What is dimethyl sulfoxide? The function and synthesis of dimethyl sulfoxide are introduced

Dimethylsulfoxide (DMSO for short) is a sulfur-containing organic compound, English Dimethylsulfoxide, molecular formula (CH3) 2SO, at room temperature is colorless odorless transparent liquid, with hypersonic flammable liquid, both high polarity, high boiling point, aprotic, water mismissibility characteristics, very low toxicity, good thermal stability, It is not mixed with alkanes, and can dissolve in water, ethanol, propanol, ether, benzene and chloroform and other most organic matter, known as “universal solvent”.

Dimethyl sulfoxide is one of the most powerful organic solvents in common use. It can dissolve most organic matter, including carbohydrates, polymers, peptides, and many inorganic salts and gases. It can dissolve solutes equal to 50-60% of its weight (other common solvents can only dissolve 10-20%), so it is important in sample management and high-speed drug screening. Under certain conditions, an explosive reaction occurs when dimethyl sulfoxide comes into contact with an acyl chloride.

Dimethyl sulfoxide is widely used as a solvent and reaction reagent, especially as a processing solvent and drawing solvent in acrylonitrile polymerization, as a polyurethane synthesis and drawing solvent, as a synthetic solvent of polyamide, polyimide and polysulfone resin, and as a solvent for aromatics, butadiene extraction and synthesis of chlorofluoraniline. In addition, in the pharmaceutical industry, dimethyl sulfoxide is also directly used as a raw material and carrier for some drugs. Dimethyl sulfoxide itself has anti-inflammatory analgesic, diuretic, sedative and other effects, and is also known as a “panacea”, often added to drugs as an active component of analgesic drugs. It has a special property that easily penetrates the skin, causing users to feel like oysters.

Dimethyl sulfoxide solution of sodium cyanide can cause cyanide poisoning through skin contact. Dso itself is less toxic. Dimethyl sulfoxide is used as an extractant by most chemical and pharmaceutical enterprises, but due to the high boiling point of DMSO, the operating temperature is too high, which causes the coking of materials, affects the recovery of dimethyl sulfoxide and equipment cleaning, and also increases energy consumption. Therefore, the recovery of DSO has become a bottleneck for its further widespread use as an extractant.

01 Identification and detection of dimethyl sulfoxide

identify

Take 1.5ml of this product, slowly drop it into 2.5ml of cooled hydroiodic acid, rapidly filter it, and dry it under reduced pressure. The resulting residue is an unstable dark purple crystalline solid with unpleasant odor, dissolved in chloroform and formed a red solution.

Inspect

Light absorption Take an appropriate amount of this product, pass it into a dry nitrogen stream for 15 minutes, immediately place it in a 1cm absorption tank, use water as blank, and measure the absorption at 275nm wavelength by spectrophotometry (page 24 of the Appendix of the second part of the 1990 Edition of Chinese Pharmacopoeia), not more than 0.30; Then the absorption was measured at the wavelength of 285nm and 295nm, and the ratio of the absorption at 275nm should not be greater than 0.65 and 0.45, respectively, and there should be no maximum absorption peak in the range of 270-350nm. Water content shall not exceed 0.2% (page 55 of the Appendix of the second part of the 1990 Edition of the Chinese Pharmacopoeia).

0.025% acetone solution was prepared by taking diphenylmethane from dimethyl sulfone as the internal standard solution. Accurately weigh the appropriate amount of dimethyl sulfone and dilute it into 0.050% solution with internal standard solution as a control solution; Another appropriate amount of this product, precision weighing, with the internal standard solution diluted into 50% solution, as the test product solution. According to gas chromatography (Chinese Pharmacopoeia 1990, Part II Appendix 31 page (3) method), with a coating concentration of 10% polyethylene glycol 20M as the fixed liquid, (the theoretical plate number calculated by dimethyl sulfone should be greater than 1500, the separation degree of dimethyl sulfone peak and internal standard peak should be greater than 2), The ratio of peak area between dimethyl sulfone and diphenylmethane in test solution measured at 150℃ should not be greater than that between dimethyl sulfone and diphenylmethane in control solution.

02 Production method of dimethyl sulfoxide

Dimethyl sulfoxide is generally obtained by dimethyl sulfide oxidation process, because of the different oxidants and oxidation methods used, so there are different production processes.

1. Methanol carbon disulfide and carbon disulfide were used as raw materials, γ-Al2O3 was used as catalyst to synthesize dimethyl sulfide, and then oxidized with nitrogen dioxide (or nitric acid) to dimethyl sulfoxide.

2. The hydrogen peroxide method uses acetone as a buffer medium to react dimethyl sulfide with hydrogen peroxide. The production of DSO by this method has high cost and is not suitable for mass production.

3. Dimethyl sulfide is produced by nitrogen dioxide process with methanol and hydrogen sulfide under the action of γ-alumina; Sulfuric acid reacts with sodium nitrite to form nitrogen dioxide; Dimethyl sulfide and nitrogen dioxide are oxidized in gas and liquid phase at 60-80℃ to produce crude dimethyl sulfoxide, or directly oxidized with oxygen to produce crude dimethyl sulfoxide, and then distilled under reduced pressure to produce dimethyl sulfoxide. This method is a relatively advanced production method.

4. Dimethyl sulfate process dimethyl sulfate reacts with sodium sulfide to produce dimethyl sulfide; Sulfuric acid reacts with sodium nitrite to form nitrogen dioxide; The crude dimethyl sulfoxide was oxidized with nitrogen dioxide, then neutralized and distilled to obtain refined dimethyl sulfoxide. In addition, dimethyl sulfoxide was produced from dimethyl sulfide by anodic oxidation.

03 The use of dimethyl sulfoxide

It can be used as organic solvent, reaction medium and intermediate of organic synthesis. Extremely versatile.

This product has high selective extraction ability, used as acrylic resin and polysulfone resin polymerization and condensation solvent, polyacrylonitrile and acetic acid fiber polymerization drawing solvent, alkane and aromatics separation extraction solvent, used in aromatics, butadiene extraction, acrylic fiber spinning, plastic solvent and organic synthetic dyes, pharmaceutical and other industries reaction medium.

In medicine, dimethyl sulfoxide has anti-inflammatory and analgesic effects, and has strong permeability to the skin, so it can dissolve some drugs, so that such drugs can penetrate into the human body to achieve therapeutic purposes.

Using this carrier property of dimethyl sulfoxide, it can also be used as an additive to pesticides. Adding a small amount of dimethyl sulfoxide to some pesticides helps the pesticide penetrate into the plant to improve its efficacy.

Dimethyl sulphoxide can also be used as a dyeing solvent, stain remover and dyeing carrier of synthetic fibers, and can also be used as an absorber for recovering acetylene and sulfur dioxide, synthetic fiber modifier, antifreeze, capacitive media, brake oil, rare metal extractor and so on.