subject: Equations Expressing Chelation And Meaning [print this page] IUPAC defines chelation as a process in a solitary atom within the same ligand in which presence and formation of bonds takes place among two or more than two binding sites which are separate. Generally these ligands are called chelators, chelants, sequestering agents or chelation agents. Ligands are basically organic compounds. Chelation agents as defined by ASTM-A- 380, are basically chemicals which form complex and soluble molecules along with metal ions, and thus making the ions inactive and by this preventing the ions from making a pair or reacting with other elements or ions. This organic compound (that is ligand) along with the substrate forms a chelate complex. In complexes where the ion from metal is bonded to two or more than two atoms of the chelation agent the above expression is reserved.
The word Chelation is derived from a Greek word "chel ",which means claw. In 1920 the term chelate was first applied for the very first time by H. D. K. Drew and Sir Gilbert T. Morgan.
For a same metal the effect of Chelation describes the superior affinity for a metal ion of chelating ligands when in comparison with the affinity of a pool of similar non chelating ligands. Taking into account the two conditions stated below (that is in aqueous solution), between en (that is ethylene diamine) and the ion of copper (II) (that is Cu2+) and on one hand and on the other hand methylamine (that is MeNH2). The mentioned equations are as follows:
Cu2+ + en [Cu (en)] 2+ (equation 1)
Cu2+ + 2 MeNH2 [Cu (MeNH2)2]2+ (equation 2)
In equation 1 the ethylene diamine which is a bi-dentate ligand with the ion of copper results in the formation of a chelate complex. The process of Chelation leads to the formation of ring which is fivemembered. In equation 2 the ethylene diamine gets substituted by two mono-dentate methylamine ligands (that have approximately the same power for donation), which means that in the two reactions the rate of formation of CU---N bonds almost similar.
Chelation can prove to be of real help for the treatment of various physical conditions such as gangrene, angina, coronary disease of artery and also the various disorders of the circulatory system of the body. These treatments before they are practically conducted have to first pass through medical tests that include sugar test, cholesterol test, kidney test , blood pressure etc.
