HU187347B - Process for preparing n-phosphonomethyl-glycine by means of the catalytic oxidation of n-phosphonomethyl-imino-diacetic acid - Google Patents

Abstract

According to the invention, the reaction is carried out in an acid-free medium in the presence of a metal compound used as a catalyst. Molybdenum oxide or molybdates are particularly preferred as catalysts. The process of the present invention eliminates processing difficulties and material losses during oxidation of N- (phosphonomethyl) iminodiacetic acid in an acidic medium. -1-

Description

The present invention relates to a novel process for the preparation of N-phosphonomethylglycine by oxidation of N-phosphonomethyl iminodiacetic acid.

N-phosphonomethylglycine can be used in plant cultivation as a plant growth regulator or herbicide. One known method of preparing N-phosphonomethylglycine is by treating N-phosphonomethyliminodiacetic acid with a liquid, solid or gaseous oxidant (U.S. Patent No. 7,307,449, U.S. Pat. No. 3,954,848). U.S. Patent No. 167,343). Liquid or solid oxidizing agents include inorganic or organic peroxides such as hydrogen peroxide, peracetic acid, peracetic acid, perbenzoic acid, m-chloroperbenzoic acid, benzoyl peroxide or benzene persulfonic acid, and other commonly known inorganic oxidizing agents, such as sodium hypochlorite, potassium potassium persulphate and the like, oxygen or oxygen-containing gas mixtures, preferably air, are used as gaseous oxidants.

According to the cited publications, peroxide oxidation is always carried out in the presence of an organic or inorganic acid, otherwise the reaction takes too long or the desired product is not obtained in sufficient yield. During the oxidation, water-soluble or water-miscible acids, such as sulfuric acid, phosphoric acid, nitric acid, acetic acid, benzenesulfonic acid, p-toluenesulfonic acid and the like (most commonly sulfuric acid) are added to the reaction mixture. Usually at least 1 mol of acid is used per mol of N-phosphonomethyliminodiacetic acid.

The disadvantages of using a highly acidic medium are numerous. From an operational point of view, the reaction medium is highly corrosive; therefore, the reaction must either be carried out in a vulnerable, easily damaged glass reactor, or the inside of the metal reactor must have a special corrosion-resistant coating. The acid used decomposes to a greater or lesser extent in the peroxide (in particular hydrogen peroxide), and results in the formation of non-oxidative materials of no value to the reaction. This phenomenon greatly increases the chemical requirements of the operation and thus the material costs of the process. The highly acidic reaction mixture is difficult to process, the acid cannot be regenerated from the reaction mixture, and the production waste water can only be discharged to the environment after prior neutralization. Further disadvantages are that the final product is significantly more soluble in the strongly acidic reaction medium than in the water. Since highly acidic reaction mixtures (mainly sulfuric acid solutions) cannot usually be worked up by evaporation, the N-phosphonomethylglycine remaining in the mother liquor can be separated only with suitable precipitating agents (usually alcohol). The use of a precipitant further increases the production cost and also has the disadvantage of separating impurities from the reaction mixture which are not or only very difficult to remove from the final product.

The present invention seeks to overcome the disadvantages of using a strongly acidic reaction medium.

It has been found in our experiments that the peroxidation of N-phosphonomethyliminodiacetic acid in the presence of metals or metal compounds does not require the addition of acid to the reaction mixture. The reaction is carried out in a relatively short time with good yields, the amount of peroxide needed to produce the unit amount of final product can be significantly reduced, and problems with the processing, treatment and disposal of the acidic reaction mixture are eliminated.

The present invention therefore relates to a process for the preparation of N-phosphonomethylglycine by oxidation of N-phosphonomethyliminodiacetic acid with peroxides. According to the invention, the reaction is carried out in an acid-free medium in the presence of a metal or a metal compound used as a catalyst.

In the process of the invention, any metal of the subgroups of the periodic table may be used as a catalyst, either alone or in the form of a compound. If noble metal catalysts are used, they are conveniently added to the reaction in the form of supported metal. Examples of supported noble metal catalysts include platinum and palladium on activated carbon, alumina, barium sulfate or the like. Other metals are suitably in the form of compounds for the reaction mixture. Examples of metal compounds are oxides (such as iron oxide, molybdenum oxide, silver oxide, lead oxide, etc.), salts (such as ferrous sulfate, tin chloride, manganese chloride, etc.), or compounds containing the metal in the form of anions or complexes (e.g. ammonium molybdate, etc.). Molybdenum compounds, in particular molybdates, have been found to be particularly preferred catalysts.

Both homogeneous (i.e. soluble in the reaction medium) and heterogeneous (i.e. insoluble in the reaction medium) catalysts can be used in the process of the invention. The lower limit of the amount of catalyst required will vary depending upon the nature of the metal or metal compounds used and their solubility in the reaction medium. Highly soluble catalysts, such as some molybdenum compounds, which are highly soluble in the reaction medium, sometimes have a good catalytic effect even at concentrations of from 10 to 100 ppm relative to the amount of N-phosphonomethyliminodiacetic acid, while in other cases higher amounts of catalyst are required. In general, it is preferred that the amount of N-phosphonomethyliminodiacetic acid is at least about 10% by weight. 0.01-0.1% by weight of catalyst is added to the reaction mixture. The catalyst is usually employed in an amount of 0.1 to 10% by weight, based on N-phosphonomethyliminodiacetic acid.

The upper limit of the amount of catalyst is not chemically decisive. Heterogeneous catalysts (e.g., iron oxide or supported noble metal catalysts) may also be used in an amount of from 10% to 30%, based on the amount of N- (phosphono-21 methyl) iminodiacetic acid.

The heterogeneous catalysts can be readily separated from the reaction mixture by filtration and reused in the reaction. The amount of catalyst increase ⁵ CONFORMITY economically limited by the fact that as a rule the catalyst is increased in parallel with increasing the amount of decrease of the peroxide compound.

Apart from the use of the catalyst, the reaction according to the invention can be carried out under standard conditions of peroxidation of N-phosphonomethyl iminodiacetic acid. The reaction is usually carried out in an aqueous medium. The reaction may also be started from an aqueous suspension of N-phosphonomethyliminodiacetic acid. As the reaction proceeds, the N-phosphonomethylglycine is significantly more soluble in water than the starting material (100ml of water at 100 ° C, 4g of N-phosphonomethyliminodiacetic acid and 10g of N-phosphonomethyl). - ²⁰ glycine can dissolve); so you still have approx. Starting from an 18-20% suspension of N-phosphonomethyliminodiacetic acid, a homogeneous solution is obtained which is easy to process. If the starting slurry contains a larger amount of N-phosphonomethyliminodiacetic acid, part of the final product is precipitated from the mixture during the reaction.

The reaction is usually carried out for approx. 50-120 ° C, preferably at the boiling point of the reaction mixture. If the reaction is continued for approx. It is carried out at a temperature below 80 ° C, usually resulting in a more impure end product. In order to further increase the reaction rate, the reaction may, in some cases, be carried out at temperatures above 100 ° C and above atmospheric pressure. 35

Any organic or inorganic peroxide may be used as the oxidizing agent in the process of the invention. Examples of inorganic peroxides are hydrogen peroxide and examples of organic peroxides are tert-butyl hydroperoxide, 40 cumyl hydroperoxide, peracids (such as peracetic acid, perbenzoic acid, etc.), benzoyl peroxide, di-tert-butyl peroxide, -phenylethyl hydroperoxide and substituted derivatives thereof are listed. Suitably, the oxidizing agent is hydrogen peroxide, which is preferably added continuously in the form of a concentrated aqueous solution (about 30%).

After completion of the reaction, if heterogeneous catalysts are used, the catalyst is separated from the reaction mixture and, if desired, the N-phosphonomethylglycine is isolated by conventional means, for example by evaporation of the mixture. If the N-phosphonomethylglycine is to be used directly for the preparation of pesticides, it is not always necessary to isolate the final product 55 because in some cases the resulting reaction mixture (an aqueous solution of N-phosphonomethylglycine) and after the addition of excipients it can be used in agriculture itself. θθ

If the amount of homogeneous catalysts used in the reaction does not exceed 100-500 ppm, based on the amount of N-phosphonomethylglycine, subsequent removal of the homogeneous catalyst is not necessary. 347 _fil desired, removing the homogeneous catalyst from the reaction mixture in a known manner (for example by forming a compound insoluble in the reaction and subsequent filtration).

The following examples illustrate the invention without limiting it.

Example 1

To a boiling solution of 4 g of N-phosphonomethyliminodiacetic acid in 100 ml of water was added 0.2 g of iron (III) oxide catalyst (heterogeneous catalyst) and 6 ml of 30% aqueous hydrogen peroxide solution was added dropwise. The resulting solution was cooled, filtered and the final product was collected by evaporation to give 2.8 g (70%) of N-phosphonomethylglycine.

Example 2

10 g of N-phosphonomethyliminodiacetic acid are suspended in 100 ml of water and 0.2 g of silver oxide (heterogeneous catalyst) is added to the suspension. The reaction mixture was heated to 100 ° C and 10.5 ml of 30% aqueous hydrogen peroxide solution was added dropwise over 24 hours. The resulting solution was cooled, filtered and the final product was collected by evaporation of the filtrate. 4.5 g (60%) of N-phosphonomethylglycine are obtained.

Example 3

10 g of N-phosphonomethyliminodiacetic acid are suspended in 100 ml of water and 0.1 g of manganese (II) chloride (homogeneous catalyst) is added to the suspension. The reaction mixture was heated to 100 ° C and 8.3 ml of 30% aqueous hydrogen peroxide solution was added dropwise over 14 hours. The resulting solution was cooled, filtered and the filtrate was evaporated to isolate the final product. 6.0 g (80%) of N-phosphonomethylglycine are obtained.

Example 4

20 g of N-phosphonomethyliminodiacetic acid are suspended in 100 ml of water and 1.0 g of tin (IV) chloride is added to the suspension. The reaction mixture was heated to 100 ° C and 20 ml of 30% aqueous hydrogen peroxide solution was added dropwise over 7 hours. The resulting slightly cloudy reaction mixture was filtered hot to remove tin hydroxide and various tin oxide hydrates formed during the reaction by hydrolysis. The filtrate was evaporated to yield 9.9 g (66%) of N-phosphonomethylglycine.

Example 5

20 g of N-phosphonomethyliminodiacetic acid are suspended in 100 ml of water and 0.2 g of lead oxide (heterogeneous catalyst) is added to the suspension. The reaction mixture was heated to 100 ° C and 23 ml of 30% aqueous hydrogen peroxide-31 were added over 3 hours.

187,347 solutions were added dropwise. The resulting mixture was filtered hot to remove the catalyst and the filtrate was evaporated. 9.9 g (66%) of N- (phosphonomethyl) glycine are obtained.

EXAMPLE 6 N-phosphonomethyliminodiacetic acid (g) was suspended in water (100 ml) and vanadium acetonyl acetate (homogeneous catalyst) (0.03 g) was added. The reaction mixture was heated at 100 C ', ^and! 20 ml of 30% aqueous hydrogen peroxide solution are added dropwise over 5 hours. The catalyst used reacts with a color reaction to the presence of peroxide: the reaction mixture is blue in the presence of peroxide and rust brown in the absence of peroxide. This phenomenon can advantageously be utilized to monitor the reaction by adding the next portion of hydrogen peroxide only when the color change of the mixture indicates that the previously added hydrogen peroxide is completely consumed. After the reaction time of 5 hours, the mixture was filtered hot and the filtrate was evaporated. N-phosphonomethylglycine was obtained in 60% yield.

Example 7

20 g of N-phosphonomethyliminodiacetic acid are suspended in 100 ml of water and 0.06 g of molybdenum oxide catalyst MM0 ₂ (heterogeneous catalyst: molybdenum content: 21.63%) is added to the suspension. The reaction mixture was heated to 100 ° C and 18 ml of 30% aqueous hydrogen peroxide solution was added dropwise over 3 hours. The catalyst used reacts with the color reaction in the presence of peroxide: the reaction mixture is yellow in the presence of peroxide and colorless in the absence of peroxide. This phenomenon is utilized as described in Example 6 to monitor the course of the reaction. After the 3 hour reaction time, the mixture was hot filtered and the filtrate was evaporated to isolate the product. N-phosphonomethylglycine was obtained in 93% yield.

Example 8

10 g of N-phosphonomethyliminodiacetic acid are suspended in 100 ml of water and 0.1 g of ammonium molybdate tetrahydrate is added to the suspension. The reaction mixture was heated to 100 ° C and 8.4 ml of 30% aqueous hydrogen peroxide solution was added dropwise over 3 hours. The catalyst used reacts with the same color reaction as in Example 7 to the presence of peroxide. After the reaction time of 3 hours, the mixture was cooled, filtered and the filtrate was evaporated to isolate the final product. N-phosphonomethylglycine was obtained in 85% yield.

Published by the National Office of Inventions Responsible for publishing: Zoltán Himer Head of Department Drawing

Taken by the Printing Light Collection Plant (877679/09) 4

Example 9

One proceeds as described in Example 8, except that sodium was used as the catalyst ⁵ as sodium molybdate heptahydrate.

The final product is obtained in 85% yield.

Example 10 ^F

20 g of N-phosphonomethyliminodiacetic acid are suspended in 100 ml of water and 0.03 g of sodium molybdate heptahydrate is added to the suspension. The reaction mixture was heated at 100 C ', and the mixture was added dropwise 18 ml of 30% aqueous hydrogen peroxide solution in ¹⁵ and 2 hours. The mixture was filtered hot and the filtrate was evaporated to isolate the final product. The N- (phosphonomethyl) glycine ₂₀ obtained in 82% yield.

Example 11

40 g of N-phosphonomethyliminodiacetic acid are suspended in 100 ml of water and 0.12 g of sodium molybdate heptahydrate are added to the reaction mixture. The reaction mixture was heated to 100 ° C and 36 ml of 30% aqueous hydrogen peroxide solution was added dropwise over 5 hours. The suspension obtained is evaporated to remove water. Give N- (phosphonomethyl) glycine ³ in 78% yield.

Example 12

100 ml of N-phosphonomethyliminodiacetic acid (10 g) are suspended and 0.03 g of sodium molybdate heptahydrate is added to the suspension. The reaction mixture was heated to 80 ° and a solution of 18 ml of 30% aqueous hydrogen peroxide was added dropwise over ⁴⁰ over 3 hours. The resulting mixture was filtered hot and the filtrate was evaporated. N-phosphonomethylglycine

Yield: 78%.

Claims (3)

⁴⁵ Claims A process for the preparation of N-phosphonomethylglycine by oxidation of N-phosphonomethyliminodiacetic acid with peroxides, characterized in that The reaction is carried out in the presence of 0.1 to 10% by weight of N-phosphonomethyliminodiacetic acid in the presence of a compound of metal, preferably silver, iron, tin, lead, manganese or molybdenum. The method of claim 1, which is an embodiment 55, characterized in that molybdenum compounds, molybdenum oxide or molybdates, are used as catalysts. 3. The process according to claim 2, wherein the catalyst is added to the reaction mixture in an amount of from 0.1 to 2% by weight, based on the amount of N-phosphonomethyliminodiacetic acid.