EP0684979B1

EP0684979B1 - Lubricant compositions containing complexes of alkoxylated amine, acid, and adenine

Info

Publication number: EP0684979B1
Application number: EP94909035A
Authority: EP
Inventors: Jacob Joseph Habeeb; Morton Beltzer
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1993-02-22
Filing date: 1994-02-22
Publication date: 1997-07-23
Anticipated expiration: 2014-02-22
Also published as: CA2156606A1; DE69404447D1; JPH09502422A; WO1994019437A1; EP0684979A1; DE69404447T2

Abstract

A composition of matter useful in lubricating oil for reducing friction in an internal combustion engine, said complex comprising the reaction product of alkoxylated amine, acid and adenine and having formula (I), wherein Z is derived from either a hydrocarbylsalicylic acid, trithiocyanuric acid, a hydrocarbylsulfonic acid, a dihydrocarbyldithiophosphoric acid or a dihydrocarbyldithiobenzoic acid and wherein R is a hydrocarbyl group of 2 to 22 carbon atoms, R1 is hydrogen or a hydrocarbyl group of 1 to 20 carbon atoms, x and y are each independently integers of from 1 to 15 with the proviso that the sum of x + y is from 2 to 20, and a, b and c are independent numbers from 1.0 to 3.0 wherein the ratios of a:b, a:c and b:c range from 1.0:3.0 to 3.0:1.0.

Description

This invention relates to a composition of matter containing a complex being the reaction product of alkoxylated amine, acid and adenine and to an improved lubricating oil composition containing the reaction product and to the use of such complexes to reduce friction and/or improve fuel economy and/or inhibit copper corrosion in an internal combustion engine.
There are many instances, as is well known, particularly under "Boundary Lubrication" conditions where two rubbing surfaces must be lubricated, or otherwise protected, so as to prevent wear and to insure continued movement. Moreover, where, as in most cases, friction between the two surfaces will increase the power required to effect movement and where the movement is an integral part of an energy conversion system, it is most desirable to effect the lubrication in a manner which will minimise this friction. As is also well known, both wear and friction can be reduced, with various degrees of success, through the addition of a suitable additive or combination thereof, to a natural or synthetic lubricant. Similarly, continued movement can be insured, again with varying degrees of success, through the addition of one or more appropriate additives.
In order to protect internal combustion engines from wear, engine lubricating oils have been provided with antiwear and antioxidant additives. The primary oil additive for the past 40 years for providing antiwear and antioxidant properties has been zinc dialkyldithiophosphate (ZDDP). For example, U.S. Patent, 4,575,431 discloses a lubricating oil additive composition containing dihydrocarbyl hydrogen dithiophosphates and a sulfur-free of hydrocarbyl dihydrogen phosphates and dihydrocarbyl hydrogen phosphates, said composition being at least 50% neutralized by a hydrocarbyl amine having 10 to 30 carbons in said hydrocarbyl group. U.S. Patent 4,089,790 discloses an extreme-pressure lubricating oil containing (1) hydrated potassium borate, (2) an antiwear agent selected from (a) ZDDP, (b) an ester, an amide or an amine salt of a dihydrocarbyl dithiophosphoric acid or (c) a zinc alkyl aryl sulfonate and (3) an oil-soluble organic sulfur compound. Oil formulations containing ZDDP, however, require friction modifiers in order to reduce energy losses in overcoming friction. Such energy losses results in lower fuel economy. Moreover, oil additive packages containing ZDDP have environmental drawbacks. ZDDP adds to engine deposits which can lead to increased oil consumption and emissions. Moreover, ZDDP is not ash-free. Various ashless oil additive packages have been developed recently due to such environmental concerns. However, many ashless additive packages tend to be corrosive to copper which leads to additional components in the additive package to protect against corrosion. Most current commercial engine oils contain reduced phosphorus due to the poisoning of the catalytic converters by phosphorus.
U.S. Patent No. 5,076,945 discloses a lubricating oil composition containing an amine salt of a dithiobenzoic acid. The amines used to prepare salts are long chain hydrocarbyl amines.
U.S. Patents 3,849,319 and 3,951,973 describe lubricant compositions containing di- and tri(hydrocarbylammonium)trithiocyanurates. The hydrocarbyl radicals include alkyl, aralkyl, aryl, alkaryl and cycloalkyl and the examples are directed to alkylamines. These lubricant compositions were stated to have improved load-carrying properties.
It would be desirable to have a lubricating oil additive which provides excellent antiwear, antioxidation, friction reducing, fuel economy and environmentally beneficial (less fuel, less phosphorus, i.e., less exhaust emissions) properties. It is also desirable to find additives which inhibit copper corrosion. It would be a further benefit if these additives do not contribute phosphorous to the lubricating oil composition.
This invention relates to a novel composition of matter containing alkoxylated amine, acid, and adenine. It also relates to an improved lubricating oil composition which reduces friction and/or improves fuel economy in an internal combustion engine and in some cases exhibit improved copper corrosion inhibition and/or antiwear and antioxidant properties.
The present invention provides a composition of matter which comprises the reaction product of alkoxylated amine, acid and adenine wherein said reaction product is a complex having the following formula (I)
wherein Z is derived from either a hydrocarbylsalicylic acid, trithiocyanuric acid, a hydrocarbylsulfonic acid, a dihydrocarbyldithiophosphoric acid or a dihydrocarbyldithiobenzoic acid and wherein R is a hydrocarbyl group of 2 to 22 carbon atoms, R¹ is hydrogen or a hydrocarbyl group of 1 to 20 carbon atoms, x and y are each independently integers of from 1 to 15 with the proviso that the sum of x + y is from 2 to 20, and a, b and c are independent numbers from 1.0 to 3.0 wherein the ratios of a:b, a:c and b:c range from 1.0:3.0 to 3.0:1.0.
In a further aspect of the present invention there is provided a lubricant composition comprising a major amount of a lubricating oil basestock and a minor amount of a complex having the formula (I).
In a further aspect the present invention provides for the use of a complex having the formula (I) set forth above for inhibiting copper corrosion associated with the use of lubricating oil compositions in an internal combustion engine.
In a further aspect the present invention provides for the use of a complex having the formula (I) set forth above for reducing friction and/or improving fuel economy in an internal combustion engine.
The present invention also provides for the use of a complex having the formula (I) set forth above for reducing wear in an internal combustion engine.
In the lubricating oil composition of the present invention, the lubricating oil will contain a major amount of a lubricating oil basestock. The lubricating oil basestocks are well known in the art and can be derived from natural lubricating oils, synthetic lubricating oils, or mixtures thereof. In general, the lubricating oil basestock will have a kinematic viscosity ranging from about 5 to about 10,000 cSt at 40°C.
Natural lubricating oils include animal oils, vegetable oils (e.g., castor oil and lard oil), petroleum oils, mineral oils, and oils derived from coal and shale.
Synthetic oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins, alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl sulfides, as well as their derivatives, analogs, and homologues thereof, and the like. Synthetic lubricating oils also include alkylene oxide polymers, interpolymers, copolymers and derivatives thereof wherein the terminal hydroxyl groups have been modified by esterification, etherification, etc. Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids with a variety of alcohols. Esters useful as synthetic oils also include those made from C₅ to C₁₂ monocarboxylic acids and polyols and polyol ethers.
Silicon-based oils (such as the polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils) comprise another useful class of synthetic lubricating oils. Other synthetic lubricating oils include liquid esters of phosphorus-containing acids, polymeric tetrahydrofurans, polyalphaolefins, and the like.
The lubricating oil may be derived from unrefined, refined, rerefined oils, or mixtures thereof. Unrefined oils are obtained directly from a natural source or synthetic source (e.g., coal, shale, or tar sands bitumen) without further purification or treatment. Examples of unrefined oils include a shale oil obtained directly from a retorting operation, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process, each of which is then used without further treatment. Refined oils are similar to the unrefined oils except that refined oils have been treated in one or more purification steps to improve one or more properties. Suitable purification techniques include distillation, hydrotreating, dewaxing, solvent extraction, acid or base extraction, filtration, and percolation, all of which are known to those skilled in the art. Rerefined oils are obtained by treating refined oils in processes similar to those used to obtain the refined oils. These rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques for removal of spent additives and oil breakdown products.
In the oil soluble complexes of the present invention having the formula (I), R is preferably a hydrocarbyl group of from 2 to 18 carbon atoms, especially 6 to 18 carbon atoms, and R¹ is preferably hydrogen or a hydrocarbyl group of from 1 to 16 carbon atoms, most preferably hydrogen. Such hydrocarbyl groups includes aliphatic (alkyl or alkenyl) and alicyclic groups. The aliphatic or alicyclic groups may be substituted with amino, hydroxy, mercapto and the like and may be interrupted by O, S or N. The sum of x+y is preferably 2 to 15.
The complexes of the present invention are prepared from the reaction of alkoxylated, preferably a propoxylated or ethoxylated, especially ethoxylated amines with acid and adenine. Adenines are commercially available or may be prepared by methods known in the art. Adenine may be purchased from Aldrich Chemical Company. Ethoxylated and/or propoxylated amines are commercially available from Sherex Chemicals under the trade name Varonic and from Akzo Corporation under the trade names Ethomeen®, Ethoduomeen® and Propomeen®. Examples of preferred amines include ethoxylated (5) cocoalkylamine, ethoxylated (2) tallowalkylamine, ethoxylated (15) cocoalkylamine and ethoxylated (5) soyaalkylamine and ethoxylated (10) stearylamine. Propoxylated may be substituted for ethoxylated amines.
The complexes of the present invention are the reaction product of:

(a) an alkoxylated, preferably a propoxylated or ethoxylated , especially an ethoxylated amine of the formula:
wherein R, x and y are as defined above,
(b) an acid being either a hydrocarbylsalicylic acid, trithiocyanuric acid, a hydrocarbylsulfonic acid, a dihydrocarbyldithiophosphoric acid or a dihydrocarbyldithiobenzoic acid, and
(c) an adenine of the formula:
where R¹ is as defined above.

Preferred hydrocarbylsalicylic acids used to react with alkoxylated amines and adenines to form the complexes of the present invention have the following formula:
wherein R¹ is a hydrocarbyl group of from 2 to 30 carbon atoms preferably a hydrocarbyl group of from 2 to 26 carbon atoms. Such hydrocarbyl groups include aliphatic (alkyl or alkenyl) and alicyclic group. The aliphatic and alicyclic groups may be substituted with hydroxy, alkoxy, cyano, nitro, and the like and the alicyclic groups may contain O, S, or N as hetero atoms. These substituted salicylic acids are commercially available or may be prepared by methods known in the art, e.g. U.S. Patent 5,023,366.
Trithiocyanuric acid may exist in different tautomeric forms represented by formulas II, III or mixtures thereof:
Trithiocyanuric acid is prepared by methods well known in the art. These methods involve the treatment of cyanuric chloride with sulfur nucleophiles according to the following reaction scheme:
Other sulfur nucleophiles which may be employed in the above reaction scheme include sodium sulfide, thiourea and thioacetic acid.
Preferred hydrocarbylsulfonic acids used to react with alkoxylated amines and adenines to form the complexes of the present invention have the following formula:
wherein R¹ is a hydrocarbyl group of from 2 to 30 carbon atoms preferably a hydrocarbyl group of from 2 to 26 carbon atoms. Such hydrocarbyl groups include aliphatic (alkyl or alkenyl) and alicyclic group. The aliphatic and alicyclic groups may be substituted with hydroxy, alkoxy, cyano, nitro, and the like and the alicyclic groups may contain O, S, or N as hetero atoms. These sulfonic acids are commercially available or may be prepared by methods well known in the art.
Preferred dihydrocarbyldithiophosphoric acids used to react with alkoxylated amines and adenines to form the complexes of the present invention have the following formula:
wherein R² and R³ are each independently hydrocarbyl groups having from 3 to 30 carbon atoms preferably 3 to 20 carbon atoms. Such hydrocarbyl groups include aliphatic (alkyl or alkenyl) and alicyclic group. The aliphatic and alicyclic groups may be substituted with hydroxy, alkoxy, cyano, nitro, and the like and the alicyclic groups may contain O, S, or N as hetero atoms. Especially preferred dialkyldithiophosphoric acids are made from mixed (85%) 2-butyl alcohol and (15%) isooctyl alcohol (mixed primary and secondary alcohols). Dihydrocarbyldithiophosphoric acids may be purchased from Exxon Chemical Company
Preferred dihydrocarbyldithiobenzoic acids used to react with alkoxylated amines and adenines to form the complexes of the present invention have the following formula:
wherein R² to R⁶ are each preferably hydrogen; a hydrocarbyl group containing from 1 to 18 carbon atoms; or a hydroxy group with the proviso that at least one of R² to R⁵ is a hydrocarbyl, preferably an alkyl group containing 1 to 18 carbon atoms, more preferably 1 to 6 carbon atoms. R³ and R⁵ are most preferably t-butyl groups and R⁴ is preferably hydroxy. The sum of x + y is preferably 2 to 15. The hydrocarbyl groups include aliphatic (alkyl or alkenyl) and alicyclic groups which may be substituted by hydroxy, amino, cyano and the like and may be interrupted by O, S or N.
Dithiobenzoic acids may be prepared from a phenol according to the following method. A Phenol of the formula:
is dissolved in a solvent such as dimethylsulfoxide and treated under nitrogen with potassium hydroxide dissolved in a minimum amount of water. Carbon disulfide is then added under nitrogen to this mixture which is maintained at about room temperature. The resulting reaction mixture is heated at between 25 to 100°C for 1-3 hours and then added to an acidified water solution. The resulting dithiobenzoic acid can be isolated by solvent extraction using, e.g. ether and the solvent evaporated.
When the complexes of the present invention are derived from a hydrocarbylsalicylic acid they are prepared by adding the salicylic acid to a mixture of adenine and alkoxylated amine. Because of the exothermic nature of the reaction, the reaction mixture should be stirred during addition of salicylic acid.
When the complexes of the present invention are derived from trithiocyanuric acid they are prepared by adding trithiocyanuric acid to a mixture of adenine and alkoxylated amine. Because of the exothermic nature of the reaction, the reaction mixture should be stirred during addition of trithiocyanuric acid. The amounts of reactants are approximately stoichiometic, although a slight excess of trithiocyanuric acid, which has three reactive hydrogens, may be employed.
When the complexes of the present invention are derived from a dihydrocarbyldithiobenzoic acid they are prepared as described below. This preparation is based on an approximate 1:1:1 mole ratio although this ratio may vary. About 10 to 20% of the required amount of alkoxylated amine (based on the thiobenzoic acid) is added to the dithiobenzoic acid with heating and stirring. Temperatures may range from about 25 to about 180°C. About 10 to 20% of the required amount of adenine is then added. This sequential addition process is repeated until the required amount (based on the above approximate 1:1:1 of amine:acid:adenine) is reached. A precipitate (polymeric and unidentified material) forms if this alternative additional procedure is not employed.
When the complexes of the present invention are derived from a hydrocarbylsulfonic acid they are prepared by adding the sulfonic acid to a mixture of adenine and alkoxylated amine. Because of the exothermic nature of the reaction, the reaction mixture should be stirred during addition of sulfonic acid.
When the complexes of the present invention are derived from a dihydrocarbyldithiophosphoric acid they are prepared as described below. This preparation is based on an approximate 1:1:1 mole ratio although this ratio may vary. About 10 to 20% of the required amount of alkoxylated amine (based on the phosphoric acid) is added to the dihydrocarbyldithiophosphoric acid with heating and stirring. Temperatures may range from about 25 to about 180°C. About 10 to 20% of the required amount of adenine is then added. This sequential addition process is repeated until the required stoichiometic amounts (1:1:1 of amine :acid:adenine) is reached. A precipitate (polymeric and unidentified material) forms if this sequential addition procedure is not employed.
The precise stoichiometry of the bonding in the complexes of the formula (I) is not known since each molecule in the complex may have several sites which can take part in the hydrogen bonding process either as an acceptor or donor. Because of the multiplicity of bonding possibilities, the molar ratios a:b:c can be varied over a wide range based on the donor/acceptor sites on each of the three molecules and therefore a, b and c in formula (I) are numbers which are not necessarily integral. When the acid is trithiocyanuric acid there exist a total of forty-five combinations of interaction sites between the three molecules comprising the complex of the formula (I). When the acid is hydrocarbylsulfonic or hydrocarbylsalicylic acid there exist a total of thirty combinations of interaction sites between the three molecules comprising the complex of the formula (I). When the acid is dihydrocarbyldithiobenzoic or dihydrocarbyldithiophosphoric acid there exist a total of fifteen combinations of interaction sites between the three molecules comprising the complex of the formula (I). For example a:b:c may be 1:2:1 or 1:1:3.
The lubricant oil composition according to the invention comprises a major amount of lubricating oil basestock and a minor amount. of the alkoxylated amine:acid:adenine complex. When the acid is either trithiocyanuric acid, hydrocarbylsulfonic acid or hydrocarbylsalicylic acid typically, the amount of complex will be from about 0.001 wt% to about 5 wt%, based on oil basestock. Preferably, the amount of amine salt is from about 0.05 wt% to about 1.0 wt%. When the acid is either dihydrocarbyldithiobenzoic acid or dihydrocarbyldithiophosphoric acid the concentration of the complex of general formula (I) may typically range from 0.1 to 5 wt% based on oil and preferably from 0.5 to 1.5 wt%. The amount of complex is such that there is an effective amount to achieve one or more of improved fuel economy, reduced friction, inhibition of copper corrosion, antiwear properties and antioxidant properties when the lubricant oil composition is used in an internal combustion engine.
If desired, other additives known in the art may be added to the lubricating oil basestock. Such additives include dispersants, antiwear agents, antioxidants, rust inhibitors, other corrosion inhibitors, detergents, pour point depressants, extreme pressure additives, viscosity index improvers, other friction modifiers, hydrolytic stabilizers and the like. These additives are typically disclosed, for example, in "Lubricant Additives" by C. V. Smalhear and R. Kennedy Smith, 1967, pp. 1-11 and in U.S. Patent 4,105,571.
The lubricating oil composition of this invention can be used in the lubrication system of essentially any internal combustion engine, including automobile and truck engines, two-cycle engines, aviation piston engines, marine and railroad engines, and the like. Also contemplated are lubricating oils for gas-fired engines, alcohol (e.g., methanol) powered engines, stationary powered engines, turbines, and the like.
This invention may be further understood by reference to the following example, which includes a preferred embodiment of the invention.

Example 1

This Example illustrates the preparation of a complex containing ethoxylated amine, trithiocyanuric acid and adenine according to the invention. 68 g of ethoxylated(5)cocoalkylamine and 13 g of adenine was heated to 70°C with stirring in a 3-neck round bottom flask fitted with a thermometer and a water cooled condenser. 14 g of trithiocyanuric acid was added gradually to the stirred amine solution. During addition, the temperature rose to 105°C due to an exothermic reaction between acid and amine adenine components. The reaction mixture was used without further purification.

Example 2

The complex containing ethoxylated amine, trithiocyanuric acid and adenine is an effective friction modifier as shown in this example. The Ball on Cylinder (BOC) friction tests were performed using the experimental procedure described by S. Jahanmir and M. Beltzer in ASLE Transaction, Vol. 29, No. 3, p. 425 (1985) using a force of 0.8 Newtons (1 Kg) applied to a 12.5 mm steel ball in contact with a rotating steel cylinder that has a 43.9 mm diameter. The cylinder rotates inside a cup containing a sufficient quantity of lubricating oil to cover 2 mm of the bottom of the cylinder. The cylinder was rotated at 0.25 RPM. The friction force was continuously monitored by means of a load transducer. In the tests conducted, friction coefficients attained steady state values after 7 to 10 turns of the cylinder. Friction experiments were conducted with an oil temperature of 100°C. Various amounts of the complex prepared in Example 1 were added to solvent 150 N. The results of BOC friction tests are shown in Table 1.
As can be seen from the results in Table 1, as little as 0.05 wt% of complex shows 79% decrease in the coefficient of friction. These results demonstrate that present complexes are capable of significant reductions in the coefficient of friction of a lubricant basestock which results in less friction and hence greater fuel economy when the lubricant oil is used in an internal combustion engine.

Example 3

This Example illustrates the preparation of a complex containing an ethoxylated amine, alkylsalicylic acid and adenine according to the invention. 101 g of ethoxylated(5)cocoalkylamine and 4 g of adenine were heated to 80°C with stirring in a 3-neck round bottom flask fitted with a thermometer and a water cooled condenser. 100 g of salicylic acid having the formula
was added gradually to the stirred amine/adenine solution. During addition, the temperature rose to 104°C due to the exothermic reaction between acid and amine. The reaction mixture was maintained at 104°C for 1.5 hours and then cooled to room temperature. The reaction mixture was a complex according to the invention and was used without further purification.

Example 4

The complex containing ethoxylated amine, alkylsalicylic acid, adenine is an effective friction modifier as shown in this example. The Ball on Cylinder (BOC) friction tests were performed using the experimental procedure described in Example 2. Various amounts of complex prepared in Example 3 were added to solvent 150 N. The results of BOC friction tests are shown in Table 2.

TABLE 2

Wt% of Ethoxylated(5)Cocoalkylamine, Alkyl Salicylic Acid and Adenine Complex in Solvent 150N	Coefficient of Friction
0.00	0.32
0.1	0.07
0.2	0.05
0.3	0.035
0.5	0.03
0.8	0.03
1.0	0.02

As can be seen from the results in Table 2, as little as 0.1 wt% of complex shows a 78% decrease in the coefficient of friction. These results demonstrate that the present complexes are capable of significant reductions in the coefficient of friction of a lubricant basestock which results in less friction and hence greater fuel economy when the lubricated oil is used in an internal combustion engine.

Example 5

A solution of 3 g ethoxylated (5) cocoalkylamine was heated to 50-110°C with stirring. 0.5 g of 4-hydroxy-3,5-ditertiarybutyldithiobenzoic acid was then added to the heated and stirred solution following by 125 mg of adenine. This procedure of sequentially adding the dithiobenzoic and adenine was repeated until 2 g of the acid and 500 mg of adenine have been added to the solution. The sequential procedure was employed to prevent precipitation of by-product polymeric materials.

Example 6

Ball on Cylinder (BOC) friction tests were performed on the ethoxylated(5)cocoalkylamine:dithiobenzoate:adenine complex from Example 5 in solvent 150N base oil using several concentrations of the additive. The BOC tests were performed using the experimental procedure described in Example 2. The data is shown in Table 3.

TABLE 3

	Concentration (wt.%) in solvent 150N	Coefficient of Friction Ethoxylated (5) cocoamine:DTB:Adenine	Ethoxylated (5) cocoamine:DTB	Primene** JMT:DTB
1	0	0.37	0.37	0.37
2	0.05	0.22	0.121	--
3	0.1	0.17	0.107	0.3
4	0.2	0.13	--	--
5	0.4	--	0.107	--
6	0.5	0.07	--	0.21
7	0.6	--	0.107	--
8	0.8	0.06	0.107	0.177

** Primene JMT is predominantly a C₁₈ t-alkyl primary amine manufactured by Rohm & Haas.

As can be seen from the data in Table 3, the adenine-containing complex achieves lower coefficient of friction than can be obtained from the comparable complex without adenine or a Primene JMT:DTB complex.

Example 7

This Example illustrates the preparation of a complex containing ethoxylated amine, alkylsulfonic acid and adenine according to the invention. 41 g of ethoxylated(2)tallowamine and 1 g of adenine were heated to 60°C with stirring in a 3-neck round bottom flask fitted with a thermometer and a water cooled condenser. 58 g of alkylsulfonic acid having the formula
was added gradually to the stirred amine/adenine solution. During addition, the temperature rose to 105°C due to the exothermic reaction between acid and amine. The reaction mixture was maintained at 105°C for 1.5 hours and then cooled to room temperature. The reaction mixture was a complex according to the invention and was used without further purification.

Example 8

The complex containing ethoxylated amine, alkylsulfonic acid and adenine is an effective friction modifier as shown in this example. The Ball on Cylinder (BOC) friction tests were performed using the experimental procedure described in Example 2. Various amounts of complex prepared in Example 7 were added to solvent 150 N. The results of BOC friction tests are shown in Table 4. TABLE 4

Wt% of Ethoxylated(2)Tallowamine, Alkylsulfonic Acid and Adenine Complex in Solvent 150N Coefficient of Friction

0.00 0.32

0.1 0.20

0.2 0.18

0.3 0.13

0.5 0.10

0.8 0.07

1.0 0.06
As can be seen from the results in Table 4, as little as 1.0 wt% of complex shows an 81% decrease in the coefficient of friction. These results demonstrate that the present complexes are capable of significant reductions in the coefficient of friction of a lubricant basestock which results in less friction and hence greater fuel economy when the lubricated oil is used in an internal combustion engine.

Example 9

This Example illustrates the preparation of the novel complex of the invention. A solution of 80 g of diisooctyldithiophosphoric acid was heated to 50-100°C with stirring. 10 g of ethoxylated(5)cocoalkylamine was then added to the heated and stirred solution followed by 1 g of adenine. This procedure of sequentially adding ethoxylated amine and adenine was repeated until 75 g of ethoxylated (5) cocoalkylamine and 7 g of adenine have been added to the solution. The sequential addition procedure was employed to prevent precipitation of byproduct. The complex was then collected on cooling and used without further purification.

Example 10

This Example illustrates the superior copper corrosion protection provided by the complex of the invention as prepared in Example 9. The test for copper corrosion were run as follows. Copper corrosion tests were based on ASTM D-2440. 25 g of oil sample is placed in a 0.5" test tube with 30 cm of copper wire coiled to 0.5" and stretched to a finished length of 2". The test tube is then heated at 110°C for 120 hours. Nitrogen is bubbled through the oil at 17 cc/min during the test period. A 5 g sample of oil is removed at the end of the test and analyzed for copper content. Results of the copper corrosion are shown in Table 5.

TABLE 5

		Copper Corrosion (ppm)

Base case -	Lubricating oil	21

Base case +1%	Ethoxylated(5)cocoamine:DDP(diisooctyl)	37
Base case +1%	Ethoxylated(5)cocoamine:DDP(diisooctyl):Adenine	17

Base case +1.5%	Ethoxylated(5)cocoamine:DDP(diisooctyl)	57
Base case +1.5%	Ethoxylated(5)cocoamine:DDP(diisooctyl):Adenine	23

Base case +1%	Ethoxylated(2)tallowamine:DDP(secondary)*	74
Base case +1%	Ethoxylated(2)tallowamine:DDP(secondary):Adenine	18

Base case +1.5%	Ethoxylated(2)tallowamine:DDP(secondary)	107
Base case +1.5%	Ethoxylated(2)tallowamine:DDP(secondary):Adenine	23

* DDP (secondary) contains a mixture of isobutyl (85%) and isooctyl (15%) as the alkyl component.

Example 11

This Example illustrates the superior antiwear properties of the complex of the invention. Antiwear properties are measured by the four-ball wear test as follows. The Four Ball test used in described in detail in ASTM method D-2266. In this test, three balls are fixed in a lubricating cup and an upper rotating ball is pressed against the lower three balls. The test balls utilized were made of AISI 52100 steel with a hardness of 65 Rockwell C (840 Vickers) and a centerline roughness of 25 mm. Prior to the tests, the test cup, steel balls, and all holders were washed with 1,1,1 trichloroethane. The steel balls subsequently were washed with a laboratory detergent to remove any solvent residue, rinsed with water, and dried under nitrogen.
The Four Ball wear tests were performed at 100°C, 60 kg load, and 1200 rpm for 45 minutes duration. After each test, the balls were washed and the Wear Scar Diameter (WSD) on the lower balls measured using an optical microscope. Using the WSD's, the wear volume (WV) was calculated from standard equations (see Wear Control Handbook, edited by M. B. Peterson and W. O. Winer, p. 451, American Society of Mechanical Engineers [1980]). The percent wear reduction (% WR) for each oil tested was then calculated using the following formula. $%WR = ( 1 - WV with additive/WV without additive) x 100$

The result of the four-ball are set forth in Table 6.

TABLE 6

% Additive in Solvent 150N*	Wear Scar Diameter (mm)
	Ethoxylated(5)cocoamine:DDP(isooctyl)	Ethoxylated(5)cocoamine:DDP(isooctyl):Adenine
	% wear volume reduction	% wear volume reduction

0	0.0	0.0
0.1	-7.3	15.5
0.2	45.5	88.1
0.4	41.1	--
0.5	--	96.4
0.6	--	97.8
0.8	15.1	99.2
1.0	-7.3	99.5
1.5	96.1	99.5

* S150 is a solvent extracted, dewaxed, hydrofined neutral lube base stock obtained from approved paraffinic crudes (viscosity, 32 cSt at 40°C, 150 Saybolt seconds)

The data in Table 6 demonstrate that even at low concentration (<0.2%), the present adenine complex has superior antiwear properties over the corresponding amine salt without adenine.

Claims

A composition of matter comprising a complex which is the reaction product of alkoxylated amine, acid and adenine, said complex having the formula (I):
wherein Z is derived from either a hydrocarbylsalicylic acid, trithiocyanuric acid, a hydrocarbylsulfonic acid, a dihydrocarbyldithiophosphoric acid or a dihydrocarbyldithiobenzoic acid and wherein R is a hydrocarbyl group of 2 to 22 carbon atoms, R¹ is hydrogen or a hydrocarbyl group of 1 to 20 carbon atoms, x and y are each independently integers of from 1 to 15 with the proviso that the sum of x + y is from 2 to 20, and a, b and c are independent numbers from 1.0 to 3.0 wherein the ratios of a:b, a:c and b:c range from 1.0:3.0 to 3.0:1.0.
A composition as claimed in claim 1 wherein Z is derived from a hydrocarbylsulfonic acid of the following formula:
wherein R¹ is a hydrocarbyl group having from 2 to 30 carbon atoms.
A composition as claimed in claim 1 wherein Z is derived from a hydrocarbylsalicylic acid of the following formula:
wherein R¹ is a hydrocarbyl group having from 2 to 30 carbon atoms.
A composition as claimed in claim 2 or claim 3 wherein R¹ is a hydrocarbyl group having from 2 to 26 carbon atoms.
A composition as claimed in claim 1 wherein Z is derived from a dihydrocarbyldithiobenzoic acid of the following formula:
wherein R² R³ R⁴ R⁵ and R⁶ are independently hydrogen or a hydrocarbyl group containing from 1 to 24 carbon atoms or a hydroxy group with the proviso that at least one of R² to R⁵ is a hydrocarbyl group.
A composition as claimed in claim 5 wherein R⁴ is hydroxy.
A composition as claimed in either claim 5 or claim 6 wherein at least one of R² to R⁵ is alkyl containing from 1 to 18 carbon atoms.
A composition as claimed in any of claims 5 to 7 wherein R³ and R⁵ are t-butyl.
A composition as claimed in claim 1 wherein Z is derived from a dihydrocarbyldithiophosphoric acid which has the following general structure;
wherein R² and R³ are each independently hydrocarbyl groups having from 3 to 30 carbon atoms.
A composition as claimed in claim 9 wherein R² and R³ are alkyl or alkenyl groups of from 3 to 20 carbon atoms.
A composition as claimed in any of claims 1 to 10 wherein R is alkyl or alkenyl of from 6 to 18 carbon atoms.
A composition as claimed in any of claims 1 to 11 wherein the sum of x+y is 2 to 15.
A composition as claimed in any of claims 1 to 12 wherein in the adenine R¹ is hydrogen.
A lubricating oil composition for internal combustion engines which comprises
(a) a major amount of a lubricating oil basestock and

(b) a minor amount of a complex as claimed in any of claims 1 to 13.
A composition as claimed in claim 14 wherein the complex is as claimed in any of claims 5 to 11 and wherein the amount of complex is from about 0.1 to about 5.0 wt.%, based on oil basestock.
A composition as claimed in claim 14 wherein the complex is as claimed in any of claims 1 to 4 and wherein the amount of complex is from about 0.001 to about 5.0 wt.%, based on oil basestock.
The use in a lubricating oil composition of a complex as claimed in any of claims 1 to 13 for improving fuel economy in an internal combustion engine.
The use in a lubricating oil composition for reducing wear and/or inhibiting copper corrosion in an internal combustion engines of a composition as claimed in any of claims 1 .to 13.
The use of a composition as claimed in any of claims 1 to 13 as a friction modifier in a lubricating oil composition for an internal combustion engine.