What is Dimethyl Sulfoxide Structure Formula Properties Reactions and Uses
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
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
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FAQs on Dimethyl Sulfoxide DMSO in Chemistry
1. What is dimethyl sulfoxide (DMSO)?
Dimethyl sulfoxide (DMSO) is a polar aprotic organic compound with the formula (CH3)2SO or C2H6OS that contains a sulfur atom double-bonded to oxygen. It is a colorless liquid widely used as a laboratory solvent.
- Functional group: sulfoxide (S=O)
- Highly polar but does not donate hydrogen bonds
- Miscible with water and many organic solvents
- Common in organic chemistry, pharmaceuticals, and polymer science
2. What is the chemical formula and structure of DMSO?
The chemical formula of dimethyl sulfoxide is (CH3)2SO, consisting of two methyl groups attached to a sulfur atom that is double-bonded to oxygen.
- Empirical formula: C2H6OS
- Structural feature: one S=O double bond
- Sulfur is bonded to two –CH3 groups and one oxygen
- Molecular geometry around sulfur is approximately trigonal pyramidal
3. Why is DMSO classified as a polar aprotic solvent?
DMSO is classified as a polar aprotic solvent because it has a large dipole moment but lacks O–H or N–H bonds to donate hydrogen atoms.
- The S=O bond creates strong polarity
- No acidic hydrogen is present for hydrogen bonding donation
- It stabilizes cations through its oxygen atom
- It enhances reactions like SN2 nucleophilic substitutions
4. What are the main uses of dimethyl sulfoxide in chemistry?
Dimethyl sulfoxide is mainly used as a highly polar organic solvent in laboratory and industrial chemistry.
- Solvent for organic reactions (e.g., SN2 reactions)
- Reaction medium for polymer synthesis
- Solvent in pharmaceutical formulations
- Cryoprotectant for preserving cells and tissues
5. How is dimethyl sulfoxide prepared?
Dimethyl sulfoxide is commonly prepared by the controlled oxidation of dimethyl sulfide (DMS) with oxygen.
- Balanced reaction: 2(CH3)2S(l) + O2(g) → 2(CH3)2SO(l)
- The oxidation must be carefully controlled to prevent further oxidation to sulfones
- Industrial production uses air or oxygen with catalysts
6. What is the difference between DMSO and dimethyl sulfide?
The main difference between DMSO and dimethyl sulfide is that DMSO contains a sulfur–oxygen double bond (S=O), while dimethyl sulfide does not.
- Dimethyl sulfide: (CH3)2S
- Dimethyl sulfoxide: (CH3)2SO
- DMSO is highly polar; dimethyl sulfide is less polar
- DMSO has a much higher boiling point due to stronger intermolecular forces
7. Why does DMSO have a high boiling point?
DMSO has a high boiling point (189 °C) because of its strong dipole–dipole intermolecular forces due to the polar S=O bond.
- Large molecular dipole moment
- Strong intermolecular attractions
- Relatively high molecular mass (78.13 g/mol)
8. Is DMSO soluble in water?
Yes, dimethyl sulfoxide is completely miscible with water in all proportions.
- The oxygen atom in DMSO forms hydrogen bonds with water
- Its high polarity enhances solubility
- It also dissolves many organic and inorganic compounds
9. What type of reactions are commonly carried out in DMSO?
DMSO is commonly used in SN2 nucleophilic substitution reactions and other reactions requiring a polar aprotic solvent.
- Enhances nucleophilicity of anions
- Stabilizes cations but not anions strongly
- Used in oxidation reactions such as the Swern oxidation
10. Is DMSO safe to handle in the laboratory?
DMSO is relatively low in toxicity but must be handled carefully because it can rapidly penetrate skin and carry dissolved substances into the body.
- Wear gloves and protective equipment
- Avoid skin contact
- Use in well-ventilated areas
