Diethyl Sulfate
A high-purity ethylating agent, supplied as diethyl sulfate for N- and O-ethylation of dye intermediates, cationic dyes and fine chemicals.
What is Diethyl Sulfate?
Diethyl Sulfate is a colourless oily liquid with a faint peppermint-like odour: the di-ester of ethanol and sulfuric acid, and the ethyl counterpart of dimethyl sulfate.
It does the same job with a different group. Where dimethyl sulfate installs a methyl, this installs an ethyl, and that single carbon makes a real difference downstream: N-ethyl and N,N-diethyl aniline intermediates absorb at different wavelengths and carry different solubility and fibre affinity from their methyl equivalents. That is why basic, cationic and disperse dye ranges are built on ethylated intermediates where a particular shade is wanted.
It reacts a little more slowly than the methyl ester and is slightly less volatile, but it carries the same class of severe health hazards. It is a closed-system material and the handling section below should be read in full before any purchase decision.
- Appearance
- Colourless oily liquid
- Odour
- Faint, peppermint-like
- Solubility
- Slight; hydrolyses
- Function
- Ethylating agent
- Grade
- Technical
The diethyl ester of sulfuric acid
- Molecular formulaC4H10O4S
- Molecular weight154.19 g/mol
- IUPAC nameDiethyl sulfate
- Functional groupsSulfate diester
- CAS number64-67-5
Technical product information
Standard specification for Chelora Dyes' technical grade Diethyl Sulfate. Higher assay grades are available on request.
| Chemical name | Diethyl Sulfate |
|---|---|
| Synonyms | Diethyl sulphate, DES, Ethyl sulfate |
| CAS number | 64-67-5 |
| Molecular formula | C4H10O4S |
| Molecular weight | 154.19 g/mol |
| Assay (purity) | ≥ 99.0% |
| Appearance | Colourless to pale yellow oily liquid |
| Melting point | Approx. −25°C |
| Boiling point | Approx. 208°C (decomposes) |
| Density | Approx. 1.17 g/cm³ at 20°C |
| Acidity (as H2SO4) | ≤ 0.1% |
| Ethanol content | ≤ 0.2% |
| Colour (APHA) | ≤ 50 |
| Solubility | Slightly soluble in water; hydrolyses to ethanol and sulfuric acid |
| Transport classification | UN 1594, diethyl sulphate (verify against current documentation) |
| Packaging | 250 kg lined MS drums; larger volumes to closed offloading systems |
| Shelf life | 12 months in sealed, dry, cool storage |
Applications of Diethyl Sulfate
N-ethylation of amines
Converts aniline intermediates to N-ethyl and N,N-diethyl derivatives for dye synthesis.
Cationic and basic dyes
Quaternises tertiary amines to build the cationic centres of basic dye ranges.
Disperse dye intermediates
Supplies ethylated components where shade and fibre affinity must be tuned.
Ethyl ethers of phenols
Ethylates phenolic intermediates where an ether rather than a free hydroxyl is required.
Pharmaceutical intermediates
Applied in ethylation steps across active ingredient and intermediate manufacture.
Fine chemical synthesis
Used as a general ethylating reagent in specialty and custom synthesis.
Why choose Chelora Dyes
Controlled assay
Acidity, ethanol and colour held low so ethylation runs clean and predictable.
Full documentation
COA, SDS, and transport classification supplied with every shipment.
Compliant logistics
Toxic goods packing and paperwork handled to the applicable transport mode.
Technical support
Closed handling, decontamination, and compliance guidance from our team.
Storage and guidelines
- Store in sealed original containers in a cool, dry, ventilated and locked store.
- Keep the store bunded, signed, and restricted to authorised trained personnel.
- Hold dilute alkali or ammonia decontamination media ready at the point of use.
- Segregate from water, alkalis, strong oxidisers and ammonia stocks in storage.
- Transfer by closed system only — no open pouring, decanting or manual sampling.
- Keep emergency response arrangements in place and tested.
Handling precautions
Diethyl Sulfate is toxic by inhalation, ingestion and skin contact, and causes severe burns to skin and eyes. It is classified as a carcinogen and a suspected mutagen.
Like dimethyl sulfate it gives poor warning of harmful vapour concentrations, and the onset of respiratory injury can lag behind the exposure. Treat any suspected exposure as significant: remove the person from the area and arrange medical observation regardless of how they feel.
Handle in closed systems under a written procedure, by trained operators only, with full chemical protective clothing, gloves and appropriate respiratory protection. Dilute alkali or ammonia hydrolyses the material and should be available as decontamination media wherever it is stored or used.
Arrange medical support and emergency response in advance rather than at the point of incident, and refer to the current Safety Data Sheet in full before any handling operation.
Frequently asked questions
What is Diethyl Sulfate used for?
It is the standard ethylating agent in dye manufacture. It transfers an ethyl group to amines, phenols and other nucleophiles, which is how N-ethyl and N,N-diethyl aniline intermediates are made for basic, cationic and disperse dyes. It is also used in pharmaceutical and fine chemical synthesis.
How does it compare with dimethyl sulfate?
They work the same way; the difference is the group transferred. Diethyl sulfate installs an ethyl group rather than a methyl group, which shifts the shade and solubility of the resulting dye. It reacts somewhat more slowly and is slightly less volatile, but it carries the same class of severe health hazards and demands the same closed handling discipline.
Why does an ethyl group matter to the finished dye?
Alkyl groups on the amine nitrogen of a dye intermediate shift the absorption of the finished chromophore and alter its solubility and substantivity. Ethyl gives a different balance from methyl, so N-ethylated intermediates are chosen where a particular shade or fibre affinity is wanted.
Is it soluble in water?
Only slightly, and it hydrolyses in contact with water to ethanol and sulfuric acid. Hydrolysis is faster in warm or alkaline conditions, which is the basis of the decontamination method.
How is it decontaminated?
Dilute alkali or ammonia solution hydrolyses it to harmless products, and decontamination media should be kept ready wherever it is handled or stored. Build the specific method from the Safety Data Sheet into your written procedures.
What purity do you supply?
Standard grade is supplied at a minimum assay of 99%, with acidity, ethanol content and colour held within tight limits. Higher assay grades can be supplied to order.
What packaging is available?
250 kg lined mild steel drums, with larger volumes available to plants with closed offloading systems. We review receiving arrangements before first shipment.
Is it hazardous to handle?
Yes, seriously. It is toxic, causes severe burns to skin and eyes, and is classified as a carcinogen and a suspected mutagen. Like dimethyl sulfate it should be treated as a closed-system-only material, handled by trained operators under a written procedure with decontamination media available, and the current Safety Data Sheet must be reviewed first.
