Reaction product of ammonium tetrathiomolybdate with basic nitrogen compounds and lubricants containing same

Antioxidant additives for lubricating oil are prepared by combining ammonium tetrathiomolybdate and a basic nitrogen compound complex to form a sulfur-and molybdenum-containing composition.

FIELD OF THE INVENTION 
This invention relates to a process for preparing lubricating oil 
additives. It also relates to new lubricating oil compositions containing 
antioxidant molybdenum compounds. 
BACKGROUND OF THE INVENTION 
Molybdenum disulfide has long been known as a desirable additive for use in 
lubricating oil compositions. However, one of its major detriments is its 
lack of oil solubility. Molybdenum disulfide is ordinarily finely ground 
and then dispersed in the lubricating oil composition to impart friction 
modifying and antiwear properties. Finely ground molybdenum disulfide is 
not an effective oxidation inhibitor in lubricating oils. 
As an alternative to finely grinding the molybdenum disulfide, a number of 
different approaches involving preparing salts of molybdenum compounds 
have been tried. One type of compound which has been prepared is 
molybdenum dithiocarbamates. Representative compositions are described in 
U.S. Pat. No. 3,419,589, which teaches molybdenum (VI) dioxide 
dialkyldithiocarbamates; U.S. Pat. No. 3,509,051, which teaches sulfurized 
oxymolybdenum dithiocarbamates; and U.S. Pat. No. 4,098,705, which teaches 
sulfur containing molybdenum dihydrocarbyl dithiocarbamate compositions. 
An alternative approach is to form dithiophosphates instead of 
dithiocarbamates. Representative of this type of molybdenum compound are 
the compositions described in U.S. Pat. No. 3,494,866, such as 
oxymolybdenum diisopropylphosphorodithioate. 
U.S. Pat. No. 3,184,410 describes certain dithiomolybdenyl acetylacetonates 
for use in lubricating oils. 
Braithwaite and Greene in Wear, 46 (1978) 405-432 describe various 
molybdenum-containing compositions for use in motor oils. 
U.S. Pat. No. 3,349,108 teaches a molybdenum trioxide complex with 
diethylenetriamine for use as an additive for molten steel. 
Russian Pat. No. 533,625 teaches lube oil additives prepared from ammonium 
molybdate and alkenylated polyamines. 
Another way to incorporate molybdenum compounds in oil is to prepare a 
colloidal complex of molybdenum disulfide or oxysulfides dispersed using 
known dispersants. U.S. Pat. No. 3,223,625 describes a procedure in which 
an acidic aqueous solution of certain molybdenum compounds is prepared and 
then extracted with a hydrocarbon ether dispersed with an oil soluble 
dispersant and then freed of the ether. U.S. Pat. No. 3,281,355 teaches 
the preparation of a dispersion of molybdenum disulfide by preparing a 
mixture of lubricating oil, dispersant, and a molybdenum compound in water 
or C.sub.1-4 aliphatic alcohol, contacting this with a sulfide ion 
generator and then removing the solvent. Dispersants said to be effective 
in this procedure are petroleum sulfonates, phenates, alkylphenate 
sulfides, phosphosulfurized olefins and combinations thereof. 
SUMMARY OF THE INVENTION 
It has now been found that a lubricating oil additive can be prepared by 
combining ammonium tetrathiomolybdate and a basic nitrogen-containing 
composition to form a sulfur and molybdenum-containing complex.

DETAILED DESCRIPTION OF THE INVENTION 
Lubricating oil compositions containing the additive prepared as disclosed 
herein are effective as either fluid and grease compositions (depending 
upon the specific additive or additives employed) for inhibiting 
oxidation, imparting antiwear and extreme properties, and/or modifying the 
friction properties of the oil which may, when used as a crankcase 
lubricant, lead to improved mileage. 
The precise molecular formula of the molybdenum compositions prepared by 
the process of this invention is not known with certainty; however, they 
are believed to be compounds in which molybdenum, whose valences are 
satisfied with atoms of oxygen or sulfur, is either complexed by or the 
salt of one or more nitrogen atoms of the basic nitrogen containing 
composition used in the preparation of these additives. 
The molybdenum compound used to prepare the complexes of this invention is 
ammonium tetrathiomolybdate, (NH.sub.4).sub.2 MOS.sub.4. 
The basic nitrogen compound must have a basic nitrogen content as measured 
by ASTM D-664 or D-2896. Typical of such compositions are succinimides, 
carboxylic acid amides, hydrocarbyl monoamines, hydrocarbon polyamines, 
Mannich bases, phosphonamides, thiophosphonamides, phosphoramides 
dispersant viscosity index improvers, and mixtures thereof. These basic 
nitrogen containing compounds are described below (keeping in mind the 
reservation that each must have at least one basic nitrogen). Any of the 
nitrogen-containing compositions may be after-treated with e.g., boron 
using procedures well known in the art so long as the compositions 
continue to contain basic nitrogen. These after-treatments are 
particularly applicable to succinimides and Mannich base compositions. 
The mono and polysuccinimides that can be used to prepare the lubricating 
oil additives described herein are disclosed in numerous references and 
are well known in the art. Certain fundamental types of succinimides and 
the related materials encompassed by the term of art "succinimide" are 
taught in U.S. Pat. Nos. 3,219,666, 3,172,892, and 3,272,746, the 
disclosures of which are hereby incorporated by reference. The term 
succinimide is understood in the art to include many of the amide, imide, 
and amidine species which are also formed by this reaction. The 
predominant product is a succinimide and this term has been generally 
accepted as meaning the product of a reaction of an alkenyl substituted 
succinic acid or anhydride with a nitrogen containing compound. Preferred 
succinimides, because of their commercial availability, are those 
succinimides prepared from a hydrocarbyl succinic anhydride, wherein the 
hydrocarbyl group contains from about 24 to about 350 carbon atoms, and an 
ethylene amine, said ethylene amines being especially characterized by 
ethylene diamine, diethylene triamine, triethylene tetraamine, and 
tetraethylene pentamine. Particularly preferred are those succinimides 
prepared from polyisobutenyl succinic anhydride of 70 to 128 carbon atoms 
and tetraethylene pentaamine or triethylene tetraamine or mixtures 
thereof. 
Also included within the term succinimide are the coligomers of a 
hydrocarbyl succinic acid or anhydride and a poly secondary amine 
containing at least one tertiary amino nitrogen in addition to two or more 
secondary amino groups. Ordinarily this composition has between 1,500 and 
50,000 average molecular weight. A typical compound would be that prepared 
by reacting polyisobutenyl succinic anhydride and ethylene dipiperazine. 
Compositions of this type are disclosed in U.S. Ser. No. 816,063, filed 
July 15, 1977 the disclosure of which is hereby incorporated by reference. 
Carboxylic amide compositions are also suitable starting materials for 
preparing the products of this invention. Typical of such compounds are 
those disclosed in U.S. Pat. No. 3,405,064, the disclosure of which is 
hereby incorporated by reference. These compositions are ordinarily 
prepared by reacting a carboxylic acid or anhydride ester thereof, having 
at least 12 to about 350 saturated aliphatic carbon atoms in the principal 
aliphatic chain and, if desired, having sufficient pendant aliphatic 
groups to render the molecule oil soluble which is with an amine or 
hydrocarbyl polyamine, such as an ethylene amine, to give a mono or 
polycarboxylic acid amide. 
Another class of compounds which are useful in this invention are 
hydrocarbyl monoamines, hydrocarbyl polyamines, preferably of the type 
disclosed in U.S. Pat. No. 3,574,576, the disclosure of which is hereby 
incorporated by reference. The hydrocarbyl, which is preferably alkyl, or 
olefinic having one or two sites of unsaturation, usually contains from 9 
to 350, preferably from 20 to 200 carbon atoms. Preferred amines are those 
which are derived, e.g., by reacting polyisobutenyl chloride and 
diethylene triamine, from polyalkylene polyamines such as ethylene 
diamine, diethylene triamine, tetraethylene pentaamine and the like, or 
2-aminoethylpiperazine, 1,3-propylene diamine, 1,2-propylenediamine and 
the like. 
Another class of compounds supplying basic nitrogen are the Mannich base 
compositions. These compositions are prepared from a phenol or 
alkylphenol, an aldehyde, such as formaldehyde or formaldehyde precursor 
such a para-formaldehyde, and an amine compound. The amine may be a mono 
or polyamine and typical compositions are prepared from methylamine, 
diethylene triamine, or tetraethylene pentaamine and the like. The 
phenolic material may be sulfurized or unsulfurized. Typical Mannich bases 
which can be used in this invention are disclosed in U.S. Pat. No. 
4,157,309, and U.S. Pat. Nos. 3,649,229, 3,368,972 and 3,539,663, the 
disclosures of which are hereby incorporated by reference. The last 
application discloses Mannich bases prepared by reacting an alkylphenol 
having at least 50 carbon atoms, preferably 50 to 200 carbon atoms with 
formaldehyde and an alkylene polyamine HN(ANH).sub.n H where A is a 
saturated divalent alkyl hydrocarbon of 2 to 6 carbon atoms and n is 1-10 
and where the condensation product of said alkylene polyamine may be 
further reacted with urea or thiourea. The utility of these Mannich bases 
as starting materials for preparing lubricating oil additives can often by 
significantly improved by treating the Mannich base using conventional 
techniques to introduce boron into the composition. 
Another class of composition useful for preparing the additives of this 
invention are the phosphoramides and phosphonamides such as those 
disclosed in U.S. Pat. Nos. 3,909,430 and 3,968,157 the disclosures of 
which are hereby incorporated by reference. These compositions may be 
prepared by forming a phosphorus compound having at least one P-N bond. 
They can be prepared, for example, by reacting phosphorus oxychloride with 
a hydrocarbyl diol in the presence of a monoamine or by reacting 
phosphorus oxychloride with a difunctional secondary amine and a 
mono-functional amine. Thiophosphoramides can be prepared by reacting an 
unsaturated hydrocarbon compound containing from 2 to 450 or more carbon 
atoms, such as polyethylene, polyisobutylene, polypropylene, ethylene, 
1-hexene, 1,3-hexadiene, isobutylene, 4-methyl-1-pentene, and the like, 
with phosphorus pentasulfide and nitrogen-containing compound as defined 
above, particularly an alkylamine, alkyldiamine, alkylpolyamine, or an 
alkyleneamine, such as ethylene diamine, diethylenetriamine, 
triethylenetetraamine, tetraethylenepentaamine, and the like. 
Another class of nitrogen-containing compositions useful in preparing the 
molybdenum compositions of this invention includes the so-called 
dispersant viscosity index improvers (VI improvers). These VI improvers 
are commonly prepared by functionalizing a hydrocarbon polymer, especially 
a polymer derived from ethylene and/or propylene, and optionally 
containing additional units from one or more co-monomers such as alicyclic 
or aliphatic olefins or diolefins. The functionalization may be carried 
out by a variety of processes which introduce a reactive site or sites 
which usually has at least one oxygen atom on the polymer. The polymer is 
then contacted with a nitrogen-containing source to introduce 
nitrogen-containing functional groups on the polymer backbone. Commonly 
used nitrogen sources include any basic nitrogen compound, especially 
those nitrogen-containing compounds and compositions described herein. 
Preferred nitrogen sources are alkylene amines, alkyl amines, and Mannich 
bases. 
Preferred basic nitrogen compounds are for use in this invention 
succinimides, carboxylic acid amides, and Mannich bases. 
The compositions of this invention may be prepared by reacting the ammonium 
tetrathiomolybdate, and basic nitrogen compound, optionally in the 
presence of an inert diluent. 
This reaction is preferably carried out at from a temperature slightly 
above that at which the reaction mixture becomes solid to reflux. The 
reaction is ordinarily carried out at atmospheric pressure; however, 
higher or lower pressures may be used, if desired, using methods that are 
well-known to those skilled in the art. A diluent which does not react 
with the ammonium tetrathiomolybdate is desirable. Typical diluents are 
lubricating oil and liquid compounds containing only carbon and hydrogen. 
The diluent provides a minimum dilution of the reaction mixture to enable 
the mixture to be efficiently stirred. 
The lubricating oil compositions containing the additives of this invention 
can be prepared by admixing, by conventional techniques, the appropriate 
amount of the molybdenum-containing composition with a lubricating oil. 
The selection of the particular base oil depends on the contemplated 
application of the lubricant and the presence of other additives. 
Generally, the amount of the molybdenum containing additive will vary from 
0.05 to 15% by weight and preferably from 0.2 to 10% by weight. 
The lubricating oil which may be used in this invention includes a wide 
variety of hydrocarbon oils, such as naphthenic bases, paraffin bases and 
mixed base oils as well as synthetic oils such as esters and the like. The 
lubricating oils may be used individually or in combination and generally 
have a viscosity which ranges from 50 to 5,000 SUS and usually from 100 to 
15,000 SUS at 38.degree. C. 
In many instances it may be advantageous to form concentrates of the 
molybdenum containing additive within a carrier liquid. These concentrates 
provide a convenient method of handling and transporting the additives 
before their subsequent dilution and use. The concentration of the 
molybdenumcontaining additive within the concentrate may vary from 0.25 to 
90% by weight although it is preferred to maintain a concentration between 
1 and 50% by weight. The final application of the lubricating oil 
compositions of this invention may be in marine cylinder lubricants as in 
crosshead diesel engines, crankcase lubricants as in automobiles and 
railroads, lubricants for heavy machinery such as steel mills and the 
like, or as greases for bearings and the like. Whether the lubricant is 
fluid or a solid will ordinarily depend on whether a thickening agent is 
present. Typical thickening agents include polyurea acetates, lithium 
stearate and the like. 
If desired, other additives may be included in the lubricating oil 
compositions of this invention. These additives include antioxidants or 
oxidation inhibitors, dispersants, rust inhibitors, anticorrosion agents 
and so forth. Also, anti-foam agents stabilizers, anti-stain agents, 
tackiness agents, anti-chatter agents, dropping point improvers, 
anti-squawk agents, extreme pressure agents, odor control agents and the 
like may be included. 
Certain molybdenum products that can be prepared by the process of 
invention also find utility in making brake lining materials, in 
high-temperature structural materials, in iron and steel alloys, in 
cladding materials, in electroplating solutions, as components for 
electrical discharge machine electrodes, as fuel additives, in making 
self-lubricating or wear-resistant structures, as mold release agents, in 
compositions for phosphatizing steel, in brazing fluxes, in nutrient media 
for microorganisms, in making electrosensitive recording material, in 
catalysts for refining coal, oil, shale, tar sands, and the like or as 
stabilizers or curing agents for natural rubber or polymers.