Claims
- 1. In a process for the production of a thiophosphoric acid ester of formula I ##STR7## wherein R.sub.1 is lower alkyl, lower alkenyl, lower alkoxy(lower)alkyl or lower alkylmercapto(lower)alkyl, R.sub.2 is hydrogen, lower alkyl or lower alkenyl and R.sub.3 and R.sub.4 are lower alkyl, which comprises reacting a dialkyl phosphoric acid halide of formula II ##STR8## wherein Hal is chlorine or bromine and R.sub.3 and R.sub.4 are as defined hereinabove, with a hydroxypyrimidine of formula III ##STR9## wherein R.sub.1 and R.sub.2 have the significance given to them above, at elevated temperatures and in the presence of an organic solvent and an acid-binding agent, the improvement which comprises adding the reactant of formula II to an essentially dry mixture of the hydroxypyrimidine of formula III and the acid-binding agent in the presence of a lower molecular weight water-insoluble aliphatic or cycloaliphatic ketone as organic solvent after removing the water of reaction from said mixture.
- 2. A process of claim 1, wherein the organic solvent is selected from branched and straight chain C.sub.5 -C.sub.8 aliphatic ketones and cyclic ketones containing a total of 5 to 7 carbon atoms.
- 3. A process of claim 2, wherein the organic solvent is methyl isobutyl ketone or cyclohexanone.
- 4. A process of claim 2, wherein there is employed 1.5 to 3 parts of solvent per part of compound of formula III.
- 5. A process of claim 1, wherein the hydroxypyrimidine of formula III is present in 2-20% molar excess and the acid-binding agent is present in 1-18% molar excess, both relative to the compound of formula II.
- 6. A process of claim 1, wherein the acid-binding agent is sodium hydroxide.
- 7. A process of claim 1, wherein the reactant of formula II is O,O-diethyl thiophosphoric acid chloride and the reactant of formula III is 2-isopropyl-6-methyl-4-hydroxypyrimidine.
- 8. A process of claim 1, wherein 1 mole of O,O-diethyl thiophosphoric acid chloride is added to an essentially dry mixture of 1.06-1.12 moles of 2-isopropyl-6-methyl-4-hydroxypyrimidine and 1.04-1.08 moles of sodium hydroxide, at an initial reaction temperature of 45.degree.-85.degree. C., in methyl isobutyl ketone as organic solvent.
- 9. A process of claim 1 wherein said acid-binding agent is added to a mixture of said hydroxypyrimidine of formula III in said low molecular weight water-insoluble aliphatic or cycloaliphatic ketone and all water is removed by distillation of the water azeotrope prior to addition of the compound of formula II.
- 10. A process of claim 1 wherein said acid binding agent is added in the form of an aqueous dispersion or solution.
- 11. A process of claim 10, wherein the acid binding agent is in the form of about a 50% aqueous sodium hydroxide solution.
- 12. A process of claim 10, wherein the hydroxypyrimidine of formula III is present in 2-20% molar excess and the acid-binding agent is present in 1-18% molar excess, both relative to the compound of formula II.
- 13. A process of claim 12, wherein the acid-binding agent is about 50% aqueous sodium hydroxide.
- 14. A process of claim 10, wherein the reactant of formula II is O,O-diethyl thiophosphoric acid chloride and the reactant of formula III is 2-isopropyl-6-methyl-4-hydroxypyrimidine.
- 15. A process of claim 13 wherein 1.04-1.08 moles of about 50% aqueous sodium hydroxide is added to 1.06-1.12 moles of 2-isopropyl-6-methyl-4-hydroxypyrimidine in methyl isobutyl ketone as solvent, all water is removed by azeotropic distillation and one mole of O,O-diethyl thiophosphoric acid chloride is added to the essentially dry mixture at an initial reaction temperature of 45.degree.-85.degree. C.
- 16. A process of claim 1 wherein said acid binding agent is added in the form of a finely divided solid.
- 17. A process of claim 16, wherein the acid-binding agent is finely divided solid sodium hydroxide.
- 18. A process of claim 17, wherein the hydroxypyrimidine of formula III is present in 2-20% molar excess and the acid-binding agent is present in 1-18% molar excess, both relative to the compound of formula II.
- 19. A process of claim 17 wherein 1.04-1.08 moles of finely divided solid sodium hydroxide is added to 1.06-1.12 moles of 2-isopropyl-6-methyl-4-hydroxypyrimidine in methyl isobutyl ketone as solvent, all water is removed by azeotropic distillation and one mole of O,O-diethyl thiophosphoric acid chloride is added to the essentially dry mixture at an initial reaction temperature of 45.degree.-85.degree. C.
CROSS-REFERENCE
This application is a continuation in-part of copending application U.S. Ser. No. 187,162, filed Apr. 28, 1988, now abandoned.
US Referenced Citations (19)
Foreign Referenced Citations (2)
Number |
Date |
Country |
097451 |
Jan 1984 |
EPX |
2343931 |
Apr 1975 |
DEX |
Non-Patent Literature Citations (1)
Entry |
Research Disclosure, 310114 (Feb., 1990). |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
187162 |
Apr 1988 |
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