Diethyl Sulfate
A high-purity ethylating agent supplied for dye, pharmaceutical, agrochemical, and surfactant synthesis — for closed-system industrial use by trained personnel only.
What is Diethyl Sulfate?
Diethyl Sulfate — DES — is the diethyl ester of sulfuric acid: a colourless oily liquid with a faint peppermint odour. It is the ethyl analogue of dimethyl sulfate and behaves in the same way, transferring an ethyl group to a nucleophile.
It is the standard reagent where an ethyl rather than a methyl group is required — on the nitrogen of a dye intermediate, on a phenol, or in quaternising a tertiary amine to a cationic surfactant. Several of the N-ethylated toluidines in this range are made using it.
At Chelora Chemicals, DES is distilled and packaged to a controlled acidity and moisture specification, since free sulfuric acid and water both reduce ethylation efficiency and shorten storage life. It carries the same severe hazard classification as dimethyl sulfate and is supplied on the same basis.
- Appearance
- Colourless to pale yellow oily liquid
- Odour
- Faint, peppermint-like (not a warning property)
- Solubility
- Slowly hydrolyses in water; soluble in organic solvents
- Function
- Ethylating agent
- Grade
- Technical / industrial
Formula diagram
A sulfate centre carrying two ethyl ester groups
- Molecular formulaC4H10O4S
- Molecular weight154.19 g/mol
- IUPAC nameDiethyl sulfate
- Functional groupsSulfate diester
- CAS number64-67-5
Technical product information
Standard specification for Chelora Chemicals' technical grade Diethyl Sulfate. Custom-grade and bulk specifications are available on request.
| Chemical name | Diethyl Sulfate |
|---|---|
| Synonyms | DES, Ethyl sulfate, Sulfuric acid diethyl ester |
| CAS number | 64-67-5 |
| Molecular formula | C4H10O4S |
| Molecular weight | 154.19 g/mol |
| Assay (purity) | ≥ 99.0% |
| Appearance | Clear, colourless to pale yellow oily liquid |
| Density (20°C) | 1.170–1.180 g/cm³ |
| Boiling point | 208°C (with decomposition) |
| Melting point | −25°C |
| Flash point | 104°C (closed cup) |
| Acidity (as H2SO4) | ≤ 0.2% |
| Packaging | 250 kg drums, IBC (dedicated service) |
| Shelf life | 12 months in sealed original packaging |
Applications of Diethyl Sulfate
Dye & pigment synthesis
Ethylates amines and phenolic intermediates to build cationic and disperse dye structures.
N-alkylated amine manufacture
Used to produce N-ethyl and N,N-diethyl anilines and toluidines for dye chemistry.
Pharmaceutical intermediates
Introduces ethyl groups on nitrogen and oxygen during API and intermediate manufacture.
Surfactants & quats
Quaternises tertiary amines to give cationic surfactants and antistatic agents.
Agrochemical synthesis
Applied in ethylation steps within crop-protection production routes.
Fine chemicals
A general-purpose ethylating reagent for specialty organic synthesis.
Why choose Chelora Chemicals
Every batch of Diethyl 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% 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 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.
- 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
Diethyl sulfate is a highly hazardous substance. It is classified as a carcinogen and a mutagen, is toxic if inhaled or swallowed, and causes severe skin and eye burns. 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.
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.
Handling requires closed transfer, effective containment, continuous ventilation, chemical-resistant PPE, and immediately available emergency respiratory protection, eyewash, and safety showers.
The carcinogen and mutagen classification means exposure must be reduced to the lowest technically achievable level, with exposure records and health surveillance where your national regulations require them.
Refer to the full Safety Data Sheet and your local regulatory requirements before ordering or handling this product.
Frequently asked questions
What is Diethyl Sulfate used for?
It is an industrial ethylating agent, used to attach ethyl groups to amines, phenols, and other nucleophiles in dye, pharmaceutical, agrochemical, and surfactant manufacture.
How does it compare with dimethyl sulfate?
They are direct analogues and behave the same way, one transferring ethyl and the other methyl. Both carry severe hazard classifications, delayed exposure effects, and poor odour warning. Choose between them purely on which alkyl group the target molecule needs.
What is it used to make in dye chemistry?
Among other things, the N-ethylated toluidines and anilines that rhodamine, xanthene, and triarylmethane dyes are built from. Several intermediates in this catalogue are ethylated using it.
How does it react with water?
It hydrolyses slowly in cold water and rapidly when hot or alkaline, giving ethanol and sulfuric acid. This is why moisture must be excluded from storage: hydrolysis consumes product and raises acidity.
Why is the odour not a useful warning?
The faint peppermint odour 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.
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 regardless of how they feel.
Is it classified as a carcinogen?
Yes, and as a mutagen. Exposure must be reduced to the lowest technically achievable level, with restricted access, exposure records, and health surveillance where your national regulations require them.
What materials of construction are compatible?
Stainless steel, glass, and lined steel in normal service. Confirm gasket and seal compatibility before commissioning any transfer line, and exclude moisture throughout the system.
What purity do you supply?
Standard technical grade is supplied at a minimum assay of 99% with acidity, calculated as sulfuric acid, at or below 0.2%. Higher specifications can be manufactured to order.
What packaging is available?
250 kg drums and IBCs in dedicated service. Because of the hazard classification, packaging and transport arrangements are confirmed case by case with the receiving site.
Is diethyl sulfate regulated?
Yes. It carries strict transport, workplace exposure, and occupational health requirements in most jurisdictions, and 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 required transport documentation.