Dimethyl Sulfate
A high-purity methylating agent supplied for dye, pharmaceutical, agrochemical, and surfactant synthesis — for closed-system industrial use by trained personnel only.
What is Dimethyl Sulfate?
Dimethyl Sulfate, abbreviated DMS, is the dimethyl ester of sulfuric acid: a colourless to pale yellow oily liquid with a faint onion-like odour. Each of its two methyl groups can be transferred to a nucleophile, with methyl sulfate leaving in its place.
That makes it one of the most efficient methylating agents in industrial chemistry. It methylates amines, phenols, thiols, and carboxylates cleanly and at moderate temperature, which is why it remains a standard reagent in dye, pharmaceutical, and surfactant manufacture despite its hazard profile.
At Chelora Chemicals, DMS is distilled and packaged to a controlled acidity and moisture specification, since free sulfuric acid and water both reduce methylation efficiency and shorten storage life. It is supplied only to industrial users with the containment, training, and emergency procedures the product requires.
- Appearance
- Colourless to pale yellow oily liquid
- Odour
- Faint, onion-like (not a warning property)
- Solubility
- Slowly hydrolyses in water; soluble in organic solvents
- Function
- Methylating agent
- Grade
- Technical / industrial
Formula diagram
A sulfate centre carrying two methyl ester groups
- Molecular formulaC2H6O4S
- Molecular weight126.13 g/mol
- IUPAC nameDimethyl sulfate
- Functional groupsSulfate diester
- CAS number77-78-1
Technical product information
Standard specification for Chelora Chemicals' technical grade Dimethyl Sulfate. Custom-grade and bulk specifications are available on request.
| Chemical name | Dimethyl Sulfate |
|---|---|
| Synonyms | DMS, Methyl sulfate, Sulfuric acid dimethyl ester |
| CAS number | 77-78-1 |
| Molecular formula | C2H6O4S |
| Molecular weight | 126.13 g/mol |
| Assay (purity) | ≥ 99.5% |
| Appearance | Clear, colourless to pale yellow oily liquid |
| Density (20°C) | 1.328–1.335 g/cm³ |
| Boiling point | 188°C (with decomposition) |
| Melting point | −32°C |
| Flash point | 83°C (closed cup) |
| Acidity (as H2SO4) | ≤ 0.1% |
| Packaging | 250 kg drums, IBC, ISO tank (dedicated service) |
| Shelf life | 12 months in sealed original packaging |
Applications of Dimethyl Sulfate
Dye & pigment synthesis
Methylates amines and phenolic intermediates to build cationic and disperse dye structures.
Pharmaceutical intermediates
Introduces methyl groups on nitrogen and oxygen atoms during API and intermediate manufacture.
Agrochemical synthesis
Used in methylation steps within herbicide, fungicide, and insecticide production routes.
Surfactants & quats
Quaternises tertiary amines to produce cationic surfactants, softeners, and antistatic agents.
Photographic & imaging chemicals
Applied in the synthesis of sensitisers and specialty imaging intermediates.
Fine & specialty chemicals
A general-purpose methylating reagent for flavour, fragrance, and specialty organic intermediates.
Why choose Chelora Chemicals
Every batch of Dimethyl Sulfate is manufactured, tested, and documented to a standard that formulators and process chemists can build on with confidence — from first sample to full production volume.
Consistent purity
Assay controlled at ≥99.5% with acidity and moisture verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Flexible volumes
From 250 kg drums to dedicated IBC and ISO tank service.
Technical support
Process, handling, and compliance guidance from our chemistry team.
Storage and guidelines
- 01Store in tightly sealed original containers in a cool, dry, well-ventilated, dedicated store.
- 02Keep below 25°C and out of direct sunlight; protect from moisture, which causes slow hydrolysis to sulfuric acid.
- 03Segregate from water, alkalis, ammonia, amines, oxidising agents, and all combustible material.
- 04Use only compatible materials of construction: stainless steel, glass, or lined steel — never aluminium or ordinary carbon steel in wet service.
- 05Keep containers in a bunded, locked area with restricted access and clear hazard signage.
- 06Have neutralising material and emergency equipment available at the storage and use points at all times.
Handling precautions
Dimethyl sulfate is a highly hazardous substance. It is fatal if inhaled, causes severe skin and eye burns, and is classified as a carcinogen and a suspected mutagen. It must only be handled in closed systems by trained personnel under a formal risk assessment.
Its odour is faint and offers no reliable warning of dangerous concentrations, and the effects of exposure — particularly on the respiratory tract — can be delayed by several hours after the exposure occurred.
Handling requires closed transfer, effective local exhaust or full containment, continuous ventilation, chemical-resistant PPE, and immediately available emergency respiratory protection, eyewash, and safety showers.
Anyone with a suspected exposure must be removed from the area and placed under medical observation even if they feel well, because symptoms may not appear immediately.
Spill response, decontamination, and disposal must follow the site emergency plan and the full Safety Data Sheet. Review the SDS and your local regulatory requirements before ordering or handling this product.
Frequently asked questions
What is Dimethyl Sulfate used for?
It is an industrial methylating agent. It transfers methyl groups to amines, phenols, thiols, and carboxylates during the manufacture of dyes, pharmaceuticals, agrochemicals, and cationic surfactants. It is a reagent, not a finished product.
Why is DMS preferred over other methylating agents?
It is liquid, easy to meter, reacts cleanly at moderate temperature, and delivers both methyl groups efficiently, which makes it cost-effective at scale. The trade-off is its hazard profile, which is why many plants weigh it against dimethyl carbonate or methyl iodide for a given step.
How does it react with water?
It hydrolyses slowly in cold water and rapidly in hot or alkaline water, producing methanol and sulfuric acid. This is why moisture must be excluded from storage: hydrolysis both consumes the product and raises acidity.
Why is the odour not a useful warning?
The onion-like odour is faint and the odour threshold sits well above the level at which the vapour is dangerous. Personnel cannot rely on smell to detect a leak, so engineering controls and monitoring are essential rather than optional.
What does 'delayed effects' mean for exposure?
Symptoms from inhalation or skin contact often do not appear immediately and can develop hours later. Anyone with a suspected exposure must be removed from the area and placed under medical observation even if they feel fine at the time.
What materials of construction are compatible?
Stainless steel, glass, and lined steel are used in normal service. Aluminium and unlined carbon steel are unsuitable where moisture may be present, since hydrolysis products are corrosive. Confirm gasket and seal compatibility before commissioning any transfer line.
What purity do you supply?
Standard technical grade is supplied at a minimum assay of 99.5% with acidity, calculated as sulfuric acid, at or below 0.1%. Higher specifications can be manufactured to order.
What packaging sizes are available?
250 kg drums, IBCs, and ISO tanks in dedicated service. Because of the hazard classification, packaging and transport arrangements are confirmed on a case-by-case basis with the receiving site.
How should DMS be stored?
In sealed original containers in a cool, dry, bunded, access-controlled store below 25°C, segregated from water, alkalis, amines, and oxidising agents, with neutralising material and emergency equipment on hand.
Is Dimethyl Sulfate regulated?
Yes. It carries strict transport, workplace exposure, and occupational health requirements in most jurisdictions, and is subject to carcinogen-specific controls in many. Confirm your national requirements and site permissions before ordering.
Do you provide a Certificate of Analysis?
Yes. Every batch is dispatched with a Certificate of Analysis and Safety Data Sheet covering assay, acidity, density, and appearance, together with the transport documentation required for the consignment.