Method for preparing formylphosphonic acid

Abstract

An improved process for the manufacture of formylphosphonic acid derivatives is reported. An aminomethylphosphonic acid substrate is contacted with a reagent selected from the group consisting of water, an alcohol, a phenol compound, and mixtures thereof and an oxidizing gas in the presence of a catalyst to form a reaction product mixture containing a formylphosphonic acid derivative and the conditions under which said contacting is carried out are controlled so that no more than 50% of the formylphosphonic acid derivative formed in the reaction product mixture is consumed by reaction with the reagent.

What is claimed is:  
     
         1 . A method for the preparation of a formylphosphonic acid derivative, the method comprising: 
 contacting an aminomethylphosphonic acid substrate, a reagent selected from the group consisting of water, an alcohol, a phenol compound, and mixtures thereof and an oxidizing gas in the presence of a catalyst to form a reaction product mixture containing a formylphosphonic acid derivative, and    controlling the conditions under which said contacting is carried out so that no more than 50% of the formylphosphonic acid derivative formed in the reaction product mixture is consumed by reaction with the reagent.    
     
     
         2 . The method of    claim 1    wherein at least about 75% of the substrate is converted to the formylphosphonic acid derivative.  
     
     
         3 . The method of  1  wherein said contacting is carried out in a batch reaction zone wherein formation of the formylphosphonic acid derivative is terminated at an end point at which at least 75% of said substrate charged to the reaction zone has been converted to the formylphosphonic acid derivative.  
     
     
         4 . The method of    claim 3    in which the reaction is terminated at or prior to reaching a residual substrate concentration in the reaction mixture at which the rate of consumption of formylphosphonic acid derivative exceeds the rate of formation of formylphosphonic acid derivative.  
     
     
         5 . The method of    claim 3    wherein the reaction between formylphosphonic acid derivative and said reagent is quenched by lowering the temperature of the reaction mixture to a temperature at which consumption of formylphosphonic acid derivative essentially ceases.  
     
     
         6 . The method of    claim 1    wherein the reaction between formylphosphonic acid derivative and said reagent is quenched by lowering the temperature of the reaction mixture to a temperature at which consumption of formylphosphonic acid derivative essentially ceases.  
     
     
         7 . The method of    claim 1    wherein the temperature of the reaction mixture is controlled so that the rate of consumption of the formylphosphonic acid derivative does not exceed the rate of formation thereof at any time during the reaction.  
     
     
         8 . The method of    claim 1    conducted in a continuous reaction zone into which said substrate and said reagent are continuously or intermittently introduced and from which a reaction product mixture comprising the formylphosphonic acid derivative is continuously or intermittently withdrawn, the residence time in said reaction zone being controlled so that at least 75% of said substrate has been converted to the formylphosphonic acid derivative and not more than 50% of the formylphosphonic acid so produced has been consumed by any further reaction.  
     
     
         9 . The method of    claim 8    wherein the rate of introduction of aminomethylphosphonic acid and said reagent into said reaction zone, and the temperature and residence time in the reaction zone, are controlled so that the reaction mixture contains the formylphosphonic acid derivative and formic acid with the molar ratio of the formylphosphonic acid derivative to formic acid being at least 2:1.  
     
     
         10 . The method of    claim 1    wherein the reaction product mixture is maintained at a temperature of less than about 115° C.  
     
     
         11 . The method of    claim 1    wherein the reaction product mixture is maintained at a temperature of less than about 95° C.  
     
     
         12 . The method of    claim 1    wherein the reaction product mixture is maintained at a temperature of less than about 85° C.  
     
     
         13 . The method of    claim 1    wherein the formylphosphonic acid derivative has the formula (I):  
       
         
           
           
               
               
           
         
         the aminomethylphosphonic acid derivative has the formula (II):  
         
           
             
             
                 
                 
             
           
         
         R 1  and R 2  are independently selected from the group consisting of H, hydrocarbyl, substituted hydrocarbyl, heterocycle, and a salt-forming cation;  
         R 3  is selected from the group consisting of —CHO and —CH(OR 8 ) (OR 9 );  
         R 4  and R 5  are independently selected from the hydrocarbyl, substituted hydrocarbyl, and heterocycle;  
         R 6  and R 7  are independently selected from the group consisting of H, hydrocarbyl, substituted hydrocarbyl, heterocycle, and a salt-forming cation; and  
         R 8  and R 9  are independently selected from the group consisting of H, hydrocarbyl, substituted hydrocarbyl, and heterocycle.  
       
     
     
         14 . The method of    claim 13    wherein the catalyst is a heterogeneous catalyst and the reaction product mixture is maintained at a temperature of less than about 115° C.  
     
     
         15 . The method of    claim 14    wherein said contacting is performed under neutral or acid conditions.  
     
     
         16 . The method of    claim 14    wherein the pH of said reaction product mixture is less than about 6.  
     
     
         17 . The method of    claim 14    wherein the pH of said reaction product mixture is less than about 3.  
     
     
         18 . The method of    claim 14    wherein the pH of said reaction product mixture is less than about 1.5.  
     
     
         19 . The method of    claim 14    wherein said reaction product mixture contains no more than one equivalent of a base per equivalent of substrate.  
     
     
         20 . The method of    claim 14    wherein said heterogeneous catalyst comprises a carbon catalyst.  
     
     
         21 . The method of    claim 14    wherein said heterogeneous catalyst comprises carbon impregnated with a noble metal.  
     
     
         22 . The method of    claim 21    wherein said noble metal is platinum or palladium.  
     
     
         23 . The method of    claim 14    wherein said oxidizing gas comprises an oxidant selected from the group consisting of 0° C., nitrogen oxides, singlet oxygen and ozone.  
     
     
         24 . The method of    claim 14    wherein said oxidizing gas is substantially comprised of O 2 .  
     
     
         25 . The process or    claim 14    wherein said oxidizing gas is air.  
     
     
         26 . The process of    claim 14    wherein the weight ratio of said heterogeneous catalyst to said aminomethylphosphonic acid derivative is in the range of about 1 to about 50.  
     
     
         27 . The process of    claim 14    wherein R 1  and R 2  are H.  
     
     
         28 . The process of    claim 14    wherein R 4  and R 5  are —CH 2 PO (OR 6 ) (OR 7 ).  
     
     
         29 . The process of    claim 14    wherein R 6  and R 7  are H.  
     
     
         30 . The process of    claim 14    wherein at least one of R 4  and R 5  is hydrocarbyl or substituted hydrocarbyl.  
     
     
         31 . The method of    claim 1    wherein said reaction mixture further comprises a solvent.  
     
     
         32 . The method of    claim 31    wherein said solvent is selected from the group consisting of water, an alcohol, a polyalcohol, a polyether, acetic acid, tetrahydrofuran, dioxane, and a mixture thereof.  
     
     
         33 . A method for the preparation of a formylphosphonic acid derivative, the method comprising contacting an aminomethylphosphonic acid substrate, a reagent selected from the group consisting of water, an alcohol, a phenol compound, and mixtures thereof, and oxidizing gas in the presence of a homogeneous catalyst to form a reaction product mixture containing a formylphosphonic acid derivative.  
     
     
         34 . The method of    claim 33    wherein said homogeneous catalyst comprises a transition metal.  
     
     
         35 . The method of    claim 34    wherein said transition metal is selected from the group consisting or vanadium, manganese, cobalt, ruthenium, and mixtures thereof.  
     
     
         36 . The method of    claim 33    wherein said contacting is performed at a temperature in the range of about 10° C. to about 115° C.  
     
     
         37 . The method of    claim 33    wherein said contacting is performed at a temperature in the range of about 25° C. to about 75° C.  
     
     
         38 . The method of    claim 1    wherein the substrate is nitrilotris (methylenephosphonic acid) or an ester or salt thereof.  
     
     
         39 . The method of    claim 1    wherein during said contacting step an amine is formed in the reaction product mixture and the amine is phosphonomethylated to regenerate the substrate.  
     
     
         40 . The method of    claim 1    wherein the method additionally comprises the steps of contacting said formylphosphonic acid derivative with glycine or a glycinate to form a condensed intermediate; and reducing said condensed intermediate to produce N-(phosphonomethyl)glycine, or a salt or an ester thereof.