JPH0312119B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to hydrocarbon-soluble molybdenum complexes of thiobisphenols, processes for their preparation, and applications in gasoline, fuel oils, and greases, industrial oils, gear oils, engines and other equipment with moving parts operating under boundary lubrication conditions. The present invention relates to their use as additives in hydrocarbon compositions such as lubricating oils, such as lubricants for industrial use. As is known, in particular "boundary lubrication" where two frictional surfaces must be lubricated or otherwise protected to prevent their wear and ensure continuous motion. There are many examples under the condition. Moreover, in cases where friction between two surfaces increases the power required to produce motion, as in many instances,
Also, where the motion is an integral part of the energy conversion system, it is most desirable to provide lubrication to minimize this friction. It is also well known that both wear and friction can be reduced with varying degrees of success by adding suitable additives or combinations thereof to natural or synthetic lubricants. Continuous motion can likewise be ensured with varying degrees of success by the addition of one or more suitable additives. There are many known additives that can be classified as anti-wear additives, anti-friction additives and extreme pressure additives, and some actually fulfill one or more of these functions and Although they can perform other useful functions, many of these additives act in different physical or chemical ways and often compete with each other, for example, they act on the surfaces of moving metal parts subject to lubrication. It is also known that there are cases where there is competition. Therefore, great care must be taken in selecting these additives to ensure compatibility and effectiveness. Metal dihydrocarbyl dithiophosphate is
It is one of the additives known to exhibit antioxidant and anti-wear properties. The most commonly used additives of this type are zinc dialkyl dithiophosphates commonly used in lubricant compositions.
Although such zinc compounds provide excellent oxidation resistance and exhibit excellent wear resistance, it has heretofore been believed that this increases or significantly limits the ability to reduce friction between moving surfaces. As a result, compositions containing zinc dialkyl dithiophosphates are not believed to provide the most desirable lubricity, and the use of compositions containing them is limited when including lubricants in the composition. It was believed that even friction would result in significant energy losses in breaking down. Known methods for solving the problem of high frictional energy losses in crankcase oils, for example, suffer from the use of expensive synthetic ester base stocks and the disadvantages of imparting a black or hazy appearance to the oil composition. Including the use of insoluble molybdenum sulfide with. U.S. Pat. No. 3,047,500 relates to an oil-soluble extreme pressure additive made from molybdenum pentachloride and an oil-soluble alkyl phenol, such as a polyalkyl or dialkyl phenol containing a total of at least 6 carbon atoms in the side chain. Yes (column 2, lines 15-20). Although this specification does not disclose or mention thiobisphenols, it teaches that molybdenum phenolates can be used in combination with oil-soluble organosulfur compounds in lubricating oils such as sulfurized whale oil (column 3, 10-
(See Table 1, line 54 and column 4). US Patent No. 3,541,014 relates to oil-soluble molybdenum complexes made from molybdenum-containing anions and various combinations of overbased materials. Accelerators for the production of these molybdenum complexes include mono- and dialkylated phenols that appear to be retained in the overbased mixture (column 5, 58-58).
(see line 67). Other types of molybdenum compounds taught to be useful in lubricating oils include alkyl esters of molybdic acid as corrosion inhibitors (see U.S. Pat. No. 2,805,997), which provide coatings with reduced coefficients of friction. It appears to be a hydrolytically unstable and nitrogen-containing thiomolybdate as a metal anti-wear additive which is said to function by providing a metal wear additive (see US Pat. No. 2,938,869). Additionally, although chloromolybdenum esters of phenols have been taught to be useful as extreme pressure additives for lubricants (U.S. Pat. No. 3,047,506), the presence of chlorine can cause corrosion in crankcase lubricants. There is sex. Other extreme pressure additives have been taught in the form of oil-soluble molybdenum complexes made by replacing carbonates from overbased metal detergents with molybdenum-containing anions (US Pat. No. 3,541,014). Similarly, anti-wear additives or oily or lubricating agents, as often cited in the prior art, function by forming a coating on the surface of a moving metal member. However, as in the case of antiwear additives, the bonding of the coating is generally caused physically rather than chemically, and in fact the bond between the antiwear additive and the surface is generally weaker than the bond formed between the abrasive additive and the metal surface. In view of the above, it appears readily apparent that there is a need for improved lubricating compositions that enable operation of moving members with reduced friction under boundary conditions. Similarly, such compositions may contain conventional base oils and other conventional additives and may be used without losing other desirable lubricity properties, particularly those provided by the zinc dialkyldithiophosphate. The need for this will also become readily apparent. Surprisingly, the above and other drawbacks of prior art lubricating oil additives and lubricating compositions formulated therewith can be summarized by the following formula: [wherein z is 1 to 3, X is selected from sulfur or oxygen, and R is a substantially It has been found that a breakthrough can be made with a new class of organomolybdenum complexes, which appear to be represented by [hydrocarbyl groups]. These complexes are particularly useful when used in conjunction with sulfur donors such as zinc dialkyldithiophosphates. It is to be understood that the R substituent can contain substituted pendant heterogroups, provided they do not deleteriously alter the hydrocarbon solubility of the molybdenum complex. In accordance with the present invention, the above and other objects and benefits are achieved by comprising a predominant amount of a hydrocarbon, such as a lubricating oil, and at least a friction reducing dose of a hydrocarbon soluble molybdenum complex, preferably (a) said hydrocarbon soluble molybdenum complex and ) A hydrocarbon composition comprising a lubricity-enhancing mixture with an oil-soluble sulfur donor, preferably a zinc dialkyl dithiophosphate, and optionally at least a sludge-dispersing amount of an oil-soluble dispersant such as an ashless dispersant and a rust-inhibiting amount of a rust-inhibiting additive. achieved with things. In practice, the lubricity-enhancing combination comprises about 0.005 to 0.2 weight percent, preferably 0.03 to 0.15 weight percent, optimally about 0.1 weight percent molybdenum, and at least about 0.25 weight percent, based on the total weight of the oil composition. %for example
Present in an amount sufficient to provide 0.25-1% by weight of sulfur donor. As previously mentioned, the hydrocarbon soluble molybdenum complexes of the present invention are believed to correspond to the above formula. The R group of the formula as defined above is hydrocarbyl in nature and thus is alkyl, aryl, aralkyl, cycloalkyl or alkaryl. However, the hydrocarbyl group can contain polar substituents such as amino, aminoalkyl, hydroxy, hydroxyalkyl, halo, mercapto, keto, phosphinyl, phosphoryl, thiophosphoryl and dithiophosphoryl groups. Specific examples of R groups are methyl, ethyl, propyl, isopropyl, isobutyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, heptyl, octyl, nonyldecyl, dodecyl, tridecyl, heptadecyl, octadecyl, polyisobutenyl. , including polypropylene. This organomolybdenum complex is the reaction product of a hydrocarbon-substituted thiobisphenol and a molybdenum source. The above thiobisphenol has the formula [In the above formula, R and z are each the same as described above].
These thiobisphenols are easily prepared from the reaction of an alkylphenol with a sulfur source such as elemental sulfur or halogenated sulfur. Useful reactants for the preparation of molybdenum complexes are of the formula
can be characterized by, and from this the structure of the preferred complex is obtained, which has the formula It seems that the structure is The source of molybdenum includes oxygen or sulfur containing molybdenum that can be reacted with thiobisphenol to provide a molybdenum complex containing about 0.5 to 20% by weight, preferably 2 to 10% by weight, optimally about 5% by weight molybdenum. It is a compound. This source of molybdenum includes molybdenum trioxide (also known as molybdenum anhydride), ammonium thiomolybdate,
Includes ammonium bismolybdate, molybdenum halide and ammonium heptamolybdate tetrahydrate. Organomolybdenum complexes are essentially the reaction product between 1 to 2 moles of substituted thiobisphenol and 1 mole of molybdenum metal derived from a molybdenum source. This reaction is easily carried out by reacting at elevated temperatures to accelerate the reaction and remove the water of reaction. The reaction may also be carried out in an inert solvent such as a light aromatic solvent such as toluene or a light hydrocarbon oil or without a solvent. Therefore, the reaction occurs at about 80-250°C.
It can be carried out for a period of 0.5 to 40 hours and/or until at least the required amount of reaction water is removed, such as by nitrogen sparging or distillation at atmospheric or reduced pressure. The reaction can also be catalyzed by including a suitable promoter in the reaction mixture. Examples of suitable promoters or catalysts are derived from alcoholic amines. Particularly preferred are glycols, diamines or alkanolamines. Examples of such accelerators are glycols such as ethylene glycol, propylene glycol,
Butylene glycol, hexylene glycol, catechol and alkylated catechols, polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and such polyamines formed from the reaction of ethylene dichloride with ammonia or ethyleneimine and ammonia. reaction products of polyamines with alkanolamines such as ethanolamine, diethanolamine, triethanolamine, hydroxyethylethylenediamine and alkylene oxides such as ethylene oxide or propylene oxide. According to the present invention, a novel class of hydrocarbon-soluble organo-molybdenum complexes is used in combination with an active sulfur donor, which can be defined as a compound that reduces the coefficient of friction by at least about 10% when used in admixture with said molybdenum complexes. It has been found that lubricating oils provide suitable lubricity enhancement when used. The active sulfur donor is present in an amount of about 0.1 to 10, preferably 0.2 to 2 parts by weight per part by weight of molybdenum complex. Examples of active sulfur donors are metal dihydrocarbyl dithiophosphates and corresponding precursor esters, phosphosulfurized pinenes, sulfurized olefins and hydrocarbons, sulfurized fatty acid esters and sulfurized alkylphenols. Preferred are salts of dihydrocarbyl esters of dithiophosphoric acid having the formula: [In the above formula, R′ and R″ may be the same or different hydrocarbyl groups containing 1 to 18, preferably 2 to 12 carbon atoms, and alkyl,
alkenyl, aryl, aralkyl, alkaryl and cycloaliphatic groups]. Particularly preferred as R and R' groups are alkyl groups of 2 to 8 carbon atoms. Thus, these groups are, for example,
Ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, amyl, n-hexyl, i-hexyl, n-heptyl, n-octyl, decyl, dodecyl, octadecyl, It may be 2-ethylhexyl, phenyl, butylphenyl, cyclohexyl, methylcyclopentyl, propenyl, butenyl, and the like. To obtain oil solubility, the total number of carbon atoms in the dithiophosphoric acid averages 5 or more. The zinc dihydrocarbyl dithiophosphate useful as the co-additive or sulfur donor of the present invention is prepared by first esterifying the dithiophosphoric acid (usually by reaction of an alcohol or phenol with P ₂ S ₅ ) according to known techniques. ) can be prepared by then neutralizing the dithiophosphate ester with a suitable zinc compound such as zinc oxide. Generally, the zinc dihydrocarbyl dithiophosphate is present in the lubricating composition from about 0.01 to about 5 parts by weight per 100 parts of lubricating oil, preferably from about 0.5 to about 1.5 parts by weight.
used at concentrations within the range of This is appropriate for the addition of sulfur, which results in improved lubricity of the lubricating oil composition due to the co-additive combination. As previously described, equally suitable active sulfur donors have the formula Dihydrocarbyl esters of dithiophosphoric acid can be represented by the above formula in which R' and R'' are as defined above. Particularly useful is dibutylphenyl dithiophosphate. Another group of dithiophosphoric diesters that are active sulfur donors are the phosphosulfurized terpenes, such as those represented by pinene, dipentene, alloocimene, and the like.
Among the terpenes, bicyclic pinenes are preferred.
The phosphorus sulfide terpene is at least 100℃ e.g. 100~
It is easily obtained by reacting about 1 mol of thiophosphoric diester with 1 mol of pinene at a temperature of 200°C. Preferred active sulfur donors are
It can be characterized as a bornyl ester of dihydrocarbyl ( _C2 - _C20 ) dithiophosphoric acid (as shown in US Pat. No. 2,689,258). Additionally, sulfurized olefins and hydrocarbons are esters of thiophosphoric acid, which are useful sulfur donors. These esters include olefins such as ethylene, propylene, isobutylene, decene, dodecene, octadecene, etc., olefin polymers having a molecular weight of 100 to 500,000 such as ethylene, propylene, isobutylene, etc., benzene, naphthalene, toluene, xylene, etc. Aromatics, petroleum fractions, and condensation products of halogenated aliphatic hydrocarbons with aromatic compounds such as wax naphthalene (U.S. Pat.
2804431)). Another group of esters that are active sulfur donors are sulfurized aliphatic esters. These products are
P ₂ S ₅ and beneficially obtained from natural sources such as linole, palmothin, behen, stearin, palmitin, laurin, caprin etc. and mixtures obtained from vegetable and animal oils such as tall oil have about 8 to 22 carbons. Easily obtained from reaction with aliphatic alcohols. The sulfurized alkylphenol is generally a _C4 - _C20 alkylphenol sulfide. These sulfurized alkylphenols are easily prepared by sulfurizing alkylphenols with halogenated sulfur or elemental sulfur. Besides the organomolybdenum complex and the active sulfur donor, the lubricating oil composition may contain other well-known lubricating oil additives, such as ashless dispersants, metal detergents, auxiliary oxidants, to provide trouble-free operation of the lubricated equipment. It can also contain corrosion inhibitors, extreme pressure additives, rust preventive additives, pour point depressants, viscosity index improvers, and the like. The term "ashless dispersant" used in the present invention is
It is understood that it describes a well-known group of metal-free oil-soluble polymeric additives or acyl derivatives of relatively high molecular weight carboxylic acids capable of dispersing contaminants and the like in hydrocarbons such as lubricating oils. . The carboxylic acids may be homo- or polycarboxylic acids, and they generally have an average of 50 to 250
It is characterized by a substantially hydrocarbon component containing 5 aliphatic carbon atoms. A preferred group of ashless dispersants are the nitrogen-containing dispersants commonly known in the art as sludge dispersants for crankcase oils. These dispersants include mineral oil soluble salts, acids, imides and esters made from high molecular weight mono- and dicarboxylic acids (and the corresponding acid anhydrides when present), as well as amino or heterocyclic nitrogen and salts. , acid, imide or ester-forming amines of various nitrogen-containing substances having at least one acid or hydroxy group. Typically, these dispersants are
They are made by condensing a succinic acid-forming material such as a monocarboxylic or dicarboxylic acid or anhydride, preferably an alkenylsuccinic anhydride, with an amine or alkylene polyamine. Typically, the molar ratio of acid or anhydride to amine is from 1:1 to 5:1. The hydrocarbon portion of the mono- or dicarboxylic acid or anhydride is preferably a polymer of _C2 to _C5 monoolefins, generally containing 50 to 250 carbon atoms, primarily because of its ready availability and low cost. derived from those with A particularly preferred polymer is polyisobutylene. Polyalkylene amines are commonly used to make metal-free dispersants. These polyalkylene amines have the general formula _NH2 ( _CH2 ) _o- [NH( _CH2 ) _o ] _n - _NH2 [wherein n is 2 to 3 and m is 0 to 10].
]. Specific compounds falling within this general formula include diethylenetriamine, tetraethylenepetamine, dipropylenetriamine, octaethylenenonamine, and tetrapropylenepentamine;
N,N-di(2-aminoethyl)ethylenediamine can also be used. Other aliphatic polyamino compounds that can be used are N-amino-alkylpiperazines such as N-(2-aminoethyl)
It is piperazine. Mixtures of alkylene polyamines close to tetraethylenepentamine are available on the market, such as "Dow E-100" sold by the Dow Chemical Company of Midland, Michigan, USA. Typical dispersants are formed by reacting about 1 molar amount of polyisobutenyl succinic anhydride with about 1 to about 2 molar amounts of tetraethylenepentamine or about 0.5 to 1 mole of a polyol such as pentaerythritol. Ru. Ashless dispersants can be modified to improve the dispersibility of the additive, generally by the addition of metals such as boron. This is easily accomplished by adding boric acid to the reaction mixture after the imidization or esterification is substantially complete and heating the mixture at a temperature of 100-150°C for several hours. Dispersants useful in combination with preferably ashless types include petroleum naphthenic acids, petroleum sulfonic acids, petroleum sulfonic acids,
Included are salts of alkylbenzene sulfonic acids, oil-soluble fatty acids, alkylsalicylic acids, alkylphenols, alkylbisphenols and hydrolyzed phosphosulfurized polyolefins, usually of basic or overbased metals such as calcium, magnesium, etc. Oxidation inhibitors include phenols, amines, sulfurized phenols and alkylphenothiazines. Pour point depressants include wax alkylated aromatic hydrocarbons, olefin polymers and copolymers, acrylate and methacrylate polymers and copolymers. Viscosity index improvers include polybutenes, olefin polymers such as ethylene-propylene copolymers, halogenated polymers, copolymers and terpolymers of styrene with isoprene and/or butadiene, alkyl acrylates or methacrylic acids. copolymers of alkyl methacrylates and N-vinylpyrrolidone or dimethylaminoalkyl methacrylate; post-grafted polymers of ethylene-propylene with active monomers such as maleic anhydride (which or alkylene polyamines), styrene/maleic anhydride polymers post-reacted with alcohols and amines, and the like. The hydrocarbons for which the additive combinations of this invention are most effective are mineral oils having a viscosity of about 2 to 40, preferably 5 to 20 centistokes at 99°C as measured by ASTM D-445. If an activator combination of an oil-soluble organomolybdenum complex and an active sulfur donor is used as an additive concentrate, this concentrate can consist essentially of about 5 to 80% of the additive combination and the remainder are satisfactory solvents such as kerosene, mineral oil, naphtha, etc. Preferred concentrates contain about 10-60% additive combination in solvent. Whether the organomolybdenum complex is used alone or in combination with an active sulfur donor, its concentration can vary considerably depending on the particular hydrocarbon. For example, when the molybdenum complex is used alone in a fuel such as gasoline, the concentration of the complex may be between 10 and 10% based on the total weight of the fuel composition.
1000 preferably within the range of 20-50 ppm by weight,
In the case of lubricants, on the other hand, it is used in combination with an active sulfur donor, the combination being about 0.5 to 5, preferably 1 to 5, based on the total weight of the lubricating oil composition.
It is within the range of 3% by weight. The present invention exemplifies preferred embodiments of the present invention,
It will be better understood by reference to the following examples which compare it with similar but different compositions. The following examples more clearly illustrate the compositions of the invention. However, these illustrations should not be construed as specifically limiting the invention. Example 1 Nonylphenol sulfide (100g), diluent oil (100g) and _C24 alkylbenzenesulfonic acid (10g) were stirred together and heated to 100<0>C. Ammonium heptamolybdate tetrahydrate (37.5g) was added and the temperature was increased to 150°C.
During this time, ethanolamine (10 g) was added.
The temperature was increased to 175°C for 4 hours. The volatiles were removed by a distillation head and the product was separated by filtration to give a dark viscous product containing 3.1% by weight Mo. Example 2 Nonylphenol sulfide (100g) and diluent oil (100g) were stirred and heated to 100°C. Ammonium heptamolybdate tetrahydrate (18.75 g) and 3 drops of silicone antifoam were added. Ethanolamine (13 g) was slowly added while increasing the temperature to 150°C. After heating at 175°C for 4 hours, the product was separated by filtration to give 4.14% by weight of
A dark colored product containing Mo was obtained. During the reaction, 3.5
cm ³ of water was removed. Example 3 Nonylphenol sulfide (100g) and diluent oil (100g) were heated together at 100°C.
Ammonium heptamolybdate tetrahydrate (18.75 g) and 4 drops of silicone antifoam were added while increasing the temperature to 150°C. Ethylenediamine (12.8g) was added dropwise and the temperature was maintained for 4 hours. During this time, 4.5 cm ³ of water was removed. The product, a dark viscous material, was separated by filtration. It contained 4.25% by weight Mo. Example 4 Nonylphenol sulfide (500 g) and diluent oil (500 g) are stirred together and
heated to ℃. Ammonium heptamolybdate tetrahydrate (187.5g) and silicone antifoam agent (5g)
(drops) and the temperature was gradually increased while adding ethanolamine. During this time (9 hours)
Next, water was removed by distillation. The reaction was completed by heating to 175° C. for 4 hours and the product was then separated by filtration. The product (950g) is
It was a dark viscous liquid containing 3.2% by weight of Mo. Example 5 Nonylphenol sulfide (100g), diluent oil (100g) and molybdenum trioxide (15.1g) were stirred together and heated to 100°C. Add ethylenediamine (12.8g) dropwise and lower the temperature.
The temperature was increased to 175°C for 4 hours. Water by distillation (2.8
cm ³ ) was removed and the product was separated by filtration to yield a product containing 4.29% by weight Mo (162.8
g) was obtained. Example 6 Nonylphenol sulfide (100g), diluent oil (100g) and molybdenum trioxide (15.1g) were stirred together and heated to 100°C. Diethylenetriamine (21.9g) was added slowly and the temperature was raised to 175°C for 4 hours. The organism was separated by filtration to yield a viscous dark oil containing 3.85% by weight Mo. Example 7 Nonylphenol sulfide (100g), diluent oil (100g) and molybdenum trioxide (15.1g) were heated together at 100°C with stirring. Add diethylenetriamine (14.6g) and reduce the temperature to
The temperature was increased to 175°C for 4 hours. During this time, water (1.6
cm ³ ) was distilled. The product (178g) was isolated by filtration. This was a dark viscous oil containing 3.85% by weight Mo. Example 8 The procedure of Example 7 was carried out, except that only 7.3 g of diethylenetriamine was used as catalyst. Example 9 The procedure of Example 7 was followed except that no catalyst was added. Example 10 Nonylphenol sulfide (550g), diluent oil (550g) and molybdenum trioxide (84.2g) were combined and heated to 100°C with stirring. Ethanolamine (72.5 g, 95% purity) was added dropwise and the temperature was increased to 175° C. for 4 hours. During this reaction,
22 cm ³ of volatiles were removed by distillation. The product (1111 g) was separated by filtration to give 4.16% by weight of
A dark viscous oil was obtained containing Mo (which was 93%
). Example 11 Nonylphenol sulfide (550g), diluent oil and molybdenum trioxide (84.2g) were heated together at 100°C with stirring. Ethylenediamine (70.3
g) was added. The temperature was increased to 175°C for 4 hours.
During the reaction, volatiles were distilled from the reaction mixture. After filtration, the product contains 4.4 wt% Mo (100%
conversion rate). Example 12 The procedure of Example 11 was followed using ammonium heptamolybdate tetrahydrate (103.2 g) as the source of molybdenum. The product contained 4.33% by weight Mo (96.8% conversion). Example 13 The procedure of Example 10 was followed using ammonium heptamolybdate tetrahydrate (103.2 g) as the source of molybdenum. Example 14 A lubricating oil composition was prepared by mixing together the individual components listed below at slightly elevated temperatures, ie, from about 45 to about 65°C, to ensure thorough mixing. The final composition of Example 14 formulated in 10W/30SE high quality automotive engine oil is as follows.

【table】

TABLE This formulation blend was subjected to the tests described below, both on its own and in modified form according to the teachings of the present invention. 1 Test Procedure A: To measure the friction properties by the following procedure, use a Roxana four-ball abrasion tester (Brown/GE variant) available from Roxana Machine Works, St. Louis, Missouri, USA.
was used. The tester was assembled in a normal wear operation as described in ASTM D2266-67 using four 1/2 inch bearing steel balls. Set the tester to 110℃, and set the temperature to 1200rpm and
Operated at 15Kg for a minimum of 45 minutes. If the friction force seen on the striptease recorder remains constant for at least 10 minutes, reduce the speed to 25 rpm. Otherwise, continue testing until the frictional force stabilizes. Test at 25rpm, 110℃
and 15 kg for 15 minutes or until the frictional force stabilizes. The compounds of the present invention were then evaluated by testing for usefulness as lubricity-enhancing and/or anti-wear additives for lubricating oils using Test Procedure A. The weight percentage of the amount of molybdenum complex added is expressed as the amount of complex added. The test results under Procedure A are shown in Table 1. From this table it can be seen that the additives of the present invention provide improved lubricity to lubricating oils when active sulfur donors are present and that they have utility as additives for lubricating oils.

【table】

Claims (1)

[Scope of Claims] 1. A majority of hydrocarbons, and (a) C ₇ to _{C 28} hydrocarbyl-substituted thiobisphenols, are added to molybdenum trioxide, ammonium thiomolybdate, ammonium bismolybdate, molybdenum halides, and heptamolybdic acid. ammonium tetrahydrate in the presence of a promoter selected from the group consisting of amines, alcohols, phenols, diamines, glycols and alkanolamines. The resulting reaction product, the formula a hydrocarbon-soluble organomolybdenum complex of the above formula in which R is a hydrocarbyl group containing 7 to 28 carbon atoms, z is 1 to 3, and X is sulfur or oxygen; and (b) an oil. A hydrocarbon composition comprising at least a friction-reducing amount of a combination with a soluble active sulfur donor, the combination comprising about 0.005-0.2% molybdenum and at least 0.25% by weight, based on the total weight of the composition. a hydrocarbon composition comprising a hydrocarbon composition present in an amount to provide % by weight of sulfur donor. 2. The composition of claim 1, wherein the hydrocarbon is mineral oil and the sulfur donor is an oil-soluble dihydrocarbyl ester of dithiophosphoric acid. 3. Claim 1 wherein the hydrocarbon is a mineral oil having a viscosity of about 2 to 40 centistokes at 99°C as measured by ASTM D-445.
Compositions as described in Section. 4. The composition of claim 1, wherein the thiobisphenol is nonylphenol sulfide, the molybdenum source is molybdenum trioxide, and the promoter is ethylenediamine. 5. The composition of claim 1, wherein the thiobisphenol is nonylphenol sulfide, the molybdenum source is ammonium heptamolybdate tetrahydrate, and the promoter is ethylenediamine. 6. The composition of claim 1, wherein the thiobisphenol is nonylphenol sulfide, the molybdenum source is molybdenum trioxide, and the promoter is ethanolamine. 7. The composition of claim 1, wherein the thiobisphenol is nonylphenol sulfide, the molybdenum source is ammonium heptamolybdate tetrahydrate, and the promoter is ethanolamine. 8. The composition of claim 1, wherein the hydrocarbon is a lubricating oil and the combination is present in an amount of about 0.5 to 5% by weight, based on the total weight of the composition.