Compositions prepared by the sulfurization of various organic materials including olefins are known in the art, and lubricants containing these compositions are also known. U.S. Pat. No. 4,191,659 describes the preparation of sulfurized olefinic compounds by the catalytic reaction of sulfur and hydrogen sulfide with olefinic compounds containing from 3 to 30 carbon atoms. The compounds are reported to be useful in lubricating compositions. U.S. Pat. No. 4,119,549 describes a similar procedure for sulfurizing olefins utilizing sulfur and hydrogen sulfide followed by removal of low boiling materials from said sulfurized material.
Sulfur-containing compositions characterized by the presence of at least one cycloaliphatic group with at least two nuclear carbon atoms of one cycloaliphatic group or two nuclear carbon atoms of different cycloaliphatic groups joined together through a divalent sulfur linkage are described in Reissue Patent Re 27,331. The sulfur linkage contains at least two sulfur atoms, and sulfurized Diels-Alder adducts are illustrative of the compositions disclosed in the reissue patent. The sulfur-containing compositions are useful as extreme pressure and anti-wear additives in various lubricating oils.
Dialdehydes containing disulfide groups and represented by the formula ##STR1## wherein both R groups are the same alkyl groups of 1 to 18 carbon atoms and both R.sub.1 groups are the same alkyl or aryl groups are described in U.S. Pat. No. 2,580,695. The compounds are reported to be useful as cross-linking agents and as chemical intermediates.
Lubricating compositions containing sulfides having the formula ##STR2## wherein R.sub.1 is a hydrocarbon group, R.sub.2 is hydrogen or a hydrocarbon group, and x is 1 to 2 are described in U.S. Pat. No. 3,296,137.
U.S. Pat. No. 3,817,928 describes the preparation of hydroxy-terminated polyesters of thia-bis-aldehydes. The derivatives are prepared by reacting a thia-bis-aldehyde with another reagent such as alcohol, organometallic compound or metal base. The derivatives are useful for industrial purposes such as in the preparation of polyurethanes. The thia-bis-aldehydes which are utilized as starting materials in the '928 patent are similar to the thia-bis-aldehydes described in the above-identified U.S. Pat. No. 3,296,137. Hydroxy-acid derivatives of the thia-bis-aldehydes are described as having the formula ##STR3## wherein R.sub.1, R.sub.2 and x are as defined above. The hydroxyacids can be converted to other derivatives such as lactones by intramolecular condensation in the presence of acetic anhydride or to amides by reaction with aqueous ammonia.
U.S. Pat. No. 4,248,723 describes the preparation of acetal and thioacetal derivatives of thia-bis-aldehydes similar to the thia-bis-aldehydes described above. The acetal and thioacetal derivatives are prepared by reacting the thia-bis-aldehydes with compounds represented by the formula EQU R.sub.3 XXH
wherein R.sub.3 is a C.sub.1-18 alkyl, C.sub.6-18 aryl, etc. group, and X is oxygen or sulfur. The acetal derivatives are useful as extreme pressure additives for lubricants.
Copper-containing compositions and the use thereof in lubricating oils are also known. U.S. Pat. No. 2,510,031 relates to an oil-soluble soap of a water-insoluble heavy metal which forms a stable sulfide in combination with a sulfurized composition which has a tendency to evolve H.sub.2 S. Copper, zinc, chromium, nickel, manganese, etc. are among the salts considered useful in the application. The purpose of this composition is to suppress the evolution of hydrogen sulfide.
Metal-containing complexes formed by reacting a non-acidic, acylated nitrogen-intermediate with certain complex forming metal compounds are described in U.S. Pat. No. 3,306,908. The metals include cadmium, chromium, manganese, iron, cobalt, nickel, copper and zinc. Lubricating compositions comprising the metal complexes are also described.
U.S. Pat. No. 2,552,570 describes hydrocarbon products, generally lubricating oils, containing cuprous salts of various phosphate esters. These compositions may also contain a wide variety of other agents such as detergents, pour depressants, sulfurized fats and the like.
Lubricants which employ a combination of oil-soluble copper compounds with oil-soluble sulfur compounds are described in U.S. Pat. No. 2,343,756. This patent teaches numerous copper and salt compounds.
U.S. Pat. No. 2,356,661 describes lubricating oil compositions which employ from 50-1000 parts of copper in the form of oil-soluble non-ionogenic organic compounds in the presence of a small proportion of sulfur in the form of oil-soluble organic sulfur compounds.
U.K. Patent Application GB 2056482A describes lubricating compositions comprising a base oil containing a specified amount of copper plus a zinc dithiophosphate. Other common lubricating oil additives are also described.
Organophosphorus and metal organophosphorus compounds are used extensively in lubricating oils as extreme pressure agents and anti-wear agents. Recently, environmental and toxicological problems associated with the use of organophosphorus compounds have become a matter of concern. Because of such problems, there is a need to develop lubricant compositions containing reduced levels of phosphorus, yet characterized as having acceptable oxidation inhibition and anti-wear properties. Lubricating compositions containing up to about 0.1% phosphorus are considered low-phosphorus containing compositions. U.S. Pat. No. 4,623,473 describes several low-phosphorus containing lubricating compositions. Each of the above-mentioned patents is hereby incorporated herein by reference for relevant disclosures contained therein.
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