What Is Dimethyl Sulfate?
Dimethyl Sulfate is the dimethyl ester of sulfuric acid.
Other names include Dimethyl Sulfate, Methyl Sulfate, Dimethyl Sulfate Ester, and DMS. Dimethyl Sulfate is strictly a conventional name.
It is classified as a priority chemical substance under the Law Concerning the Evaluation of Chemical Substances and Regulation of Their Manufacture, etc. (Chemical Substances Control Law). It is also regulated under the Industrial Safety and Health Law, Poisonous and Deleterious Substances Control Law, and Fire Service Law, in addition to being a regulated item under the Water Pollution Control Law’s Accidental Measures (Designated Substances).
Uses of Dimethyl Sulfate
Dimethyl Sulfate is widely used as a strong alkylating agent. As a result, it is often used as a pharmaceutical or synthetic raw material. Specifically, it is often used to methylate the hydroxy group (-OH) of phenols and alcohols, the amino group (-NH2) of amines, and the thiol group (-SH) of thiols.
It is also a well-known alkylating agent used in the chemical methylation of nucleic acids. Historically, it was used for DNA sequencing by the Maxam-Gilbert sequencing method.
Properties of Dimethyl Sulfate
Dimethyl Sulfate has a melting point of -32°C and decomposes at 188°C. It is a colorless oily liquid with a weak onion-like odor. It is soluble in ethanol, acetone, dichloromethane, and various ethers. It is insoluble in water and is gradually hydrolyzed.
Dimethyl Sulfate is not irritating, but is extremely toxic to the human body. If the vapor is inhaled or left on the skin, it can be absorbed into the body and cause poisoning. Kidneys, liver, and heart may be affected, and death may result from necrosis of the skin and inflammation of the respiratory mucous membranes, so care must be taken when handling it.
Structure of Dimethyl Sulfate
Dimethyl Sulfate is a neutral ester with the chemical formula (CH3)2SO4 or (CH3O)2SO2. It is also denoted as Me2SO4. Its molar mass is 126.13 g/mol and density is 1.33 g/ml.
Other Information on Dimethyl Sulfate
1. Synthesis of Dimethyl Sulfate
Reaction of fuming sulfuric acid with dry methanol or dimethyl ether yields methyl hydrogen sulfate. Methyl hydrogen sulfate can be distilled and converted to Dimethyl Sulfate.
Methyl hydrogen sulfate can also be synthesized by reacting methyl chlorosulfonate with methyl nitrite.
In industrial use, it is synthesized by the sequential reaction of dimethyl ether with sulfur trioxide (SO3).
2. Reaction of Dimethyl Sulfate
Dimethyl Sulfate is generally used in the methylation of phenols and is also suitable for the methylation of alcohols. For example, tert-butyl methyl ether can be synthesized from tert-butanol. In the case of alkoxides, methylation is immediate. As with alcohols, methylation of thiols also occurs readily. Thioesters can be produced from thiocarboxylic acids.
Methylation of amines allows the synthesis of tertiary amines and quaternary ammonium salts. Quaternary ammonium compounds with long-chain alkyl groups can be used in clothing softeners and surfactants.
Dimethyl Sulfate can also cleave DNA base-specifically through the ring-opening reaction of the imidazole ring of guanine, which is useful in DNA strand breaks and sequencing. When reacted with copper(I) oxide, copper(I) sulfate is obtained.
3. Hazards of Dimethyl Sulfate
Cancer has been observed in rats after inhalation or intravenous administration. Because it is toxic and difficult to handle, it tends to be substituted for other methylating agents in the laboratory.
Methyl iodide is used for O-methylation and is expensive but less hazardous. Dimethyl carbonate is less toxic than methyl iodide and dimethyl sulfate and can be used in place of dimethyl sulfate for N-methylation. However, Dimethyl Sulfate may be judged an appropriate reagent because of its higher reaction efficiency and easier availability.