![EDDS Free Acid (CAS 20846-91-7) — Industrial-Grade [S,S]-Isomer, Raw Material for Biodegradable Chelating Agents](https://image.chemsrc.com/caspic/167/20846-91-7.png)
Product Overview
EDDS (Ethylenediamine-N,N'-disuccinic acid, CAS 20846-91-7) is an aminopolycarboxylate chelating agent existing as three stereoisomers — [S,S], [R,R], and meso. Among them, [S,S]-EDDS is the only isomer with rapid biodegradation behavior. This grade contains ≥ 92% [S,S]-isomer and is supplied as raw material for direct substitution of EDTA and DTPA in detergent, personal care, agricultural, and water-treatment formulations.
Technical Specifications
| Item | Specification | Method |
|---|---|---|
| Appearance | White to off-white crystalline powder | Visual |
| Assay (dry basis) | ≥ 98.0% | HPLC |
| [S,S]-isomer content | ≥ 92.0% | HPLC / polarimetry |
| Loss on drying | ≤ 1.0% | 105 °C / 2 h |
| Chloride (as Cl) | ≤ 50 ppm | IC |
| Sulfate (as SO₄) | ≤ 100 ppm | IC |
| Heavy metals (as Pb) | ≤ 10 ppm | ICP-MS |
| Iron (Fe) | ≤ 10 ppm | ICP-MS |
| pH (1% aqueous, 25 °C) | 2.0 – 3.0 | Potentiometric |
Key Physicochemical Parameters
- CAS Number: 20846-91-7
- Molecular formula: C₁₀H₁₆N₂O₈
- Molecular weight: 292.24 g/mol
- pKa₁ / pKa₂ / pKa₃ / pKa₄: ≈ 2.4 / 3.9 / 6.8 / 9.8
- Aqueous solubility (free acid, 25 °C): ≈ 0.3 g/L — neutralize to sodium salt for higher solubility
Stability Constants (log K, 25 °C, I = 0.1 M)
| Metal ion | EDDS | EDTA (ref.) | DTPA (ref.) |
|---|---|---|---|
| Cu²⁺ | 18.4 | 18.8 | 21.5 |
| Fe³⁺ | 22.0 | 25.1 | 28.0 |
| Zn²⁺ | 13.4 | 16.5 | 18.3 |
| Mn²⁺ | 9.0 | 13.6 | 15.5 |
| Ca²⁺ | 4.6 | 10.7 | 10.7 |
Within pH 4 – 10, EDDS provides Cu²⁺ and Fe³⁺ chelation comparable to EDTA and can be used as a direct drop-in. Its weaker Ca²⁺ binding makes it well suited for hard-water-sensitive systems when blended with GLDA or citric acid.
Typical Applications & Performance
1. Detergents & Cleaning Products
Replaces phosphates and EDTA in automatic dishwashing powders and tablets at 0.5 – 2.0% w/w. Provides stable Ca²⁺/Mg²⁺ sequestration at pH 9 – 11 with reduced glass and glaze corrosion versus phosphate formulations.
2. Personal Care
Chelating agent and preservation booster in bar soaps, syndet bars, and shampoos. Stabilizes trace transition metals that catalyze lipid oxidation and prevents discoloration; lower skin irritation than EDTA.
3. Agriculture & Micronutrient Fertilizers
Raw material for Fe-, Mn-, Zn-, Cu-EDDS chelate fertilizers. In calcareous soils (pH > 7.5), Fe-EDDS is markedly more effective than Fe-EDTA and Fe-DTPA. Foliar application at 0.05 – 0.1% rapidly corrects iron chlorosis.
4. Industrial Water Treatment
Hydrogen peroxide stabilizer in bleaching and cooling-tower systems at 10 – 50 mg/L; replaces silicate and phosphate programs with reduced scaling.
5. Pulp Bleaching & Textile
H₂O₂ stabilizer in TCF bleaching sequences; alternative to sodium silicate with cleaner equipment and lower effluent load.
Regulatory & Compliance
- REACH: registered (EU EC No. 432-270-4)
- EPA Safer Chemical Ingredients List: listed
- OECD 301B ready biodegradability: > 70% in 28 days ([S,S]-isomer)
- ECOCERT / COSMOS: approved for natural and organic certified formulations
- FDA 21 CFR: suitable for indirect food-contact applications (case-by-case evaluation)
Packaging & Supply
- Standard packaging: 25 kg fiber drum with PE liner; 500 kg / 1000 kg supersacks on request
- MOQ: 25 kg from stock; ≥ 1 MT negotiable for bulk contracts
- Lead time: stock ≤ 7 working days; customized specifications 4 – 6 weeks
- Annual capacity: 300 MT (EDDS free acid and sodium salts combined)
- COA, TDS, SDS and formulation support supplied with shipment
For samples, technical data sheets or quotations, please contact the Synverta sales team.