The correct structure of ethylenediaminetetraacetic acid (EDTA) is

Coordination Compounds PYQ — JEE Advanced 2010 · Shift 1 · Q18 with Solution

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Correct answer: C

The problem asks to identify the correct chemical structure for ethylenediaminetetraacetic acid (EDTA).

Deconstruct the name: The name of the compound can be broken down into its constituent parts to determine the structure.
- Ethylenediamine: This part of the name indicates the core structure is derived from ethylenediamine. The structure of ethylenediamine is H₂N−CH₂−CH₂−NH₂. It consists of an ethylene bridge (−CH₂−CH₂−) with two amine groups (−NH₂), one at each end.
- Tetraacetic acid: This part indicates the presence of four (tetra) acetic acid groups. The structure of an acetic acid group is −CH₂COOH.
Assemble the structure: The name implies that the four acetic acid groups are attached to the ethylenediamine backbone. In ethylenediamine, each nitrogen atom has two hydrogen atoms. These four hydrogen atoms are replaced by the four acetic acid groups.
- Start with the ethylenediamine backbone: N−CH₂−CH₂−N.
- Each of the two nitrogen atoms has two available sites for substitution (where the H atoms were).
- Attach two acetic acid groups (−CH₂COOH) to each nitrogen atom.
Final structure: This leads to the following structure:
- One nitrogen atom is bonded to two −CH₂COOH groups, resulting in (HOOCCH₂)₂N−.
- The other nitrogen atom is also bonded to two −CH₂COOH groups, resulting in −N(CH₂COOH)₂.
- Connecting these with the ethylene bridge gives the complete structure of EDTA: $(\text{HOOCCH}_2)_2\text{N}−\text{CH}_2−\text{CH}_2−\text{N}(\text{CH}_2\text{COOH})_2$ Graphically, this is represented as:
```
      HOOC−CH₂     CH₂−COOH               \   /                N−CH₂−CH₂−N               /   \      HOOC−CH₂     CH₂−COOH
```
Evaluate the options:
- Option A: This structure has an incorrect backbone and arrangement of functional groups. The carboxylic acid groups (−COOH) are attached to carbons, not nitrogens.
- Option B: This structure contains amide bonds (−NH−C(=O)−), which are not present in EDTA. It is a derivative of an acid anhydride and ethylenediamine.
- Option C: This structure perfectly matches the structure derived from the name. It has an ethylenediamine backbone with four acetic acid groups attached to the nitrogen atoms.
- Option D: This structure contains a hydrazine (−N−N−) linkage, which is incorrect. The backbone is not ethylenediamine.
Conclusion: Based on the analysis, Option C is the correct structure for ethylenediaminetetraacetic acid (EDTA).

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View written solutionFree

Correct answer: C

The problem asks to identify the correct chemical structure for ethylenediaminetetraacetic acid (EDTA).

Deconstruct the name: The name of the compound can be broken down into its constituent parts to determine the structure.
- Ethylenediamine: This part of the name indicates the core structure is derived from ethylenediamine. The structure of ethylenediamine is H₂N−CH₂−CH₂−NH₂. It consists of an ethylene bridge (−CH₂−CH₂−) with two amine groups (−NH₂), one at each end.
- Tetraacetic acid: This part indicates the presence of four (tetra) acetic acid groups. The structure of an acetic acid group is −CH₂COOH.
Assemble the structure: The name implies that the four acetic acid groups are attached to the ethylenediamine backbone. In ethylenediamine, each nitrogen atom has two hydrogen atoms. These four hydrogen atoms are replaced by the four acetic acid groups.
- Start with the ethylenediamine backbone: N−CH₂−CH₂−N.
- Each of the two nitrogen atoms has two available sites for substitution (where the H atoms were).
- Attach two acetic acid groups (−CH₂COOH) to each nitrogen atom.
Final structure: This leads to the following structure:
- One nitrogen atom is bonded to two −CH₂COOH groups, resulting in (HOOCCH₂)₂N−.
- The other nitrogen atom is also bonded to two −CH₂COOH groups, resulting in −N(CH₂COOH)₂.
- Connecting these with the ethylene bridge gives the complete structure of EDTA: $(\text{HOOCCH}_2)_2\text{N}−\text{CH}_2−\text{CH}_2−\text{N}(\text{CH}_2\text{COOH})_2$ Graphically, this is represented as:
```
      HOOC−CH₂     CH₂−COOH               \   /                N−CH₂−CH₂−N               /   \      HOOC−CH₂     CH₂−COOH
```
```
      HOOC−CH₂     CH₂−COOH               \   /                N−CH₂−CH₂−N               /   \      HOOC−CH₂     CH₂−COOH
```
Evaluate the options:
- Option A: This structure has an incorrect backbone and arrangement of functional groups. The carboxylic acid groups (−COOH) are attached to carbons, not nitrogens.
- Option B: This structure contains amide bonds (−NH−C(=O)−), which are not present in EDTA. It is a derivative of an acid anhydride and ethylenediamine.
- Option C: This structure perfectly matches the structure derived from the name. It has an ethylenediamine backbone with four acetic acid groups attached to the nitrogen atoms.
- Option D: This structure contains a hydrazine (−N−N−) linkage, which is incorrect. The backbone is not ethylenediamine.
Conclusion: Based on the analysis, Option C is the correct structure for ethylenediaminetetraacetic acid (EDTA).

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