| Other names
Dimethyl ester of sulfuric acid
Sulfuric acid dimethyl ester
|Molar mass||126.13 g/mol|
|Appearance||Colorless, oily liquid|
|Density||1.333 g/cm3 (25 °C)|
|Melting point||−32 °C (−26 °F; 241 K)|
|Boiling point||188 °C (370 °F; 461 K) (decomposes)|
|Solubility||Miscible with acetone, dichloromethane, methanol|
|Vapor pressure||0.1 mmHg (20 °C)|
|Safety data sheet||Sigma-Aldrich|
|Flash point||83 °C (182 °F; 356 K)|
|Lethal dose or concentration (LD, LC):|
LD50 (Median dose)
| 205 mg/kg (rat, oral)|
140 mg/kg (mouse, oral)
| Sulfuric acid|
Sodium methyl sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Dimethyl sulfate reacts exothermically with water, to give sulfuric acid and methanol.
- (CH3O)2SO2 + 2 H2O → H2SO3 + 2 CH3OH
Dimethyl sulfate is a colorless oily liquid with a slight onion-like odor (although smelling it would represent significant exposure). It reacts with water, but it's miscible with many organic solvents, such as methanol and halocarbons.
Dimethyl sulfate is sold by chemical suppliers. Due to its high toxicity, it's extremely difficult to acquire this compound.
- SO3 + 2 CH3OH → (CH3O)2SO2 + H2O
- SO3 + (CH3O)2O → (CH3O)2SO2
Thermal decomposition of sodium methyl sulfate yields dimethyl sulfate:
- 2 CH3NaSO4 → Na2SO4 + (CH3)2SO4
Methyl nitrite and methyl chlorosulfonate also result in dimethyl sulfate:
- CH3ONO + (CH3)OSO2Cl → (CH3)2SO4 + NOCl
- Methylating agent
- Make methyl esters
- Preparation of quaternary ammonium salts and tertiary amines
Dimethyl sulfate is corrosive and highly poisonous. Like all strong alkylating agents, Me2SO4 is extremely toxic, to both touch and inhalation. Dimethyl sulfate is absorbed through the skin, mucous membranes, and gastrointestinal tract, and can cause a fatal delayed respiratory tract reaction. There is no strong odor or immediate irritation to warn of lethal concentration in the air.
Should be kept in an airtight container, inside another larger container filled with a neutralizing medium. A lided bucket with sand may be used.
The compound can be neutralized by very carefully adding it dropwise to crushed ice, then an alkali is gently added until all the remaining acid is neutralized. This procedure must be done outside or in a remote location.