US3755172A - Preparation of overbased nitrogen-containing ashless dispersions - Google Patents

Abstract

An overbased dispersion useful as a lubricating oil additive is prepared by adding a metal alkoxide-carbonate complex to an alcohol or alcohol-aromatic solution of a metal free, oil soluble, neutral or basic dispersing agent containing an acylated nitrogen atom. The dispersing agent is preferably an amide, imide or ester derived from the reaction of a high molecular weight alkenyl carboxylic acid or acid anhydride with an organic nitrogen-containing compound having at least one amino group or hydroxyl group. Concurrently with, or following, addition of the alkoxide-carbonate complex, the complex is hydrolyzed to yield a dispersion of fine particles of metal carbonate. The solvents are then stripped from the dispersion to form a bright, clear composition having a base number of from about 50 to about 250 and useful as an ashless detergent-dispersant additive to lubricating oils.

Description

United States Patent Woods et a1.

[ PREPARATION OF OVERBASED NITROGEN-CONTAINING ASHLESS DISPERSIONS [75] Inventors: Warren W. Woods; Mack W. Hunt,

both of Ponca City, Okla.

[73] Assignee: Continental Oil Company, Ponca City, Okla.

[22] Filed: Aug. 2, 1971 [21] Appl. No.: 168,423

[52] US. Cl 252/515 A [51] Int. Cl. C10m 1/32, C10m 1/36 [58] Field of Search 252/51.5 A

[56] References Cited UNlTED STATES PATENTS 3,121,057 2/1964 Gee et al. 252/515 A 3,278,426 10/1966 Criddle 252/515 A Aug. 2 8, 1973 Primary Examiner-Werten F. W. Bellamy 57 ABSTRACT An overbased dispersion useful as a lubricating oil additive is prepared by adding a metal alkoxide-carbonate complex to an alcohol orv alcohol-aromatic solution of a metal free, oil soluble,-neutral or basic dispersing agent containing an acylated nitrogen atom. The dispersing agent is preferably an amide, imide or ester derived from the reaction of a high molecular weight a1- kenyl carboxylic acid or acid anhydride with an organic nitrogen-containing compound having at least one amino group or hydroxyl group. Concurrently with, or following, addition of the alkoxide-carbonate complex, the complex is hydrolyzed to yield a dispersion of fine particles of metal carbonate. The solvents are then stripped from the dispersion to form a bright, clear composition having a base number of from about 50 to about 250 and useful as an ashless detergent-dispersant additive to lubricating oils.

16 Claims, No Drawings PREPARATION OF OVERBASED NITROGEN-CONTAINING ASII'LESS DISPERSIONS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to ashless detergent-dispersant additives for lubricating oils, and more particularly, to a method of preparing overbased dispersions in which the dispersant is an acylated nitrogen-containing metal free compound. 4

2. Brief Description of the Prior Art Overbased dispersions have been used as additives to detergent-type lubricating oils for the purpose of dis-v persing deleterious insoluble particles formed by fuelcombustion and oil oxidation, and to neutralize harmful acidic combustion products and acidic lacquer pre cursors. The latter requirement is met by the high reserve basicity which is characteristic of the overbased dispersions used as additives.

Various types of overbased dispersions have been formulated for the described lubricating oil additive usage. These additives have included overbased soaps, alkyl phenates, alkyl phenol sulfides and metal salts of organic sulfonic acids. Overbasing of the organic sulfonic acid dispersions has been accomplished in a num* ber of ways, but in general entails the suspension of fine particles of a metallic neutralizing agent, such as a metal oxide, hydroxide or carbonate. This produces a dispersion containing an amount of metal in excess of the amount that is theoretically required to replace the acidic hydrogen of the acid used as the starting material, and which, when neutralized, functions as the dispersant.

The overbased sulfonate dispersions have been widely used in lubricating oils because of their high temperature performance. Their dispersing capability at lower temperatures, has, for many lubricating oil additive applications, however, been less than optimum, and other additives have frequently been used in conjunction with the sulfonate additives to impart improved low temperature dispersancy to the lubricating oils. One of the most useful of these types to be recently proposed is nitrogen-containing derivatives of alkenyl succinic acids and succinic anhydrides. These so-called ashless dispersants complement the overbased sulfo nates, and are advantageously characterized in producing little or no ash upon oxidation or combustion of the oils which contain them.

In several recently issued patents, it has been pro posed to overbase the nitrogen-containing succinic acid derivatives to provide valuable lubricating oil additive compositions having reserve alkalinity independently of other additives, such as sulfonates. For many usages, this permits the overbased sulfonates to be omitted without sacrifice of adequate high temperature performance, and has the resultant advantages of reducing the ash content of the final lubricating oil blend and reducing the tacky engine residues typical of lubricating oils containing overbased sulfonate additives. In U.S. Pat. No. 3,451,931, issued to Kahn .et al., it is proposed to overbase high molecular weight succinic acid derivatives of the type described by suspending a metal base compound in the derivative and treating the suspension with an acidic gas, such as. carbon dioxide. This produces a colloidal dispersion of metal salt having high basicity and good dispersing capability.

In US. Pat. No. 3,306,908 to Le Suer, a metal complex is formed by reacting certain specified salts of metals having atomic-numbers of from 24 to 30 with the nitrogen-containing succinic acid derivative. Although the value of the metal complex produced as a lubricating oil additive is discussed, the patentee does not discuss its overbasing capability, but implies that the metal in the complex is not free to readily enter into an acid neutralizing role by stating that the chemical linkage between the metal and the'nitrogen-containing succinic acid derivative is a stable linkage.

A slightly different product which does not entail the over basing of a nitrogen-containing succinic acid derivative, but which, nevertheless, is an overbased lubricating oil additive derived from succinic acid is described in US. Pat. No. 3,567,637. Here, the additive is prepared by neutralizing a long chain alkenyl-substituted succinic anhydride or acid with an inorganic basic alkaline earth compound in the presence of a lower alkanol. This results in neutralization of the acid or anhydride concurrently with the incorporation of stoichiometric excess of the alkaline earth compound in the resulting dispersion. The dispersion is then blown with sufficient amounts of gaseous carbon dioxide to convert the excess of basic alkaline earth compoundto carbonate. Ammonia is employed as a catalyst.

BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention provides an improved process for preparing overbased, nitrogen-containing carboxylic acid and carboxylic acid anhydride derivatives which are highly useful as ashless dispersants imparting reserve alkalinity to lubricating oils to which they are added. The process of the invention advantageously provides for the uniform dispersion orpeptisation of a large amount of very fine particles of basic alkaline earth metal compounds in the additive composition. Difficulties previously encountered in the overbasing of the nitrogen-containing carboxylic acid derivatives of the type described as a result of the requirement to obtain maximum solubilization of basic metal compounds such as oxides or hydroxides incorporated in the nitrogen-containing derivative are obviated.

Broadly described, the present invention comprises initially preparing a solution of an oil soluble acylated nitrogen-containing dispersant in a monohydric alcohol containing from one to four carbon atoms, or in a solvent which includes one or more of such alcohols and an aromatic monocylic hydrocarbon, such as benzene, toluene or xylene. The dispersants utilized are preferably amides, imides or esters prepared by reacting a high molecular weight alkenyl carboxylic acid or anhydride with an organic nitrogen-containing compound having at least one amino group or hydroxyl group. Preferably, a high molecular weight succinic anhydride is utilized as one reactant.

The dispersant solution is heated to a temperature of from, about 25 C to about C, and is mixed with an oil soluble metal alkoxide-carbonate complex and water in an amount which is a stoichiometric excess of that required to hydrolyze the complex. The metal in the metal alkoxide-carbonate complex is selected from the group consisting of magnesium, calcium and barhim. After hydrolyzing the complex by means of the water present, the mixture is heated to remove the volatile solvents. An important aspect of our invention is the identification of the solvent systems in which the dispersant may be initially dissolved, and which we have found to be critical to the practice of the invention The employment of a C -C monohydric alcohol, or such alcohol and a monocylic aromatic hydrocarbon appears to be essential to the production of a suitable overbased product. Preferably, a solvent which includes equal parts by weight of alcohol and aromatic is used.

An object of the present invention is to provide a process for preparing a highly overbased ashless dispersant additive composition suitable for incorporation in lubricating oils for the purpose of imparting reserve basicity and high dispersancy thereto.

A more specific object of the invention is to provide a method for 'overbasing in an efficient, easily practiced and economical manner, a nitrogen-containing derivative of succinic acid or succinic anhydride compounds of high molecular weight.

Additional objects and advantages of the invention will become apparent as the following detailed description of preferred embodiments of the invention is considered.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION As has been indicated, the initial step in the practice of the process of the invention is the formation of an alcohol solution or alcohol and monocylic aromatic hydrocarbon solution of certain oil soluble, metal free compounds containing an acylated nitrogen atom. Particularly suitable compounds are esters, amides and imides derived from high molecular weight carboxylic acids, The derivative functions as a dispersantdetergent in the overbased additive composition resulting from the process, and is characterized in being a neutral or slightly basic oil soluble material of relatively high molecular weight, The preparation of these materials is well understood in the art, and is described in considerable detail in U.S. Pat. No. 3,451,931 to Kahn et al., U.S. Pat. No. 3,338,831 to Elliott et al., U.S. Pat. No. 3,376,864 to Elliott et al., and U.S. Pat. No. 3,172,892 to Le Suer et al. Preferably, the nitrogencontaining dispersant constituting the starting material in the process of the present invention is derived from the reaction of an alkenyl succinic acid or succinic acid anhydride with an organic nitrogen-containing compound having at least one amino group or hydroxyl group, including such compounds as alkylene polyamines and hydroxy alkylamines. The alkenyl succinic acid anhydrides may be easily prepared by thermally condensing maleic anhydride with a branched polyalkene, such as polybutene. A relatively high molecular weight polymer, which is an alkenyl succinic anhydride, is produced by the thermal condensation. In general, this polymer will have a molecular weight of from about 600 to about 4,000. The succinic acid anhydride material thus produced is then reacted with a nigrogencontaining organic compound which is preferably a polyamine such as diethylene triamine or tetraethylene pentamine. The dispersants produced by the described reactions may be amides, imides or esters having a molecular weight of from about 4,000 to about 10,000. Frequently, the dispersant will contain a mixture of imides, amides and esters produced by the reaction between the succinic acid or succinic acid anhydride and the organic nitrogen-containing compound, and in a given dispersant composition, either the amide or the imide may predominate.

It should be here pointed out that the nitrogencontaining derivatives of the alkenyl succinic acids and succinic acid anhydrides used as the preferred dispersant starting materials in the process of the present invention are well known in the art, as are the processes by which they are manufactured. A number of these materials are presently commercially available, and neither their composition nor method of preparation, as such, constitutes a part of the present invention.

An important aspect of the present invention is the solvent system used for diluting the nitrogen-containing high molecular weightashlcss dispersants of the invention at the commencement of the process of the invention. The dispersants, as commecially available, or as prepared, will almost always be dissolved in an oil soluble, non-volatile (boiling above about C) carrier material which may be a naphthenic or parafiinic oil, such as pale oil. The amount of this carrier material will usually be from about 10 weight percent to about 40 weight percent. If desired, the amount of non-volatile carrier material can be increased to as much as about 60 weight percent. We have found that it is critical to the successful practice of the process that the solution of dispersant in non-volatile carrier material mixed with either a monohydric alcohol containing from one to four carbon atoms be employed, or with a mixture of such alcohols with a monocylic aromatic hydrocarr bon. The mechanism which is responsible for the criticality of the use of the alcohol or alcohol-aromatic solvent has not been thoroughly discemed'. It appears, however,t hat this type of solvent functions to permit the hydrolysis of the metal alkoxide-carbonate complex to proceed efficiently, and enables very small particles of the overbasing metal compound to be formed upon hydrolysis and uniformly dispersed in the dispersant material.

Examples of alcohols which can be employed. are methanol, ethanol, iso-propanol, n-propanol, isobutanol, n-butanol, and certain monoethersof ethylene glycol, including the monoethyl ether of ethylene glycol, available commercially under the trademark Cellosolve, and the monomethyl ether of ethylene glycol, available commercially under the trademark methyl Cellosolve. Examples of suitable monocylic aromatic hydrocarbons which are suitable include benzene, xylene and toluene.

The amount of the solvent utilized will, of course, vary with the particular alcohol, or mixture thereof with aromatic, which is used as the solvent, and with the particular dispersant in use. In general, however, a weight ratio of from about 1.25:1 toabout 2.5:1, solvent to the dispersant-non-volatile carrier starting material is definitive of both the minimum amount, and preferred amount of solvent. Larger amounts of solvent can be utilized, but this provides no advantage. A preferred solvent-dispersant system includes a pale oil solution 'of an alkenyl. succinirnide having a moleclar weight of from about 5,000 to about 9,000, and a solvent'consisting of equal parts by weight of a C C, monohydric alochol and benzene. The weight ratio of the dispersant-oil starting material, alcohol and benzene in this preferred system is about 1:1:1.

For the purpose of overbasing the dispersant by the suspension of small particles of basic metal compounds therein, a quantity of an oil-soluble metal alkoxidecarbonate complex is introduced to the dispersant solution, and is hydrolyzed in-situ to convert the complex to the overbasing metal compounds. This method of overbasing possesses the advantage over those previously proposed for overbasing such nitrogencontaining succinic acid derivatives of permitting a greater total amount of overbasing metal to be more easily suspended in the dispersant. Although the general mechanism entailed in, and the advantages attendant upon, the use of oil-soluble complexes of the type described for overbasing lubricating oil additives have been previously recognized, such recognition has been with reference to the use of this overbasing procedure for the overbasing of oil-soluble sulfonate type additives. The adaption of this procedure to the overbasing of ashless dispersants of the akylated nitrogencontaining type has not previously been accomplished. We have, in fact, determined that this general type of overbasing procedure, as it has previously been utilized for overbasing high temperature, sulfonic acid dispersing agents must be altered in unexpected ways in order to successfully accomplish the overbasing of the described nitrogen-containing succinic acid-derivatives.

Already described, of course,.are the unexpected requirements of the solvent system, and such paraff'mic solvent as hexane or heptane'which are useful in the overbasing of sulfonic acid dispersants do not function effectively in the present invention. Moreover, the amount of water which is utilized for effectively accomplishing the hydrolysis of the metal alkoxide-carbonate complex is, in general, less than that utilized when overbasing sulfonates. This will be referred to further hereinafter.

carbonate complex being utilized for overbasing. In the case of a calcium-containing complex, from about 1.5 to about 4 moles of water are used per mole of the complex, with from 1.6 to 2.4 moles being preferred. For magnesium-containing complexes, from about 2 to about 4 moles of water are used per mole of the complex, with from 3 to 3.5 moles being preferred. In the case of barium complexes, from about 2 to about 4 moles of water are preferably used for each mole of the complex added.

As has been indicated, it is preferred to add the water to the dispersant-alcohol solution concurrently with the addition of the complex to the solution. It is also desir- The metal alkoxide-carbonate complexes utilized are I of the type described in detail in Hunt et a1 U.S. Pat. No. 3,150,088 and Hunt U.S. Pat. No. 3,150,089. These metal alkoxide-carbonate complexes have the formula ATT where M is a bivalent metal ion selected from the group consisting of calcium, magnesium, and barium, and R is either a C 1 to C alkyl group or an organic radical of the formula where R is a C to C alkyl group, and x is from 0.5 to 1.5, preferably 0.75 to 1.0. The method of making these complexes is detailed in the cited patents.

The water which is used to hydrolyze the complex while it is dissolved in the dispersant-may be added to the dispersant either'before or, more desirably, concurrently with the complex. The water added to the dispersant solution must be present in a stoichiometric excess over that theoretically required to hydrolyze all of the g metal alkoxide-carbonate complex added. This prethe desired level of reserve alkalinity or-overbasing which is sought. This latter property is defined in terms of the base number of the'final composition as determined by acetic acidtitration. In general, the oil soluble, metal free nitrogen-containing materials constituting the dispersants employed in the invention cannot be A as highly overbased as can oil soluble sulfonate disper- Y sions, and for this reason, for a given weight (percent active) of the dispersant, only about half as much metal alkoxide-carbonate complex is used to achieve maximum overbasing as it has been the practice to use in achieving maximum overbasing of an equivalent amount of oil soluble sulfonic acid high temperature dispersants. Compositions having base numbers as high as about-250 can be prepared by the process of the present invention.

To further aid in the understanding of the process of the invention, the amounts of the several materials charged to the reaction mixture in the course of the process are tabulated in suitable and preferred weight percent ranges as follows:

Suitable Preferred Dispersant 4 35 6 20 Non-volatile Carrier 5 40 10 30 Metal Alkoxidefiarbonate Complex 5 35 10 20 Water 0.5 6.0 0.9 3.5 Volatile Solvent '35 85 45 Includes any non-volatile oil present in the dispersant as prepared or available "Includes the dispersant solvent of alcohol, or alcohol and ammatic, as hereinbefore described, and any process solvents boiling below lC added during the process as hereinafter described scribed temperature, the metal alkoxide-carbonate complex is added slowly to the solution. If all the required water has not previously been added to the solution, it is added concurrently with the addition of the complex, and in fact, such concurrent addition is preferred. As stated previously, it is further desired'that the added water be in the form of a water-monoether alcohol azeotrope.

Under the completion of the addition of the metal alkoxide-carbonate complex (which is preferably added in the form of an alcohol solution of the complex) to the dispersant solution in the manner described, the volatile solvents, which include the alcohol or alcohol-benzene solvent for the dispersant, alcohol produced upon hydrolysis of the complex, and water, are removed from the reaction mixture. Although in some instances, solvent removal can be accomplished substantially entirely by distillation, it is preferable to blow the reaction mixture with an inert gas to facilitate the removal of the last portions of the solvent, and the gas utilized for this is preferably carbon dioxide or a mixture of carbon dioxide and nitrogen. In general, for the purpose of solvent removal, the reaction mixture will be heated to temperatures up to about 125 C to 190 C, followed by C stripping at this temperature. The distillation is preferably carefully conducted to prevent the formation of a gel, or the development of a haze within the reaction mixture, and, if desirable for the purpose of maintaining the contents of the reaction mixture fluid, small amounts of light hydrocarbon process solvents boiling below about 175 C, and preferably below about 150 C may be added toward the end of the distillation. Suitable process solvents include petroleum naphtha, hexane, heptane, octane, benzene, toluene or xylene. Hexane is particularly suitable.

AMOUNTS OF MATERIALS IN PRODUCT The amounts of oil soluble, nitrogen-containing, metal free dispersing agent, non-volatile carrier oil and basic alkaline earth metal compounds in the final product compositions are shown in the table below in parts by weight.

Suitable Preferred Dispersing Agent 15 70 25 50 Non-volatile Carrier 5 8O 35 65 Basic Metal Compound 5 25 8 (as metal) The overbased compositions prepared by the present invention are stable dispersions which are fluid, relatively clear and are bright to transmitted light. The dispersions may be added to engine lubricating oils to effectively disperse solid particulate products of fuel combustion and engine oil degradation, and to neutralize acidic products formed during engine operation.

The following examples will further serve to illustrate the manner in which the invention is practiced.

EXAMPLE 1 A commercially available composition contains a succinimide of the general formula where R is an alkenyl radical, and R is a different alkenyl radical. The composition contains also a lesser amount of the corresponding succinamide, and the total nitrogen-containing succinic acid derivative content of the composition is about 58 weight percent. Ad-

ditionally, the composition contains about 23 weight percent of unreacted polyisobutene with the balance being pale oil. The nitrogen-containing dispersant in the composition has an approximate molecular weight of about 5,000, and the total sample contains from 1.4 to 1.8 weight percent nitrogen.

91.1 grams of the described commercially available succinimide composition and grams of benzene were mixed until a solution was formed, and the solution was then heated to 40 C. To the heated benzene solution of the dispersant were then added at a constant rate, 49 grams of the complex, calcium methyl Cellosolve carbonate, which complex contained 7.3 weight percent calcium and 7.9 percent bound C0,. Concurrently with the addition of the complex, 4.5 grams of an azeotrope, which contained 53.5 weight percent water and the balance methyl Cellosolve, were added. The complex and the azeotrope were both slowly added over a period of 35 minutes.

Following the addition of the complex and azeotrope, the solvents were removed from the reaction mixture by slowly heating the mixture to a temperature of C, and then, upon obtainment of this temperature, stripping the mixture with carbon dioxide for a period of about 20 minutes. The final product remaining upon removal of the solvents was very hazy, contained gel particles, and was considered unsuitable as a lubricating oil additive.

EXAMPLE 2 91.1 grams of the commercially available succinimide dispersant composition utilized in Example 1 were mixed in a one liter flask with 25 grams of benzene and 100 grams of isopropyl alcohol. The mixture was agitated until a homogeneous mixture having the appearance of an emulsion was formed. The mixture was then heated to 40 C, and the addition of 49 grams of the overbasing complex used in Example 1 was commenced, concurrently with the'addition of 6.5 grams of the water-alcohol azeotrope used in Example 1. This amount of azeotrope represented an addition of 2.1 moles of water per mole of calcium in the overbasing complex. The addition of the complex and azeotrope were carried out concurrently over aperiod of 35 minutes.

During the final 15 minutes of the addition of the complex and azeotrope, the mixture was heated to 55 C in order to maintain fluidity. Upon completion of the addition, the solvents were removed from the reaction mixture by heating it to 150 C, and upon obtainment of this temperature, the mixture was blown with carbon dioxide for a period of about 20 minutes.

The final product formed upon completion of solvent removal was bright, clear and fluid. It was soluble in aromatics but only partly soluble in other hydrocarbon materials. Thus, when blended into a light mineral oil, the mixture was slightly cloudy, and the composition thus developed was less than optimum for additive purposes. Examples 1 and 2 thus show that while an ac ceptable product can be prepared by the use of a dispersant diluent consisting of a mixture of isopropyl alcohol and benzene, the use of benzene alone does not yield a satisfactory product.

EXAMPLE 3 The materials and procedures used in Example 2 were utilized in another run except that 50 grams of benzene were used in the starting mixture instead of 25 grams. The overbased product yielded demonstrated improved compatibility in base oils, hexane, and naphtha as compared to the overbased product produced in Example 2.

EXAMPLE 4 The materials and procedures used in Examples 2 and 3 were repeated except that 100 grams of benzene were used, along with the 100 grams of isopropyl alcohol, to constitute the solvent system, rather than the lesser amounts of benzene used in Example 2 and 3. The final overbased product yielded was bright, clear and fluid, and was found to be completely soluble in all hydrocarbons.

All of the products produced in Examples 1-4 were found to have base numbers of approximately 100 as determined by the acetic acid titration method.

EXAMPLE 5 Another commercially available succinimide composition contains 37 weight percent of a succinimide succinamide mixture substantially identical to that described in Example 1. This commercially available dispersant compsition further contains about 12 weight percent unreacted polyisobutene, and the balance consists essentially of a non-volatile carrier oil. The nitrogen-containing dispersant has an average molecular weight of approximately 5,500. The nitrogen content of the composition, as commercially marketed is between about 1.04 weight percent and 1.06 weight percent.

205 grams of the described succinimide dispersant composition were mixed with 375 grams of methyl Cellosolve. The mixture was then heated to 38C, and concurrent addition of a magnesium alkoxide-carbonate complex and an azeotrope of the general type previously described was commenced. V

The metal complex contained 5.64 weight percent magnesium and was added slowly to the mixture in an amount of 86 grams. The addition of the complex required 173 minutes. 23.4 grams of the azeotrope were added over a period of 162 minutes. The azeotrope contained 53.6 weight percent water, with the balance being methyl Cellosolve.

Upon completion of the concurrent addition of complex and azeotrope, solvent removal was commenced by heating the reaction mixture slowly to 150 C. Upon attainment of this temperature, carbon dioxide blowing of the mixture was commenced and continued for a period of about 15 minutes. The described process yielded 222 grams of a bright, clear, viscous fluid. The overbased dispersion product had a base number of 100.

EXAMPLE 6 To 205 grams of the commercially available succinimide dispersant composition described in Example 5 wre added 375 ml. of anhydrous methanol. 75 ml. of methyl Cellosolve were added to the mixture to improve the homogeneity thereof. The mixture was then heated to 45 C. At this point, addition of a magnesium alkoxide-carbonate complex was commenced, concurrently with the addition of a water-methyl Cellosolve azeotrope. In this addition, 86.7 grams of the complex, which contained 5.64 weight percent magnesium, were added over a period of 60.5 minutes, with the addition being made below the surface of the dispersant mixture. 20.3 grams of the azeotrope, which contained 53.6 weight percent water (constituting a mole ratio of water to the magnesium in the complex of 3:1) were added to the surface of the dispersant mixture over a period of 55 minutes.

Upon completion of the addition of the complex and azeotrope, the reaction mixture was distilled to a bottoms temperature of 150 C. Blowing with carbon dioxide was then commenced and was continued for a period of 15 minutes to sparge the light ends from the mixture. A bright, clear product having an acetic acid base number of about and a 8.8. and W. (bottom sediments and water) value of 0.4 weight percent was produced.

EXAMPLE 7 205 grams of the commercially available succinimide composition described in Examples 5 and 6 were placed in a one liter, three-necked flask, and to the dispersant were added 375 m1. of methyl Cellosolve. After homogenization of the mixture, the temperature was elevated to 38 C, and the concurrent addition of overbasing complex and water-containing azeotrope was commenced. The complex was a magnesium alkoxidecarbonate complex containing 5.64 weight percent magnesium. 86.7 grams of this complex were added to the dispersant mixture over a period of 177 minutes. 15.3 grams of azeotrope containing 47.3 weight percent water (equivalent to a mole ratio of water to magnesium of 2:1) were added to the reaction mixture over a period of 164 minutes.

Upon completion of the addition of complex and azeotrope, the volatile solvents were distilled from the mixture .until a bottoms temperature of C was reached. The mixture was then blown for a period of 15 minutes with carbon dioxide.

225 grams of clear, bright product having an acetic acid base number of about 100 and a BS. and W. of 0.2 weight percent were produced.

EXAMPLE 8 205 grams of the commercially available succinimide dispersant described in Examples 5-7 were placed in a reaction flask with 375 ml. of methyl Cellosolve. The mixture was heated to 45 C, and the addition of a magnesium-containing carbonate complex and a water containing azeotrope was commenced. 86.7 grams of the complex which contained 5.64 weight percent magnesium were added over a period of 80 minutes, and 13.5 grams of the azeotrope containing 53.6 weight percent water (mole ratio of water to magnesium 2:1) were added over a period of 72 minutes. Upon completion of the addition of the complex, the volatile solvents were removed in the manner described in Example 6 to produce 226.5 grams of a clear and bright product having a BS. and W. of 0.3 weight percent.

EXAMPLE 9 A commercially available succinimide composition of the type described in Example 5 was utilized in preparing a dispersant composition overbased with magnesiumcarbonate in the following manner. 138.8 grams of the commercially available succinimide composition, 250 ml. of benzene and 50 ml. of methyl Cellosolve were mixed in a reaction flask, and heated to a temperature of between 40 and 45 C. At this temperature, 42.8 grams of a magnesium alkoxide-carbonate complex containing 7.62 weight percent magnesium and 14 ml. of an azeotrope containing 53.6 weight percent water, with the balance being methyl Cellosolve, were added concurrently to the reaction flask over a 25 minute period. The water added in the azeotrope was equivalent to 3 moles per mole of the magnesium added with the complex.

Upon completion of the addition of the complex and azeotrope to the reaction mixture, 25 ml. of methyl Cellosolve were used to rinse the addition funnel, and in the rinsing process, were added to the reaction mixture. Distillation for the purpose of removing the solvents was then commenced and continued for a period of 45 minutes. At this time, the temperatue of the mixture was 150 C, and the mixture was bright and clear. Carbon dioxide was then used for a period of 15 minutes to strip the light ends from the mixture. The process yielded 150 grams of a bright, fairly fluid product which had a base number of 103.

EXAMPLE 69.4 grams of the commercially available succinimide dispersant composition employed as a starting material in Examples 1-4 were mixed with 69.4 grams of pale oil having a viscosity of 170 SSU at 210 C, and the diluted dispersant composition placed in a reaction flask with 250 ml. benzene and 50 ml. methyl Cellosolve. The mixture was heated to a temperature of from 40 to 45 C, at which time the addition of the magnesium containing complex and the water azeotrope described in Example 9 were commenced. 20.5 grams of the magnesium complex and 7 ml. of the azeotrope were concurrently added to the mixture over a 10 minute period. The dropping funnel used for the addition of the complex was then rinsed with 10 ml. of methyl Cellosolve.

Upon completion of the addition of complex and azeotrope, distillation was commenced and continued over a period of 50 minutes, during which the temperature of the reaction mixture was gradually increased to 150 C. Carbon dioxide stripping of light ends was then commenced and continued for a period of minutes. Upon termination of the stripping, there were produced 143.7 grams of a bright, fluid overbased dispersion product. The product had a base number of 74.

EXAMPLE 1 l 172 grams of the commercially available succinimide dispersant composition described in Example 5 were added to a three-necked reaction flask, along with 250 ml. of benzene and 50 ml. methyl Cellosolve. After mixing the materials in the flask, the mixture was heated to a temperature of between 40 C and 45 C. 92.5 grams of a calcium alkoxide-carbonate complex containing 7.29 weight percent calcium was then added to the mixture, concurrently with 12.3 ml. of a watermethyl Cellosolve azeotrope containing 53.6 weight percent water. The addition of the complex was completed in 30 minutes, and the addition of the azeotrope was completed in 35 minutes. When about threefourths of the complex had been added to the mixture, the mixture became slightly hazy and continued to be hazy until the addition of the complex was completed. At this time, the mixture was refluxed for a period of 30 minutes at 83 C, and upon such refluxing, the mixture became bright and fluid. Distillation to remove the volatile solvents was then commenced and continued for a period of 45 minutes until the temperature of the mixture had reached 150 C. The mixure was then stripped with carbon dioxide for a period of 30 minutes. 190 grams of a bright, fluid product having a base member of 100 were obtained.

EXAMPLE 12 172 grams of another commercially available ashless nitrogenous dispersant composition having an average molecular weight of about 9,000 was mixed with 250 ml. of benzene and 200 ml. of isopropyl alcohol in a reaction flask and the mixture heated to between 40 C and 45 C. When this temperature was attained, 92.5 grams of a calcium alkoxide-carbonate complex containing 7.29 weight percent calcium were added to the reaction flask concurrently with 12.2 ml. of a watermethyl Cellosolve azeotrope containing 53.6 weight percent water. The addition of complex and azeotrope was completed after 35 minutes.

Distillation for the purpose of removing the solvents from the mixture was then commenced and carried on for a period of 1 hour, gradually raising the temperature during this time to 84 C. At this point, 350 ml. of solvent had been removed overhead and the reaction mixture in the flask had become very viscous and tended to separate into two phases. 250 ml. of normal hexane were added to the flask and the distillation again started. At C the fluidity of the mixture in the flask improved, and the distillation was continued until a pot temperature of 150 C was attained. 200 ml. of normal heptane was then added to the flask to wash down a gel-like emulsion covering the top of the flask, and this added heptane then removed by distillation. Finally, 200 ml. of benzene and ml. of isopropanol were added to the reaction mixture, and the distillation continued to increase the temperature of the reaction mixture to 190 C. At this time, the distillation was terminated. 195.4 grams of a product which was fairly bright to transmitted light was yielded.

EXAMPLE 13 1,720 grams of the commercially available succinimide dispersant composition described in Example 5 were mixed with 1,888 grams (2,147 ml.) of benzene and 1,888 grams (2,047 ml.) of isopropyl alcohol in a 12 liter creased reaction flask. The contents of the flask were heated to a temperature of between 40 C and 45 C. There were then concurrently added to the flask at constant rate, 925.1 grams of calcium alkoxidecarbonate intermediate (containing 7.3 weight percent calcium and 8.44 weight percent carbon dioxide, and 122.7 grams of a water-methyl Cellosolve azeotrope containing 53.4 weight percent water. The azeotrope was added over a period of 30 minutes, and the complex addition was completed in 35 minutes. The temperature of the reaction mixture was then elevated slowly over a period of 3 hours to a temperature of C. The product was stripped with carbon dioxide for a period of one hour. There were produced 1,881 grams of a bright, fluid product.

For the purpose of preparing sufficient product to' permit engine testing, the described procedure for overbasing the succinimide dispersant composition by the use of the calcium complex was repeated a sufficient number of times to yield 11,025 grams of total product. The combined products from the several repeated runs had a base number of 102. I

EXAMPLE 14 In an engine test of the overbased dispersant composition prepared in accordance with the invention, the calcium oberbased succinimide dispersion prepared as described in Example 13 was added to a solvent refined Mid-continent S.A.E. 30 paraffinic base oil. The dispersant additive constituted weight percnet of the lubricating oil composition. thus prepared, and the composition further contained 1 weight percent zinc dithiophosphate as anoxidation inhibitor. The lubricating oil composition was then tested in a diesel engine test under Caterpillar l-H conditions. The test was run for 240 hours, and the lubricating oil composition was assigned a pass rating. The volume percent of the top groove of the piston which was filled by lacquer deposits upon completion of the test was 1.2 The lower grooves were clean. On the first land, a slight deposit of lacquer was noticed, but the remaining lands and the underside of the piston were clean.

EXAMPLE 15 860 grams of the commercially available succinimide dispersant composition described in Example 5, 860 grams of 100 pale oil, 2,500 ml. of benzene and 2,000 ml. of isopropanol were mixed in a flask and heated to a temperature of between 40 C and 45 C. 1,185 grams of calcium alkoxide-carbonate complex containing 7.29 weight percent calcium, and 314 m1. of azeotrope containing 53.6 weight water were added concurrently to the mixture over periods of 35 and 30 minutes, respectively. After completion of the addition of the complex, an additional 157 ml. of the azeotrope were added over a period of 10. mixtures. The solvents were distilled over a period of 2 hours and minutes to a pot temperature of 150 C. The product was stripped with carbon dioxide for one hour, and after stripping,

[1,952 grams of a bright, fluid overbased dispersion were yielded.

An additional batch of the calcium overbased dispersion was prepared as described in the preceding paragraph, except that 170 pale oil was utilized instead of 100 pale oil. This batch of the dispersion contained 940' grams of product. The same procedure was then used to prepare an additional standards.

EXAMPLE 16 939 grams of product, andthe three product batches were combined for the purpose of engine testing. The combined products from the three runs had an acetic acid base number of 151.

The calcium overbased succinimide dispersion thus prepared was added to a solvent refined Mid-continent S.A.E. 30 parafi'mic base oil to provide 8 weight perby the process of this invention had a piston varnish rating of 8.

Another criteria employed in the standard engine test is total varnish rating (based on the total accumulation served, and a rating of 39.1 was assigned, again based cent of the dispersion in the base oil. The lubricating oil composition as thus formulated also contained 1.05 weight percent zinc dithiophosphate asan oxidation inhibitor.

The lubricating oilformualtion wassubjected to testing and evaluation in a standard" MS Sequence VB. internal combustion engine test, using astandard Ford engine of 289 cubic inches displacement. 1n the industry-accepted standards utilized in this test, piston varnish accumulation is rated on a scale of l to 10,fwith 10 being a clean piston characteristic of a new engine. The overbased lubricatingv oil compositioncontaining the calcium overbasedsuccinimide dispersion-prepared upon a scale of l to 50 with 50 being a clean engine with a total absence of sludge. The lubricating oil composition was considered to be somewhat better than acceptable by prevailing industry 205 grams of a commercially available, ashless, nitrogen-containing dispersant composition was mixed with 375 ml. of methyl Cellosolve in a reaction flask equipped with stirrer, thermometer and condenser and heated to 38 C. The dispersant was one prepared by the procedural steps described in Example 1 of U.S. Pat. No. 3,338,831, using 2,000 molecular weight polyisobutylene in preparing the polyisobutenyl succinic anhydride, and using a molar ratio of this succinic anhydride to amine of 1.1 in preparing the acylated nitrogen-containing dispersant. The concentration of dispersant in non-volatile carrier oil in the starting composition was 55 weight percent, and the composition contained 0.9 weight percent nitrogen, and a total base number of 13.

To the heated mixture of dispersant composition and methyl Cellosolve were then added concurrently 86.7 grams of magnesium alkoxide-carbonate complex (containing 5.64 weight magnesium) and 20.3 grams of water-methyl Cellosolve azeotrope (containing 53.6 weight percent water). In this addition, the complex was added below the stirrer over 172 minutes, and the azeotrope was added to the surface of the reaction mixture over 158 minutes.

Upon completion of the addition of complex and azeotrope, the mixture was distilled to a bottoms temperature of 150 C. During the distillation the mixture became very thick and viscous between C and C. It then commenced to become thinner and less viscous at C. After distillation the mixture was stripped with C0,. 223.2 grams of a bright, fluid product was formed having a BS. and W. value of 0.4 weight percent.

EXAMPLE 17 In this example, an ashless, nitrogen-containing dispersant composition manufactured by the method descried in Example 1 of US. Pat. No. 3,338,831 was utilized. The polyisobutylene employed in preparing the dispersant composition had a molecular weight of 1,100, and the molar ratio of polyisobutenyl succinic anhydride to amine employedin the process was 2:1. The concentration of the dispersant in non-volatile carrier oil (100 pale oil) in the starting composition was 50 weight percent, and the dispersant composition contained 1.4 weight percent nitrogen, and had a total base number of l l. The overbasing procedure described in Example 16 was carried out, using methyl Cellosolve, and the same magnesium-containing complex and azeotrope materials in the same weight ratio as described in that example. in this run, howeer, the azeotrope was added to the reaction mixture over a period of 166 minutes, andthe complex was added over a period of 179 minutes. During the heating and distillation, the reaction mixture remained fairly thin, and upon completion of nitrogen stripping, 222.3 grams of a bright, fluid product remained. The product had a B.S. and W. value of 0.2 weight percent.

EXAMPLE .18

375 ml. of methyl Cellosolve were mixed in a reaction flask with 205 grams of an ashless, nitrogencontaining dispersant composition prepared as described in Example 1 of US. Pat. No. 3,367,864. The polyisobutylene used in the ashless dispersant and oil was then subjected to the overbasing procedure described in Examples 16-18, except for the addition of the azeotrope to the reaction mixture over a period of 160 minutes, and the addition of the complex to the reaction mixture over a period of 177 minutes. In this instance, upon completion of the CO stripping, there was a small amount of translucent gel on the sides of the reaction flask, and the product, though clear, was relatively viscous. The product had a B.S. and W. value of 1.0 weight percent.

EXAMPLE 19 In the overbasing procedure here utilized, a dispersant composition was used which was prepared identically to that described in Example 18, except that the polyisobutylene starting material had a molecular weight of 2,000, and the succinic anhydride was reacted with the tetraethylene pentamine compound in a molar ratio of 1:1. The resulting succinimide was then reacted with propane sultone in a 1:1 ratio, and the product contained 0.6 weight percent nitrogen and 1.1 weight percent sulfur. lts base number was 9. A 50 weight percent solution of A succinimide dispersant composition was prepared as described in US. Pat. No. 3,172,892, utilizing 1,000 I molecular weight polyisobutylene as a starting material, and reacting the resulting succinic anhydride in a molar ratio of 2:1 with tetraethylene pentamine to pro duce the imide. The dispersant composition, as subjected to overbasing, contained 85 weight percent of tis succinimide dispersant in pale oil. The dispersant composition contained 2 weight percent nitrogen, and had a total base number of 42. 375 ml. of methyl Cellosolve were added to the dispersant composition in a reaction flask, and the mixture heated to 38 C. At this temperature, some condensate had collected on the walls of the reaction flask defining the vapor space above the reaction mixture. The reaction mixture at this point was fairly thin and homogeneous.

The azeotrope and magnesium complex described in Example 16 were then added concurrenty to the reaction mixture. The azeotrope was added over a period of 156 minutes, and the complex was added over a period of 176 minutes. After about 80 minutes of the concurrent addition, the reaction mixture became nonhomogeneous and remained non-homogeneous through the completion of addition of azeotrope and complex, and during the distillation until a bottoms temperature of 80C was reached. Homogeneity of the reaction mixture then returned.

Upon completion of the carbon dioxide stripping, 225 grams of viscous product was obtained which had a B.S. and W. value of 0.05 weight percent. 5

EXAMPLE 20 Preparation had a molecular wefiht ifi ljlmf and the molar ratio of succinic anhydride to tetraethylene pentamine used in preparing the dispersant was 2:1. The succinimide was then reacted with propane sultone in a .1:1 molar ratio. The dispersant composition contained 50 weight percent non-volatile carrier oil, 1.1 weight percent nitrogen and 1 weight percent sulfur. It had a total base number of 14. and a total acid number of 10.

The mixture of methyl Cellosolve and dispersant composition was heated to 38 C prior to the commencement of addition of magnesium complex and azeotrope. The magnesium complex and azeotrope used were the same as those described in Example 16, and were added concurrently to the reaction mixture over a period of minutes and 157 minutes, respectively.

Distillation was then commenced and was carried to a EXAMPLE 21 A succinimide composition prepared as described in Example 20, except for using a 211.2 mole ratio of succinic anhydride to amine compound, and using 66 weight percent of the succinimide dispersant in oil, was mixed with 375 ml. of methyl Cellosolve, and the overbasing procedure then carried out as described in Example 20. The time of addition of the azeotrope was minutes, and the magnesium complex was added over a period of minutes. Again, the development of non-homogeneity was observed, followed by a reinstatement of homogeneity when the temperature reached 80 C during distillation. 225.6 grams of a viscous product having a B.S. and W. value of 0.05 weight percent were recovered.

Although certain preferred embodiments of the inventions have been herein described in order to provide'examples adequate to guide those skilled in the art in the practice of the invention, it is to be understood hat various modifications in the reactants employed in the actual working examples, and various deparatures from the process conditions, can be effected without relinquishment of the basic principles underlying the invention. Changes and innovations of this type are therefore deemed to be circumscribed by the spirit and scope of the invention except as the same may be necessarily limited by the appended claims or reasonable equivalents thereof.

What is claimed is:

l. The process of preparing a stable dispersion of an inorganic metal compound in a metal free, oil-soluble ashless dispersant compound containing acylated nitrogen comprising: dispersant mixing with an organic solvent selected from the group consisting of monohydric alcohols containing from one to four carbon atoms, and mixtures of said alcohols with monocyclic aromatic hydrocarbons containing six to eight carbon atoms in which the alcohol-aromatic hydrocarbon mixture. contains at least 25 weight percent of one or more said alcohols. a mixture containing:

a. from about 10 weight percent to about 60 weight percent of a non-volatile, oil soluble hydrocarbon carrier material boiling above about 150 C; and

b. from about 40 weight percent to about 90 weight percent of a metal free, acylated nitrogen- 17 containing ashless, oil soluble dispersant compound, said organic solent and mixture of oil soluble carrier material and dispersant compound being mixed in a weight ratio of at least 1.25:1, organic solvent to mixture; heating the mixture of organic solvent, nonvolatile carrier material and dispersant compound to a temperature of from about 25 C to'about 100 C; adding to the heated mixture of solvent, oil soluble carrier material and dispersant compound, while the temperature thereof is maintained between about 25 C and about 100 C, from about weight percent to about 35 weight percent of a metal alkoxide-carbonate complex, said addition of complex being completed in the presence of an amount of water in the solvent, oil soluble carrier and dispersant mixture exceeding the stoichiometric requirement to hydrolyze the metal alkoxidecarbonate complex, and constituting from about 0.5 weight percent to about 6.0 weight percent water, based on the total weight of the mixture including water and complex; removing from the reaction mixture to which the complex is added, at least all of the volatile materials boiling below about 125 C, said process being characterized further in that i. said metal free, acylated nitrogen-containing oil soluble dispersant compound has a molecular weight of from about 4,000 to about 10,000 and is selected from the group consisting of imides, amides and esters formed by reacting an alkenyl carboxylic acid or alkenyl carboxylic acid anhydride with a nitrogen-containing organic compound selected from the group consisting of aklylene polyamines and hydroxy alkylamines, and

ii. said metal alkoxide-carbonate complex is represented by the formula O f H M o CHgCHgO R OC-O CHCH, O R

where R is a C to C alkyl group, X is from 0.5 to 1.5,

and said complex contains from about 5 weight percent to about 8 weight percent metal.

2. A process as defined in claim 1 wherein said water is added to said mixture of said organic solvent and dispersant in an amount of from about 1.5 moles of water per mole of the complex, to about 4 moles of water per mole of the complex.

3. The process defined in claim 1 wherein said mixture of organic solvent and dispersant is heated to a temperature of from about 30 to about 60 C, and maintained in this temperature range during addition of said complex.

4. The process defined in claim 1 wherein the pressure of water in the solvent-dispersant mixture during addition of said complex is accomplished by adding to said solvent-dispersant mixture concurrently with the addition of the complex, an alcohol-water azeotrope.

5. The process defined in claim 1 wherein said organic solvent is Z-methoxy l-ethanol.

6. The process defined in claim 1 wherein said volatile material removal is accomplished by distilling said volatile materials from the reaction mixture toa pot. temperature of between about C and about 10 C; then stripping light ends from the reaction mixture by blowing carbon dioxide through the reaction mixture.

7. The process defined in claim 1 wherein said complex contains from about 7 weight percent to about 8 weight percent calcium metal, and wherein the amount of water present in the solvent-dispersant mixture during the addition of complex is from about 1.5 moles to about 4 moles per mole of the complex added.

8. The process defined in claim 1 wherein said complex contains from about 5 weight percent to about 6 weight percent magnesium metal, and wherein the amount of water present in the solvent-dispersant mixture during addition of the complex is from about 2 moles to about 4 moles per mole of the complex added.

9. The process defined in claim 1 wherein said nitrogen-containing dispersant compound is formed by reacting an alkenyl succinic anhydride having a molecular weight of 600 to 4,000 with a polyamine selected from the group consisting of diethylene triamine and tetraethylene pentamine.

10. The process defined in claim 9 wherein said nitrogen-containing dispersant compound consists essentially of succinimide and succinamide compounds, with a major amount of succinimide compounds being present, said succinimide compounds having the general formula I wherein R is an alkenyl radical and R is a different alkenyl radical.

11. The processs defined in claim 1 wherein said organic solvent contains about 50 weight percent of said C -C monohydric alcohol, and about 50 weight percent benzene.

12. The process defined in claim 1 wherein the organic solvent employed contains at least 25 weight percent 2-methoxy l-ethanol, said complex is added in a solution of Z-methoxy l-ethanol, and the presence of water in the solvent-dispersant mixture during addition of said complex is accomplisehd by adding to said solvent-dispersant mixture, concurrently wihtthe addition of the complex, an azeotrope of water and 2-methoxy l-ethanol.

13. The process defined in claim 7 wherein the amount of water present in the solvent-dispersant mixture during addition of the complex is from about 1.6 moles to about 2.4 moles.

14. The process defined in claim 13 wherein said organic solvent utilized is a mixture consisting essentially of equal amounts of isopropanol and benzene.

l5. The process of claim 9 wherein a. the metal complex has the formula V r 1 08(0CHzCHtOCH)1-;(Ol0CHzCHjOCHQ:

g wherein x is from 0.75 to 1.0, wherem x from to b. said organic solvent contains about 50 weight perb. said organic solvent contains about 50 percent C1-C4 monohydric alcohol and about 50 weight C1-C4 monohydnc alcohol and about 50 weight percent benzene, and

percent benzene, and f l d t said mixture of organic solvent and said dispersant 10 Sal 0 Organ: so vent an Sal Spersam compound IS heated to a temperature of from compound is heated to a temperature of from about 30 to about 60 and maintained in this temabout C to abou C and maintaincd in this perature range during the addition of said complex. temperature range during the addition of said com- 16. the process of claim 9 wherein plex. a. the metal complex has the formula

Claims (15)

1. 2. A process as defined in claim 1 wherein said water is added to said mixture of said organic solvent and dispersant in an amount of from about 1.5 moles of water per mole of the complex, to about 4 moles of water per mole of the complex.
2. 3. The process defined in claim 1 wherein said mixture of organic solvent and dispersant is heated to a temperature of from about 30* to about 60* C, and maintained in this temperature range during addition of said complex.
3. 4. The process defined in claim 1 wherein the pressure of water in the solvent-dispersant mixture during addition of said complex is accomplished by adding to said solvent-dispersant mixture concurrently with the addition of the complex, an alcohol-water azeotrope.
4. 5. The process defined in claim 1 wherein said organic solvent is 2-methoxy - 1-ethanol.
5. 6. The process defined in claim 1 wherein said volatile material removal is accomplished by distilling said volatile materials from the reaction mixture to a pot temperature of between about 125* C and about 10* C; then stripping light ends from the reaction mixture by blowing carbon dioxide through the reaction mixture.
6. 7. The process defined in claim 1 wherein said complex contains from about 7 weight percent to about 8 weight percent calcium metal, and wherein the amount of water present in the solvent-dispersant mixture during the addition of complex is from about 1.5 moles to about 4 moles per mole of the complex adDed.
7. 8. The process defined in claim 1 wherein said complex contains from about 5 weight percent to about 6 weight percent magnesium metal, and wherein the amount of water present in the solvent-dispersant mixture during addition of the complex is from about 2 moles to about 4 moles per mole of the complex added.
8. 9. The process defined in claim 1 wherein said nitrogen-containing dispersant compound is formed by reacting an alkenyl succinic anhydride having a molecular weight of 600 to 4,000 with a polyamine selected from the group consisting of diethylene triamine and tetraethylene pentamine.
9. 10. The process defined in claim 9 wherein said nitrogen-containing dispersant compound consists essentially of succinimide and succinamide compounds, with a major amount of succinimide compounds being present, said succinimide compounds having the general formula
10. 11. The processs defined in claim 1 wherein said organic solvent contains about 50 weight percent of said C1-C4 monohydric alcohol, and about 50 weight percent benzene.
11. 12. The process defined in claim 1 wherein the organic solvent employed contains at least 25 weight percent 2-methoxy - 1-ethanol, said complex is added in a solution of 2-methoxy - 1-ethanol, and the presence of water in the solvent-dispersant mixture during addition of said complex is accomplisehd by adding to said solvent-dispersant mixture concurrently wiht the addition of the complex, an azeotrope of water and 2-methoxy - 1-ethanol.
12. 13. The process defined in claim 7 wherein the amount of water present in the solvent-dispersant mixture during addition of the complex is from about 1.6 moles to about 2.4 moles.
13. 14. The process defined in claim 13 wherein said organic solvent utilized is a mixture consisting essentially of equal amounts of isopropanol and benzene.
14. 15. The process of claim 9 wherein a. the metal complex has the formula
15. 16. the process of claim 9 wherein a. the metal complex has the formula