Hydrocarbyl Carbamidopropanamide, Its Method of Preparation and Lubricating Oil Composition Containing Same

1. Field of the Invention

This invention lies in the field of art relating to a lubricating oil composition adapted for use between a plurality of moving surfaces with which the fluid composition is in contact for the purpose of reducing the friction between these surfaces and to provide protection from wear and corrosion. These lubricant compositions tend to deteriorate under conditions of use with the attendant formation of sludge, lacquer and carbonaceous or resinous materials which adhere to the engine parts, particularly the piston rings, grooves and skirts, and cyclinder walls thus reducing the operating efficiency of the engine. To counteract the formation of these deposits, and/or to ameliorate the effects of such deposits, certain chemical additives have been found, which when added to a lubricating oil, have the ability to minimize the formation of the deposits or to maintain the deposits formed suspended in the oil so that the engine is kept clean and in efficient operating condition for extended periods of time. These agents are known in the art to which this invention pertains as detergents, dispersants or detergent-dispersants. Metal organic compounds are particularly useful in this respect and are exemplified by the oil-soluble zinc, calcium and barium salts of petroleum sulfonic acids, alkylated hydroxy benzoic acids, dialkyl dithiophosphoric acids and the like.

There are drawbacks associated with the use of organic metal salts in a lubricating oil composition for an internal combustion engine. A major drawback is that the metal salts formed by neutralization of the acids resulting from the combustion process are generally insoluble in the lubricating oil composition. More importantly, these insoluble metal salts occur as hard deposits on the piston rings, piston skirts or the cylinder liners and in the groove of the engine. These hard deposits are believed to be a major contributor to the wear that is experienced in an internal combustion engine. This problem is particularly acute with compression ignition engines, such as diesel engines, wherein the engine oil is subjected to extremely high temperature and compression stresses.

It is an object of the present invention to provide a new class of compounds which are useful as additives in lubricating oil compositions.

It is another object to provide an improved lubricating oil composition for an internal combustion engine.

It is a further object to provide a deposits-modifying additive for lubricants which is effective for reducing engine wear.

It is another object to provide a lubricating oil composition useful in diesel engines.

2. Description of the Prior Art

U.S. Pat. No. 3,796,663 discloses the preparation and use of an N-hydroxy hydrocarbyl-substituted succinimide in a lubricating oil composition.

U.S. Pat. No. 4,104,182 discloses N-alkoxy hydrocarbyl succinimides as deposit modifiers for lubricating oil compositions.

A copending application Ser. No. 149,222 filed May 12, 1980 discloses hydrocarbyl dihydrouracil containing same.

The disclosures of the above are incorporated herein by reference.

The novel hydrocarbyl-substituted carbamidopropanamide compound of this invention is represented by the formula: ##STR2## in which R is a hydrocarbyl radical having an average molecular weight ranging from about 150 to 2000 and R' in each occurrence represents hydrogen, a hydrocarbyl radical having from 1 to 20 carbon atoms or an R"(X-R'").sub.y -- radical in which R" is an alkyl radical having from 1 to 12 carbon atoms, X is oxygen or an --NH-- radical, R'" is a divalent hydrocarbyl radical having from 1 to 3 carbon atoms and y is an integer from 1 to 3. The novel process of the invention for preparing the noted carbamidopropanamide involves a multi-step reaction between an N-hydroxyhydrocarbyl succinimide and an amine employing at least two moles of amine per mole of the succinimide. The N-hydroxyhydrocarbyl succinimide is initially reacted with a nucleating agent, e.g., p-toluene-sulfonyl chloride, in the presence of a base to form an intermediate reaction product followed by a reaction with the amine to produce the noted carbamidopropanamide.

A novel lubricating oil composition is also provided comprising a base oil of lubricating viscosity and the above described carbamidopropanamide.

The hydrocarbyl-substituted carbamidopropanamide compound of the invention is represented by the formula: ##STR3## in which R is a hydrocarbyl radical having an average molecular weight (MW) ranging from about 150 to 2000 and R' in each occurrence is hydrogen, a hydrocarbyl radical having from 1 to 20 carbon atoms or an R"(X-R'").sub.y -- radical in which R" is an alkyl radical having from 1 to 12 carbon atoms, X is oxygen or an --NH-- radical, R'" is a divalent hydrocarbyl radical having from 1 to 3 carbon atoms and y is an integer from 1 to 3. The hydrocarbyl radicals represented by R' and R" can be an alkyl, aryl, cycloaliphatic, alkaryl or aralkyl radical such as phenyl, tolyl, benzyl, methyl, ethyl, isobutyl, decyl, octadecyl and hexadecyl radical. A more preferred carbamidopropanamide of the invention comprises the compound in which the hydrocarbyl radical has a molecular weight ranging from about 150 to 1300. An effective carbamidopropanamide compound of the invention comprises a carbamidopropanamide compound in which the hydrocarbyl radical has an average molecular weight ranging from about 800 to 1400.

A particularly preferred class of hydrocarbyl-substituted carbamidopropanamides are those in which the hydrocarbyl radical is an alkenyl or polyalkenyl radical. Typically, the alkenyl or polyalkenyl radical is one which has been derived through the polymerization of a low molecular weight olefin, such as ethylene, propylene, 1-butene, 2-butene and isobutylene or a mixture of low molecular weight olefins to produce a polyolefin having an average molecular weight corresponding to the molecular weight of the hydrocarbyl radical "R". A particularly preferred polyalkenyl radical is one derived from isobutylene to produce a polyisobutenyl radical having a molecular weight within the molecular weight ranges prescribed hereinabove. An effective polyalkenyl radical can be prepared by copolymerizing a mixture of ethylene and propylene by known methods. The average molecular weight of hydrocarbyl, alkenyl or polyalkyl radical represented by R is determined by vapor phase osmometry.

The R' substituents on the prescribed carbamidopropanamide described hereinabove can be the same or different. When R' is a hydrocarbyl radical it can be an aliphatic, cycloaliphatic, aromatic, alkaryl or aralkyl radical. A preferred hydrocarbyl radical is one having from 6 to 18 carbon atoms. A particularly preferred hydrocarbyl radical is an aromatic or alkaryl radical having from 6 to 10 carbon atoms. Examples of these preferred hydrocarbyl radicals include phenyl, tolyl, benzyl, 2-ethylhexyl, decyl dodecyl, tetradecyl, octadecyl and hexadecyl.

The starting reactant employed for preparing the hydrocarbyl-substituted carbamidopropanamide of the invention is an N-hydroxyhydrocarbyl-substituted succinimide represented by the formula: ##STR4## in which R is a hydrocarbyl radical having an average molecular weight ranging from 150 to 2000. The hydrocarbyl radical represented by R in the starting reactant corresponds to the above defined hydrocarbyl radical in the hydrocarbyl-substituted carbamidopropanamide compound of the invention.

The N-hydroxy hydrocarbyl-substituted succinimide is reacted with p-toluene sulfonyl chloride on an equimolar basis in the presence of a solvent and a base or acid acceptor, such as pyridine. The reaction can be conducted at a temperature ranging from about 0.degree. C. to 10.degree. C. Desirably, the reaction vessel is cooled in an ice-water bath to control the rate of reaction. On completion of this reaction, an intermediate addition reaction product of the succinimide and the p-toluene sulfonyl chloride is produced accompanied by splitting off of hydrogen chloride. This intermediate reaction is depicted by the following formula: ##STR5##

In the second step of the reaction, the intermediate reaction product is reacted with a primary or a secondary amine. A mole ratio of at least two moles of amine per mole of the intermediate reaction product is essential in order to produce the prescribed hydrocarbyl-substituted carbamidopropanamide. Excess amine can be employed. The amine to intermediate reaction product mole ratios ranging from 2:1 to 4:1 or more being effective.

A suitable amine reactant which can be employed in the process of the invention is represented by the formula:

in which R' in each occurrence is hydrogen, a hydrocarbyl radical having from 1 to 20 carbon atoms or an R"(X--R'").sub.y -- radical in which R" is an alkyl radical having from 1 to 12 carbon atoms, X is oxygen or an --NH-- radical, R'" is a divalent hydrocarbyl radical having from 1 to 3 carbon atoms and y is an integer from 1 to 3. As defined above, this hydrocarbyl radical can be an alkyl, aryl, cycloaliphatic, alkaryl or aralkyl radical such as phenyl, tolyl, benzyl, methyl, ethyl, isobutyl, decyl, octadecyl and hexadecyl radicals.

The amine reactants is added directly to the reaction mixture containing the intermediate reaction product. This reaction can be conducted at a temperature ranging from about 0.degree. to 100.degree. C. Generally, the reaction mixture is allowed to warm up to room temperature and then heated to its reflux temperature and maintained at this temperature for about an hour. Th final product mixture is cooled, water washed, dried, filtered and the solvent removed to yield the hydrocarbyl-substituted carbamidopropanamide of this invention.

The following examples illustrate the practice of this invention.

A mixture of polyisobutenyl (1290 MW) N-hydroxy succinimide (138 g, derived from Indopol H-300 alkenyl succinic acid anhydride and hydroxylamine) 300 mls. of heptane and 20 mls. of pyridine is stirred in an ice-water bath. 65 mmole of p-toluene sulfonyl chloride is added. After about 15 minutes, 538 mmole of aniline is added. The reaction mixture is allowed to warm up to room temperature and heated to reflux for about one hour. The reaction product is filtered, washed with 500 mls. of methanol and water aspirated to remove the heptane solvent. A yield of 130 grams (about 90%) of N-phenyl-beta-polyisobutenyl (1290 MW)-beta-(N,N'-phenyl) carbamidopropanamide as a dark brown oil is recovered as identified by infrared analysis peaks at 3378 cm.sup.-1 and 1643 cm.sup.-1.

A mixture of polyisobutenyl (1290 MW) N-hydroxy succinimide (138 g, derived from Indopol H-300 alkenyl succinic acid anhydride and hydroxylamine) 300 mls. of heptane and 20 mls. of pyridine is stirred in an ice-water bath. 65 mmol of p-toluene sulfonyl chloride is added. After about 15 minutes, 260 mmol of decyloxypropylaminopropyl amine is added. The reaction mixture is allowed to warm up to room temperature and heated to reflux for about one hour. The reaction product is filtered, washed with 500 mls. of methanol and water aspirated to remove the heptane solvent. The yield of 153.7 grams (about 89%) of N-decyloxypropylaminopropyl-beta-polyisobutenyl-(1290 MW)-beta-(N,N'-decyloxypropylaminopropyl) carbamidopropanamide as a dark brown oil is recovered as identified by infrared analysis peaks at 3390 cm.sup.-1 and 1639 cm.sup.-1.

A mixture of N-hydroxytetrapropenyl succinimide (107 mmol), 200 mls. of ethyl ether and 40 mls. of pyridine is stirred in an ice-water bath. 107 mmol of p-toluenesulfonyl chloride is added while the mixing is continued. After about 15 minutes, 269 mmol of aniline is introduced. The reaction mixture is warmed to room temperature and then heated at reflux for one hour. The reaction mixture is then cooled, washed with 300 mls. of water, dried over anhydrous magnesium sulfate and filtered. The solvent is removed using a water aspirator to yield 31 grams (90%) of a viscous product. Infrared analysis peaks at 3448 cm.sup.-1, and 1661 cm.sup.-1 indicates that the product is N-phenyl-beta-tetrapropenyl-beta-(N,N'-phenyl) carbamidopropanamide.

A mixture of 138 grams of polyisobutenyl (1290 MW) N-hydroxy succinimide, and hydroxylamine, 300 mls. of heptane and 20 mls. of pyridine is stirred in an ice-water bath. Sixty-five mmols of p-toluene-sulfonyl chloride is added with mixing. After about 10 minutes, 530 mmols of dodecyloxypropylamine is introduced. The reaction mixture is gradually warmed to room temperature and then it is heated to reflux and refluxed for one hour. The mixture is filtered and the filtrate is washed with 500 mls. of methanol. The heptane solvent is removed by a water aspirator to leave a substantial yield of the product, N-dodecyloxypropyl-beta-polyisobutenyl-(1290 MW)-(N,N'-dodecyloxypropyl) carbamidopropanamide.

Examples of other effective hydrocarbyl-substituted carbamidopropanamides include N-butyl-beta-tetrapropenyl-(N,N'-butyl) carbamidopropanamide, N-2-ethylhexyl-beta-tetrapropyl-(N,N'-2-ethylhexyl) carbamidopropanamide, N-octadecyl-beta-tetrapropyl-(N,N'-octadecyl) carbamidopropanamide, N-decyl-beta-tetrapropyl-(N,N'-tetradecyl) carbamidopropanamide, N-phenyl-beta-tetrapropyl-(N,N'-dodecyl) carbamidopropanamide, N-phenyl-beta-polyisobutenyl-(800 MW)-(N,N'-phenyl) carbamidopropanamide.

The additive of the invention can be employed in a mineral or synthetic base oil of lubricating viscosity or in a lubricating oil composition. The hydrocarbon mineral base oil can be a paraffinic base, naphthene base or mixed paraffin-naphthene base distillate or residual oil. Paraffin base distillate lubricating oil fractions are preferred for the formulation of the highest quality engine motor oils. The lubricating oil base will generally have been subjected to solvent refining to improve its lubricity and viscosity temperature relationship as well as to solvent dewaxing to remove waxy components and to improve the pour of the oil. Generally, mineral lubricating oils having an SUS viscosity at 100.degree. F. between 50 and 1000 can be used in the preparation of oil composition of the invention with the preferred base oils having a viscosity range from 70 to 300 SUS at 100.degree. F. A blend of base oils can be employed to provide a suitable base oil for either a single or multigrade motor oil.

Other lubricating oil bases can be employed such as synthetic hydrocarbon oils obtained by the polymerization of olefins as well as synthetic lubricating oils of the alkylene oxide type of the mono- and polycarboxylic acid ester type, such as the acids of adipic acid, sebasic acid and azelaic acid.

The additive of the invention can be employed in oil compositions and lubricating oils or concentrates therefor in concentrations ranging from 0.01 to about 50 percent by weight. A blended lubricating oil composition will generally contain from about 0.1 to about 5 percent by weight of the additive with the preferred concentrations ranging from 0.2 to 3 percent by weight. In addition, the lubricating oil composition may contain other lubricating oil additives such as oiliness agents, extreme pressure agents, rust inhibitors, oxidation inhibitors, corrosion inhibitors, viscosity index improving agents, detergents and dispersants.

The following examples illustrate lubricating oil compositions of this invention.

A mineral lubricating oil composition having an SUS viscosity in centistokes at 100.degree. F. of 100 containing 1% by weight of N-phenyl-beta-polyisobutenyl-(1290 MW)-beta-(N,N'-phenyl) carbamidopropanamide.

A mineral lubricating oil composition having an SUS viscosity in centistokes at 100.degree. F. of 150 containing 2 weight percent of N-decyloxypropylaminopropyl-beta-polyisobutenyl-(1290 MW)-beta-(N,N'-decyloxypropylaminopropyl) carbanidopropanamide.

An SAE-20 mineral lubricating oil containing 1.5 weight percent of N-phenyl-beta-tetrapropenyl-beta-(N,N'-phenyl) carbamidopropanamide.

A mineral lubricating oil composition having an SUS viscosity in centistokes at 100.degree. F. of 125 and at 200.degree. F. of 12.3 containing 2.0 weight percent of zinc dialkyldithiophosphate, 1.75 weight percent of an overbased sulfurized alkylphenolate and 2% of N-dodecyloxypropyl-beta-polyisobutenyl-(1290 MW)-(N,N'-dodecyloxypropyl) carbamidopropanamide.

An ester base lubricating oil composition comprising a major portion of an aliphatic ester based oil formed from the reaction of pentaerythritol and a mixture of organic monocarboxylic acids having 5 to 10 carbon atoms containing 2.0 weight percent of N-dodecyl-beta-polyisobutenyl-(800 MW)-beta-(N,N'-dodecyl) carbamidopropanamide.

An SAE-30 mineral lubricating oil containing 3 weight percent of N-octadecyl-beta-polyisobutenyl-(1200 MW)-beta-(N,N'-octadecyl) carbamidopropanamide.

An SAE-20 mineral lubricating oil containing 2 weight percent of the product of Example 4, 2.5 weight percent calcium sulfonate and 2% of an alkenyl succinimide derived from N-phenyl-beta-polyisobutenyl-(300 MW)-beta-(N,N'-phenyl) carbamidopropanamide.

The property of the additive of the invention for modifying the deposits formed by a lubricating oil composition in an internal combustion engine was demonstrated in a bench test which correlates well with the Mack ENDT-675 Engine Test which is a modification of the Mack T-1 Diesel Piston Deposit Test. In the bench test, a burner nozzle is positioned midway inside a six-inch heat shielded well which rests on a hot plate as a source of heat. An aluminum panel is placed at the bottom of the well three inches below the vertically positioned downwardly directed nozzle. The surface temperature of the aluminum panel is controlled by a thermocouple.

In operation, the temperature of the aluminum panel is maintained at 680.degree. F. The test oil is passed through the nozzle at a rate of 9 liters per minute in conjunction with an air jet. A deposits build-up forms on the aluminum panel over a run period of 2 hours duration. On completion of the high temperature oil oxidation run, the aluminum panel with the adhering oil deposits in cooled to room temperature. A segment of the adhering deposits on the disc was isolated by removal of adjacent deposits. The isolated segment covering a known area of the disc was then subjected to a shearing stress parallel to the disc face. The shearing tool was a flat metal specimen attached to the beam of a laboratory balance. Weights were added to the beam until the deposit segment was sheared off. The results expressed in grams measure the shearing force and permit a comparison of the adhesion/cohesion property of the deposits formed by the oil compositions.

The adhesion/cohesion property of three oil compositions containing the additive of the invention was determined in the following tests in comparison to oil compositions without the additive. Base Oil A was a solvent neutral oil of paraffinic character.

Commercial Oil B was a crankcase lubricating oil composition containing an overbased calcium sulfonate, a zinc dithiophosphate, a methacrylate VI improver and a conventional dispersant, antioxidant and foam inhibitor.

Commercial Oil C was a lubricating oil composition containing conventional additives including a calcium carbonate overbased calcium sulfonate, a zinc diisodecyldithiophosphate, a methacrylate pour depressant, an ashless dispersant, a dinonyldiphenylamine antioxidant and a foam inhibitor. The inspection values for the above oils were as follows:

The effect of the additive of the invention on the adhesion/cohesion properties of the deposits formed by the the oil compositions of the invention in the above-described test are set forth in the following table:

The foregoing tests demonstrate that the hydrocarbyl-substituted carbamidopropanamide compound of the invention was surprisingly effective for reducing the adhesive/cohesive properties as oxidized oil deposits formed from both conventionally formulated lubricating oil compositions and a base mineral oil that did not contain conventional lubricating oil additives.

The effectiveness of the carbamidopropanamide of the invention was also determined in the Mack ENDT-675 Engine Test. This engine test is similar to the Mack T-1 Test except that a 400 hour test sequence is used with a steady high speed, high output operation at 2100 rpm resulting in an approximately 8% higher load and fuel flow than the Mack T-1 stage 3 condition. After the test is run, the cylinders are examined for cylinder liner wear and the results reported as the percent heavy bore polishing. The results are set forth in the table below:

The foregoing results show that the hydrocarbyl-substituted carbamidopropanamide of the invention was highly effective for reducing heavy bore polishing of a diesel engine tested in the Mack ENDT-675 Engine Test. These results are attributed to a physical property modification of the deposits due to the additive of the invention.