Synthesis and chemical characterization of the novel agronomically relevant pentadentate chelate 2-(2-((2-hydroxybenzyl)amino)ethylamino)2-(2- hydroxyphenyl)acetic Acid (DCHA)

Abstract

Iron chelates analogous to o,o-EDDHA/Fe3- are the fertilizers chosen to treat iron chlorosis in plants growing on calcareous soil. The isomer o,p-EDDHA/Fe3+ presents less stability but faster assimilation by the plant than o,o-EDDHA/Fe3+, because only five coordinating groups are able to complex Fe3+. The new chelating agent 2-(2-((2- hydroxybenzyl)amino)ethylamino)-2-(2-hydroxyphenyl)acetic acid (DCHA) has been synthesized to obtain an iron fertilizer with intermediate stability between o,o-EDDHA/Fe3+ and o,p-EDDHA/Fe3- and with fast assimilation. Its synthesis has been done starting from phenol, N-acetylethylendiamine, glyoxylic acid, and NaOH in a three-step sequence. The purity of the DCHA chelating agent, its protonation, and Ca2-, Mg2+, Fe3+, and Cu2+ stability constants, together with its ability to maintain iron in solution in different agronomic conditions, have been determined. The results indicate that the chelate DCHA/Fe3+ has intermediate stability between those of o,o-EDDHA/Fe3- and o,p-EDDHA/Fe3+ complexes and that it is capable of maintaining the Fe3- in agronomic conditions. This new chelating agent may be effective in correcting iron chlorosis in plants. © 2010 American Chemical Society.