Dimethyl Sulfoxide

What is Dimethyl Sulfoxide?

Dimethyl sulfoxide is an organosulfur compound which has two methyl groups, one oxygen atom and one sulfur atom. Chemical formula of dimethyl sulfoxide is (CH3)2SO. It is a colorless liquid which has the ability to dissolve both polar and non - polar compounds. It is also known as DMSO (abbreviation of dimethyl sulfoxide). It is known by other names as well such as methylsulfinylmethane or methyl sulfoxide etc. 

Formula of Dimethyl Sulfoxide 

S. No.

Formula of Dimethyl sulfoxide 

1.

Empirical Formula 

C2H6OS

2.

Molecular Formula 

C2H6OS

3.

Structural Formula 

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Structure of Dimethyl Sulfoxide 

Dimethyl sulfoxide is a polar aprotic compound. It has idealized Cs symmetry. It has a trigonal pyramidal molecular geometry. In dimethyl sulfoxide, S=O bond length is 167.8 pm and S-C bond length is 186.2 pm. O-S-C bond angle is 105.1° and C-S-C bond angle is 98°. 

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The sulfur atom in dimethyl sulfoxide has a non bonded electron pair. 

Properties of Dimethyl Sulfoxide 

It shows following physical and chemical properties –

  • Its molar mass is 78.13 g/mol.

  • It is a colorless liquid.

  • It is a polar aprotic solvent. 

  • It can dissolve both polar and non - polar compounds. 

  • It is soluble in many organic solvents. But not soluble in diethyl ether. 

  • It is soluble in water as well. 

  • Its density is 1.10 g/cm3

  • Its melting point is 19 °C.

  • Its boiling point is 189 °C.

  • It has a garlic like taste. 

  • Reaction with electrophile – Dimethyl sulfoxide acts as a nucleophile and reacts with electrophiles. Its sulfur center acts as nucleophile for weak electrophiles while its oxygen center acts as nucleophile for strong electrophiles. For example, it reacts with methyl iodide and forms trimethylsulfoxonium iodide. Reaction is given below – 

(CH3)2SO + CH3I → [(CH3)3SO]I

This reaction can be used to form sulfur ylide. When trimethylsulfoxonium iodide salt reacts with sodium hydride, it forms sulfur ylide. Reaction is given below –

[(CH3)3SO]I + NaH → (CH3)2S(CH2)O + NaI + H2

  • Dimethyl sulfoxide is a weakly acidic compound and shows reaction with base. 

  • It acts as a mild oxidant. For example, in Swern oxidation reaction. 

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  • It works as a common ligand in coordination chemistry. For example, [RuCl2(DMSO)4]. Its structure is given below –

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Synthesis of Dimethyl Sulfoxide 

Dimethyl sulfoxide was first synthesized by the Russian Scientist Alexander Zaytsev in 1867. At industrial level, it is produced from dimethyl sulfide by oxidation with oxygen or nitrogen dioxide. It is a by – product of the Kraft process. 

What is Dimethyl Sulfoxide Used for? 

Due to its unique properties such as miscibility in organic solvents, polar aprotic solvent and less toxic nature, it is used in various fields for various purposes. Few of its applications are listed below –

  • It is a good solvent for polar and non non – polar organic and inorganic compounds. So, it is used in the synthesis of many compounds. It is used in the Finkelstein reactions and various nucleophilic reactions. 

  • It is widely used as an extractant in cell biology and biochemistry. 

  • Being a weak acid, it can tolerate strong bases, so it is used in the study of carbanions. 

  • Acid dissociation constant can be determined for various organic compounds by using a DMSO solution.

  • Its solution is used in NMR – spectroscopy as well. 

  • It can be used for manufacturing of microelectronic devices. 

  • It is used in advanced packaging applications.

  • It is used in LCD – flat panel displays. 

  • It is used in stem cell baking or biopreservation. 

  • It is a safer option as paint stripper than nitromethane and dichloromethane. 

  • It is used in drug design and sample management as it’s a good solvent and can dissolve various compounds. 

  • Its biological uses include its usage as an inhibitor for DNA primers in polymerase chain reaction or PCR. 

  • It acts as a reversible cell cycle arrester of human lymphoid cells. 

  • It is used for protecting tissues from freezing damage. It is added into the cell media to reduce ice formation so that cells will not die due to over freezing. 

  • It is used as co – solvent as well in many biological adsorption processes. For example, C. elegans nematode uses it for absorption of flavonol glycoside. 

  • It has been used in medicines since 1963. It can enter into the cell, without damaging the cell membrane. It is used in analgesics, anti – inflammatory and antioxidant drugs. 

  • It is used in the transdermal drug delivery systems. 

  • It is one of the ingredients of antifungal medicines. 

  • It is used as a drug vehicle in - in vitro and in vivo experiments. 

  • It is used as a cryoprotectant. 

  • It is used as an alternative medicine for treatment of many diseases. It is being used as an alternative medicine for the treatment of cancer as well. 

  • It is used in the medicines used for treatment of skin related problems in horses. 

Although it is widely used as a solvent, but it has a disadvantage that it is very difficult to remove DMSO completely. So, it becomes difficult to recover the samples dissolved in DMSO. 

Dimethyl Sulfoxide: Summary in Tabular Form 

Dimethyl Sulfoxide 

Chemical Formula 

C2H6OS or (CH3)2SO

IUPAC Name 

Dimethyl sulfoxide 

Molar Mass 

78.13 g/mol

Melting Point 

19 °C

Boiling Point 

189 °C

Density 

1.10 g/cm3

Appearance 

Colorless liquid 

Molecular Symmetry 

Cs symmetry 

State at STP

Liquid 

Solubility in Water 

It is miscible in water. 

Solubility in Organic Solvents 

It is soluble in many organic solvents. But does not dissolve in diethyl ether. 

Preparation 

Obtained as a by – product of Kraft process. 

Main Properties 

Miscible in organic solvents and used as polar aprotic solvent for many polar and non-polar compounds. 

Main Use 

As solvent for many biological processes and synthesis of drugs. 

Disadvantage 

It is difficult to recover the sample from DMSO solution as its very difficult to remove all traces of dimethyl sulfoxide from the sample solution.  


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