Diethyl Sulfate
A high-purity ethylating reagent, supplied as diethyl sulfate (DES) for use as a process chemical across dye, pigment and fine chemical manufacture.
What is Diethyl Sulfate?
Diethyl sulfate, abbreviated DES, is a colourless to pale yellow oily liquid, the diester of sulfuric acid with ethanol, carrying two ethyl groups attached to a central sulfate unit.
Like its methyl homologue dimethyl sulfate, DES is a process chemical rather than a chromophore or dye precursor itself — it is a widely used ethylating agent, transferring an ethyl group onto phenolic, amino and thio nucleophiles under controlled conditions. It is chosen specifically where the target molecule requires an ethyl rather than methyl substituent, across dye, agrochemical, pharmaceutical and fine chemical manufacture.
At Chelora Dyes, DES is manufactured and packaged to a controlled assay and low acidity, so ethylation reactions downstream run predictably and give a consistent, reproducible intermediate batch to batch.
- Appearance
- Colourless / pale yellow liquid
- Odour
- Faint, characteristic
- Reactivity
- Hydrolyses slowly in water
- Function
- Ethylating agent
- Grade
- Technical / process
Sulfate diester with two ethoxy substituents
- Molecular formulaC4H10O4S
- Molecular weight154.18 g/mol
- IUPAC nameDiethyl sulfate
- Functional groupsSulfate ester (x2 ethyl)
- CAS number64-67-5
Technical product information
Standard specification for Chelora Dyes' technical grade Diethyl Sulfate. Custom-grade and bulk specifications are available on request.
| Chemical name | Diethyl sulfate |
|---|---|
| Synonyms | DES, Sulfuric acid diethyl ester |
| CAS number | 64-67-5 |
| Molecular formula | C4H10O4S |
| Molecular weight | 154.18 g/mol |
| Assay (purity) | ≥ 98.0% |
| Appearance | Colourless to pale yellow oily liquid |
| Boiling point | 208–210°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 Diethyl Sulfate
Dye & pigment ethylation
Introduces ethoxy and N-ethyl groups during synthesis of dye and pigment intermediates.
Agrochemical intermediates
Used in the ethylation step of herbicide, fungicide and other agrochemical active ingredient synthesis.
Pharmaceutical intermediates
Applied in the manufacture of pharmaceutical intermediates requiring selective O- or N-ethylation.
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 an ethylating step in specialty rubber and polymer additive synthesis.
Fine chemical & specialty synthesis
Used across research and process-scale synthesis wherever efficient ethylation is required.
Why choose Chelora Dyes
Consistent purity
Assay controlled at ≥98% 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, ethylation, 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
Diethyl sulfate is classified as a suspected human carcinogen and mutagen, and is toxic if inhaled, with symptoms that can be delayed after exposure — a hazard profile that makes it essential to have exposure controls confirmed in advance rather than relying on immediate symptom feedback.
It is corrosive to skin, eyes and the respiratory tract, and vapour exposure can cause serious injury even at low concentrations.
Handling must be restricted to trained personnel using closed transfer systems, full chemical-resistant PPE including appropriate 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 Diethyl Sulfate used for?
Diethyl sulfate is a potent ethylating agent used to introduce ethyl groups onto oxygen, nitrogen and sulfur atoms during the manufacture of dyes, dye intermediates, agrochemicals, pharmaceuticals and other fine chemicals.
How does Diethyl Sulfate differ from Dimethyl Sulfate?
Both are sulfate diesters used as alkylating agents, but diethyl sulfate transfers an ethyl group rather than a methyl group. It is chosen wherever the target molecule specifically requires an ethyl substituent, such as certain ethoxylated dye intermediates and N-ethyl compounds, rather than the methylated analogue.
Is Diethyl Sulfate soluble in water?
It has limited solubility in water and hydrolyses slowly, releasing ethanol 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 98%, with acidity and moisture held within tight limits appropriate for ethylation 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. Diethyl sulfate is classified as a suspected human carcinogen and mutagen, is toxic if inhaled, and is 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 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.