Basic Information

（DMSO）It is a sulfur-containing organic compound with a molecular formula of C2H6OS. It is a colorless, odorless, transparent liquid at room temperature and is a hygroscopic flammable liquid. It has the characteristics of high polarity, high boiling point, good thermal stability, aprotic, and water miscibility. It can be dissolved in most organic substances such as ethanol, propanol, benzene and chloroform, and is known as a "universal solvent". Heating in the presence of acid will produce a small amount of compounds such as methyl mercaptan, formaldehyde, dimethyl sulfide, and methanesulfonic acid. Decomposes at high temperature, reacts violently with chlorine, burns in air and emits a light blue flame. It can be used as organic solvent, reaction medium and organic synthesis intermediate. It can also be used as a dyeing solvent for synthetic fibers, a dye remover, a dyeing carrier, and an absorbent for recovering acetylene and sulfur dioxide.

physical properties

Colorless viscous liquid. Flammable, almost odorless, with a bitter taste, hygroscopic. In addition to petroleum ether, it can dissolve general organic solvents. It can be miscible with any water, ethanol, acetone, acetaldehyde, pyridine, ethyl acetate, dibutyl phthalate, dioxane and aromatic compounds, and insoluble in aliphatic hydrocarbon compounds other than acetylene. It has strong hygroscopicity. At 20°C, when the relative humidity is 60%, it can absorb 70% of its own weight from the air. The product is a weak oxidizing agent, and dimethyl sulfoxide without water is non-corrosive to metals. When containing water, it is corrosive to iron, copper and other metals, but not to aluminum. Stable to alkali. Heating in the presence of acid will produce a small amount of methyl mercaptan, formaldehyde, dimethyl sulfide; methanesulfonic acid and other compounds. Decomposes at high temperature, reacts violently with chlorine, burns in air and emits a light blue flame.

Physical data

1、Properties: Colorless viscous transparent oily liquid or crystals. Weakly alkaline, almost odorless, slightly bitter, commonly used organic solvents.

2、Relative density（g/mL，20/4℃）：1.100

3、relative vapor density（g/L，空气=1）：2.7 

4、melting point（℃）：18.45

5、boiling point（℃）：189

6、Refractive index：1.4795 ^[3] 

7、viscosity（mPa·s）：1.987（25℃）；2.2（20℃）；1.290（50℃）

8、Flash point（℃，开口）：95

9、ignite：300~302℃ ^[3] 

10、heat of evaporation（kJ/mol，℃）：52.92 

11、heat of fusion（kJ/mol）：13.94 

12、generate heat（kJ/mol）：-197.66 

13、Heat of combustion（kJ/mol，定容）：1793.16 

14、specific heat capacity（kJ/(kg·K)，℃，定压）：1.95 

15、Conductivity（S/m，℃）：3×10^-8 

16、Vapor Pressure（kPa，℃）：0.049

17、Vapor Pressure（kPa,20ºC）：0.049 

18、Lower explosion limit（%，V/V）：2.6 

19、Explosive ceiling（%，V/V）：28.5 

20、volume expansion coefficient（K^-1）：0.00088 

21、Solubility：It can be mixed with water in any proportion, and can dissolve common organic solvents except petroleum ether. At 20°C, it can absorb 30% (weight) of hydrogen chloride, 30% (weight) of nitrogen dioxide, and 65% (weight) of sulfur dioxide. It is insoluble in aliphatic hydrocarbon compounds except acetylene. It has the ability to dissolve many kinds of compounds. Soluble in water, ethylene glycol, acetone, benzene, hydrocarbon chlorides, ethylene glycol esters, etc.

use

Dimethyl sulfoxide is a common solvent for many chemical reactions, especially in the SN2 alkylation reaction. It is an excellent solvent: if potassium hydroxide is used as the base to alkylate indole, a very high yield can be obtained; it can also be used Phenols substituted for indoles undergo a similar reaction. Dimethyl sulfoxide reacts with iodomethane to generate sulfonium ions and reacts with sodium hydride to generate sulfur ylides. The methyl group in DMSO is slightly acidic (pKa = 35) due to the stabilizing effect of the sulfoxyl group on its conjugate base.