Abstract: The invention relates to the process for the preparation of iron(III) chelates of N,N?-di(2-hydroxybenzyl)ethylenediamine-N,N?-diacetic acid and its derivatives of the formula (I) wherein both R substituents have the same meaning and represent H, C1-C4 alkyl, CH2OH, SO3M or COOM, and M is a sodium, potassium or ammonium cation, wherein the aqueous solution of a corresponding chelating agent is contacted with metallic iron by the circulation of said aqueous solution through the bed of pieces of metallic iron in a flow reactor while simultaneously blowing air or oxygen through the aqueous solution of the chelating agent in the flow reactor, optionally in the presence of a hydrogen peroxide solution. Chelates of the formula (I) are useful as the components of plant fertilizers.

Abstract: The invention relates to a process for the preparation of N,N?-bis(2-hydroxybenzyl)-ethylenediamine-N,N?-diacetic acid and its derivatives of general formula (I), wherein both R have the same meaning and are selected from H, C1-C4alkyl, CH2OH, SO3M, and COOM; and all M have the same meaning and represent hydrogen atom, Na, K or NH4; which comprises reductive amination of glyoxylic acid with a salan compound of general formula (II), in the presence of an amine proton acceptor. The compounds of formula (I) can be used as chelating agents for micronutrients in fertilizer preparations for plants.