BENTO MARTINHO DE SA PEREIRA M (PT)
BENTO MARTINHO DE SA PEREIRA M (PT)
| EP0464018A1 | 1992-01-02 | |||
| US5095140A | 1992-03-10 |
| 1. | Process for producing Nphosphonomethylglycine by the oxidation of N phosphonomethyliminodiacetic acid to form an intermediate NoxideN phosphonomethyliminodiacetic acid and converting the intermediate to N phosphonomethylglycine, characterised for using hydrogen peroxide as oxidative agent and catalytic amount of a mixture of alkaline metal tungstate and alkaline metal chromate, to form NoxideN phosphonomethyliminodiacetic acid at temperature of 7173°C and thereafter converting the NoxideNphosphonomethyliminodiacetic acid to N phosphonomethylglycine in the presence of a mixture of iron (II) sulphate and nickel (II) sulphate or cobalt (II) sulphate. |
| 2. | In the process of claim 1 wherein the amount of catalyst is between 0,01 % and 0, 3 %, based on the weight of the Nphosphonomethyliminodiacetic acid. |
| 3. | In the process of claim 2 wherein the catalyst is a mixture of alkaline metal tungstate and alkaline metal chromate. |
| 4. | In the process of claim 3 wherein the weight ratio of tungsten compound to chromium compound is 70: 30. |
| 5. | In process of claim 1 characterised for using to convert the intermediate, N oxideNphosphonomethyliminodiacetic acid to Nphosphonomethylglycine a mixture of iron (II) sulphate and nickel (II) sulphate or cobalt (II) sulphate in concentrations between 0,5 % and 2 % based on the weight of the N phosphonomethyliminodiacetic acid. |
| 6. | In process of claim 5 where the concentration of iron (II) sulphate to nickel (11) sulphate or cobalt (11) sulphate is 10: 0, 5 to 10: 0,1. |
2. Background of the invention The present invention describes a process for the preparation N- phosphonomethylglycine, by the formation of N-oxide-N- phosphonomethyliminodiacetic acid, with hydrogen peroxide in the presence of a mixture of catalyst containing tungsten and chromium salts, thereafter converting the intermediate N-oxide-N-phosphonomethyliminodiacetic acid to N- phosphonomethylglycine.
There are many methods for the preparation of the N- phosphonomethylglycine by the oxidation of N-phosphonomethyliminodiacetic acid with hydrogen peroxide1 23, using as catalyst noble metals, silver2, iron, lead2, manganese2, molybdenum2, mixture of the tungstates3 and molybdates3.
Each one of the described methods used specific interval of the temperature and suitable catalyst concentrations.
Although satisfactory results are obtained by the described methods1 to make N-phosphonomethylglycine, all of them present one or more disadvantages, such as the use of excessive amounts of hydrogen peroxide2, elevated temperatures1, side products and elevated amounts of the catalyst3.
The paper4 of the company lnterox published the use of sodium tungstate and sodium molibdate as a catalyst in the reaction of oxidation of aminoacids.
The patent2 claims protection for the use of iron salts in the oxidation of N- phosphonomethyliminodiacetic acid to N-phosphonomethylglycine.
The patent'-claims protection for a particular range of temperatures and concentrations for the use of both the catalyst sodium tungstate and iron salts iri the oxidation of N-phosphonomethyliminodiacetic acid to N- phosphonomethylglycine.
We found that a better range of temperatures and concentrations can be chosen, in order to improve the yield and reducing side productos.
3. Detailed description of the invention The present invention describes a process for the production N- phosphonomethylglycine by reacting N-phosphonomethyliminodiacetic acid with hydrogen peroxide in the presence of an effective amount of a catalyst consisting a mixture of alkaline metal tungstates and alkaline metal chromates to form an intermediate N-oxide-N-phosphonomethyliminodiacetic acid, at temperatures of the 71-73°C. The intermediate is than converted to N- phosphonomethylglycine in the presence of iron (II) sulphate, nickel (H) sulphate and cobalt (II) sulphate.
The concentration of the hydrogen peroxide is very important for the yield of final reaction, the better results are obtained with concentrations between 35- 45 % on weight.
The amount of catalyst to convert the N-phosphonomethyliminodiacetic acid to the intermediate N-oxide-N-phosphonomethyliminodiacetic acid can vary within wide limits. The better results are obtained with concentrations between 0,01 and 0, 3 % on the weight of the N-phosphonomethyliminodiacetic acid.
The best results have been obtained when the ratio of alkaline metal tungstates and alkaline metal chromates 70: 30.
To catalyse the reaction of the N-oxide-N-phosphonomethyliminodiacetic acid to N-phosphonomethylglycine is used a mixture of iron (II) sulphate, nickel (II) sulphate and cobalt (II) sulphate. Excellent results are obtained with concentrations between 0, 5 and 2 % on the weight of the N- phosphonomethyliminodiacetic acid.
EXEMPLE To a 500 ml round bottom flask was added: - N-phosphonomethyliminodiacetic acid 113,5 g - Water 170 g -Sodium tungstatelsodium chromate 0,1 g The mixture was heated to 71 °C, was added 51 g of the hydrogen peroxide 40 % (1,2 eq) and maintained at this temperature until a solution was obtained (about 1: 30 hours). The solution was then allowed to cool to room temperature, was added a aqueous solution of a mixture of iron (II) sulphate and nickel (II) sulphate (0,5 g FeS04, 0,5 g NiS04, 9,0 g water) and maintained the temperature between 50 and 80 °C. The reaction mixture was allowed to cool to room temperature from 12 hours, the solids were filtered and the filtrate and solids were analyzed by HPLC. The conversion of N- phosphonomethyliminodiacetic acid to N-phosphonomethylglycine was 94 %.
BIBLIOGRAPHY 1. United States patent; 3,950, 402 (13-04-1976).
2. Hungarian patent; 187,347 (28-12-1985).
3. European patent; 464,018 (24-01-1991).
4. "Peroxygen Compounds in Organic Synthesis", Interox.