Nitrogen-free phosphorus compounds and lubricants containing the same
A composition obtained by reacting an O,O′-dialkyldithiophosphoric acid with a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate, and reacting the product thereof with a dialkylphosphite provides good antiwear protection.
1. A composition comprising a material represented by the formula
wherein R 1 and R 2 are each independently hydrocarbyl groups of 3 to about 12 carbon atoms, or are groups represented by
or wherein R 1 and R 2 together with the adjacent O and P atoms form a ring containing 2 to 6 carbon atoms; R 3 is hydrogen or a methyl group, R 4 is an alkylene group of 2 to 6 carbon atoms, R 5 is hydrogen or a hydrocarbyl group of 1 to about 12 carbon atoms, and n is 1 or 2.
2. The composition of claim 1 wherein the material is represented by the formula
3. The composition of claim 1 wherein R 1 and R 2 are 2-ethylhexyl groups or 4-methyl-2-pentyl groups or mixtures thereof.
4. The composition of claim 1 obtained or obtainable by reacting
(a) an O,O-dialkyldithiophosphoric acid with
(b) a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate, and reacting the product thereof with
(c) a dialkylphosphite.
5. The composition of claim 4 wherein the components (a), (b), and (c) are reacted in a molar ratio of about 2:2:1.
6. The composition of claim 4 wherein the alkyl groups of (a) the O,O-dialkyldithiophosphoric acid each are independently C3 to C12 alkyl groups.
7. The composition of claim 4 wherein the alkyl groups of (a) are each independently C6 or C8 alkyl groups.
8. The composition of claim 4 wherein the alkyl groups of (a) are 2-ethylhexyl groups or 4-methyl-2-pentyl groups or mixtures thereof.
9. The composition of claim 4 wherein (b) the hydroxyalkyl acrylate or hydroxyalkyl methacrylate comprises a hydroxyalkyl acrylate.
10. The composition of claim 4 wherein the hydroxyalkyl group of (b) is a 2-hydroxyethyl group.
11. The composition of claim 4 wherein the dialkylphosphite comprises alkyl groups of, independently, 1 to about 12 carbon atoms.
12. The composition of claim 4 wherein the dialkylphosphite comprises dimethylphosphite.
13. The composition of claim 4 wherein the O,O-dialkyldithiophosphoric acid of (a) is added to the hydroxyalkyl acrylate or -methacrylate of (b) and reacted at about 40 to about 80 ° C., and the dialkylphosphite of (c) is added thereto, optionally in the presence of base, with heating to about 80 to about 110 ° C.
14. A method for preparing the composition of claim 1 , comprising reacting
(a) an O,O-dialkyldithiophosphoric acid with
(b) a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate, and reacting the intermediate product thereof with
(c) a dialkylphosphite.
15. The method of claim 14 wherein the O,O-dialkyldithiophosphoric acid of (a) is added to the hydroxyalkyl acrylate or -methacrylate of (b) and reacted at about 40 to about 80 ° C., and the dialkylphosphite of (c) is added thereto, optionally in the presence of base, with heating to about 80 to about 110 ° C.
16. The composition prepared by the method of claim 14 .
17. A lubricant comprising an oil of lubricating viscosity and the composition of claim 1 .
18. The lubricant of claim 17 wherein the amount of the composition is about 0.01 to about 5 percent by weight.
19. A method for lubricating a surface, comprising supplying thereto the lubricant of claim 17 .
20. The method of claim 19 wherein the surface is a part of a transmission, a clutch, a gear, a hydraulic system, a metal-working system, or an internal combustion engine.
21. The method of claim 19 wherein the surface is a part of a farm tractor or an off-highway vehicle.