Methanesulfonic Acid (MSA) CAS: 75-75-2
Methanesulfonic acid (MSA) is a strong, non-oxidizing organic acid that serves as a biodegradable alternative to harsh mineral acids. It is primarily used as an electrolyte in high-speed tin electroplating for electronics and as an efficient acid catalyst in pharmaceutical and chemical synthesis, valued for the high solubility of its metal salts.
1. Overview
MSA is a colorless, strong organic acid (pKa ≈ -1.9). It serves as a non-oxidizing, biodegradable alternative to mineral acids (H₂SO₄, HCl) in electroplating, catalysis, and pharmaceutical synthesis.
2. Key Features
Strong acidity – comparable to mineral acids
Non-oxidizing – no side reactions
High metal salt solubility – ideal for electroplating
Biodegradable – eco-friendly
Low volatility – minimal fumes
Thermally stable – up to 250°C
3. Key Specifications
| Parameter | Typical Value | Explanation |
|---|---|---|
| Appearance | Colorless to pale yellow liquid | Darkening = impurities |
| Assay | ≥99.5% – ≥99.9% | Higher purity for pharma/electronics |
| Density (20°C) | 1.48 – 1.49 g/mL | Heavier than water |
| Melting Point | 19 – 20°C | Solidifies at room temp; warm to use |
| Water Content | ≤0.1% – ≤0.5% | Low moisture critical |
| Chloride | ≤1 – 5 ppm | High Cl causes corrosion |
| Heavy Metals | ≤1 – 10 ppm | Critical for pharma grade |
4. Applications
| Area | Uses |
|---|---|
| Electroplating | Tin, lead, copper plating (high solubility MSA salts) |
| Organic Synthesis | Esterification, alkylation, catalyst |
| Pharmaceuticals | API synthesis, salt formation |
| Battery Electrolytes | Lead-acid batteries (MSA-based) |
| Cleaning | Descaling, industrial cleaning (non-fuming) |
| Polymerization | Catalyst for polyoxymethylene (POM) |
5. Grade Comparison
| Grade | Purity | Water | Heavy Metals | Use |
|---|---|---|---|---|
| Industrial | ≥99.5% | ≤0.5% | ≤10 ppm | Cleaning, general synthesis |
| Electroplating | ≥99.7% | ≤0.1% | ≤5 ppm | Tin/lead plating baths |
| Pharma Grade | ≥99.9% | ≤0.05% | ≤1 ppm | API synthesis |
| Electronic | ≥99.9% | ≤0.02% | ≤1 ppm | Semiconductor cleaning |
6. Buying Guide
Select by application:
Electroplating → ≥99.7%, low chloride and sulfate
Pharmaceuticals → ≥99.9%, low heavy metals
Industrial cleaning → ≥99.5% standard grade
Storage & Handling:
Store in HDPE, PP, or PTFE containers (not carbon steel)
Keep above 20°C to prevent solidification
Shelf life: 24 months
Corrosive – use PPE (gloves, goggles, acid-resistant apron)
Quality checks:
Request CoA for water content, chloride, heavy metals
Check color (APHA ≤100 for standard grade)
7. FAQ
Q: MSA vs H₂SO₄ – which is better?
MSA – non-oxidizing, less fuming, biodegradable, better metal salt solubility.
H₂SO₄ – cheaper, stronger oxidizing. MSA preferred for tin/lead plating and sensitive syntheses.
Q: Is MSA hazardous?
Yes, corrosive. GHS: H290 (corrosive to metals), H302 (harmful if swallowed), H314 (severe skin burns/eye damage). Use PPE.
Q: Does MSA freeze in winter?
Yes. Melting point ~19–20°C. Warm to >25°C to liquefy before use. Quality unaffected after remelting.
Q: Is MSA biodegradable?
Yes – rapidly biodegrades in wastewater treatment (>70% in 28 days).
Q: Can MSA replace HCl in reactions?
Yes, if non-oxidizing conditions and chloride-free product are needed. MSA salts are non-volatile vs. HCl salts.
8. Delivery & Service
Packaging: 25kg, 250kg, 1000kg HDPE drums; 20–25 MT isotank
Lead time: Stock: 3–5 days; bulk: 2–3 weeks
Documentation: CoA, MSDS, TDS
Certifications: ISO 9001; pharma grade: GMP available
Shipping: Class 8 corrosive (UN 3265); requires hazardous documentation
