US3175971A - Lubricating oils containing organo-mo- lybdenum tricarbonyl compounds - Google Patents

Description

llnited States latent ice V r 3,175,971 LUBRICATING OILS CDNTAINiNG ORGANO-MO- LYBDENUM TRICAREONYL COMPOUNDS Edwin L. De Young, Milwaukee, Wis, assignor to Standard Oil Company, Qhicago, 111., a corporation of Indiana No Drawing. Filed Dec. 19, 1960, Ser. No. 76,473

3 Claims. (Cl. 252-33) This invention relates to novel oil-soluble organo-molybdenum co-ordination compounds as new compositions of matter, and to 'compositions containing the same, which compositions possess corrosion and/or oxidation inhibiting properties. More particularly, it concerns novel oilsoluble hydrocarbyl substituted benzene molybdenum carbonyl co-ordination compoundsand their use as additives to lubricants to impart anti-oxidation characteristics thereto.

Within recent years it has become common practice to impart improved properties to lubricants through the use of various types of additives or addition agents. Lubricating oils employed in internal combustion engines such as automotive and diesel engines requirethe use of one or more addition agents to improve their serviceability under certain adverse operating'conditions. Among the more important additives employed are the type which function to prevent the formation and accumulation of sludge and varnish-like'coatings on pistons and cylinder walls of'the engine. Such additives which have the property of maintaining clean engines are referred to as detergent-type lubricant additives. .The more effective addition agents which have been developed for compounding with lubricantsaremany sulfur-containing organic compounds such as, by way of example, sulfurized'terpenes, sulfurized hydrocarbon oils, vegetable oils or animal oils, organic polysulfides, particularly polyalkyl polysuliides, metal salts of organo-substituted thioacids of phosphorus, metal salts of the reaction product of a phosphorus sulfide and a hydrocarbon such as, for example, polybutenes and other polyolefins, and combinations of the foregoing.

Corrosion inhibitors also play an important part in the formulation of efficient lubricants. Such corrosion inhibitors should effectively inhibit the corrosion of metal alloys of the type used in engine bearings and other engine parts. Recent increased use of silver and similar metals in the construction of improved internal combustion engines has created new problems in the use of. sulfur-containing additives in lubricants for such engines; the primary problem created being the corrosion of such silver parts of the engine by'the sulfur-containing. additives. While such corrosion can be eliminated by avoiding the use of sulfur-containing additives in lubricants for such engines, this solution of the problem is accompanied by the lossof the highly desired beneficial effects. of the additives of this type.

An object of the present invention is to provide novel oil-soluble organo-molybdenum,co-ordination compounds anda method of preparing the same. Another object is to provide novel oil-soluble organo-molybdenum coordination compounds having particular utility as lubricant additives.- A particular object is to provide novel oil-soluble hydrocarbyl substituted benzene molybdenum carbonyl co-ordination compounds which have anti-oxidative properties in addition to having substantial metal corrosion inhibiting properties when added to mineral lubricating oils. A further object is to providea composition which will inhibit the corrosion of silver and similar metals by sulfur and/or organic sulfur-containing compounds. Still another object is to provide a method of inhibiting the corrosion of engine parts. in contact with lubricant compositions which contain sulfur and/ or organic sulfurcontaining compounds which are normally corrosive to specific examples.

3,175,971 Patented Mar. 30, 1965 metals. Other objects and advantages of the present invention will become apparent from the ensuing description thereof.

It has been discovered that certain novel oil-soluble hydrocarbyl substituted benzene molybdenum carbonyl co-ordination compounds have anti-oxidant and/ or anticorrosive properties. Such compounds are extremely useful as additives for lubricants which are normally corrosive to metals with which such lubricants are in contact. Thus, in accordance with the present invention, the oilsoluble molybdenum carbonyl co-ordination compounds are prepared by reacting molybdenum hexacarbonyl with a hydrocarbyl substituted benzene having at least one aliphatic substituent containing at least four carbon atoms. The reactants being employed in equimolar amounts, preferably with a slight excess of the substituted benzene reactant. The reaction is carried out at atmospheric pressure and at temperatures of from about C. to about C. Depending upon the temperatures, employed, the reaction time may vary from about 18 hours to about 72 hours, or until evolution of carbon monoxide ceases.

The new products are crystalline solids of varying oil solubility depending upon the amount and nature of hydrocarbon substitution in the structure and nature of the base oil. They have particular value as, anti-oxidants for lubricating oil lubricants, as bearing corrosion inhibitors and, because they are non-corrosive to silver in lubricant,

compositions, have a wide range of applicability. In general, it is desirable that the molybdenum carbonyl coordination compounds contain at least-four carbon atoms, preferably 8 to 18 carbon atoms, in the monoaliphatic or polyaliphatic substituted benzene reactant in order to provide adequate oil solubility. The products then can be handled in the form of mineral oil concentrates which facilitate handling in the formulation of commercial lubricating oils and greases. The level of use in the finished lubricant, however, is usually quite small. For use as an oxidation inhibitor in a hydrocarbon oil susceptible to oxidative deterioration the concentration of the additive should be at least 0.2% by weight. Amounts above 0.5% give satisfactory results, but since such results may beobtained' with lesser amounts, it is usually not economical to employ more than 0.5%.

In commercial formulation, the substituted benzenemolybdenum-carbonyl compounds will ordinarily'be used,

as is customary in conjunction with other compatible lubricating oil additives, for example, pour depressants, viscosity index improvers, anti-rust agents, anti-foam agents and the like. The base may comprise any hydrocarbon oil subject to oxidative deterioration. For most applications, the oil' will comprise a mineraLoil fraction of the usual viscous lubricating oil range.

The new oil-soluble organo-molybdenum co-ordination compounds of the present invention are the co-ordination reaction products of molybdenum he'xacarbonyl' and an aliphatic substituted benzene, which co-ordination reaction products have the general formula RMo (CO) wherein R is a benzene radical having at least one aliphatic substituent containing at least four carbon atoms.

The aliphatic substituted benzene employed in preparing the molybdenum carbonyl co-ordinationcompounds can be monoor poly, straight or branched chain, aliphatie substituted benzenes. Examples of suitable benzenes are: butylbenzene, cyclopentylbenzene, hexylbenzene, octylbenzene, nonylbenzene, dodecylbenzene', hexadecylbenzene, octadecylbenzene, cyclohexylbenzene, and mixtures thereof.

The invention will be further illustrated by means of In the examples, dodecyl benzene is shown by way of example as representative of the class of hydrocarbyl substituted benzenes which are suitable for purposes of the present invention and the new additives were evaluated by means of the modified stirring sand corrosion test (MSSCT) and the modified EMD silver bearing corrosion test.

The MSSCT test was run as follows: A copper-lead test specimen is lightly abraided with steel wool, washed with naphtha, dried and weighed to the nearest milligram. The cleaned copper-lead test specimen is suspended in a glass beaker, cleaned with a hot tri-sodium phosphate solution, rinsed with water, acetone and dried, and 300 grams of the oil to be tested, and 50 grams of a 3035 mesh sand charged to the beaker. The beaker is then placed in a bath or heating block and heated to a temperature of 330 F. (i2 F.) while the contents are stirred by means of a stirrer rotating at 1300 r.p.m. The contents of the beaker are maintained at this term perature for forty-eight hours, after which the copperlead test specimen is removed, rinsed with naphtha, dried and weighed. The test specimen is then replaced in the beaker and the test continued for another twenty-four hours (seventy-two hours total). At the conclusion of this time, the test specimen is removed from the beaker, rinsed with naphtha, dried and weighed.

In the modified EMD test a silver strip 2 cm. x 5.5 cm. with a small hole at one end for suspension is lightly abraded with No. steel wool, wiped free of any adhering steel wool, washed with carbon tetrachloride, airdried and then weighed to 0.1 milligram. Three hundred cc. of the oil to be tested is placed in a 500 cc. lipless glass beaker and the oil is heated to a temperature of 300 F. (i2 F.) and the silver test strip suspended in the oil so that the strip is completely immersed therein. The oil in the beaker is stirred by means of a glass stirrer operating at 300 rpm. At the end of twenty-four hours, the silver strip is removed and while still hot rinsed thoroughly with carbon tetrachloride and air-dried. The appearance of the strip is then visually noted and given ratings according to the following scale:

1Bright 2Stained 3Grey-black 4Black, smooth 5--Black, flake and weighed. A weight loss of 20 mg. or less is considered passing.

Example I A charge of 88 grams (0.33 mole) of molybdenum hexacarbonyl and 82 grams (.33 mole) of dodecyl benzene was placed in a glass reaction vessel equipped with a thermometer and stirrer. The mixture was heated at atmospheric pressure to 120 C. and held for approxi mately 24 hours. Thereafter the reaction mixture was cooled and washed with acetone. After evaporation of the acetone the precipitate which formed in the reaction mixture was recovered by filtration and washed with hexane. 87 grams of light gray crystals were recovered having a molybdenum analysis of 20.5%. Calculated 22.5% molybdenum for dodecyl benzene molybdenum tricarbonyl. The crystals sublimed from 105 to 130 C.

The product was tested at the 0.5% concentration level in solvent extracted SAE 40 grade Mid-Continent oil containing about 3% calcium petroleum sulfonate and about 1.25% calcium sulfide phenate. The oil gave a gright EMD silver strip and MSSCT Weight losses of 103.5 mg. at 48 hours and 294.6 mg. at 72 hours; whereas the same oil without the product of this example gave a MSSCT loss of 870.4 mg. at 48 hours.

Example II A solvent extracted SAE 30 grade Mid-Continent oil containing about 3% of a detergent of the neutralized phosphorus sulfide-polybutenes reaction product type gave 752.4 mg. weight loss at 48 hours. When 0.5 of the product from Example I was added to the above oil the MSSCT losses Were 61.4 mg. at 48 hours and 134.4 mg. at 72 hours.

Example III A solvent extracted SAE, 63 VI, grade Mid-Continent oil gave MSSCT loss of 740.9 mg. at 48 hours. When 0.25% and 0.5 of the product from Example I was added to the above oil the MSSCT losses were 108.4 mg. at 48 hours and 283.3 mg. at 72 hours, and 71.6 mg. at 48 hours and 146.6 mg. at 72 hours, respectively.

Example IV The product was tested at 0.5% concentration level in solvent extracted SAE 30 grade Mid-Continent oil containing about 3% of a detergent of the borated barium neutralized phosphorus sulfide-polybutene reaction product type. The oil gave a bright EMD silver strip and MSSCT weight losses of 96.1 mg. at 48 hours and 227.0 mg. at 72 hours.

While the above-described reaction products can be suitably employed alone in combination with a base oil, they are usually used in combination with other lubricant addition agents which impart various desired characteristics to the base oil. Usually, these reaction products are used in conjunction with detergent-type additives, particularly those which contain sulfur or phosphorus and sulfur addition agents. This type is usually used in amounts of from about 0.002% to about 10%, and preferably from about 0.01% to about 5%. Among the phosphorusand sulfur-containing addition agents are the neutralized reaction products with a phosphorus sulfide and a hydrocarbon, an alcohol, a ketone, an amine or an ester. Of the phosphorus sulfide reaction product additives, I prefer to employ the neutralized reaction products of a phosphorus sulfide, such as a phosphorus pentasulfide, and a hydrocarbon of the type described in U.S. 2,316,082, issued to C. M. Loane et al., April 6, 1943. As taught in this patent, the preferred hydrocarbon constituent of the react-ion is a mono-olefin hydrocarbon polymer resulting from the polymerization of low molecular weight mono-olefin hydrocarbons, such as propylene, butenes, amylenes or copolymers thereof. Such polymers may be obtained by the polymerization of mono-olefins of less than 6 carbon atoms in the presence of a catalyst, such as sulfuric acid, phosphoric acid, boron fluoride, aluminum chloride, or other similar halide catalysts of the Friedel- Crafts type.

The phosphorus sulfide-hydrocarbon reaction product normally shows a titratable acidity which is neutralized by treatment with a basic reagent. The phosphorus sulfidehydrocarbon reaction product, when neutralized with a basic reagent containing a metal constituent, is characterized by the presence or retention of the metal constituent of the basic reagent.

The neutralized phosphorus sulfide-hydrocarbon reaction product can be obtained by treating the acidic reaction product with a suitable basic compound, such as hydroxide, carbonate, oxide or sulfide of an alkaline earth metal or an alkali metal, such as for example, potassium hydroxide, sodium hydroxide, sodium sulfide, calcium oxide, lime, barium hydroxide, barium oxide, etc. Other basic reagents can be used, such as for example, ammonia, or an alkyl or aryl-substituted ammonia, such as amines. The neutralization of the phosphorus sulfidehydrocarbon reaction product is carried out preferably in a non-oxidizing atmosphere by contacting the acidic reaction product either as such or dissolved in a suitable solvent, such as naphtha with a solution of the basic reagent. As an alternative method, the reaction product can be treated Withsolid alkaline compounds, such as KOH, NaOH, Na CO CaO, BaO, Ba(OH) Na S, and the like, at an elevated temperature of from about 100 F. to about 600 F. Neutralized reaction products containing a heavy metal constituent such as for example, tin, tita nium, aluminum, chromium, cobalt, zinc, iron and the like can be obtained by reacting a salt of the desired heavy metal with the phosphorus sulfide-hydrocarbon reaction product which has been treated with the phopshorus sulfide-hydrocarbon reaction product which has been treated with a basic reagent, such as above-described.

Other phosphorus sulfide reaction products which can be used are the reaction products of a phosphorus sulfide and a fatty acid ester of the type described in US. 2,399,243; the phosphorus sulfide-degras reaction products of US. 2,413,332; the reaction product of an alkylated phenol with the condensation product of P 8 and turpentine of US. 2,409,877 and US. 2,409,878; the reaction product of a phosphorus sulfide and stearonitrile of US. 2,416,807, etc.

The above-described molybdenum carbonyl compounds can be used in combination with lubricant base oils, such as hydrocarbon oils, synthetic hydrocarbon oils, such as those obtained by the polymerization of hydrocarbons, such as olefin polymers, for example, polybutenes, polypropylene and mixtures thereof, etc; synthetic lubricating oils of the alkyleneoxide type, for example, the Ucon oils, marketed by Carbide and Carbon Corporation, as well as other synthetic oils, such as the polycarboxylic acid ester-type-oils, such as the esters of adipic acid, se bacic acid, maleic acid, azelaic acid, etc.

While this invention has been described in connection with the use of the herein-described additives and lubricant compositions, their use is not limited thereto; but the same can be used in products other than lubricating oils, such as for example, fuel oils, insulating oils, greases, non-drying animal and vegetable oils, waxes. asphalts, and any fuels for internal combustion engines, particularly where oxidation must be combatted.

Concentrates of a suitable oil base containing more than 10% of an oil-soluble hydrocanb-yl substituted benzene molybdenum carbonyl coordination compound alone or in combination with other additives can be used for blending with hydrocarbon oils or other oils in the proportions desired for the particular conditions of use to give a finished product containing at least 0.2% of the molybdenum carbonyl co-ordination compound.

Percentages given herein and in the appended claims are weight percentages unless otherwise stated.

Although the present invention has been described with reference to specific preferred embodiments thereof, the invention is not to be considered as limited thereto but includes within its scope such modifications and variations as come within the spirit of the appended claims.

I claim:

1. A mineral lubricating oil containing from about 0.2 to about 0.5% of an oil-soluble organo-molybdenum tricarbonyl compound having the formula RMo(CO) wherein R is benzene mono-substituted by alkyl of 4-18 carbon atoms.

2. A mineral lubricating oil containing from about 0.2 to about 0.5% of dodecylbenzene molybdenum tricarbonyl.

3. A lubricating oil composition having improved oxidation stability comprising (a) a major amount of a mineral lubricating oil base; (b) 0.5% of dodecylbenzene molybdenum tricar'bonyl; (c) 3.0% of calcium petroleum sulfonate; and (d) 1.25% of calcium sulfide phenate.

References Cited in the file of this patent UNITED STATES PATENTS 2,818,417 Brown et al Dec. 31, 1957 2,849,399 Matuszak et a1. Aug. 28, 1958 2,850,452 Sands et al. Sept. 2, 1958 2,952,523 Podall Sept. 13, 1960 2,964,547 De Witt et a1. Dec. 13, 1960 2,993,922 Wyman July 25, 1961 3,001,858 Antonsen Sept. 26, 1961 3,010,978 Antonsen Nov. 28 1961

Claims (1)

1. 3. A LUBRICATING OIL COMPOSITION HAVING IMPROVED OXIDATION STABILITY COMPRISING (A) A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL BASE; (B) 0.5% OF DODECYLBENZENE MOLYBDENUM TRICARBONYL; (C) 3.0% OF CALCIUM PETROLEUM SULFONATE; AND (D) 1.25% OF CALCIUM SULFIDE PHENATE.