Transformation of the plant growth regulator daminozide (Alar) and structurally related compounds with CuII ions: oxidation versus hydrolysis.
As part of a study of metal ion effects on chemical transformations of nitrogen-containing agrochemicals, conversion of daminozide to succinate via cleavage of the hydrazide C-N bond was examined in the presence and absence of divalent metal ions. No conversion was observed in metal ion-free solutions or in the presence of 1.0 mM NiII, ZnII, and PbII. CuII, in contrast, markedly increased rates of daminozide to succinate conversion. Halide ions (CI-, Br-) had no effect on daminozide conversion in the absence of metal ions but markedly increased conversion rates observed in the presence of CuII. The nitrogen-donor ligands ethylenediamine, N-(2-hydroxyethyl)ethylenediamine, and 1,4,7,10-tetraazacyclododecane decreased rates of CuII-facilitated conversion, while 1,5,9-triazacyclododecane actually increased rates of conversion. H NMR and UV spectroscopy provide evidence for the formation of 1:1 CuII-daminozide complexes. Halide ion effects and nitrogen-donor ligand effects point to an oxidative mechanism for CuII-facilitated daminozide breakdown, rather than hydrolysis. The structurally related compound butyric acid 2,2-dimethylhydrazide (BH) is subject to the same CuII-facilitated breakdown via an oxidative mechanism. N,N-Dimethylsuccinamic acid (SA), in contrast, breaks down via a hydrolytic mechanism.
Huang
Ching-Hua
CH
Department of Geography and Environmental Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA. ching-hua.huang@ce.gatech.edu
Stone
Alan T
AT
D003300:Copper / Q000737:chemistry*; D006868:Hydrolysis; D007477:Ions; D010084:Oxidation-Reduction; D010937:Plant Growth Regulators / Q000737:chemistry*; D012989:Soil Pollutants; D013386:Succinates / Q000737:chemistry*
D007477:Ions; D010937:Plant Growth Regulators; D012989:Soil Pollutants; D013386:Succinates; D003300:Copper; C014499:daminozide