Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Reexamination Certificate
1999-07-22
2001-02-13
Medley, Margaret (Department: 1721)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
Reexamination Certificate
active
06187722
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is related to lubricants, especially lubricating oils, and, more particularly, to a class of ashless and nonphosphorus-containing antiwear, antifatigue, and extreme pressure additives derived from imidazole thiones.
2. Description of Related Art
In developing lubricating oils, there have been many attempts to provide additives that impart antifatigue, antiwear, and extreme pressure properties thereto. Zinc dialkyldithiophosphates (ZDDP) have been used in formulated oils as antiwear additives for more than 50 years. However, zinc dialkyldithiophosphates give rise to ash, which contributes to particulate matter in automotive exhaust emissions, and regulatory agencies are seeking to reduce emissions of zinc into the environment. In addition, phosphorus, also a component of ZDDP, is suspected of limiting the service life of the catalytic converters that are used on cars to reduce pollution. It is important to limit the particulate matter and pollution formed during engine use for toxicological and environmental reasons, but it is also important to maintain undiminished the antiwear properties of the lubricating oil.
In view of the aforementioned shortcomings of the known zinc and phosphorus-containing additives, efforts have been made to provide lubricating oil additives that contain neither zinc nor phosphorus or, at least, contain them in substantially reduced amounts.
Illustrative of non-zinc, i.e., ashless, non-phosphorus-containing lubricating oil additives are the reaction products of 2,5-dimercapto-1,3,4-thiadiazoles and unsaturated mono-, di-, and tri-glycerides disclosed in U.S. Pat. No. 5,512,190 and the dialkyl dithiocarbamate-derived organic ethers of U.S. Pat. No. 5,514,189.
U.S. Pat. No. 5,512,190 discloses an additive that provides antiwear properties to a lubricating oil. The additive is the reaction product of 2,5-dimercapto-1,3,4-thiadiazole and a mixture of unsaturated mono-, di-, and triglycerides. Also disclosed is a lubricating oil additive with antiwear properties produced by reacting a mixture of unsaturated mono-, di-, and triglycerides with diethanolamine to provide an intermediate reaction product and reacting the intermediate reaction product with 2,5-dimercapto-1,3,4 thiadiazole.
U.S. Pat. No. 5,514,189 discloses that dialkyl dithiocarbamate-derived organic ethers have been found to be effective antiwear/antioxidant additives for lubricants and fuels.
U.S. Pat. Nos. 5,084,195 and 5,300,243 disclose N-acyl-thiourethane thioureas as antiwear additives specified for lubricants or hydraulic fluids.
The disclosures of the foregoing references are incorporated herein by reference in their entirety.
SUMMARY OF THE INVENTION
The present invention relates to imidazole thione compounds of the formula
wherein R
1
, R
2
, R
3
, and R
4
are independently selected from the group consisting of alkyl, functionalized alkyl, and hydrogen.
In the above structural formulas, R
1
, R
2
, R
3
, and/or R
4
can be a straight or branched chain, fully saturated or partially unsaturated, alkyl moiety, preferably having from 1 to 40 carbon atoms, e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, oleyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, triacontyl, pentatriacontyl, tetracontyl, and the like, and isomers and mixtures thereof. Additionally, R
1
, R
2
, R
3
, and/or R
4
can be a straight or branched chain, a fully saturated or partially unsaturated hydrocarbon chain, preferably having from 1 to 40 carbon atoms, within which may be ester groups or heteroatoms, such as, oxygen, sulfur, and nitrogen, which may take the form of ethers, polyethers, sulfides, amines, and amides. This is what is meant by “functionalized alkyl.”
The imidazole thione compounds of this invention are useful as ashless, non-phosphorus-containing antifatigue, antiwear, extreme pressure additives for lubricating oils.
The present invention also relates to lubricating oil compositions comprising a lubricating oil and a functional property-improving amount of at least one imidazole thione compound of the above formulas. More particularly, the present invention is directed to a composition comprising:
(A) a lubricant, and
(B) at least one imidazole thione compound of the formula:
wherein R
1
, R
2
, R
3
, and R
4
are independently selected from the group consisting of alkyl, functionalized alkyl, and hydrogen.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The imidazole thione compounds of the present invention are compounds of the formula:
wherein R
1
and R
2
are independently selected from the group consisting of alkyl, functionalized alkyl, and hydrogen.
In the above structural formula, R
1
, R
2
, R
3
, and/or R
4
can be an alkyl moiety, preferably of 1 to 40 carbon atoms, more preferably of 1 to 18 carbon atoms, most preferably of 1 to 10 carbon atoms, and can have either a straight chain or a branched chain, a fully saturated or partially unsaturated hydrocarbon chain, e.g. methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, oleyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, triacontyl, pentatriacontyl, tetracontyl, and the like, and isomers, e.g., 2-ethylhexyl, and mixtures thereof. R
1
, R
2
, R
3
, and/or R
4
can have from 1 to 40 carbon atoms, preferably 1 to 18 carbon atoms, most preferably of 1 to 10 carbon atoms, and can be either a straight chain or a branched chain, a fully saturated or partially unsaturated hydrocarbon chain, wherein said chains may contain ester groups or heteroatoms, such as oxygen and/or sulfur and/or nitrogen, which may take the form of ethers, polyethers, sulfides, amines, amides, and the like. As employed herein, the term “alkyl” is also intended to include “cycloalkyl.” Where the alkyl is cyclic, it preferably contains from 3 to 9 carbon atoms, e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and the like. Cycloalkyl moieties having 5 or 6 carbon atoms, i.e., cyclopentyl or cyclohexyl, are more preferred.
Additionally, R
1
and R
2
and/or R
3
and R
4
can be fused together as part of a Spiro cyclic alkyl group CH
2
(CH
2
)
n
CH
2
, where n=0-4.
As noted above, R
1
, R
2
, R
3
, and/or R
4
can also be hydrogen; it is preferred, however, that no more than three of R
1
, R
2
, R
3
, or R
4
be hydrogen. In other words, it is preferred that at least one of the ring carbon atoms of the imidazole thiones of the present invention have an alkyl or functionalized alkyl substituent, as defined herein, attached thereto. It is more preferred that all of R
1
, R
2
, R
3
, and R
4
be alkyl and most preferred that they all be methyl.
Those skilled in the art will understand that analogous imidazole thiones useful as described in this invention can be prepared from cyanohydrins derived from any simple ketone or aldehyde. Preferred ketones for the preparation of these imidazole thiones include, but are not limited to, propanone, butanone, 3-methyl-2-butanone, 2-pentanone, 3-pentanone, 4-methyl-2-pentanone, 2-hexanone, 3-hexanone, 5-methyl-2-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 5-methyl-2-heptanone, cyclopentanone, cyclohexanone, cycloheptanone, and the like. Preferred aldehydes for the preparation of these imidazole thiones include, but are not limited to, butanal, pentanal, hexanal, heptanal, 2-ethylheptanal, and the like.
The use of the imidazole thione compounds of this invention can improve the antifatigue, antiwear, and extreme pressure properties of a lubricant.
General Synthesis of Additives of This Invention
The imidazole thione compounds of the present invention were synthesized as follows.
Into a 1000 mL three neck round bottom flask, equipped with a mechanical stirrer, thermometer, and dropping funnel, was placed 494 mL of (NH
4
)
2
S(22.6%). To this was
Migdal Cyril A.
Rowland Robert G.
Grandinetti Paul
Medley Margaret
Thompson Raymond D.
Uniroyal Chemical Company, Inc.
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