Dimethyl sulfoxide (DMSO)

Dimethyl sulfoxide (DMSO) is an organic substance made up of the elements sulphur, carbon, oxygen and hydrogen. At the center of its molecule is a sulfur atom, which has a double bond to an oxygen and also has two methyl groups. The sulfonyl group formed from sulfur and oxygen is typical of the sulfoxide class of substances. It has a strong electric dipole moment with a negative charge center on the oxygen atom and a positive charge center on the sulfur atom. Because of this property, dimethyl sulfoxide is particularly suitable as a solvent for other non-polar compounds.

At normal room temperature, dimethyl sulfoxide (DMSO) is in the form of a colorless liquid with hygroscopic properties. However, the compound already reaches its melting point at a temperature of 18 °C and solidifies to a crystalline solid on further cooling. On the other hand, the substance is initially very resistant to high temperatures; it only boils when heated to 189 °C. Dimethyl sulfoxide does not have a noticeable odor of its own; a slightly putrid odor after prolonged storage indicates that parts of the substance have been converted into dimethyl sulfide.

The compound is an aprotic, nucleophilic and dipolar solvent which is miscible in any proportion even with water and many organic solvents such as acetone, methanol, ethanol, chloroform, diethyl ether, benzene and benzene.

Dimethyl sulfoxide (DMSO) is chemically stable when stored as directed. However, once the boiling point of 189 °C has been reached, the compound begins to thermally decompose, which can lead to explosive and very dangerous reactions. In addition, this process can start at significantly lower temperatures with basic or acidic catalysis. Fluorinating agents, periodic acid, metal perchlorates, metal nitrates, sodium hydride and halogen compounds can also cause a violent decomposition reaction of dimethyl sulfoxide. Dangerous reactions with strong heat development are also to be expected with strong reducing agents, strong oxidizing agents, strong bases and strong acids.

The compound is flammable, but is difficult to ignite. However, the vapors and aerosols of the liquid can form highly flammable and explosive vapor-air mixtures with the ambient air. Due to their high density, the vapors of dimethyl sulfoxide can collect on the floor of the workrooms and spread out unnoticed. To avoid dangerous remote ignition, open containers of the substance must therefore be kept far away from possible sources of ignition such as hot surfaces, electrostatically charged devices, mechanically generated sparks and open flames. The combustion and thermal decomposition of dimethyl sulfoxide produces irritant and harmful gases such as carbon dioxide, carbon monoxide and nitrogen oxides.

Dimethyl sulfoxide (DMSO) poses acute health risks. The compound itself has only a low toxicity, but as a carrier medium it can significantly increase the dermal absorption of other toxic substances. On the skin, dimethyl sulfoxide can cause redness, hypersensitivity, itching and burning pain. Wetted parts of the skin should be cleaned immediately with soap and water. If symptoms persist, a medical examination should be carried out. After contact of the compound with the eye, unpleasant irritation of the mucous membrane, reddening of the conjunctiva and temporary clouding of the lens can occur. In addition to immediate rinsing under running water, prompt ophthalmological treatment should be arranged.

Inhalation of compound vapors and aerosols will cause respiratory irritation. Very high exposure can cause breathing difficulties and acute lung failure. Affected persons should be taken to fresh air immediately. Medical assistance must be called directly to the scene of the accident. After swallowing dimethyl sulfoxide, painful irritation of the mucous membranes and gastrointestinal symptoms such as diarrhoea, nausea and vomiting can occur. The absorption of the compound into the metabolism can cause respiratory distress, central nervous system disorders and liver damage.

Dimethyl sulfoxide is considered to be slightly hazardous to water and should not get into the ground, wastewater or bodies of water.