereafter,

(B) simultaneous

(B-1) adding a further portion of a basic alkali metal compound to the reaction mixture;

(B-2) adding at least one acidic inorganic material or lower carboxylic acid material to the reaction mixture and

(B-3) removing water from the reaction mixture, wherein at least steps (B-1), (B-2) and (B-3) are carried out in the presence of an accelerator.

According to a second aspect of the present invention there is provided a process for preparing basic alkali metal salts of acidic organic compounds comprising the steps:

(A) adding a portion of a basic alkali metal compound to a reaction mixture comprising a hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl moiety is derived from a polyalkene having a number average molecular weight of at least 600 to form an alkali metal salt of an acidic compound and removing the free water from the reaction mixture and then

(B) adding a further portion of a basic alkali metal compound to the reaction mixture and

(C) adding at least one acidic inorganic material or lower carboxylic acid material to the reaction mixture, whereby water is removed from the reaction mixture, wherein at least steps (B) and (C) are carried out in the presence of an accelerator.

According to a third aspect of the present invention there is provided a composition comprising at least one borated overbased alkali metal salt, at least one hydrocarbyl substituted acidic organic compound wherein the hydrocarbyl moiety is derived from a polyalkene having a number average molecular weight of at least 600, and wherein the overbased alkali metal salt is prepared by a process according to the above process.

According to a fourth aspect of the present invention there is provided a composition comprising at least one borated overbased alkali metal salt of at least one acid selected from the group consisting of hydrocarbyl-substituted carboxylic acids or their anhydrides, or phosphoric acids or their anhydrides, wherein the hydrocarbyl moiety is derived from a polyalkene having a number average molecular weight of at least 900.

According to a fifth aspect of the present invention there is provided a process for producing basic alkali metal salts of acidic organic compounds comprising the steps:

(A) adding a portion of a basic alkali metal compound in at least a stoichiometric excess to a reaction mixture comprising a hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl radical is derived from a polyalkene having a number average molecular weight of at least 600, and an accelerator, and removing free water from the reaction mixture,

(B) adding at least one acidic inorganic material or lower carboxylic acid material to the reaction mixture, whereby the free water is removed from the reaction mixture,

(C) adding a further portion of the basic alkali metal compound to the reaction mixture and

(D) adding at least one acidic inorganic material or lower carboxylic acid material to the reaction mixture, whereby water is removed from the reaction mixture.

According to a sixth aspect of the present invention there is provided a composition comprising at least one borated overbased alkali metal salt of at least one hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl moiety is derived from a polyalkene having a number average molecular weight of at least 600, and wherein the overbased alkali metal salt is obtainable by the above methods.

The term "hydrocarbyl" includes hydrocarbon radicals as well as substantially hydrocarbon radicals. The term "substantially hydrocarbon" describes radicals that contain non-hydrocarbon radicals that do not alter the predominantly hydrocarbon character of the radical.

Examples of hydrocarbyl radicals include the following:

(1) Hydrocarbon radicals, ie aliphatic radicals (such as alkyl or alkenyl radicals), alicyclic radicals (such as cycloalkyl or cycloalkenyl radicals), aromatic-, aliphatic- and alicyclic-substituted aromatic radicals and the like, as well as cyclic radicals, where the ring is completed by another part of the molecule (ie, any two specified radicals can together form an alicyclic radical);

(2) substituted hydrocarbon radicals, i.e. those radicals containing non-hydrocarbon radicals which, in the context of this invention, do not alter the predominant hydrocarbon radical. Such radicals are known to the person skilled in the art (e.g. halogen atoms (especially chlorine and fluorine atoms), hydroxyl groups, alkoxy radicals, mercapto, alkylmercapto, nitro, nitroso, sulfoxy groups, etc.);

(3) Hetero groups, i.e., groups which, while predominantly hydrocarbon in character in the context of the present invention, contain other than carbon atoms in a ring or chain otherwise composed of carbon atoms. Suitable hetero atoms are known to those of ordinary skill in the art and include, for example, sulfur-oxygen-nitrogen atoms and such groups as pyridyl, furyl, thienyl, imidazolyl, etc. Generally, no more than about two, preferably no more than about 1, non-hydrocarbon groups are present per 10 carbon atoms in the hydrocarbyl group. Typically, no such non-hydrocarbon groups will be present in the hydrocarbyl group. Therefore, the hydrocarbyl group is a pure hydrocarbon. The present lubricant compositions contain a basic alkali metal salt of a carboxylic acid, sulfonic acid, phosphoric acid or a phenol. These basic salts are often referred to as overbased salts. The overbased salts are single-phase homogeneous Newtonian systems characterized by a metal content in excess of that which would be present according to the stoichiometry of metal and the particular organic compound reacted with the metal. The amount of excess metal is usually expressed by the metal ratio. The term "metal ratio" is the ratio of total equivalents of metal to equivalents of acidic organic compound. A neutral metal salt has a metal ratio of 1. A salt having 4.5 times the metal content as would be present in a normal salt has a metal excess of 3.5 equivalents, or a ratio of 4.5. In the present invention, these salts preferably have a metal ratio of about 1.5 to about 40, more preferably about 3 to about 30, and most preferably about 3 to about 25.

The overbased materials are prepared by reacting acidic material, typically carbon dioxide, with a mixture comprising a carboxylic acid, a sulfonic acid, a phosphoric acid or a phenol, a reaction medium comprising at least one inert organic solvent for said organic material, a stoichiometric excess of the metal compound described above, and an accelerator. Preferably, the overbased materials are prepared with carboxylic acids or sulfonic acids. The carboxylic and sulfonic acids may contain radicals derived from the polyalkenes. The polyalkene is characterized by a content of at least about 45, preferably at least about 50, more preferably about 60, up to about 300 carbon atoms, generally about 200, preferably about 100, more preferably about 80. In one embodiment, the polyalkene is characterized by a Mn value (number average molecular weight) of at least about 600. In general, the polyalkene is characterized by a Mn value of about 600, preferably about 700, preferably about 800, more preferably about 900 up to about 5000, preferably 2500, preferably 2000 and especially about 1500. In another embodiment, the Mn value varies between about 600, preferably about 700, more preferably about 800 up to about 1200 or 1300.

The abbreviation Mn is the general symbol for indicating the number average molecular weight. Gel permeation chromatography (GPC) is a method that provides both the weight average and number average molecular weight, as well as the overall molecular weight distribution of the polymer. For the purposes of this invention, a series of fractionated polymers of isobutene, polyisobutene, are used as calibration standards in GPC.

The techniques for determining the Mn and Mw values of polymers are well known and described in a number of books and articles. For example, methods for determining the Mn and molecular weight distribution of polymers are described in W. W. Jan, J. J. Kirkland and D. D. Bly, "Modern Size Exclusion Liquid Chromatographs", J. Wiley & Sons, Inc., 1979.

The polyalkenes include homopolymers and interpolymers of polymerizable olefin monomers of 2 to about 16 carbon atoms, usually 2 to about 6, preferably 2 to about 4, and especially 4 carbon atoms. The olefins can be monoolefins such as ethylene, propylene, 1-butene, isobutene and 1-octene or a polyolefin monomer, preferably diolefin monomers such as 1,3-butadiene and isoprene. The polyalkenes are prepared according to conventional methods.

Suitable carboxylic acids from which useful alkali metal salts can be prepared include aliphatic, cycloaliphatic and aromatic mono- and polybasic Carboxylic acids which are free of acetylenic bonds, including naphthenic acids, alkyl- or alkenyl-substituted cyclopentanoic acids, alkyl- or alkenyl-substituted succinic acids or anhydrides, alkyl- or alkenyl-substituted cyclohexanoic acids, and alkyl- or alkenyl-substituted aromatic carboxylic acids. The acids are generally prepared by reacting an unsaturated acid or derivative thereof with one of the polyalkenes or derivatives thereof described above. Generally, the unsaturated acid is an α, β-unsaturated carboxylic acid. Examples of these acids include maleic, itaconic, citraconic, glutaric, crotonic, acrylic and methacrylic acids or derivatives thereof. The derivatives of the unsaturated carboxylic acid include acids, anhydrides, metal or amine salts, lower alkyl esters (C₁₋₇ alkyl esters) and the like.

Examples of carboxylic acids include propylenyl-substituted glutaric acid, polybutenyl-substituted succinic acids derived from a polybutene (Mn approximately about 200-1500, preferably about 300 to 1500), propenyl-substituted succinic acids derived from polypropylenes (Mn approximately 200 to 1000), acids, acids formed by oxidation of petrolatum or of hydrocarbon waxes, available mixtures of 2 or more carboxylic acids and mixtures of these acids, their metal salts and/or their anhydrides.

In one embodiment, the carboxylic acids are aromatic carboxylic acids. One group of useful aromatic carboxylic acids are those of the formula

wherein the radical R₁ is an aliphatic hydrocarbyl radical preferably derived from the polyalkenes described above, the subscript a is a number in the range from 1 to about 4, usually 1 or 2, the radical Ar is an aromatic radical, each radical X is independently a sulfur or oxygen atom, preferably oxygen atom, the subscript b is a number in the range from 1 to about 4, usually 1 to or 2, the subscript c is a number in the range from 0 to about 4, usually 1 to 2, with the proviso that the sum of a, b and c does not exceed the number of valences of Ar. Examples of aromatic carboxylic acids include substituted benzoic, phthalic and salicylic acids.

The R₁ group is a hydrocarbyl group directly bonded to the aromatic group Ar. Examples of the R₁ groups include groups derived from polymerized olefins such as polyethylenes, polypropylenes, polybutylenes, ethylene-propylene copolymers, chlorinated olefin polymers, and oxidized ethylene-propylene copolymers.

The aromatic group Ar may have the same structure as any of the aromatic groups Ar discussed below. Examples of the aromatic groups useful herein include the polyvalent aromatic groups derived from benzene, naphthalene, anthracene, etc., preferably benzene. Specific examples of the Ar groups include phenylenes and naphthylenes, such as methylphenylenes, ethoxyphenylenes, isopropylphenylenes, hydroxyphenylenes, dipropoxynaphthylenes, etc.

Within this group of aromatic acids, a useful class of carboxylic acids is those with the general formula

in which the radical R₁ is as defined above, the index a is a number in the range from 1 to about 4, preferably 1 to about 3, the index b is a number in the range from 1 to about 4, preferably 1 to about 2, the index c is a number in the range from 0 to about 4, preferably 1 to about 2 and in particular 1, with the proviso that the sum of a, b and c does not exceed the value 6. Preferably b and c each have the value 1 and the carboxylic acid is a salicylic acid.

Particularly useful are overbased salts prepared from salicylic acids wherein the aliphatic hydrocarbon radicals (R₁) are derived from the polyalkenes described above, particularly polymerized lower 1-monoolefins such as polyethylene, polypropylene, polyisobutylene, ethylene/propylene copolymers and the like and have an average carbon content of about 50 to about 400 carbon atoms.

The above aromatic carboxylic acids are well known or can be prepared according to known methods. Carboxylic acids of the type represented by these general formulae and methods for preparing their neutral and basic metal salts are well known and are described, for example, in U.S. Patents 2,197,832, 2,197,835, 2,252,662, 2,252,664, 2,714,092, 3,410,798, and 3,595,791.

The sulfonic acids useful in preparing overbased salts (A) of the invention include the sulfonic and thiosulfonic acids. Generally, they are salts of sulfonic acids. The sulfonic acids include the mono- or polynuclear aromatic or cycloaliphatic compounds. The oil-soluble sulfonic acids can be represented for the most part by one of the following formulas: R2-T- (SO3)aH and R3-(SO3)bH, in which the T group is a cyclic nucleus such as benzene, naphthalene, antracene, diphenylene oxide, diphenylene sulfide, petroleum naphthenes, etc. Specific examples of the R2 and R3 groups are groups derived from petrolatum, saturated and unsaturated paraffin wax, and the polyalkenes described above. The T, R2 and R3 groups are each of the following formulas: and R₃ in the above general formulas can also contain other inorganic or organic radicals in addition to the radicals given above, such as hydroxyl groups, mercapto groups, halogen atoms, nitro, amino, nitroso, sulfide, disulfide groups, etc. In the above general formulas, the indices a and b have at least the value 1

Examples of these sulfonic acids include polybutene or polypropylene substituted naphthalene sulfonic acids, sulfonic acids obtained by treating polybutenes having a number average molecular weight (Mn) in the range of 700 to 5000, preferably 700 to 1200, more preferably about 1500 with chlorosulfonic acids, paraffin wax sulfonic acids, polyethylene (Mn approximately about 900 to 2000, preferably about 900 to 1500, more preferably 900 to 1200 or 1300) sulfonic acids, etc. Preferred sulfonic acids are mono-, di- and trialkylated benzene (including hydrogenated forms thereof) sulfonic acids. In another embodiment, the hydrocarbyl substituted acidic organic compound is a phenol. The phenol may be a coupled or uncoupled phenol, preferably a substituted phenol. The phenols may be alkylene-coupled, wherein the alkylene moiety contains from 1 to about 8 carbon atoms, preferably from 1 to about 4 carbon atoms, and most preferably 1 carbon atom. The alkylene-coupled phenols are prepared by known processes. Generally, the phenol is reacted with an aldehyde, usually formaldehyde or a formaldehyde precursor such as paraformaldehyde, at a temperature of from about 50 to about 175°C. A diluent may be used, such as a mineral oil, naphtha, kerosene, toluene or xylene.

The phenol may be a sulfur-coupled phenol prepared by reacting a sulfurizing agent with the phenol. The sulfurizing agent is generally elemental sulfur or a sulfur halide such as sulfur monochloride or sulfur dichloride, preferably sulfur dichloride. Sulfur-coupled phenols, also referred to as polyphenol sulfides, are generally prepared by reacting a sulfur halide with a phenol at a temperature of about 50 to about 75°C. A diluent may also be used as described above.

In a preferred embodiment, the phenol is substituted with one of the polyalkene radicals described above. Preferably, the phenol carries a polybutene or polypropylene radical having a number average molecular weight of about 700 to about 1200 or 1300.

The phenols useful in preparing the overbased salts of the invention can be represented by the general formula (R1)a-Ar-(OH)b, in which R1 is as defined above, Ar is an aromatic radical, subscripts a and b are independently numbers having a value of at least 1, the sum of a and b ranges from 2 to the number of displaceable hydrogen atoms in the aromatic nucleus or the nucleus of Ar. Preferably, a and b are independently numbers ranging from 1 to about 4, more preferably 1 to about 2. R1 and a are preferably such that an average of at least about 8 aliphatic carbon atoms are provided by the R1 radicals for each phenolic compound.

The term "phenol" used herein is not intended to limit the aromatic radical of phenol to benzene. Accordingly, the aromatic radical "Ar" in other formulas of this description and the claims may also be a mononuclear radical, such as a phenyl, a pyridyl, or a thienyl radical, or a polynuclear radical. The polynuclear residues can be of the condensed type, in which an aromatic nucleus is condensed to another nucleus at two points, such as in naphthyl, anthranyl esters, etc. The polynuclear residue can also be of the linked type, in which at least two nuclei (either mononuclear or polynuclear) are bound (linked) to one another via bridging bonds. These bridging bonds can be selected from the group consisting of alkylene bonds, ether bonds, keto bonds, sulfide bonds, polysulfide bonds of 2 to about 6 sulfur atoms, etc.

The number of aromatic nuclei, condensed, linked or both, in the Ar radical can play a role in determining the integer values of a and b. For example, if Ar contains a single aromatic nucleus, the sum of a and b is 2 to 6. If the Ar radical contains two aromatic nuclei, the sum of a and b is 2 to 10. If the Ar radical is trinuclear, the sum of a and b is 2 to 15. The value of the sum of a and b is limited by the fact that it cannot exceed the total number of replaceable hydrogen atoms in the aromatic nuclei or the nucleus of the Ar radical.

The accelerators, i.e. those materials that facilitate the incorporation of excess metal into the overbased material, improve the contact between the acidic material and the acidic organic compound (substrate to be overbased). Generally, the accelerator is a material that is slightly acidic and capable of forming a salt with the basic metal compound. The accelerator must also be an acid weak enough to be displaced by the acidic material, usually carbon dioxide. Generally, the accelerator has a pKa in the range of about 7 to about 10. A particularly comprehensive discussion of suitable accelerators can be found in U.S. Patents 2,777,874, 2,695,910, 2,616,904, 3,384,586 and 3,492,231.

In one embodiment, the accelerators include the phenolic accelerators. Phenolic accelerators include a variety of hydroxy-substituted benzenes and naphthalenes. A particularly useful class of phenols are the alkylated phenols of the type described in U.S. Patent 2,777,874, such as heptylphenols, octylphenols and nonylphenols. Mixtures of various accelerators are sometimes used. The inorganic acidic material and the lower carboxylic acid material which is reacted with the mixture of accelerator, basic metal compound, reaction medium and acidic organic compound is disclosed in the above-identified patents, such as U.S. Patent 2,616,904. Included in the known group of useful acidic materials are lower Carboxylic acids having 1 to about 8, preferably 1 to about 4, carbon atoms. Examples of these acids include formic acid, acetic acid, propionic acid, etc., preferably acetic acid. Useful inorganic acidic compounds include HCl, SO₂, SO₃, CO₂, H₂S, N₂O₃, etc., and are commonly used as the acidic materials. Preferred acidic materials are carbon dioxide and acetic acid, particularly carbon dioxide.

The alkali metals present in the overbased alkali metal salts include primarily lithium, sodium and potassium, with sodium being preferred. The overbased metal salts are prepared using a basic alkali metal compound. Examples of basic alkali metal compounds are hydroxides, oxides, alkoxides (typically those in which the alkoxy group contains up to 10 and preferably up to 7 carbon atoms), hydrides and amides of alkali metals. Thus, useful basic alkali metal compounds include sodium oxide, potassium oxide, lithium oxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium propoxide, lithium methoxide, potassium ethoxide, sodium butoxide, lithium hydride, sodium hydride, potassium hydride, lithium amide, sodium amide and potassium amide. Particularly preferred are sodium hydroxide and the lower sodium alkoxides (i.e., those containing up to 7 carbon atoms).

The overbased materials of the present invention can be prepared by known procedures. The procedures generally involve adding the acidic material to a reaction mixture comprising the hydrocarbyl-substituted acidic organic compound, the promoter and a basic alkali metal compound. These procedures are described in the following U.S. Patents: 2,616,904, 2,616,905, 2,616,906, 3,242,080, 3,250,710, 3,256,186, 3,274,135, 3,492,231 and 4,230,586.

In the present invention, the hydrocarbyl-substituted acidic organic materials have relatively high molecular weights. Generally, higher temperatures are used to accelerate the contact between the acidic material, the acidic organic compound and the basic alkali metal compound. The higher temperatures also accelerate the formation of the salt of the weakly acidic promoter by removing water. In preparing the overbased metal salts by the processes of the present invention, water must be removed from the reaction.

The reaction is generally carried out at temperatures from about 100°C to the decomposition temperature of the reaction mixture or the individual components of the reaction. The reaction can be carried out at temperatures below 100°C, such as 60°C, or above if a reduced pressure is applied. Generally, the reaction is carried out at a temperature of from about 110 to about 200°C, preferably 120 to about 175°C, and most preferably about 130 to about 150°C. Preferably, the reaction is carried out in the presence of a reaction medium including naphtha, mineral oil, xylenes, toluenes, and the like. In the present invention, water can be removed by applying a reduced pressure, by purging the reaction mixture with a gas such as nitrogen, or by removing the water as an azeotrope such as a xylene-water azeotrope. Generally, in the present invention, the acidic material is provided as a gas, usually carbon dioxide. The carbon dioxide, in addition to participating in the overbasing process, also serves to remove the water if the carbon dioxide is added at a rate that exceeds the rate at which the carbon dioxide is consumed in the reaction.

The overbased metal salts can be prepared in a batch or continuous process. The batch process involves the following steps: (A) adding a basic alkali metal compound to a reaction mixture comprising an acidic organic compound and removing free water from the reaction mixture to form an alkali metal salt of the acidic organic compound; (B) adding the basic alkali metal compound to the reaction mixture and removing free water from the reaction mixture; and (C) adding the acidic material to the reaction mixture while removing the water. Steps (B) and (C) are repeated until a product having the desired metal ratio is obtained.

A novel aspect of the present invention is the semi-continuous process for preparing the overbased alkali metal salts. The process involves: (A) adding at least one basic alkali metal compound to a reaction mixture comprising an alkali metal salt of an acidic organic compound and removing the free water from the reaction mixture; and (B) immediately thereafter (1) adding a basic alkali metal compound to the reaction mixture; (2) adding an inorganic acidic material or lower carboxylic acid material to the reaction mixture; and (3) removing the water from the reaction mixture. The inventors have found that the addition of the basic alkali metal compounds together with the inorganic material or the lower carboxylic acid material can be carried out by a process in which the addition is carried out continuously, in addition to removing the water. This process shortens the processing time of the reaction.

The term "free water" refers to the amount of water that can be easily removed from the reaction mixture. This water is typically removed by azeotropic distillation. The water that remains in the reaction mixture is considered to be coordinated, associated, or solvated. The water may be in the form of water of hydration. Some basic alkali metal compounds may be added to the reaction mixture as aqueous solutions. The excess water or free water added with the basic alkali metal compound is then usually removed by azeotropic distillation or stripping under reduced pressure.

Water forms during the overbasing process and is desirably removed as it forms to minimize or eliminate the formation of oil-insoluble metal carbonates. During the above overbasing process, the amount of water present prior to the addition of the inorganic acidic material or lower carboxylic acid material (steps (C) and B-1 above) is less than about 30% by weight of the reaction mixture, preferably 20% by weight, and more preferably 10% by weight. Generally, the amount of water present after the addition of the inorganic acidic material or lower carboxylic acid material is up to about 4% by weight of the reaction mixture, preferably about 3% by weight, and more preferably about 2% by weight.

When the process involves the simultaneous addition of the basic alkali metal compounds and the inorganic acidic material or lower carboxylic acid material, the hydrocarbyl moiety of the acidic organic compound is derived from the polyalkenes described above. The measures concerning the polyalkene of the sulfonic acid and the mixture of the acidic organic compound are only preferred embodiments.

In another embodiment, the overbased alkali metal salts are borated overbased alkali metal salts. Borated overbased metal salts are prepared by reacting a boron compound with the basic alkali metal salt. Boron compounds include boron oxide, boron oxide hydrate, boron trioxide, boron trifluoride, boron tribromide, boron trichloride, boric acid (boron-containing acid), such as boronic acid, boric acid (orthoboric acid), tetraboric acid and metaboric acid, boron hydrides, boronamides and various esters of Boric acids. The boric acid esters are preferably lower alkyl (1 to 7 carbon atoms) esters of boric acid (orthoboric acid). Preferably, the boron compounds are boric acid (orthoboric acid). Generally, the overbased metal salt is reacted with a boron compound at about 50 to about 250°C, preferably 100 to about 200°C. The reaction can be carried out in the presence of a solvent such as mineral oil, naphtha, kerosene, toluene or xylene. The overbased metal salt is reacted with a boron compound in amounts to provide at least about 0.5% by weight, preferably about 1 to about 5% by weight, more preferably about 4% by weight, and most preferably about 3% by weight boron in the composition.

The following examples illustrate the overbased alkali metal salts of the present invention and methods for their preparation. In the examples and elsewhere in the specification, unless otherwise indicated, temperatures are in degrees Celsius, amounts are in weight percent, and pressure is at atmospheric pressure.

example 1

A reaction vessel is charged with 1122 parts (2 equivalents) of a polybutenyl substituted succinic anhydride derived from a polybutene (Mn = 1000), 105 parts (0.4 equivalents) of tetrapropenylphenol, 1122 parts of xylene and 100 g of a 100% neutral mineral oil. The mixture is stirred under nitrogen and heated to 80°C. Then 580 parts of a 50% aqueous solution of sodium hydroxide are added to the reaction vessel over 10 minutes. The mixture is heated from 80 to 120°C over 1.3 hours. The water is removed by azeotropic distillation and the temperature is raised to 150°C over 6 hours, collecting 300 parts of water. (1) The reaction mixture is cooled to 80°C where 540 parts of a 50% aqueous solution of sodium hydroxide are added to the vessel. (2) The reaction mixture is heated to 140°C over 1.7 hours and the water is removed under reflux conditions. (3) The reaction mixture is carbonated at 0.028 m³/h (1 standard cubic foot per hour; scfh) for 5 hours while removing the water. Steps (1) - (3) are repeated using 560 parts of an aqueous sodium hydroxide solution. Steps (1) - (3) are repeated using 640 parts of an aqueous sodium hydroxide solution. Steps (1) - (3) are then repeated with an additional 640 parts of a 50% aqueous sodium hydroxide solution. The reaction mixture is cooled and 1000 parts of 100 neutral mineral oil are added to the reaction mixture. The reaction mixture is stripped under reduced pressure at about 30 mm Hg at 115ºC. The residue is filtered through diatomaceous earth. The filtrate has a Total base number of 361 (theory 398), 43.4% sulphurised ash (theory 50.3), 39.4% oil and a specific gravity of 1.11.

Example 2

A reaction vessel is charged with 700 parts of 100 neutral mineral oil, 700 parts (1.25 equivalents) of the succinic anhydride of Example 1 and 200 parts (2.5 equivalents) of a 50% aqueous sodium hydroxide solution. The reaction mixture is stirred and heated to 80°C where 66 parts (0.25 equivalents) of tetrapropenylphenol are added to the reaction vessel. The reaction mixture is heated from 80 to 140°C over 2.5 hours in a stream of nitrogen and 40 parts of water are removed. Carbon dioxide (28 parts, 1.25 equivalents) is added over 2.25 hours at a temperature of 140 to 165°C. The reaction mixture is purged with 0.056 m³/h (2 scfh) of nitrogen and a total of 112 parts of water are removed. The reaction temperature is lowered to 115ºC and the reaction mixture is filtered through diatomaceous earth. The filtrate has 4.06% sodium (theory 3.66), a total base number of 89, a specific gravity of 0.948 and 44.5% oil.

Example 3

A reaction vessel is charged with 281 parts (0.5 equivalents) of succinic anhydride from Example 1, 281 parts of xylene, 26 parts of tetrapropenyl substituted phenol, and 250 parts of 100 neutral mineral oil. The reaction mixture is heated to 80°C and 272 parts (3.4 equivalents) of an aqueous sodium hydroxide solution are added to the reaction mixture. The reaction mixture is purged with 0.028 m³/h (1 scfh) of nitrogen and the reaction temperature is raised to 148°C. The reaction mixture is then purged with 0.028 m³/h (1 scfh) of carbon dioxide for 1 hour and 25 minutes, collecting 150 parts of water. The reaction mixture is cooled to 80°C where 272 parts (3.4 equivalents) of the above sodium hydroxide solution are added to the reaction mixture and the mixture is purged with 0.028 m³/h (1 scfh) of nitrogen. The reaction temperature is increased to 140°C where the reaction mixture is purged with 0.028 m³/h (1 scfh) of carbon dioxide for 1 hour and 25 minutes, collecting 150 parts of water. The reaction temperature is reduced to 100°C and 272 parts (3.4 equivalents) of the above sodium hydroxide solution are added and the mixture is purged with 0.028 m³/h (1 scfh) of nitrogen. The reaction temperature is raised to 148ºC and the reaction mixture is purged with 0.028 m³/h (1 scfh) carbon dioxide for 1 hour and 40 minutes, using 160 parts water The reaction mixture is cooled to 90°C and 250 parts of 100% neutral mineral oil are added to the reaction mixture. The reaction mixture is stripped under reduced pressure at 70°C and the residue is filtered over diatomaceous earth. The filtrate contains 50.0% sodium sulfate ash (53.8%) according to ASTM-D-874, a total base number of 408, a specific gravity of 1.18 and 37.1% oil.

Example 4

A reaction vessel is charged with 700 parts of the product of Example 3. The reaction mixture is heated to 75°C where 340 parts (5.5 equivalents) of boric acid are added over 30 minutes. The reaction mixture is heated to 110°C over 45 minutes and the reaction temperature is maintained for 2 hours. A 100% neutral mineral oil (80 parts) is added to the reaction mixture. The reaction mixture is purged with 0.028 m3/h (1 scfh) of nitrogen at 160°C for 30 minutes collecting 95 parts of water. Xylene (200 parts) is added to the reaction mixture and the reaction temperature is maintained at 130-140°C for 3 hours. The reaction mixture is stripped at reduced pressure at 150ºC and 20 mm Hg. The residue is filtered over diatomaceous earth. The filtrate contains 5.84% boron (C theory 6.43) and 33.1% oil. The residue has a total base number of 309.

Example 5

A reaction vessel is charged with 224 parts (0.4 equivalents) of the succinic anhydride of Example 1, 21 parts (0.08 equivalents) of a tetrapropenylphenol, 224 parts xylene, and 224 parts of 100 neutral mineral oil. The mixture is heated and 212 parts (2.65 equivalents) of a 50% aqueous sodium hydroxide solution are added to the reaction vessel. The reaction temperature is raised to 130ºC and 41 parts of water are removed while purging with 0.028 m³/h (1 scfh) of nitrogen. The reaction mixture is then purged with 0.028 m³/h (1 scfh) of carbon dioxide for 1.25 hours. The sodium hydroxide solution (432 parts, 5.4 equivalents) is added over 4 hours under a carbon dioxide purge of 0.014 m³/h (0.5 scfh) at 130ºC. During the addition, 301 parts of water are removed from the reaction vessel. The reaction temperature is increased to 150ºC and the carbon dioxide purge rate is increased to 0.042 m³/h (1.5 scfh) and maintained for 1 hour and 15 minutes. The reaction mixture is cooled to 150ºC and purged with nitrogen at 0.028 m³/h (1 scfh) while 176 parts of oil are added to the reaction mixture. The reaction mixture is purged with 0.0504 for 2.5 hours. m³/h (1.8 scfh) of nitrogen and the mixture is then filtered through diatomaceous earth. The filtrate contains 15.7% sodium and 39% oil. The filtrate has a total base number of 380.

Example 6

A reaction vessel is charged with 561 parts (1 equivalent) of succinic anhydride from Example 1, 52.5 parts (0.2 equivalent) of a tetrapropenylphenol, 561 parts of xylene and 500 parts of a 100 neutral mineral oil. The mixture is heated to 50°C under nitrogen and 373.8 parts (6.8 equivalents) of potassium hydroxide and 299 parts of water are added to the mixture. The reaction mixture is heated to 135°C removing 145 parts of water. The azeotropic distillate is clear. Carbon dioxide is added to the reaction mixture at 0.028 m³/h (1 scfh) for 2 hours azeotropically removing 195 parts of water. The reaction mixture is cooled to 75°C where a second portion of 373.8 parts potassium hydroxide and 150 parts water are added to the reaction vessel. The reaction mixture is heated to 150°C where 70 parts water are azeotropically removed. Carbon dioxide (0.028 m³/h (1 scfh)) is added over 2.5 hours where 115 parts water are azeotropically removed. The reaction mixture is cooled to 100°C where a third portion of 373.8 parts potassium hydroxide and 150 parts water are added to the reaction vessel. The reaction mixture is heated to 150°C where 70 parts water are removed. The reaction mixture is purged with 0.028 m³/h (1 scfh) carbon dioxide for 1 hour where 30 parts water are removed. The reaction temperature is reduced to 70ºC. The reaction mixture is again heated to 150ºC under nitrogen. At 150ºC, the reaction mixture is purged with 0.028 m³/h (1 scfh) carbon dioxide for 2 hours, removing 80 parts of water. The carbon dioxide is replaced with a nitrogen purge and 60 parts of water are removed. The reaction mixture is then purged with 0.028 m³/h (1 scfh) carbon dioxide for 3 hours, removing 64 parts of water. The reaction mixture is cooled to 75ºC where 500 parts of a 100% neutral mineral oil are added to the reaction mixture. The reaction mixture is stripped under reduced pressure at 115ºC and 25 mm Hg. The residue is filtered over diatomaceous earth. The filtrate contains 35% oil and has a base number of 322.

Example 7

An overbased sodium salt of a substituted phenol is prepared according to the procedure of Example 1 using 994 parts (1 equivalent) Polybutenyl-substituted phenol derived from a polybutene (Mn=900) reacted with 1440 parts (18 equivalents) of a 50% aqueous sodium hydroxide solution.

Example 8

An overbased sodium sulfonate is prepared according to the procedure described in Example 6 using 980 parts (1 equivalent) of a sodium polypropenyl-substituted benzene sulfonate derived from a polypropene (Mn = 800) and 800 parts (10 equivalents) of a 50% aqueous sodium hydroxide solution.

Example 9

An overbased lithium carboxylate is prepared according to the procedure described in Example 1 using 1072 parts (1 equivalent) of a polybutenyl carboxylate prepared by reacting polybutenyl chloride derived from a polybutene (Mn = 1000) and acrylic acid, which is reacted with 756 parts (18 equivalents) of lithium hydroxide monohydrate.

Example 10

An overbased sodium sulfonate carboxylate is prepared according to the procedure described in Example 1 using 562 parts of the succinic anhydride from Example 1 and 479 parts of a polybutenyl substituted sulfonic acid derived from a polybutene (Mn=800) and 1632 parts (20.4 equivalents) of a 50% aqueous sodium hydroxide solution

Lubricant compositions

The overbased alkali metal salts of the present invention can be used in lubricants or in concentrates, by themselves or in combination with other known additives, including, but not limited to, dispersants, detergents, antioxidants, antiwear agents, extreme pressure agents, emulsifiers, demulsifiers, antifoams, friction modifiers, antirust agents, corrosion inhibitors, viscosity improvers, pour point depressants, paints and solvents to improve handling and may include alkyl and/or aryl hydrocarbons. These additives can be present in various amounts depending on the requirements of the final product.

Dispersants include, but are not limited to, hydrocarbon-substituted succinimides, succinamides, carboxylic acid esters, Mannich dispersants, and mixtures thereof, as well as materials that act as both dispersants and viscosity improvers. The dispersants include nitrogen-containing carboxylic acid dispersants, ester dispersants, Mannich dispersants, or mixtures thereof. Nitrogen-containing carboxylic acid dispersants are prepared by reacting a hydrocarbyl carboxylic acid acylating agent (usually a hydrocarbyl-substituted succinic anhydride) with an amine (usually a polyamine). Ester dispersants are prepared by reacting a polyhydroxy compound with a hydrocarbyl carboxylic acid acylating agent. The ester dispersant may be further treated with an amine. Mannich dispersants are prepared by reacting a hydroxyaromatic compound with an amine and aldehyde. The above-mentioned dispersants can be post-treated with reagents such as urea, thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydride, nitriles, epoxides, boron compounds, phosphorus compounds and the like.

Detergents include, but are not limited to, Newtonian or non-Newtonian, neutral or basic salts of alkaline earth or transition metals with one or more hydrocarbyl sulfonic acid, carboxylic acid, phosphoric acid, thiophosphoric acid, dithiophosphoric acid, phosphinic acid, thiophosphinic acid, sulfur-coupled phenol or phenol. Basic salts are salts that contain a stoichiometric excess of metal per acid function.

Examples of auxiliary extreme pressure agents and corrosion and oxidation inhibiting agents which may be included in the lubricants of the invention are chlorinated aliphatic hydrocarbons such as chlorinated wax, organic sulfides and polysulfides such as benzyl disulfide, bis-(chlorobenzyl)-disulfide, dibutyl tetrasulfide, the sulfurized methyl ester of oleic acid, sulfurized alkylphenol, sulfurized dipentene, and sulfurized terpene, phosphorus-sulfurized hydrocarbons such as the reaction product of a phosphorus sulfide with turpentine or methyl oleate, phosphorus esters including mainly dihydrocarbon and trihydrocarbon phosphites such as dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenyl phosphite, dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite, dimethylnaphthyl phosphite, Oleyl-4-pentylphenyl phosphite, polypropylene-substituted (molecular weight 500) phenyl phosphite, diisobutyl-substituted phenyl phosphite, metal thiocarbamates such as zinc dioctyldithiocarbamate and barium heptylphenyldithiocarbamate, boron-containing Compounds including boric acid esters, molybdenum compounds, Group II metal dithiophosphates such as zinc dicyclohexyl dithiophosphate, zinc dioctyl dithiophosphate, barium di(heptylphenyl) dithiophosphate, cadmium dinonyl dithiophosphate, and the zinc salt of a dithiophosphoric acid prepared by reacting phosphorus pentasulfide with an equimolar mixture of isopropyl alcohol and n-hexyl alcohol.

Viscosity improvers include, but are not limited to, polyisobutenes, polymethacrylate acid esters, polyacrylate acid esters, diene polymers, polyalkylstyrenes, alkenyl-aryl conjugated diene copolymers, polyolefins, and multifunctional viscosity improvers.

Pour point depressants are a particularly useful type of additive often included in the lubricating oils described herein. See, for example, page 8 of "Lubricant Additives" by C. V. Smalheer and R. Kennedy Smith (Lesius-Hiles Company Publishers, Cleveland, Ohio, 1967).

Antifoam agents for preventing or reducing the formation of stable foam including silicones or organic polymers. Examples of these additional antifoam compositions are described in Henry T. Kerner, "Foam Control Agents", Noyes Data Corporation, pages 125-162, 1976.

These and other additives are described in more detail in U.S. Patent No. 4,582,618 (column 14, lines 52 through column 17, line 16, inclusive). Other additives that can be used in conjunction with the present invention are also described.

The concentrate may contain from 0.01 to 90% by weight of the overbased alkali metal salt. The overbased alkali metal salts may be present in the final product, mixture or concentrate (in a lesser amount, i.e., up to 50% by weight) in any amount effective to act as a detergent, but is preferably present in the oil of lubricating viscosity, hydraulic fluids, fuel oils, gear oils or automatic transmission oils in an amount of from 0.1 to about 10% by weight, preferably from 0.25 to about 2% by weight, and most preferably from about 0.50 to about 1.25% by weight.

The lubricant compositions and methods for their preparation use an oil of lubricating viscosity, including natural or synthetic lubricating oils and mixtures thereof. Natural oils include animal oils, vegetable oils, Mineral lubricating oils, solvent or acid treated mineral oils, and oils derived from coal or shale. Synthetic lubricating oils include hydrocarbon oils, halogen substituted hydrocarbon oils, alkylene oxide polymers, esters of carboxylic acids and polyols, esters of polycarboxylic acids and alcohols, esters of phosphorus-containing acids, polymeric tetrahydrofurans, silicone based oils and mixtures thereof.

Specific examples of oils with lubricating viscosity are described in US-PS 4,326,972 and EP-A-0 107 282.

A basic, brief description of lubricating base oils can be found in the article by D. V. Brock, "Lubricant Base Oils," Lubricant Engineering, Volume 43, pages 184-185, March 1987. This article is incorporated herein by reference as to its disclosure concerning lubricating oils. A description of oils of lubricating viscosity can be found in U.S. Patent No. 4,582,618 (column 2, line 37 through column 3, line 63, inclusive).

The following examples illustrate the lubricant compositions of the present invention. The amount of each component in Examples AC indicates the amount of oil-containing product of the additives indicated.

The lubricating oil compositions of the present invention exhibit a reduced tendency to deteriorate under conditions of use, thereby reducing rust and corrosive wear and the formation of such undesirable deposits as varnish, sludge, carbonaceous materials, and resinous materials which tend to adhere to various engine parts and reduce the efficiency of the engines. Lubricating oils can also be formulated according to this invention which result in improved fuel economy when used in crankcases of passenger vehicles.

Although the invention has been explained with reference to its preferred embodiments, it will be apparent that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims.

Claims (50)

1. A process for the preparation of basic alkali metal salts of acidic organic compounds comprising the steps: (A) adding a portion of a basic alkali metal compound to a reaction mixture comprising a hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl moiety is derived from a polyalkene having a number average molecular weight of at least 600, to form an alkali metal salt of the acidic compound, and removing the free water from the reaction mixture and then, (B) simultaneous (B-1) adding a further portion of a basic alkali metal compound to the reaction mixture, (B-2) adding at least one acidic inorganic material or lower carboxylic acid material to the reaction mixture and (B-3) removing water from the reaction mixture, wherein at least steps (B-1), (B-2) and (B-3) are carried out in the presence of an accelerator. 2. The method of claim 1, wherein the accelerator has a pKa value of 7 to 10. 3. The process according to claim 1 or 2, wherein the reaction temperature is 110°C to 200°C. 4. The process according to claim 1 or 2, wherein the reaction temperature is 130°C to 150°C. 5. A process according to any one of claims 1 to 4, wherein the accelerator is an alkyl or alkenylphenol or a nitroalkane. 6. A process according to any one of claims 1 to 5, wherein the basic salt has a metal ratio of 1.5 to 40. 7. A process according to any one of claims 1 to 6, wherein the acidic organic compound is a sulfonic or carboxylic acid. 8. A process according to any one of claims 1 to 7, wherein the metal salt is a sodium or potassium salt. 9. A method according to any one of claims 1 to 8, wherein the overbased salt is an overbased succinate. 10. The method of any one of claims 1 to 9, wherein the overbased salt is an overbased sodium succinate. 11. The process according to any one of claims 1 to 10, wherein the polyalkene has a Mn value of 800 to 5000. 12. The process of claim 11, wherein the hydrocarbyl radical is derived from a polyalkene having a Mn of at least 900. 13. The process according to any one of claims 1 to 12, wherein the polyalkene is polybutene. 14. Process for the preparation of basic alkali metal salts of acidic organic compounds comprising the steps: (A) adding a portion of a basic alkali metal compound to a reaction mixture comprising a hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl moiety is derived from a polyalkene having a number average molecular weight of at least 600, to form an alkali metal salt of an acidic compound, and removing the free water from the reaction mixture and then (B) adding a further portion of a basic alkali metal compound to the reaction mixture and (C) adding at least one acidic inorganic material or lower carboxylic acid material to the reaction mixture, whereby water is removed from the reaction mixture, wherein at least steps (B) and (C) are carried out in the presence of an accelerator. 15. The method of claim 14, wherein steps (B) and (C) are repeated at least once. 16. The method of claim 14 or 15, wherein the accelerator has a pKa value of 7 to 10. 17. A process according to any one of claims 14 to 16, wherein the accelerator is an alkyl or alkenylphenol or a nitroalkane. 18. A process according to any one of claims 14 to 17, wherein the reaction temperature is 110°C to 200°C. 19. A process according to any one of claims 14 to 17, wherein the reaction temperature is 130°C to 150°C. 20. The method according to any one of claims 14 to 19, wherein the basic alkali metal compound is a basic sodium compound. 21. The method according to any one of claims 14 to 20, wherein the acidic organic composition contains at least one carboxylic acid. 22. A process according to any one of claims 14 to 21, wherein the hydrocarbyl radical is derived from a polyalkene having a Mn value of 900 to 5000. 23. A composition comprising at least one borated overbased alkali metal salt of at least one hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl moiety is derived from a polyalkene having a number average molecular weight of at least 600 and wherein the overbased alkali metal salt is prepared by a process according to any one of claims 14 to 22. 24. The composition of claim 23, wherein the basic salt has a metal ratio of 1.5 to 40. 25. The composition of claim 23, wherein the basic salt has a metal ratio of 9 to 25. 26. A composition according to any one of claims 23 to 25, wherein the polyalkene has a Mn value of 800 to 5000. 27. A composition according to any one of claims 23 to 25, wherein the polyalkene has a Mn value of 900 to 1500. 28. A composition according to any one of claims 23 to 27, wherein the polyalkene is polybutene. 29. A composition according to any one of claims 23 to 28, wherein the basic salt is an overbased succinate. 30. A composition according to any one of claims 23 to 28, wherein the basic salt is an overbased sodium succinate. 31. A composition prepared according to the process of any one of claims 1 to 13 comprising at least one borated overbased alkali metal salt of at least one acid selected from the group consisting of hydrocarbyl substituted carboxylic acids or their anhydrides, or phosphoric acids or their anhydrides, wherein the hydrocarbyl radical is derived from a polyalkene having a number average molecular weight of at least 900. 32. The composition of claim 31, wherein the alkali metal is sodium. 33. A composition according to claim 31 or 32, wherein the acid is at least one carboxylic acid or acid anhydride. 34. A process for preparing basic alkali metal salts of acidic organic compounds comprising the steps: (A) adding a portion of a basic alkali metal compound at least in a stoichiometric excess to a reaction mixture comprising a hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl radical is derived from a polyalkene having a number average molecular weight of at least 600 and an accelerator, and removing free water from the reaction mixture, (B) adding at least one acidic inorganic material or lower carboxylic acid material to the reaction mixture, whereby the free water is removed from the reaction mixture, (C) adding a further portion of the basic alkali metal compound to the reaction mixture and (D) adding at least one acidic inorganic material or lower carboxylic acid material to the reaction mixture, whereby water is removed from the reaction mixture. 35. The method of claim 34, wherein steps (C) and (D) are repeated at least once. 36. The method of claim 34 or 35, wherein the accelerator has a pKa value of 7 to 10. 37. A process according to any one of claims 34 to 36, wherein the accelerator is an alkyl or alkenyl phenol or a nitroalkane. 38. A process according to any one of claims 34 to 37, wherein the basic alkali metal compound is a basic sodium compound. 39. A process according to any one of claims 34 to 38, wherein the acidic organic composition contains at least one carboxylic acid. 40. A composition comprising at least one borated overbased alkali metal salt of at least one hydrocarbyl-substituted acidic organic compound, wherein the hydrocarbyl moiety is derived from a polyalkene having a number average molecular weight of at least 600 and wherein the overbased alkali metal salt is obtainable by the process of any one of claims 34 to 39. 41. The composition of claim 40, wherein the basic salt has a metal ratio of 1.5 to 40. 42. A composition according to claim 40 or 41, wherein the polyalkene has a Mn value of 800 to 5000. 43. A composition according to any one of claims 40 to 42, wherein the basic salt is an overbased succinate. 44. A composition according to any one of claims 40 to 43, wherein the basic salt is an overbased sodium succinate. 45. A lubricant composition comprising a major amount of an oil of lubricating viscosity and a basic metal salt prepared by a process according to any one of claims 1 to 13, 14 to 22 and 34 to 39. 46. A lubricant composition comprising a major amount of an oil of lubricating viscosity and the composition of any one of claims 23 to 30 and 31 to 33. 47. A lubricant composition according to any one of claims 45 and 46, further comprising (B) at least one dispersant. 48. The composition of claim 47, wherein the dispersant is (a) at least one nitrogen-containing carboxylic acid dispersant, (b) at least one ester dispersant, (c) at least one Mannich dispersant, (d) at least one post-treated dispersant, or mixtures of two or more thereof. 49. The composition of claim 47 or 48, wherein the lubricant composition further comprises (C) at least one metal dihydrocarbyl dithiophosphate. 50. The composition of claim 47, wherein the metal dihydrocarbyl dithiophosphate (C) is at least one zinc dihydrocarbyl dithiophosphate.