WO2009079862A1

WO2009079862A1 - New preparation method of glyphosate by oxidation pmida with air

Info

Publication number: WO2009079862A1
Application number: PCT/CN2007/003774
Authority: WO
Inventors: Yulai Guo; Yingwu Yin; Jinping Tian; Huijuan Yan
Original assignee: Beijing Unis Insight Chemical Technology Co., Ltd.
Priority date: 2007-12-25
Filing date: 2007-12-25
Publication date: 2009-07-02

Abstract

The invention provides a new preparation method of glyphosate by oxidation of PMIDA, which uses air or oxygen as oxidant and the combination of activated carbon or carbon nanotube with supersonic wave as catalyst. The advantages of the method comprise high yield, high selectivity, high purity of the product, cheap catalyst, low cost, no reducer and no hydrogen peroxide.

Description

A new process for preparing glyphosate by air oxidation of glyphosate

The invention relates to a novel process for catalytic oxidation of glyphosate to synthesize an important pesticide-herbicide glyphosate.

Background technique

Glyphosate (glyphosate, N-(phosphonocarboxyl)-glycine) is a herbicide selected by Monsanto Chemical Company in the 1960s and belongs to amino acid derivatives. The good biological activity of glyphosate makes it a highly effective, low-toxic, post-emergence herbicide for a wide range of applications. Currently, annual sales rank first among pesticide products.

The synthesis methods of glyphosate mainly include two methods: glycine method and iminodiacetic acid method. The glycine method mainly produces glyphosate by reacting glycine as a raw material. This method has higher yield, higher cost, and consumes a large amount of alkali due to recovery of solvent and catalyst, which increases equipment, energy consumption and workload. The iminodiacetic acid method, also known as the IDA method, firstly reacts IDA with furfural or phosphorous acid to obtain glyphosate (PMIDA), and then oxidizes PMIDA to obtain glyphosate. The raw materials of this method are easy to obtain, simple to operate, the process conditions are moderate, the equipment requirements are not high, the product yield is high, and the economic benefits are good, which is suitable for China's national conditions and domestic market demand. Compared with the one-step method, it has obvious advantages such as low cost. The key to PMIDA oxidation is the choice of oxidation process and oxidation catalyst.

Oxidative Synthesis of Glyphosate from Glyphos

The currently used methods for the oxidative synthesis of glyphosate from glyphosate mainly include two methods of hydrogen peroxide oxidation and catalytic oxidation.

1. Hydrogen peroxide oxidation The hydrogen peroxide oxidation method includes two main ones: one is sodium tungstate-stone ferrous acid as a catalyst or sodium molybdate-sodium metabisulfite as a catalyst, hydrogen peroxide is an oxidant to synthesize glyphosate, and the other is Activated carbon is a catalyst, and hydrogen peroxide is an oxidizing agent for synthesizing glyphosate.

The first method uses a hydrogen peroxide oxidation method to synthesize glyphosate, which is a long process, including oxidation and reduction. The oxidation process has high requirements for the acceleration and temperature of the hydrogen peroxide droplets. At the same time, the catalysts such as ferrous ions or concentrated acid are used in the oxidation process, so that the product is not easy to be placed for a long time, and the yield of the glyphosate raw powder is low, and the product color is yellowish. The formation of three wastes of glyphosate mother liquor is an urgent problem to be solved.

The second method is a method in which activated carbon as reported in the CN1183100 patent is used as a catalyst and oxidized by hydrogen peroxide to prepare glyphosate. The advantage of this method is that the catalyst is cheap and easy to obtain, and the process is easy to control. Although the yield of glyphosate raw powder is higher than that of the first process, the cost is less, but the consumption of hydrogen peroxide is twice that of the sodium tungstate-ferrous sulfate-hydrogen peroxide method. Moreover, the activated carbon is easily deactivated and cannot be continuously recycled.

2. Preparation of glyphosate by catalytic oxidation

The preparation of glyphosate by catalytic oxidation utilizes oxygen-containing gas such as air or oxygen as an oxidizing agent, metal or metal salt as a catalyst, and has research value and industrial application value. The catalytic oxidation methods that have been reported are mainly classified into two types: transition metal salt complex catalytic oxidation method and noble metal catalytic oxidation method depending on the type of catalyst.

1. Catalytic oxidation of transition metal complexes and catalytic oxidation of noble metal catalysts

Monsanto has conducted more research on this. Complexes of transition metals such as manganese, cobalt and vanadium can catalyze the oxidation of glyphosate in the presence of oxygen. The patent (EP0314662) recommends an oxidation temperature of 70. ~ 100 ° C, pressure 30-1000 psig, oxygen is bubbled into the aqueous solution of diglycine. Compared with precious metal catalysts, transition metal catalysts are low in cost and belong to homogeneous catalysis, eliminating the catalyst filtration section in the process and simplifying the work. Although the transition metal is low in cost, the target product conversion rate and catalyst selectivity are not as good as those of the precious metal catalyst, and the reaction conditions are relatively harsh. Glyphosate is synthesized by catalytic oxidation of diphosphonium with noble metal. The reaction yields high glyphosate content, reaction selectivity and conversion rate. It is reported that Monsanto Company of the United States uses this method to synthesize PMG, which has obvious technical advantages and Economic advantage.

The literature (US3950402) introduces the use of precious metals (Pd, Pt, Rh, etc.) supported on activated carbon, and oxidizes glyphosate with oxygen. At a temperature of 90 ° C to 100 ° C and a pressure of 30 psig, a purity of 97% can be obtained by reacting for 3 hours. Glyphosate, yield up to 96%.

Monsanto reported a method for preparing glyphosate by using activated carbon supported noble metal as a catalyst, heterogeneous air oxidation, and a method for preparing glyphosate by air oxidation using a noble metal complex containing an organic ligand as a catalyst. The defects of these methods include several aspects: 1) Using expensive precious metal catalysts, the catalyst recovery is difficult, and the catalyst is easily lost; 2) The organic ligand preparation method is complicated, which increases the difficulty of product separation and purification. 3) The catalyst needs to be replaced regularly; 4) There are patent restrictions.

3, activated carbon - air - hydrogen peroxide catalytic oxidation

Patent CN96195765.4 reports that activated carbon is a catalyst, first using air as an oxidant, and finally requiring hydrogen peroxide to oxidize the remaining diglycine. Although this method reduces the amount of hydrogen peroxide, it does not completely eliminate the use of hydrogen peroxide. The disadvantage of this method is that the glyphosate needs to react with oxygen or air under a certain pressure to partially react. In view of the deficiencies of the prior art, the inventors conducted in-depth research, and we found in the research that the ultrasonic wave can not only promote the three-phase mixing of the solid-liquid gas, but also continuously update the phase interface, strengthen the mass transfer process, and promote the dissolution of the hg-glyphosate. And dispersion, and can generate hydroxyl radicals in solution, hydroxyl radicals promote the oxidation of activated carbon and oxygen to glyphosate. The invention adopts activated carbon and ultrasonic as catalyst, air or oxygen as oxidant, the process is easy to control, the reaction selectivity is high, the amount of by-products is small, the activated carbon is easy to recover, and can be repeatedly applied repeatedly, the reaction liquid is directly concentrated, and the purity of the product can reach 98. %the above. And the product is white, good appearance, high raw powder yield, less mother liquor, low energy consumption, and is the most valuable green new technology in glyphosate synthesis. The distinguishing feature of this process is the combination of cheap air and activated carbon and ultrasonic combined oxidation of bisphosphonate, replacing the hydrogen peroxide in the existing method, the expensive precious metal and transition metal, sodium tungstate/sodium molybdate, and no reducing agent. . The activated carbon used in the present invention includes purified activated carbon prepared by various methods. The method combines the advantages of the hydrogen peroxide method and the catalytic oxidation method, on the one hand, overcomes the consumption of a large amount of hydrogen peroxide by the activated carbon-hydrogen peroxide method, directly utilizes air or other oxygen-containing gas as an oxidant, and greatly reduces the cost; on the other hand, the method does not use Activated carbon supported on precious metals can react, overcoming the problems of difficult catalyst recovery, easy loss, and high recovery costs. Therefore, the process has the advantages of low investment, high cost, high quality and no waste.

Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a process for preparing glyphosate by oxidizing diphosphonate with an oxygen-containing gas in combination with ultrasonic waves and activated carbon.

The preparation method of the present invention is represented by a synthetic route as follows:

Specifically, the main steps of the preparation method of the present invention are:

The mixed solution of glyphosate (PMIDA), activated carbon and water reacts under ultrasonic wave at a certain temperature, and is detected by nuclear magnetic resonance or liquid chromatography. After the disappearance of the glyphosate, the reaction is stopped, the activated carbon and the product are separated, and the activated carbon is applied. When the activated carbon is used, it can be applied only after simple washing, and has no effect on the reaction selectivity. The activated carbon is recovered as a catalyst, and the operation method is the same as above, and the reaction effect is the same. The activated carbon prepared by different methods and raw materials was used as a catalyst, and there was no significant difference in reaction selectivity and yield.

Detailed ways

Example 1

The ultrasonic generator used in this experiment has a frequency of 25 kHz and a power of 100 watts.

Add 2.5 g of activated carbon (made of charcoal as raw material) to a three-necked flask, 50 ml of water, 10 g of PMIDA, heat and stir, introduce air into the reaction solution, turn on the ultrasonic generator, and raise the temperature to 40 ° C to detect the glyphosate. Complete reaction, reaction time 15 hours, glyphosate reaction selectivity 89.1%, finally obtained glyphosate original powder 6.49g, content 99%.

Example 2:

The recovered activated carbon in Example 1, 100 ml of water, 10 g of PMIDA, heated and stirred, air was introduced into the reaction solution, the ultrasonic generator was turned on, the temperature was raised to 80 ° C, and the disappearance of the glyphosate was detected, the reaction was stopped, and the reaction time was At 12 hours, the glyphosate reaction selectivity was 90.68%, and finally the glyphosate original powder was 6.53 g, and the content was 99.5%.

Example 3:

The recovered activated carbon in Example 2, 100 ml of water, 10 g of PMIDA, heated and stirred, air was introduced into the reaction solution, the ultrasonic generator was turned on, the temperature was raised to 90 ° C, and the disappearance of the glyphosate was detected, and the reaction was stopped. At 12 hours, the selectivity of glyphosate reaction was 88.4%, and finally the original glyphosate powder was 6.24 g, and the content was 99.4%.

Example 4:

The recovered activated carbon in Example 3, 100 ml of water, 10 g of PMIDA, heated and stirred, air was introduced into the reaction solution, the ultrasonic generator was turned on, the temperature was raised to 70 ° C, and the detection of the disappearance of the glyphosate was stopped, and the reaction was stopped. At 12 hours, the glyphosate reaction selectivity was 91.10%, and finally the glyphosate original powder was 6.55 g, and the content was 99.2%. The recovered activated carbon in Example 4, 100 ml of water, 10 g of PMIDA, heated and stirred, air was introduced into the reaction solution, the ultrasonic generator was turned on, the temperature was raised to 60 ° C, and the disappearance of the glyphosate was detected, and the reaction was stopped. At 12 hours, the selectivity of glyphosate reaction was 90.12%, and finally the original glyphosate powder was 6.50 g, and the content was 99.5%.

Example 6:

The recovered activated carbon in Example 5, 100 ml of water, 10 g of PMIDA, heated and stirred, air was introduced into the reaction solution, the ultrasonic generator was turned on, the temperature was raised to 50 ° C, and the detection of the disappearance of the glyphosate was stopped, and the reaction was stopped. At 12 hours, the selectivity of glyphosate reaction was 89.88%, and finally the crude glyphosate powder was 6.48 g, and the content was 99.1%.

After the above six batches of reaction were separated and activated carbon, the solution was concentrated, and the content of the original glyphosate powder was more than 98%, and the yield was more than 87%.

Example 7

Add 2.5 g of activated carbon, 50 ml of water, 10 g of PMIDA to the three-necked flask, heat and stir. The air is sucked into the reaction solution by the pump, the ultrasonic generator is turned on, the temperature is raised to 78 ° C, and the phosphonium is detected to completely react with the glyphosate. The reaction was about 16 hours, and the selectivity of glyphosate reaction was 90.1%. Finally, the original glyphosate powder was 6.44 g, and the content was 98.5%.

Example 8

Add 2.5 g of activated carbon, 50 ml of water, 10 g of P DA to the three-necked flask, heat and stir. Oxygen is introduced into the reaction solution under normal pressure, the ultrasonic generator is turned on, the temperature is raised to 63 ° C, and the phosphorus spectrum is detected to completely react with the glyphosate. The reaction was about 3 hours, and the selectivity of glyphosate reaction was 89.1%. Finally, the original glyphosate powder was 6.40 g, and the content was 98.2%.

Example 9

Add 2.5 g of activated carbon, 50 ml of water, 10 g of PMIDA to the autoclave, heat and stir, pass air into the reaction solution, turn on the ultrasonic generator, the temperature is raised to 50 °C, the pressure is 0.5 MPa, and the phosphorus spectrum is detected to be completely glyphosate. Reaction, reaction for about 2 hours, glyphosate reaction selection Selective 88.1%, the final glyphosate powder 6.39g, the content of 98.2%.

Example 10

Add 5.0 g of activated carbon, 50 ml of water, 10 g of PMIDA to the three-necked bottle, heat and stir, pass air into the reaction solution, turn on the ultrasonic generator, and the temperature rises to 55 ° C. The phosphorus is detected to completely react with the glyphosate. At 6 hours, the glyphosate reaction selectivity was 87.1%, and finally the glyphosate original powder was 6.35 g, and the content was 98.3%.

Example 11:

Add 4.0 g of activated carbon, 50 ml of water, 10 g of PMIDA to the three-necked bottle, heat and stir, pass the air into the reaction solution, turn on the ultrasonic generator, and the temperature rises to 65 ° C. The phosphorus is detected to completely react with the glyphosate. At 8 hours, the glyphosate reaction selectivity was 86.6%, and finally the glyphosate original powder was 6.32 g, and the content was 98.0%.

Example 12:

Add 2.5 g of activated carbon, 150 ml of water, 10 g of PMIDA to the three-necked bottle, heat and stir, pass oxygen into the reaction solution, turn on the ultrasonic generator, the temperature rises to 65 ° C, and the phosphorus spectrum is detected to completely react with the glyphosate. At 10 hours, the glyphosate reaction selectivity was 87.4%, and finally the glyphosate original powder was 6.30 g, and the content was 98.5%.

Example 13

Add 2.0 g of activated carbon, 250 ml of water, 10 g of PMIDA to the three-necked bottle, heat and stir, pass oxygen into the reaction solution, turn on the ultrasonic generator, the temperature rises to 65 ° C, and the phosphorus spectrum is detected to completely react with the glyphosate. At 8 hours, the glyphosate reaction selectivity was 88.2%, and finally the glyphosate original powder was 6.38 g, and the content was 98.4%.

Example 14

2.5 grams of carbon nanotubes, 100 ml of water, 10 g of PMIDA were added to the three-necked flask, heated and stirred, oxygen was introduced into the reaction solution, the ultrasonic generator was turned on, the temperature was raised to 65 ° C, and the phosphorus spectrum was detected to completely react with the glyphosate. The reaction is about 15 hours, and the selectivity of glyphosate reaction is 85.9%. Finally, 6.17 g of glyphosate powder was obtained, and the content was 98.1%.

Example 15

Five grams of carbon nanotubes (typical multi-walled carbon nanotubes prepared by Fe-Mo/A1203) were mixed with about 100 milliliters of concentrated nitric acid, heated to 90 degrees Celsius, and stirred continuously for 3-4 hours. Filtration, filter residue Carbon nanotubes were washed with deionized water to neutrality.

Add 2.5 grams of nitric acid treated carbon nanotubes, 100 ml of water, 10 g of PMIDA to the three-necked flask, heat and stir, pass oxygen to the reaction solution, turn on the ultrasonic generator, and raise the temperature to 65 ° C. The phosphine was completely reacted, the reaction was about 10 hours, the glyphosate reaction selectivity was 87.9%, and finally the glyphosate original powder was 6.30 g, and the content was 98.4%.

Some basic parameters of the carbon nanotubes used by the inventors are shown below.

Typical multi-walled carbon nanotubes prepared by Fe-Mo/A1203

Outer diameter: 8.6nm

Inner diameter: 3.5nm

Heap specific gravity: 0.05g/cm3

Specific surface area: 200-300m2/g

Carbon content: 98%

Comparative Example 1

A three-necked flask was charged with 2.5 g of activated carbon (prepared from charcoal), 50 ml of water, 10 g of PMIDA, heated and stirred, and air was introduced into the reaction solution. The temperature was raised to 70 ° C, and the reaction was carried out for 2.5 hours. Phosphorus spectrum detection of glyphosate was carried out. Does not react.

Comparative Example 2

50 ml of water, 10 g of PMIDA was added to the three-necked flask, and the mixture was heated and stirred. Air was introduced into the reaction solution, and the ultrasonic generator was turned on. The temperature was raised to 70 ° C for 2.5 hours, and no phosphorus glyphosate was formed in the phosphorus detection.

Comparative Example 3 Add 2.5 g of activated carbon, 50 ml of water, 10 g of PMIDA to the three-necked flask, heat and stir, turn on the ultrasonic generator, and do not pass the gas. The temperature is raised to 70 ° C, and the reaction is carried out for 2.5 hours. Phosphorus is detected without glyphosate formation.

Comparative Example 4

Add 0.06 g of sodium tungstate, 50 ml of water, 20 g of PMIDA to the three-necked flask, heat and stir, the temperature is raised to 60 ° C, 5.6 g of 30% hydrogen peroxide is added dropwise, and the reaction is kept for 1 hour. The phosphorus detection has almost no glyphosate. The temperature was lowered, and the ferrous sulfate solution was added dropwise. The final conversion rate of glyphosate was 90%, and the original powder yield was 72.5%.

Claims

Claim

1. A new process for the preparation of glyphosate by direct oxidation of glyphosate with air or oxygen by the combined action of ultrasonic waves and activated carbon or carbon nanotubes.

2. The method according to claim 1, wherein the ultrasonic wave is any device capable of inducing ultrasonic waves, and the ultrasonic wave is transmitted to the mechanical wave of the reaction system through the solid-liquid shield, and the general frequency is greater than 15 kHz.

The method according to claim 1, wherein the activated carbon is activated carbon or porous carbonaceous material of any source, a mixture of activated carbon and carbon nanotubes or inorganic materials, activated carbon loaded with metal or precious metal, and recycled activated carbon.

4. The method according to claim 1, wherein the carbon nanotubes comprise multi-walled, single-walled or mixed carbon nanotubes prepared by various methods, and may also be carbon nanotubes for recycling. Preferred are carbon nanotubes having a surface treated with a large amount of hydroxyl groups and/or carboxyl groups.

The method according to claim 1, wherein the activated carbon/carbon nanotube is used in an amount of 0.05% by weight to 100% by weight, preferably 5% to 50% by weight based on the weight of the glyphosate.

The method according to claim 1, wherein the reaction temperature is 20 to 100 ° C, preferably 40 to 80 ° C.

7. A method according to claim 1 wherein the oxygen containing gas is air and / or oxygen and / or other oxygen containing gas, preferably air.

8. The method of claim 1 wherein the reaction pressure is at atmospheric pressure, reduced pressure, and pressure that the industrial reactor can withstand.

The method according to claim 1, wherein the reaction system is added in an amount of from 1 to 50 times, preferably from 2 to 30 times the weight of the glyphosate.

10. The method according to claim 1, wherein the reactor is various types of reactors industrially employed, such as a tank reactor with an ultrasonic generator built therein, having a cycle characteristic A tubular reactor of an external ultrasonic generator, an external ultrasonic reactor having a circulating characteristic.

11. The method according to claim 1, wherein the reaction mode is a continuous or intermittent reaction.

12. The method of claim 1 wherein it may be a mixture of activated carbon and carbon nanotubes.