NEW CRYSTALLINE POLYMORPHIC FORM OF GLYPHOSATE - SYNTHESIS, CRYSTAL AND MOLECULAR-STRUCTURES OF N-(PHOSPHONOMETHYL)GLYCINE

Synthesis of the herbicide glyphosate, N-(phosphonomethyl)glycine has been modified by using MnO2 in the presence of H2SO4 for the oxidation of substrate, i.e., N-(phosphonomethyl)iminodiacetic acid. The obtain ed solid appeared to be a new, crystalline polymorphic form of glyphos ate. The x-ray structure of the compound has shown that the crystals a re monoclinic with P2(1) space group, a = 7.1190(5), b = 5.428(1), c = 9.1225(5)angstrom, beta = 105.043(6)-degrees, V = 340.41(7)angstrom3, Z = 2. The solution by direct methods and refinement gave final resid uals of R = 0.0318, wR -0.0395 and s = 0.78. The crystal structure of commercial glyphosate which was solved previously by three independent groups. was solved again for comparison. This determination is the mo st accurate so far. The bond lengths and angles are practically identi cal in both crystalline forms of glyphosate. The conformation of the m olecule's backbone is however different as the torsion angles in Table IV show.