ABSTRACT
N-alkyl glyphosates in aqueous solution can be aerobically oxidized to glyphosate over platinum catalysts under mild conditions. Other noble metals and homogeneous catalysts are ineffective. Although supported platinum catalysts are active, most inorganic supports are unstable in the reaction medium while carbon supports lead to an undesired side reaction. Thus, platinum black is the most practical catalyst for the oxidation. N-alkyl glyphosate oxidation is a two-electron, nitrogen-centered oxidation and thus differs from the well-known oxidation ofN-phosphonomethyl iminodiacetic acid ("glyphosate intermediate"). The latter, the most widely practiced method for preparing glyphosate, proceeds in two I -electron steps via a Kolbe mechanism.
