Organic compounds -- part of the class 532-570 series – Organic compounds – Phosphorus acids or salts thereof
Reexamination Certificate
2000-03-14
2001-08-14
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Phosphorus acids or salts thereof
C562S008000, C562S024000, C558S166000, C558S169000
Reexamination Certificate
active
06274760
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the preparation of formylphosphonic acid, its salts, and its esters, and particularly to novel processes for the preparation of formylphosphonic acid by the catalytic decomposition of a (phosphonomethyl)amine N-oxide compound in the presence of a decomposition catalyst.
2. Description of Related Art
Phosphorus-containing compounds such as formylphosphonic acid are important precursors for the synthesis of organophosphorus compounds. Such organophosphorus compounds have numerous applications. For example, formylphosphonic acid can be used as a precursor in the synthesis of N-(phosphonomethyl)glycine, a highly effective commercial herbicide (common name glyphosate, available under the trade name Roundup®) useful for the control of a large variety of weeds. Formylphosphonic acid can alternatively be used as an advanced intermediate in the preparation of medicinally important compounds such as the antiviral agent phosphono hydroxyacetic acid. As a reagent or intermediate, formylphosphonic acid has potential for chemical transformation at the carbonyl, phosphorus, or hydroxyl moieties.
Researchers have reported electrochemical processes in which formylphosphonic acid forms. For example, Wagenknecht (Synth. React. Inorg. Met.-Org. 4:567-572 (1974)) spectrophotometrically observes or isolates formylphosphonic acid in the electrochemical oxidation of nitrilotris(methylenephosphonic acid) to the secondary amine. A similar reaction is reported in U.S. Pat. No. 3,907,652. In J. Electrochem. Soc. 123:620-624 (1976) Wagenknecht reports the electrochemical oxidation of substituted iminodimethylenediphosphonic acids to produce the secondary amine. In that study, formylphosphonic acid was isolated in unreported yield as a side product. Wagenknecht, et al. again reports the formation of formylphosphonic acid as a side product in the electrochemical oxidation of nitrilotris(methylenephosphonic acid) in Synth. React. Inorg. Met.-Org. 12:1-9 (1982). However, these reactions suffer from several shortcomings. Yields of formylphosphonic acid are poor or unreported. Wagenknecht (1982) reports that formylphosphonic acid degrades under the electrolysis reaction conditions. The electrochemical reaction requires the addition of a strong hydrochloric acid solution which presents safety, environmental, and equipment corrosion problems. Electrochemical methods generally require an external power source and other equipment which typically have higher maintenance needs and costs than do non-electrochemical reactions. It would be advantageous to have a method for the preparation of formylphosphonic acid in high yield which does not require specialized electrochemical equipment and does not require the handling of large quantities of strong mineral acids.
Hershman et al., in U.S. Pat. No. 4,072,706, disclose a process in which (phosphonomethyl)amines are oxidized with molecular oxygen in the presence of an activated carbon catalyst to cleave a phosphonomethyl group and produce a secondary amine. According to Hershman et al., formylphosphonic is produced as an intermediate cleavage fragment, with the fragment undergoing hydrolysis in a second step to formic acid and phosphonic acid. Hershman et al., however, identify formylphosphonic acid as an intermediate cleavage fragment in only one reaction run and although the yield is unreported it is apparently low. In addition, Hershman et al. fail to disclose any means to limit the hydrolysis of the intermediate cleavage fragment.
Disclosures have been made of a process wherein N-(phosphonomethyl)iminodiacetic acid N-oxide is catalytically decarboxymethylated to form N-(phosphonomethyl)glycine, carbon dioxide, and formaldehyde. For example, Fields, et al. disclose such a reaction in U.S. Pat. No. 5,043,475. However, the Fields, et al. decarboxymethylation is highly selective for an acetic acid arm of the N-oxide and cleavage of the phosphonomethyl arm is not reported.
Thus, a need exists for a convenient, environmentally-compatible, safe, and cost-effective process for the reaction of aminomethylphosphonic acid derivatives to produce formylphosphonic acid in high yield with minimal degradation.
SUMMARY OF THE INVENTION
To address this and other needs, an improved process for the manufacture of formylphosphonic acid derivatives is now disclosed. Among the several objects of the present invention is an improved process for the manufacture of formylphosphonic acid, its esters, salts, acetals, hemiacetals, and hydrate.
Briefly, therefore, one aspect of the present invention is directed to a process for the preparation of formylphosphonic acid, its esters, salts, acetals, hemiacetals, and hydrate (collectively herein referred to as formylphosphonic acid derivatives), especially of formylphosphonic acid, wherein the process comprises decomposing a (phosphonomethyl)amine N-oxide compound in the presence of a decomposition catalyst to produce the formylphosphonic acid derivative and a dephosphonomethylated amine.
The present invention is also directed to a process for the preparation of formylphosphonic acid, its esters, salts, acetals, hemiacetals, and hydrate, especially of formylphosphonic acid, wherein the process comprises oxidizing nitrilotris(methylenephosphonic acid) or a salt thereof to form nitrilotris(methylenephosphonic acid) N-oxide or a salt thereof, and decomposing the nitrilotris(methylenephosphonic acid) N-oxide or salt thereof in the presence of a decomposition catalyst.
Another aspect of the present invention is directed to a process for preparing N-(phosphonomethyl)glycine, or a salt or an ester thereof, wherein the method comprises decomposing a (phosphonomethyl)amine N-oxide compound in the presence of a decomposition catalyst to produce a formylphosphonic acid derivative and a dephosphonomethylated amine, and reacting the formylphosphonic acid derivative to produce N-(phosphonomethyl)glycine or a salt or an ester thereof. Of particular interest is an embodiment of this process in which the reaction to produce N-(phosphonomethyl)glycine is achieved by condensing the formylphosphonic acid derivative with a glycine compound, and reducing the condensed product to produce N-(phosphonomethyl)glycine. Another embodiment which is of particular interest is one in which the formylphosphonic acid derivative is condensed with 1-amino-2-hydroxyethane to produce a condensed alcohol intermediate, the condensed alcohol intermediate is reduced to produce an N-(2-hydroxyethyl)-N-(phosphonomethyl)amine compound, and the N-(2-hydroxyethyl)-N-(phosphonomethyl)amine compound is oxidized to produce N-(phosphonomethyl)glycine.
Further scope of the applicability of the present invention will become apparent from the detailed description provided below. However, it should be understood that the following detailed description and examples, while indicating preferred embodiments of the invention, are given by way of illustration only since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 3784590 (1974-01-01), Firestone
patent: 3907652 (1975-09-01), Wagenknecht et al.
patent: 3969398 (1976-07-01), Hershman
patent: 4072706 (1978-02-01), Hershman et al.
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patent: 4348332 (1982-09-01), Oediger et al.
patent: 4568432 (1986-02-01), Rogers
patent: 4624937 (1986-11-01), Chou
patent: 4937376 (1990-06-01), Fields, Jr. et al.
patent: 5023369 (1991-06-01), Fields, Jr.
patent: 5043475 (1991-08-01), Fields, Jr.
patent: 5047579 (1991-09-01), Glowka et al.
patent: 5072033 (1991-12-01), Fields, Jr. et al.
patent: 98/50391 (1998-11-01), None
CA:116:173339 abs J Chem Soc Perkin Trans 2 by Croft (2) pp 153-60, 1992.*
CA:97169801 abs of Vestn. Mosk. univ. Ser 2: Kim. 23 (4) p. 378-82, 1982*
Cairns, J., et al. “The Synthesis and Chemistry of Formylphophonate,”Phosphorus, Sulfur, and Siliconvols. 144-146 (1999), pp. 385-388.
Hamilton, R., M.A. McKerve
Finkelstein Ira D.
Howrey Simon Arnold & White , LLP
Monsanto Co.
Vollano Jean F.
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