EDTA chemical structure

Chemical Name N,N -1,2-Ethanediylbis[N-(carboxymethyl)glycine] -disodium ssit Common Name EDTA disodium Structural Formula NaOOCCH2... 

An inspection of the ingredients in many sandwich spreads, mayonnaises, margarines, and salad dressings reveals the abbreviation EDTA. Even real mayonnaise has this important ingredient. The chemical structure of this substance helps this additive perform its important function as a preservative. 

Figure 14.7. Chemical structures of some chelators and enhancers used in time-resolved fluoroimmunoas-says 1, isothiocyanatophenyl-EDTA 2, Ari-p-(isothiocyanatobenzyl)-diethylenetriaminetetraaceticacid 3, diethylenetriaminepentaacetic anhydride (DTPA) 4, Tb3+-DTPA-/t-aminosalicylic acid S, Eu3+-pyridine-bisfmethylaminodiacetic acid) 6, benzoyltrifluoroacetone (BTA, a /i-diketone) 7, trifluoroacetylacetone (a/jt-diketone) 8,4,7-bis(chlorosulfonylphenyl)-l,10-phenanthroline-2,9-dicarboxylic acid (BCPDA).

FIGURE 2. Chemical structure of EDTA (tetramethyl ester) and proposed structures of EDTA-like organic compounds identified in water from waste trenches 19S and 27 and from inert atmosphere well W2NA. The proposed structures/for the MW 219, MW 244, and MW 288 organic species are based on mass fragmentation patterns from GC-MS analyses. 

Examples showing that metal speciation is important to metal toxicity include arsenic, copper, selenium, and chromium. While ionic copper (Cu2+) and CuClj are highly toxic, Q1CO3 and Cu-EDTA have low toxicity (Morrison et al, 1989). Toxicity tests show that As(III) is about 50 times more toxic than As(VI). Trivalent chromium is much less toxic than hexavalent chromium, probably because Cr(VI) is much smaller and the chemical structure of chromate is similar to sulfate. A special channel already exists in biomembranes for sulfate transport. While modeling metal speciation is not always possible, and redox equilibrium is not achieved in all natural waters, geochemical modeling of equilibrium species distribution remains one of the methods of discerning metal speciation. 

Figure 1. Chemical structure of sodium iron EDTA...

Figure 1. Chemical structures of ligating organosUanes (EDTA not shown).

Numerous positive delayed skin tests in patients with contrast medium-induced non-immediate skin reactions have been reported when the patients were tested with the culprit contrast medium [summarized in 1]. In a large European multicenter study, 37% of patients with non-immediate reactions were positive in delayed IDEs and/or patch tests [13]. The majority of the patients also reacted to the culprit contrast medium and also to other, structurally similar RCM. Notably, in more than 30% of those skin test-positive patients a RCM had been administered for the first time. Thus, there is a lack of a sensitization phase. Again it may be hypothesized that these previously non-exposed patients may have already been sensitized. Different patterns of RCM cross-reactivity indicate that several chemical entities could be involved. No positive skin tests have been obtained with other contrast medium excipients, such as ethylenediaminetetraacetic acid (EDTA), and only rarely patients have been found to react to inorganic iodide. 

A chelating ligand contains two or more donor atoms in a structure that allows the ligand to wrap around the metal. Examples featured in Chapter 18 are the bidentate ligand ethylenediamine (en, chemical formula H2 NCH2 CH2 NH2) and the hexadentate ethylenediaminetetraacetate (EDTA). 

The availability of the trace metals is easily determined without any of the above risks, and the results used to assess both deficiencies and toxici-ties. The metals need to be removed from the sites where they are bound to the soil particles by use of an even stronger binding agent than the soil. This is achieved with two possible complexing reagents EDTA and DTPA. They are a class of chemicals known as complexones, which form complex molecules with metals in a cage-like structure called a chelate. 

The parameters a), b) and c) determine the topography of the complex. One may consider a complex formed by a multidentate ligand as a combination of several sub-units comprizing three donor atoms and two condensed chelate rings. A complex with a hexadentate ligand of type EDTA, for example, gives six possible combinations of such sub-units. Such a tridentate unity offers two structural possibilities as shown in Fig. 4. Different chemical characteristics of the currently employed ligands are... 

Figure 3.6 shows 12 structures that may correspond to the abbreviation DPA. Six of them can be output by the ACD/Name to Structure software package, and six more were found by browsing the Internet. Note that even a specific context cannot guarantee an exact meaning. For example, both structures 3 and 8 were found in publications about coordination compounds. In general, chemical abbreviations are not unique and can rarely be distinguished from other trivial names except for the rather weak criterion that all letters are capitalized. We can conclude that conversion of any trivial name shorter than about five or six characters is not safe. A few rarer exceptions do exist, but this is a very short list. Examples include reserved abbreviations such as those for dimethyl sulfoxide (DMSO) and ethylenediaminetetraacetic acid, EDTA. 

---