Oxalic acid dihydrate (CAS 6153-56-6) — Citrus N/A Note Fragrance Ingredient

ByThe Good Scents
Citrus · Floral

Oxalic acid dihydrate

CAS 6153-56-6

Origin
synthetic
Note
N/A
IFRA
Professional use
Data as of: Apr 2026

What Is Oxalic acid dihydrate?

Oxalic acid dihydrate is a synthetic compound primarily used in industrial applications and cleaning products. It’s not commonly found in consumer fragrances due to its strong acidic properties. This ingredient matters in perfumery primarily as a pH adjuster in niche technical applications, though its use is highly restricted due to safety concerns.

Safety Profile

PROFESSIONAL USE
Generally safeUse with awarenessProfessional use
⚠ Severe skin and eye irritant
✗ Not recommended for consumer products
CAS
6153-56-6
Formula
Mixture
MW
Variable
Odor Family
Citrus · Floral
Layer 1 · Enthusiast

What Does Oxalic acid dihydrate Smell Like?

Oxalic acid dihydrate is odorless in pure form but has a sharp, acidic character when concentrated. In solution, it may release faint vinegar-like notes due to its acidic nature, but it lacks any distinct aromatic profile that would classify it as a traditional fragrance material.

Layer 2

2D Molecular Structure

Oxalic acid dihydrate

SMILES: O.O.OC(=O)C(O)=O

Chemistry, Properties & Perfumer Guide

The Chemistry

Oxalic acid dihydrate is the crystalline form of oxalic acid, a simple dicarboxylic acid. It’s produced synthetically through the oxidation of carbohydrates or ethylene glycol. The dihydrate form contains two water molecules per oxalic acid molecule, making it more stable than the anhydrous form. Its strong chelating properties make it useful in metal cleaning applications rather than perfumery.

Physical & Chemical Properties

Melting Point101-102 °C
Density1.653 g/cm³

Perfumer Guide

Note Position
N/A
Volatility
N/A
Blending
N/A
ApplicationTypical %RangeNotes
IndustrialNot usedNot applicableAvoid in fragrance applications

Classic Accords

Tip: This material should not be used in fragrance formulations due to safety concerns.

Alternatives & Comparisons

1
Citric acid CAS 77-92-9

A safer acidic pH adjuster for fragrance applications when acidity control is needed.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

General reference only. Consult current IFRA Standards Library before formulating.

IFRA Status

Not listed by IFRA due to its non-fragrance applications.

GHS Classification

H302 Harmful if swallowed H312 Harmful in contact with skin H318 Causes serious eye damage

RIFM Assessment

Not evaluated by RIFM for fragrance use.

Sustainability

Oxalic acid dihydrate is produced synthetically with minimal environmental impact in its manufacturing process. However, its use is discouraged in consumer products due to toxicity concerns.

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References

  1. PubChem Compound Summary for Oxalic acid CID 971

Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.

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Layer 3 · Practical

  • Molecular Weight: 126.07 g/mol

Ingredient Data Sheet

CAS 6153-56-6

Physical Properties

Molecular Weight126.07 g/mol🔬 PubChem
Boiling Point318 °C🔬 EPA CompTox
Vapor Pressure0.0002 mmHg @ 25°C📊 OPERA
SMILESC(=O)(C(=O)O)O.O.O🔬 PubChem

Volatility & Performance

Fragrance NoteBase💻 Calculated
Volatility ClassVery slow💻 Calculated
Persistence Score5.2 / 5💻 Calculated
Data Sources & Attribution
Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.

Physicochemical Properties

DTXSID: DTXSID2075003

Physical Properties

Molecular Weight 126.064 g/mol🔬 EPA CompTox
Density 1.65 g/cm^3🔬 EPA CTX
Boiling Point 318 °C📊 OPERA
Melting Point 101.2 °C🔬 EPA CTX

Partition & Solubility

LogP (Octanol-Water) -0.81 Log10 unitless🔬 EPA CTX
LogD (pH 5.5) -5.73 Log10 unitless📊 OPERA
LogD (pH 7.4) -7.63 Log10 unitless📊 OPERA
LogKoa (Octanol-Air) 6.48 Log10 unitless📊 OPERA
Water Solubility 1.071 mol/L🔬 EPA CTX
Henry's Law Constant 0 atm-m3/mole📊 OPERA

Transport Properties

Vapor Pressure 0 mmHg📊 OPERA

Molecular Descriptors

Topological Polar Surface Area 137.6 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 22.5 cm^3/mol💻 Computed

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.

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