What Is Dimethyl Sulfoxide (DMSO)?
Dimethyl sulfoxide (DMSO, CAS 67-68-5, molecular formula C2H6OS) is a colorless, hygroscopic, slightly viscous liquid with a faint garlic-like odor. It is one of the most powerful polar aprotic solvents known, dissolving both polar and nonpolar compounds and mixing completely with water and most organic solvents. DMSO 99% refers to the standard high-purity industrial grade, with higher-purity grades (99.9%) available for pharmaceutical and electronic applications.
Key Properties
| Property | Value |
|---|---|
| CAS number | 67-68-5 |
| Molecular formula | C2H6OS / (CH3)2SO |
| Molecular weight | 78.13 g/mol |
| Boiling point | 189 C |
| Melting point | 18.5 C |
| Flash point | 87 - 95 C (closed cup) |
| Density (20 C) | 1.10 g/cm3 |
| Water solubility | Miscible; strongly hygroscopic |
Main Industrial Uses of 99% DMSO
Agrochemical formulations: improves the solubility and plant uptake of pesticides, herbicides and fungicides.
Polymer processing: dissolves polyacrylonitrile (PAN) for carbon fiber spinning and improves pigment dispersion in paints and coatings.
Electronics manufacturing: cleans electronic components and is used as a solvent in lithium-ion battery electrolyte formulations.
Organic synthesis: polar aprotic reaction medium for substitution, elimination and oxidation reactions, including pharmaceutical intermediate production.
Pharmaceutical and biotech: cryopreservation medium for cells and tissues and a penetration enhancer in topical drug delivery.
Industrial cleaning: component of paint strippers and precision cleaning formulations.
Safety: the Skin Penetration Warning
DMSO has low acute toxicity, but it penetrates intact human skin rapidly and can carry any dissolved substance into the body. This is the single most important handling rule: never handle DMSO with bare hands, especially when it contains dissolved chemicals, and always wear chemical-resistant (for example, butyl or nitrile) gloves. Avoid inhalation of vapors, prevent eye contact, and keep containers tightly closed because DMSO absorbs water from the air. Crystallization at about 18.5 C in cool climates is normal; warm gently before use.
Frequently Asked Questions
Q: What is 99% DMSO used for in industry?
Agrochemical, polymer, electronics, organic synthesis and pharmaceutical applications, mainly as a powerful polar aprotic solvent.
Q: Why must DMSO containers be kept tightly closed?
DMSO is strongly hygroscopic and absorbs moisture from the air, which lowers purity and can disturb downstream processes, so containers should be sealed and exposure to humid air minimized.
Q: Which gloves should be used when handling DMSO?
Butyl or nitrile chemical-resistant gloves are recommended, because DMSO penetrates intact skin rapidly and can carry any dissolved substance into the body; bare-hand contact must be avoided.
Q: How is DMSO used in pharmaceutical and biotech applications?
DMSO is used as a cryopreservation medium for cells and tissues and as a penetration enhancer in topical drug delivery, and it dissolves many poorly water-soluble drug candidates in formulation development.
Q: Can DMSO dissolve both polar and nonpolar compounds?
Yes, DMSO is one of the most powerful polar aprotic solvents, dissolving both polar and nonpolar substances and mixing completely with water and most organic solvents.
Q: What is the boiling point of DMSO?
DMSO boils at about 189 C and is a high-boiling, low-volatility solvent, which makes it convenient for reactions run at elevated temperature.