Organic compounds -- part of the class 532-570 series – Organic compounds – Phosphorus esters
Reexamination Certificate
1999-11-29
2001-04-17
Higel, Floyd D. (Department: 1613)
Organic compounds -- part of the class 532-570 series
Organic compounds
Phosphorus esters
C558S145000, C562S010000, C562S877000
Reexamination Certificate
active
06218563
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to cyanophosphon method for their preparation.
2. Description of Related Art
Organophosphorus compounds have numerous and varied applications, for example, in herbicides, insecticides, fertilizers, flame retardants and plasticizers and as precursors for the synthesis of other organophosphorus compounds. Cyanophosphonates and their derivatives, as well as salts thereof, are of particular interest due to their versatility in synthetic pathways, and a wide range of chemistries may extend from both the phosphorus and cyano moieties. For example, cyanophosphonate derivatives may be converted to aminomethylphosphonate derivatives, which have been particularly important precursors in the synthesis of N-phosphonomethylglycine, commonly known as glyphosate, a highly effective commercial herbicide (available under the trade name ROUNDUP®) useful for the control of a large variety of weeds.
There is a need in the art for alternative processes for preparing cyanophosphonate derivatives to be used in the synthesis of amino phosphonate compounds. It is desirable for such derivatives to include a wide range of primary and secondary amine derivatives in order to provide a broad basis for further chemistry. It is also desirable for the derivatives to be isolable as the monoacid or as a salt. There is a further need for such novel processes that are economical and environmentally safe.
SUMMARY OF THE INVENTION
The present invention provides a process for preparing a cyanooxyphosphorus compounds comprising contacting phosphoric anhydride and a cyanide, preferably in the presence of a Lewis base, to produce a cyanophosphonate intermediate, and subsequently contacting the cyanophosphonate intermediate with an amino compound. The amino compound is preferably an aliphatic or aromatic primary or secondary amine, or an amino acid derivative. The cyanooxyphosphorus compounds produced in the process of the present invention can further be used to produce other organophosphorous compounds, such as aminomethylphosphonates or N-phosphonomethylglycine.
The processes and compositions according to the invention offer significant advantages in that they provide a novel, economic route to synthesize cyanophosphonate derivatives and other cyanooxyphosphorus compounds having improved environmental impact over conventional processes using halogen-containing phosphorus starting materials.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
The invention is broadly directed to a process that involves contacting phosphoric anhydride (P
4
O
10
) and a cyanide, preferably in the presence of a Lewis base, in a reaction mixture under conditions to produce a cyanooxyphosphorous compound. The step of contacting phosphoric anhydride and a cyanide can produce a variety of cyanooxyphosphorus compounds, herein defined as compounds comprising an —O—P—CN moiety. Examples of cyanooxyphosphorous compounds include cyanophosphonates, dicyanophosphinates, dicyanopyrophosphonates, dicyanotripolyphosphates, monocyanopyrophosphates, monocyanopolyphosphates, and dicyanopolyphosphates. A preferred cyanooxyphosphorous compound is cyanophosphonate or a cyanophosphonate derivative. The cyanooxyphosphorous compound, e.g. cyanophosphonate derivative, is subsequently contacted with an amino compound to produce a cyanophosphonamide.
In another embodiment, the invention is directed to a process that involves contacting the cyanooxyphosphorous compound with an amino compound to produce a cyanooxyphosphonamide. The cyanooxyphosphorous compound can be provided by the method described above or by any other method known to the skilled artisan.
Cyanophosphonamides of the present invention can be generally represented by the following formula:
wherein R
1
and R
2
are determined by the amino compound used, as set forth herein.
For example, the inventive process may involve charging a reaction vessel with one equivalent of phosphoric anhydride, optionally with a nonreactive, polar solvent. A Lewis base is then added, preferably in an amount ranging from about 1 to about 10 molar equivalents relative to phosphoric anhydride, more preferably about 2 to about 8 molar equivalents, and most preferably about 3 to about 6 molar equivalents. That mixture is then heated under suitable conditions to dissolve or partially dissolve the phosphoric anhydride, e.g., preferably at a temperature of about 40° C. and for about 10 minutes.
Subsequently, a cyanide compound is added, preferably in an amount ranging from about 1 to about 15 molar equivalents relative to phosphoric anhydride, more preferably about 2 to about 10 molar equivalents and most preferably about 3.5 to about 8.5 molar equivalents. This mixture is then heated under suitable conditions to carry out the reaction. The reaction temperature is preferably between about 0° C. and about 150° C., and more preferably between about 30° C. and about 90° C. The reaction time preferably ranges from about 0.5 to about 50 hours, more preferably from about 1 to about 20 hours and most preferably from about 1 to about 6 hours. The Lewis base and any solvent can subsequently be removed from the product mixture, for example, under reduced pressure. An amino compound is then added to the remaining residue to produce the cyanophosphonamide. The amount of the amino compound added is generally between about 0.2 and 20 equivalents, preferably between about 0.9 and 5 equivalents. The temperature of the contacting is preferably between about 0° C. and 80° C., and more preferably between about 20° C. and 50° C. The reaction time of the contacting preferably ranges from about 1 to about 100 hours, more preferably from about 2 to about 20 hours.
Phosphoric anhydride is available in high purity, for example, from Aldrich Chemical Co. in purities in excess of 99.99%. The phosphoric anhydride is generally available in the form of a powder and may be added to the reaction mixture in various forms. For example, phosphoric anhydride can be added directly as a powder or as a slurry in a solvent or cosolvent, such as acetonitrile, propionitrile, adiponitrile, benzylcyanide, and sulfolane.
The cyanide compound can be hydrogen cyanide or a cyanide salt that is sufficiently reactive with phosphoric anhydride to produce a cyanophosphorus compound. For example, the cyanide compound can be an alkali metal cyanide, an alkaline earth metal cyanide, a Group IB metal cyanide, an ammonium cyanide, a tetraalkyl ammonium cyanide, a tetraalkyl phosphonium cyanide, a trialkyl sulfonium cyanide, a cyanide of a cationic form of an organic amine, or mixtures thereof. The cyanide compound is preferably hydrogen cyanide, calcium cyanide, potassium cyanide, sodium cyanide, lithium cyanide, silver cyanide, gold cyanide, copper cyanide, tetrabutylammonium cyanide or mixtures thereof. More preferably, the cyanide compound is potassium cyanide, sodium cyanide, tetrabutylammonium cyanide or mixtures thereof.
The Lewis base is generally any base suitable for promoting the production of the desired compounds according to the invention. Preferably, the Lewis base is a tertiary amine Lewis base, such as triethylamine, trimethylamine, 4-tert-butylpyridine, or quinuclidine, or mixtures thereof. More preferably, the Lewis base is 4-tert-butylpyridine or quinuclidine. The Lewis base can be added to the reaction mixture in an amount ranging from about 1 to about 10 molar equivalents, more preferably from 2 to about 8 molar equivalents and most preferably from 3 to about 6 molar equivalents.
The solvent can be any material which enhances the solubility of the reactants or promotes the formation of the desired products. For the step of reacting phosphoric anhydride and a cyanide, preferably the solvent is a polar aprotic solvent, for example, a nitrile such as acetonitrile, benzylcyanide, adiponitrile, propionitrile, dimethylacetonitrile, sulfolane, or mixtures thereof. More preferably, the solvent is acetonitrile, benzylcyanide, adiponitrile, or sulfolane.
For the step of reacting a cyanooxyp
Lennon Patrick J.
Vulfson Serge G.
Finkelstein Ira D.
Higel Floyd D.
Howrey Simon Arnold & White , LLP
Monsanto Company
Sackey Ebenezer
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