Abstract: The present invention provides a method for isolating N-phosphonomethylglycine which comprises adding an acid to precipitate salts from an aqueous solution of an alkali metal salt and/or an alkaline earth metal salt of N-phosphonomethylglycine solution to neutralize and adjust the same to a pH of 2.5 or higher, removing the precipitated salts, and adjusting the pH to 2.5 or lower to crystallize N-phosphonomethylglycine. N-phosphonomethylglycine is thus isolated and purified in high purity and good yield.

Abstract: The novel non-hygroscopic crystals of p-aminomethylbenzoic acid can be obtained by heating hygroscopic crystals of p-aminomethylbenzoic acid with keeping the hygroscopic crystals in contact with moisture to transit the hygroscopic crystals to non-hygroscopic crystals.The non-hygroscopic crystals of p-aminomethylbenzoic acid can be particularly advantageously handled in the atmosphere as compared with the conventional hygroscopic crystals. Especially when the p-aminomethylbenzoic acid is used for the non-aqueous reaction, the crystals of the invention are exceptionally advantageous from the viewpoints of removal of moisture and humidity control.

Abstract: The present invention provides a method for producing N-phosphonomethylglycine which comprises reacting an aminomethylphosphonic acid with glycolonitrile, or formaldehyde and hydrogen cyanide in situ, under an alkaline condition to convert the aminomethylphosphonic acid into an N-phosphonomethylglycinonitrile salt or a mixture of an N-phosphonomethylglycinonitrile salt and N-phosphonomethylglycinonitrile, and then hydrolyzing the product under an acidic condition. Subsequent to a reaction step for the production of N-phosphonomethylglycinonitrile, the reaction product is hydrolyzed by adding thereto an acid in a prescribed amount. Accordingly, the use of a large amount of an alkaline metal hydroxide and the neutralization step for obtaining N-phosphonomethylglycine after hydrolysis, which steps are necessary in a conventional alkali hydrolysis method, are omitted in the present invention.

Abstract: The present invention relates to a method of manufacturing N-phosphonomethylglycine and salts thereof, which can be biologically degraded, and have superior effectiveness against weeds and are useful as herbicides, by means of alkali hydrolysis of N-phosphonomethylglycinonitrile. In order to obtain high yields of the desired high purity, the amount of salt produced as a by-product is reduced by using the alkali so as to result in not less than 2 molecules and less than 3 molecules of the alkali for each molecule of N-phosphonomethylglycinonitrile when the alkali is monovalent, and not less than 1 molecule and less than 1.5 molecules of the alkali for each molecule of N-phosphonomethylglycinonitrile when the alkali is divalent.

Abstract: The invention is directed to a process for preparing N-phosphonomethylglycine comprising the steps of reacting an aminomethylphosphonic acid with a glyconitrile in the presence of an alkali metal hydroxide to form a product, and then hydrolyzing the product by adding an alkali metal hydroxide in an amount sufficient to neutralize the resulting carboxylic acid.

Abstract: N-acylaminomethylphosphonic acid is prepared from an N-methylolamide compound and a phosphorus trihalide. The starting compounds are mixed and heated in an aprotic solvent in the presence of water in a 0.25 to 2.5 times molar amount relative to the phosphorus trihalide at 60.degree. to 160.degree. C., and the reaction mixture is contacted with water. The N-methylolamide compound is a compound selected from the group consisting of N-methylol-lower alkylamides and N-methylolarylamides. The phosphorus trihalide is preferably phosphorus trichloride. As the aprotic solvent is used one or more of hydrocarbons, halogenated hydrocarbons, ethers, polyethers, nitriles, and aromatic nitro compounds. The mixing may be carried out at a temperature of 60.degree. C. The water present at the initiation of the reaction is in a 1.0 to 1.8 times molar amount relative to the phosphorus trihalide.