JEE Challenger
More from Coordination Compounds
ChemEasyAdv 2010 • Paper 1

Identification of the Chemical Structure of EDTA

The correct structure of ethylenediaminetetraacetic acid (EDTA) is

Options

A
Option A Diagram 1
B
Option B Diagram 1
C
Option C Diagram 1
Correct
D
Option D Diagram 1

Topics & Concepts

Coordination CompoundsCoordination Compounds

Step-by-Step Solution

Ethylenediaminetetraacetic acid, commonly abbreviated as EDTA, is derived from ethylenediamine, H2N−CH2−CH2−NH2\mathrm{H_2N-CH_2-CH_2-NH_2}.

In EDTA, the four hydrogen atoms attached to the two nitrogen atoms of ethylenediamine are replaced by four carboxymethyl (acetic acid) groups, −CH2−COOH-\mathrm{CH_2-COOH}.

The resulting molecular structure consists of:

  1. An ethylene bridge: −CH2−CH2−-\mathrm{CH_2-CH_2}- connecting two tertiary nitrogen atoms.
  2. Two acetate groups, −CH2−COOH-\mathrm{CH_2-COOH}, bonded to each of the two nitrogen atoms.

Thus, the chemical formula can be represented as:
(HOOC−CH2)2N−CH2−CH2−N(CH2−COOH)2(\mathrm{HOOC-CH_2})_2\mathrm{N-CH_2-CH_2-N}(\mathrm{CH_2-COOH})_2

Now, evaluating the given options:

  • Option A has a vinylene bridge (−CH=CH−-\mathrm{CH=CH}-) rather than an ethylene bridge (−CH2−CH2−-\mathrm{CH_2-CH_2-}).
  • Option B directly attaches carboxyl groups (−COOH-\mathrm{COOH}) to the nitrogen atoms rather than acetic acid groups (−CH2−COOH-\mathrm{CH_2-COOH}).
  • Option C correctly shows the ethylene bridge (−CH2−CH2−-\mathrm{CH_2-CH_2}-) linking the two nitrogen atoms, each of which is bonded to two −CH2−COOH-\mathrm{CH_2-COOH} groups.
  • Option D displays an incorrectly substituted and branched structure.

Therefore, the correct structure of EDTA corresponds to option C.

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