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United States Patent 3,152,080 AIVHDD-BIS-IMEAZGLINES IN LUBRICATING 01L CGMPOSI'I'EONS rank A. Stuart, Qrinda, and Warren Lowe, Berkeley, Calif., assignors to California Research Corporation,
San Francisco, Calif., a corporation of Delaware No Drawing. Filed May 31, 1960, Ser. No. 32,573 2 Claims. (Cl. 252-515) This invention pertains to lubricating oil compositions having incorporated therein metal-free detergents. These metal-free detergents are certain particular imidazoline compounds.
lrnidazolines are variously well known in the art. For example, U.S. Patent 2,907,646 describes the use of 1,2 disubstituted imidazolines in amounts less than 0.005%, by weight, as a synergist in combination with tall oil to inhibit rusting by fuel oils. U.S. Patent 2,622,067 describes mononuclear imidazolines as emulsifying agents for emulsifiable oils. Again, certain mononuclear imidazolines are described in U.S. Patents 2,839,371 and 2,922,707 as additives for gasoline compositions. However, these imidazolines of the prior art do not encompass the particular imidazolines described in detail hereinbelow and which are significantly effective as detergents in lubricating oil compositions.
Present day internal combustion engines operate at high speeds and high compression ratios. Vfhen used in the so-called city stop-and-go driving, which includes the greater part of the driving condition for a large percentage of todays automobiles, the internal combustion engines do not reach the most efficient operating temperature. Under city driving conditions, large amounts of partial oxidation products are formed, and reach the crankcase of the engine by blowing past the piston rings. Most of these partial oxidation products are oil insoluble polymeric products which tend to form deposits on pistons, piston rings, etc. These deposits markedly reduce the efficiency of engine operations, and cause excessive wear and loss of power. For the purpose of preventing the deposition of such products, it is necessary to incorporate detergents in the lubricatin oil compositions, thus keeping these polymeric products highly dispersed in a condition unfavorable for deposition on metals.
For the most part, the various detergents which are added to lubricating oils to reduce this formation of sludges and varnishes are metal organic compounds, particularly those compounds wherein the metal is linked to an organic group through an oxygen atom. Although these metal-containing organic compounds have some effectiveness as detergents for dispersing the precursors of deposits within the oil itself rather than permitting them to form added deposits on the engine parts, they have the disadvantage of forming ash deposits in the engine. These ash deposits lower engine performance by fouling spark plugs and valves, and contributing to preignition.
Different detergents act variously to inhibit the formation of deposits. Some detergents react chemically with deposit precursors to form harmless compounds which are solubilized in the lubricating oils. Other detergents prevent the coagulation of solid particles in the oil by dispersing such particles and keeping them suspended in the oil.
The compounds described herein are metal-free detergents which perform both of the above functions, namely, react chemically with the deposit precursors and prevent coagulation of solid particles in the oils.
It is a particular object of this invention to provide lubricating oil compositions which are compounded with a metal-free detergent.
Therefore, in accordance with this invention, it has 3,l52,0ii0 Fatented Oct. 6, 1964 been discovered that lubricating oil compositions particularly useful for heavy duty service are obtained by incorporating acyl bis-[,B-(Z-aliphatic imidazolyl)ethyl] amines in oils of lubricating viscosity. For simplicity, these acyl bis-[,B-(Z-aliphatic imidazolyl)ethyl] amines will hereinfater be termed amido-bis-imidazolines.
By the use of lubricating oil compositions containing the amido-bis-imidazolines described herein, diesel and gasoline engine parts remain remarkably free of deposits and varnish, even under severe operating conditions.
The amido-bis-irnidazolines, which are believed to be new compounds, are described by the formula:
wherein the Rs are radicals derived from saturated and unsaturated aliphatic monocarboxylic acids containing from 10 to 20 carbon atoms, preferably saturated alipatic monocarboxylic acids. In the above formula, the Rs are preferably alkyl radicals containing from 9 to 19 carbon atoms.
The monocarboxylic acids from which the Rs are derived are exemplified by lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, palmitoleic acid, oleic acid, elaidic acid, etc.
Lubricating oils which can be used as base oils for the compositions described herein include a wide variety of lubricating oils, such as naphthenic base, paraflin base, and mixed base lubricating oils, other hydrocarbon lubricants, e.g., lubricating oils derived from coal products, and synthetic oils, e.g., alkylene polymers (such as polymers of propylene, butylene, etc., and the mixtures thereof), alkylene oxide-type polymers (e.g., propylene oxide polymers) and derivatives, including alkylene oxide polymers prepared by polymerizing the alkylene oxide in the presence of water or alcohols, e.g., ethyl alcohol, dicarboxylic acid esters (such as those Which are prepared by esterifying such dicarboxylic acids as adipic acid, azelaic acid, suberic acid, sebacic acid, succinic acid, fumaric acid, maleic acid, etc., with alcohols such as butyl alcohol, hexyl alcohol, 2-ethyl hexyl alcohol, dodecyl alcohol, etc.), liquid esters of acids of phosphorus, alkyl benzenes, (e.g., monoalkyl benzene such as dodecyl benzene, tetradecyl benzene, etc., and dialkyl beruenes (e.g., biphenyls and terphenyls), alkyl biphenyl ethers, polymers of silicon (e.g., tetraethyl silicate, tetraisopropyl silicates, tetra(4- methyl-Z-tetraethyl) silicate, hexyl(4-methyl-2-pentoxy) disiloxane, poly(methyl) siloxane, poly(methylphenyl) siloxane, etc.
The above base oils may be used individually or in combinations thereof, wherever miscible or wherever made so by the use of mutual solvents.
The amido-bis-irnidazolines can be used in oils of lubricating viscocity in amounts of O.l% to 15%, by weight, preferably 0.25% to 5%, by weight. In the formation of lubricating oil concentrates thereof, amounts up to 60% and greater can be incorporated in lubricating oils.
The amido-bis-imidazolines described herein can be obtained in one step by reacting 1 mol of tetraethylenepentamine with 3 mols of an aliphatic monocarboxylic acid at temperatures in excess of 200 C. Alternately, a bisirnidazoline can be formed by first reacting 1 mol of tetraethylenepentamine with 2 mols of an aliphatic monocarboxylic acid at a temperature of at least 225 C., then reacting 1 mol of the resulting bis-imidazoline further with 1 mol of aliphatic monocarboxylic acid to yield the amido-bis-imidazoline.
The GD Nos. refer to the percentage deposits in the piston ring grooves; a evaluation being a clean groove; and a number of 100 being a groove full of deposits.
The base oil was a California SAE base oil.
The preparation of amido-bis-imidazolines is illustrated in the following example.
EXAMPLE I Preparation of Octadecanoyl Bis-[B-(Z-Heptadecyl Imidazolyl)Ethyl] Amine A mixture of 95 grams of tetraethylenepentamine (0.5 mol), 304 grams of actadecanoic acid (1 mol), and 150 cc. of toluene was agitated in a glass reaction vessel for several hours at a temperature of 160 C. This resulted in the liberation of 28 cc. of water which compares favorably with the amount of water produced by the formation of one imidazoline ring (27 cc. water). The mixture was then heated for 24 hours at temperatures between 238 C. and 274 C. At the end of 24 hours, cc. of water was collected. This corresponds to a theoretical value of 36 cc. for dehydration to produce two imidazoline rings. The reaction mixture was heated to 177 C. at 5 mm. of mercury pressure to remove the toluene.
A mixture of 72 grams (0.1 mol) of the above bisimidazoline, 30 grams (0.1 mol) of octadecanoic acid, and 100 cc. of toluene was then agitated at a temperature of about 200 C. for several hours. Two centimeters of water were collected in the trap, and this corresponds exactly with the theoretical amount of water expected for the amidization of the bis-imidazoline. The resulting product was heated to a temperature of 177 C. at 4 mm.
of mercury pressure to remove the toluene.
Table I hereinbelow presents data on the effectiveness of amido-bis-imidazolines as lubricating oil additives.
The tests were made in a Caterpillar L-1 engine according to Supplement I conditions for a perior of 120 hours as described in the Coordinating Research Council Handbook, January 1946.
The PD Nos. refer to the piston discoloration rating. After the engine test, the three piston lands are examined visually. To a piston skirt which is completely black is assigned a PD number of 800; to one which is completely clean, a PD number of 0; to those intermediate between completely black and completely clean are assigned PD numbers intermediate in proportion to the extent and degree of darkening.
In addition to illustrating the elfectiveness of the amidobis-imidazolines as lubricating oil additives, the above data show that these amido-bis-imidazolines are markedly superior to diamido-imidazolines.
In addition to the amido-bis-imidazolines described hereinabove, the lubricating oil compositions of this invention may also contain other detergents, viscosity index improving agents, rust inhibitors, oiliness agents, grease thickening agents, etc.
1. A lubricating oil composition comprising a major proportion of an oil of lubricating viscosity, and from about 0.1% to about 15% by weight of an acyl bis-[)8- (2-alkyl-imidazolyl)ethyl] amine, wherein said alkyl radical contains from 9 to 19 carbon atoms, and said acyl radical contains from 10 to 20 carbon atoms, said amine being prepared by first reacting 1 mole of tetraethylene pentamine with 2 moles of alkyl monocarboxylic acid at a temperature of at least 225 C. and then reacting 1 mole of the resulting bis-imidazoline further with 1 mole of alkyl monocarboxylic acid.
2. A lubricating oil composition consisting essentially of an oil of lubricating viscosity, and from about 0.1% to 15% by weight of an acyl bis-[fi-Z-alkyl-imidazolyl) ethyl] amine, wherein said alkyl radical contains from 9 to 19 carbon atoms, and said acyl radical contains from 10 to 20 carbon atoms, said amine being prepared by first reacting 1 mole of tetraethylene pentamine with 2 moles of alkyl monocarboxylic acid at a temperature of at least 225 C. and then reacting 1 mole of the resulting bisimidazoline further with 1 mole of alkyl monocarboxylic acid.
References Cited in the file of this patent UNITED STATES PATENTS 2,622,067 White et al Dec. 16, 1952 2,647,125 Gunderson July 28, 1953 2,759,894 Matuszak Aug. 21, 1956 2,783,206 Messina Feb. 26, 1957 2,846,440 Hughes Aug. 5, 1958 2,895,961 Hughes July 21, 1959 3,018,250 Anderson et al Jan. 23, 1962
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