What Is Organic DMSO?
Dimethyl sulfoxide (DMSO) is an organosulfur compound with the chemical formula C2H6OS and CAS number 67-68-5. It is a colorless, odorless, hygroscopic liquid at room temperature, with a slightly bitter taste. The term organic DMSO simply emphasizes that the compound is a carbon-containing organic molecule, in contrast to inorganic solvents. DMSO is produced industrially by the oxidation of dimethyl sulfide, which is recovered from lignin in the Kraft papermaking process or synthesized from methanol and carbon disulfide. Its remarkable ability to dissolve both polar and nonpolar substances has earned it the nickname universal solvent.
Key Physical and Chemical Properties
DMSO has a melting point of 18.4 degrees Celsius, a boiling point of 189 degrees Celsius, and a density of approximately 1.10 g/cm3 at 20 degrees Celsius. It is completely miscible with water, ethanol, acetone, and most organic solvents, and it is itself an excellent solvent for many polymers, salts, and gases. DMSO is a polar aprotic solvent with a high dielectric constant and strong hydrogen-bond-accepting ability, which makes it valuable in substitution and elimination reactions. It is thermally stable under normal conditions but can decompose when heated in the presence of acids or strong oxidizers, releasing products such as methyl mercaptan and formaldehyde. DMSO also penetrates skin readily, so protective gloves are required during handling.
Available Purity Grades
Industrial grade (99.0-99.5 percent): Used as a reaction solvent, cleaning agent, and extraction medium in chemical plants.
Electronic grade: Low-metal-ion DMSO used in semiconductor and flat-panel display processing, including photoresist stripping.
Pharmaceutical grade (USP/EP): High-purity DMSO conforming to pharmacopoeia standards, used as a penetration enhancer and in topical formulations.
Analytical grade: High-purity solvent for chromatography and spectroscopy applications.
Main Applications of DMSO
In the electronics industry, DMSO is widely used to strip photoresist in TFT-LCD flat panel display manufacturing and in advanced packaging processes such as wafer-level packaging and solder bump patterning. In pharmaceuticals, DMSO is used as a solvent and permeation enhancer in topical drug delivery, as a cryoprotectant in cell and tissue preservation, particularly in stem cell banking, and as a pharmaceutical intermediate. In chemical synthesis, it serves as a polar aprotic reaction medium for nucleophilic substitution reactions, oxidation reactions, and polymer processing. It is also used as a paint stripper component, an analytical solvent, and a carrier in agricultural formulations.
Safety, Storage, and Handling
Although DMSO has low acute toxicity, it readily penetrates the skin and can carry dissolved substances into the body, so nitrile or butyl rubber gloves are recommended. Work with DMSO in a well-ventilated area and avoid heating it with strong acids or oxidizers, which can cause decomposition and release malodorous or hazardous byproducts. DMSO is hygroscopic; containers should be kept tightly sealed to prevent water absorption. It can also cause container corrosion if stored improperly, so stainless steel or compatible plastic containers are preferred. Spills should be absorbed with inert material and disposed of according to local regulations.
Frequently Asked Questions
Why is DMSO called the universal solvent?
DMSO dissolves an exceptionally wide range of polar and nonpolar compounds, including many polymers, salts, and organic substances that are poorly soluble in other solvents, which is why it is often described as a universal solvent.
Is DMSO safe to use in pharmaceutical applications?
Pharmaceutical-grade DMSO conforming to USP or EP specifications is approved for certain topical uses. Industrial-grade DMSO is not suitable for pharmaceutical use because of possible impurities.
How should DMSO be stored?
Store DMSO in tightly sealed containers in a cool, dry place to prevent water absorption. Avoid storage with strong acids or oxidizing agents and keep containers away from direct sunlight.
What is the boiling point of DMSO?
The boiling point of DMSO is approximately 189 degrees Celsius at atmospheric pressure, which makes it useful for high-temperature reactions.
Can DMSO be mixed with water?
Yes, DMSO is completely miscible with water in all proportions. Mixing releases heat, so large-scale dilution should be done with controlled agitation and cooling.
What gloves should be used when handling DMSO?
Nitrile or butyl rubber gloves are recommended because DMSO can penetrate latex and many other glove materials, carrying dissolved chemicals into the skin.
