Dimethyl sulfate
| Names | |
|---|---|
| Other names
Dimethyl ester of sulfuric acid
Dimethyl sulphate DMSO4 Me2SO4 Methyl sulfate Sulfuric acid dimethyl ester | |
| Properties | |
| C2H6O4S (CH3O)2SO2 | |
| Molar mass | 126.13 g/mol |
| Appearance | Colorless, oily liquid |
| Odor | Faint, onion-like |
| Density | 1.333 g/cm3 (25 °C) |
| Melting point | −32 °C (−26 °F; 241 K) |
| Boiling point | 188 °C (370 °F; 461 K) (decomposes) |
| Reacts | |
| Solubility | Miscible with acetone, dichloromethane, methanol |
| Vapor pressure | 0.1 mmHg (20 °C) |
| Hazards | |
| 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) |
| Related compounds | |
| Related compounds
|
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). | |
| Infobox references | |
Dimethyl sulfate is a chemical compound with chemical formula (CH3O)2SO2. As the diester of methanol and sulfuric acid, its formula is often written as (CH3)2SO4 or Me2SO4, where CH3 or Me is methyl.
Contents
Properties
Chemical
Dimethyl sulfate reacts exothermically with water, to give sulfuric acid and methanol.
- (CH3O)2SO2 + 2 H2O → H2SO3 + 2 CH3OH
Physical
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.
Availability
Dimethyl sulfate is sold by chemical suppliers. Due to its high toxicity, it's extremely difficult to acquire this compound.
Preparation
Dimethyl sulfate can be prepared by reacting sulfur trioxide with anhydrous methanol or dimethyl ether.
- 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
Projects
- Methylating agent
- Make methyl esters
- Preparation of quaternary ammonium salts and tertiary amines
Handling
Safety
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.
Storage
Should be kept in an airtight container, inside another larger container filled with a neutralizing medium. A lided bucket with sand may be used.
Disposal
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.
