Claims for Patent: 7,553,863
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Summary for Patent: 7,553,863
| Title: | Ultrapure 4-methylpyrazole |
| Abstract: | Disclosed is an ultrapure 4-methylpyrazole containing less than 0.1% pyrazole and containing less than 10 ppm each of hydrazine and nitrobenzaldehyde. The ultrapure 4-methylpyrazole is prepared by a novel process so that less than 0.01% of ethylvinyl ether is present. |
| Inventor(s): | Reardan; Dayton T. (Shorewood, MN), Combe; Michel D. (Fox Point, WI) |
| Assignee: | Paladin Labs (Barbados) Inc. (Barbados, BB) |
| Application Number: | 11/279,708 |
| Patent Claims: |
1. A solution containing 4-methyl pyrazole containing less than 0.1% pyrazole.
2. The solution of claim 1 containing less than 10 ppm each of hydrazine and nitrobenzaldehyde. 3. The solution of claim 2, wherein the nitrobenzaldehyde is p-nitrobenzaldehyde. 4. A process of making 4-methylpyrazole containing less than 0.1% pyrazole comprising the steps: (a) reacting propionaldehyde with triethyl orthoformate to produce 1,1-diethoxypropane; (b) reacting the 1,1-diethoxypropane of step (a) with an amine and an acid at a temperature of about 140-160.degree. C. to produce 1-ethoxy-1-propene; (c) washing the 1-ethoxy-1-propene with water and drying it without distillation; (d) reacting the dried 1-ethoxy-1-propene of step (c) with triethyl orthoformate in the presence of a catalytic amount of boron trifluoride-diethyl etherate to produce 1,1,3,3-tetraethoxy-2-methylpropane; and (e) reacting the 1,1,3,3-tetraethoxy-2-methylpropane of step (d) with hydrazine or a hydrazonium salt to produce 4-methylpyrazole containing less than 0.1% pyrazole. 5. A process of making 4-methylpyrazole containing less than 0.1% pyrazole and less than 10 ppm each of hydrazine and nitrobenzaldehyde comprising the steps: (a) reacting propionaldehyde with triethyl orthoformate to produce 1,1-diethoxypropane; (b) reacting the 1,1-diethoxypropane of step (a) with an amine and an acid at a temperature of about 140-160.degree. C. to produce 1-ethoxy-1-propene; (c) washing the 1-ethoxy-1-propene with water and drying it without distillation; (d) reacting the dried 1-ethoxy-1-propene of step (c) with triethyl orthoformate in the presence of a catalytic amount of boron trifluoride-diethyl etherate to produce 1,1,3,3-tetraethoxy-2-methylpropane; and (e) reacting the 1,1,3,3-tetraethoxy-2-methylpropane of step (d) with hydrazine or a hydrazonium salt to produce 4-methylpyrazole containing less than 0.1% pyrazole and less than 10 ppm each of hydrazine and nitrobenzaldehyde. 6. The process of claim 4 or 5 wherein the molar ratio of acid to amine is about 1:0.4-0.6. 7. The process of claim 6 wherein the reaction temperature is about 160.degree. C. 8. The process of claim 4 or 5 wherein the 1-ethoxy-1-propene of step (b) is dried over a drying agent in step (c). 9. The process of claim 8 wherein the drying agent is magnesium sulfate. 10. The process of claim 4 or 5 wherein the dried 1-ethoxy-1-propene of step (c) contains less than 0.01% ethylvinyl ether. 11. The process of claim 10 wherein less than 0.01% ethylvinyl ether is present in the dried 1-ethoxy-1-propene of step (c) as a result of the molar ratio of acid to amine, the reaction temperature, and the washing and drying of the product without distillation. 12. The process of claim 4 or 5 wherein in step (e) a slight molar excess of 1,1,3,3-tetraethoxy-2-methylpropane is used relative to the hydrazine or hydrazonium salt. 13. The process of claim 12 wherein the molar excess is about 0.1% to about 0.5%. 14. The process of any one of claims 4, 5 or 12 wherein a hydrazonium salt is used in step (e). 15. The process of claim 14 wherein the hydrazonium salt is hydrazine hydrosulfate. 16. A composition consisting essentially of 4-methyl pyrazole containing less than 0.1% pyrazole. |
