Dimethyl Sulfate
A high-purity methylating reagent, supplied as dimethyl sulfate (DMS) for use as a process chemical across dye, pigment and fine chemical manufacture.
What is Dimethyl Sulfate?
Dimethyl sulfate, abbreviated DMS, is a colourless to pale yellow oily liquid, the diester of sulfuric acid with methanol, carrying two methyl groups attached to a central sulfate unit.
Like chlorosulfonic acid, DMS is a process chemical rather than a chromophore or dye precursor itself — it is one of the most widely used methylating agents in industrial chemistry, transferring a methyl group onto phenolic, amino and thio nucleophiles under controlled conditions. That single reagent step underlies large parts of dye, agrochemical, pharmaceutical and fine chemical manufacture wherever an O-methyl, N-methyl or S-methyl group needs to be installed efficiently and at scale.
At Chelora Dyes, DMS is manufactured and packaged to a controlled assay and low acidity, so methylation reactions downstream run predictably and give a consistent, reproducible intermediate batch to batch.
- Appearance
- Colourless / pale yellow liquid
- Odour
- Faint, onion-like
- Reactivity
- Hydrolyses slowly in water
- Function
- Methylating agent
- Grade
- Technical / process
Sulfate diester with two methoxy substituents
- Molecular formulaC2H6O4S
- Molecular weight126.13 g/mol
- IUPAC nameDimethyl sulfate
- Functional groupsSulfate ester (x2 methyl)
- CAS number77-78-1
Technical product information
Standard specification for Chelora Dyes' technical grade Dimethyl Sulfate. Custom-grade and bulk specifications are available on request.
| Chemical name | Dimethyl sulfate |
|---|---|
| Synonyms | DMS, Sulfuric acid dimethyl ester |
| CAS number | 77-78-1 |
| Molecular formula | C2H6O4S |
| Molecular weight | 126.13 g/mol |
| Assay (purity) | ≥ 99.0% |
| Appearance | Colourless to pale yellow oily liquid |
| Boiling point | 188–190°C |
| Free acidity (as H2SO4) | ≤ 0.2% |
| Moisture content | ≤ 0.1% |
| Reactivity | Hydrolyses slowly in water; faster under hot or alkaline conditions |
| Packaging | Corrosion-resistant drums; ISO tank containers on request |
| Shelf life | 12 months in sealed original packaging |
Applications of Dimethyl Sulfate
Dye & pigment methylation
Introduces methoxy and N-methyl groups during synthesis of dye and pigment intermediates.
Agrochemical intermediates
Used in the methylation step of herbicide, fungicide and other agrochemical active ingredient synthesis.
Pharmaceutical intermediates
Applied in the manufacture of pharmaceutical intermediates requiring selective O- or N-methylation.
Surfactant & quaternary ammonium synthesis
Used to quaternise amines in the production of cationic surfactants and specialty chemicals.
Rubber & polymer chemical intermediates
Applied in smaller volumes as a methylating step in specialty rubber and polymer additive synthesis.
Fine chemical & specialty synthesis
Used across research and process-scale synthesis wherever efficient methylation is required.
Why choose Chelora Dyes
Consistent purity
Assay controlled at ≥99% with acidity and moisture verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Safe logistics
Corrosion-resistant packaging and ISO tank supply matched to regulated transport requirements.
Technical support
Process, methylation, and compliance guidance from our chemistry team.
Storage and guidelines
- Store only in sealed, corrosion-resistant original packaging.
- Keep isolated from moisture, strong bases, ammonia and amines — contact can generate heat and hazardous decomposition products.
- Store in a cool, dry, well-ventilated area away from heat, direct sunlight and incompatible materials.
- Restrict access to a dedicated, clearly signed storage area with appropriate spill containment.
- Use only compatible corrosion-resistant drums or tanks, clearly labelled with hazard information.
- Inspect containers regularly for integrity; never transfer using open pouring or non-dedicated equipment.
Handling precautions
Dimethyl sulfate is classified as a suspected human carcinogen and mutagen, and is fatal if inhaled, with serious symptoms that can be delayed by several hours after exposure — a hazard profile that makes it especially important to have exposure controls confirmed before, not after, symptoms appear.
It is severely corrosive to skin, eyes and the respiratory tract, and vapour exposure at even low concentrations can cause serious injury.
Handling must be restricted to trained personnel using closed transfer systems, full chemical-resistant PPE including supplied-air or full-face respiratory protection, dedicated emergency eyewash and safety showers, and site-specific spill and decontamination procedures established in advance.
Consult the full Safety Data Sheet and applicable local regulations for exposure limits, engineering controls, transport classification, spill containment, disposal, and first-aid measures before any handling operation.
Frequently asked questions
What is Dimethyl Sulfate used for?
Dimethyl sulfate is a potent methylating agent used to introduce methyl groups onto oxygen, nitrogen and sulfur atoms during the manufacture of dyes, dye intermediates, agrochemicals, pharmaceuticals and other fine chemicals.
Why is Dimethyl Sulfate used as a methylating agent?
It transfers a methyl group readily and cleanly to nucleophilic sites such as phenolic oxygens, amines and thiols under relatively mild conditions, making it one of the most efficient and cost-effective methylating reagents available for large-scale process chemistry.
Is Dimethyl Sulfate soluble in water?
It has limited solubility in water and hydrolyses slowly, releasing methanol and sulfuric acid; hydrolysis is much faster in hot or alkaline conditions. It is miscible with most organic solvents.
What purity do you supply?
Standard technical grade is supplied at a minimum assay of 99%, with acidity and moisture held within tight limits appropriate for methylation process use. Higher assay grades can be manufactured to order.
What packaging is available?
Supplied in corrosion-resistant drums and ISO tank containers, sized to suit process consumption and regulated transport requirements. Speak with our team about the packaging format that fits your site.
How should it be stored, and for how long?
In sealed original packaging in a cool, dry, well-ventilated store, isolated from moisture, strong bases and ammonia. Shelf life is 12 months from manufacture when storage conditions are maintained; container integrity should be inspected regularly.
Is it hazardous to handle?
Yes. Dimethyl sulfate is classified as a suspected human carcinogen and mutagen, is fatal if inhaled, and is severely corrosive to skin, eyes and the respiratory tract, often with delayed symptom onset after exposure. It must only be handled by trained personnel using closed transfer systems, dedicated PPE with full respiratory protection, and site-specific emergency and decontamination procedures. Review the Safety Data Sheet and applicable local regulations before any handling operation.
Do you provide a Certificate of Analysis?
Yes. Each batch ships with a Certificate of Analysis and Safety Data Sheet covering assay, acidity and relevant process specifications.