Ethanedioic acid (CAS 144-62-7) — Citrus N/A Note Fragrance Ingredient
Ethanedioic acid
CAS 144-62-7
What Is Ethanedioic acid?
Ethanedioic acid, commonly known as oxalic acid, is a naturally occurring compound found in plants like spinach and rhubarb. It’s also synthesized industrially for cleaning and bleaching applications. While not typically used in fragrances, it plays a role in certain niche perfumery processes and pH adjustment. Oxalic acid’s presence matters because it can affect the stability and performance of fragrance formulations, especially in aqueous systems.
Safety Profile
PROFESSIONAL USEWhat Does Ethanedioic acid Smell Like?
Oxalic acid itself is odorless in pure form, but its presence can influence the perceived scent of formulations by altering pH or chelating metal ions. In solutions, it may contribute a faint metallic sharpness reminiscent of rust or unripe fruit acidity. The compound doesn’t evolve on skin like traditional fragrance ingredients but can modify the behavior of other components.
2D Molecular Structure
SMILES: OC(=O)C(O)=O
Chemistry, Properties & Perfumer Guide
The Chemistry
Ethanedioic acid is the simplest dicarboxylic acid, with two carboxyl groups directly bonded. It occurs naturally as calcium oxalate in many plants and is produced industrially by oxidation of carbohydrates or ethylene glycol. The dihydrate form is common, with planar molecular geometry that facilitates strong hydrogen bonding. While not chiral itself, oxalic acid can form chiral metal complexes that influence fragrance chemistry.
Physical & Chemical Properties
| Melting Point | 189.5 °C (dihydrate) |
|---|---|
| Solubility | 10 g/100 mL (water, 20°C) |
| Density | 1.653 g/cm³ (dihydrate) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Industrial | Trace | 0-0.1% | pH adjustment only |
| Cleaning | 5-10% | Up to 15% | Not for fragrance use |
Classic Accords
Tip: Never use directly in consumer fragrances – handle only in controlled industrial settings.
Alternatives & Comparisons
Safer pH adjuster for fragrances with similar chelating properties but lower toxicity.
Gentler acidulant that won’t interfere with fragrance chemistry as severely.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
Not regulated by IFRA but prohibited in consumer products due to toxicity.
GHS Classification
RIFM Assessment
Not evaluated by RIFM – considered unsuitable for fragrance applications.
Sustainability
While naturally occurring, industrial production via fossil fuel oxidation raises environmental concerns. Sustainable alternatives exist for all legitimate perfumery applications where acidification is required. Proper disposal is critical to prevent ecosystem damage.
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References
- National Center for Biotechnology Information. PubChem Compound Summary for CID 971, Oxalic acid. PubChem CID 971
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID0025816
Physical Properties
| Molecular Weight | 90.034 g/mol🔬 EPA CompTox |
| Density | 1.683 g/cm^3🔬 EPA CTX |
| Boiling Point | 246.9 °C🔬 EPA CTX |
| Melting Point | 169.648 °C🔬 EPA CTX |
| Flash Point | 157.664 °C📊 OPERA |
| Refractive Index | 1.48 Dimensionless📊 OPERA |
| Molar Volume | 50.8 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | -1.255 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | -5.627 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | -6.697 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 6.48 Log10 unitless📊 OPERA |
| Water Solubility | 1.981 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 0 mmHg🔬 EPA CTX |
| Viscosity | 4.194 cP📊 OPERA |
| Surface Tension | 57.716 dyn/cm📊 OPERA |
| Thermal Conductivity | 170.542 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 74.6 Ų💻 Computed |
| H-Bond Donors | 2 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 0 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 14.444 cm^3/mol📊 OPERA |
| Polarizability | 5.726 Å^3📊 OPERA |
Data Sources:
🔬 EPA Experimental data from U.S. EPA CompTox Chemicals Dashboard & CTX APIs. 📊 OPERA Predicted using EPA's OPERA QSAR models. 💻 Computed Calculated from SMILES using RDKit.
