Methylating Agent · API & Agro Intermediate · UN 1595
Dimethyl sulfate (DMS) is the low-cost, highly reactive methylating agent behind methyl ethers, N-methyl amines and quaternary ammonium salts. Sourced by Chelora Pharmachem, Mumbai, and delivered across India with a batch COA and SDS.
How Buying Works
Send the quantity, grade (technical or synthesis, assay ≥ 99%), packing, delivery city and target date. Quote CAS 77-78-1 so there is no confusion.
Price, lead time and packing in one reply, with the specification, COA and SDS/MSDS for your QA team to review.
Samples can be arranged for QC checks and trial methylations, in UN-approved Packing Group I packing, before your commercial order.
Packed, labelled and sent with invoice, batch COA and transport documents. Repeat orders are planned with you.
Product Overview
Dimethyl Sulfate (dimethyl sulphate, DMS, sulphuric acid dimethyl ester; CAS 77-78-1) is the dimethyl ester of sulphuric acid, with the formula (CH3O)2SO2. It is a colourless, oily liquid with a faint onion-like odour that boils at about 188 °C with decomposition. In industry it is one of the most widely used methylating agents: it transfers a methyl group to oxygen, nitrogen and sulphur atoms, and it is preferred over many alternatives because it is cheap, reactive and easy to dose as a liquid.
That reactivity makes dimethyl sulfate a key reagent for methyl ethers of phenols, N-methyl amines and quaternary ammonium compounds, including the methyl sulphate (methosulphate) quats used as fabric softeners. It serves API, agrochemical, dye, fragrance and surfactant producers. The same property also makes it very toxic and a probable human carcinogen: vapour and liquid can cause severe, delayed injury to the lungs, eyes and skin without any warning odour, so it must be handled only in closed systems by trained staff.
As a chemical supplier in Mumbai, Chelora Pharmachem supplies dimethyl sulfate to API, intermediate, agrochemical, dye and specialty-chemical manufacturers across India. Every lot is packed in UN-approved containers and shipped as a Class 6.1 dangerous good by licensed transporters, with a batch-wise COA, SDS/MSDS and specification for your QA, stores and EHS teams. Buyers who need an ethyl group instead of a methyl group can also source Diethyl Sulfate from us.
In Depth
Dimethyl sulfate is a simple diester: a sulphate group whose two acidic hydrogens are replaced by methyl groups. The sulphate is an excellent leaving group, so each methyl carbon is strongly electrophilic. It is a dense, oily liquid that mixes with methanol, acetone, dichloromethane and aromatic solvents, dissolves only sparingly in water, and slowly hydrolyses there to methyl hydrogen sulphate, methanol and finally sulphuric acid.
In an SN2 reaction a nucleophile such as a phenoxide, amine or thiolate attacks a methyl carbon and displaces methyl sulphate. Under mild conditions only the first methyl group reacts readily; the second needs heat or stronger bases. A base such as sodium hydroxide or potassium carbonate is normally used, and the reaction gives methyl ethers, N-methyl amines, quaternary ammonium methyl sulphates or methyl thioethers.
Commercial dimethyl sulfate is made by the continuous reaction of dimethyl ether with sulphur trioxide in closed equipment, followed by distillation. Esterifying sulphuric acid directly with methanol does not work well, because the equilibrium favours methyl hydrogen sulphate and dimethyl ether. The finished product is checked for assay, free acidity and colour, which buyers most often limit on a specification.
Methyl ethers and N-methyl groups appear in many drug molecules and their intermediates, and dimethyl sulfate is a standard way to introduce them on scale. A classic example is methylating gallic acid to 3,4,5-trimethoxybenzoic acid, a building block for trimethoxyphenyl APIs. Because it is genotoxic, process chemists quench excess reagent and show that residual dimethyl sulfate is controlled in the isolated product.
Start with assay by GC, appearance and colour, then compare limits for free acidity (as H₂SO₄), methyl hydrogen sulphate and water, which reduce effective strength and can affect yield. Confirm the packing suits closed transfer at your site and that drums are UN-approved for Packing Group I. Ask for the COA and SDS of the actual batch, and check your storage licence and emergency arrangements.
Chelora Pharmachem supplies dimethyl sulfate (CAS 77-78-1) from its centralized sales office in Mumbai to API, intermediate, agrochemical, dye, fragrance and surfactant manufacturers across India. Share the grade, quantity, packing and delivery location, and our team replies with price, lead time, dangerous-goods transport details and documents, from trial lots for process development to regular bulk supply.
Global Sourcing
Our focus is the Indian market. When local supply is short, or you need a specific purity or origin, our international sourcing desk brings dimethyl sulfate in from trusted producers abroad, and our Mumbai team handles import, dangerous-goods documents and delivery to your plant.
Product Profile
The identifiers and properties purchase and QA teams ask for first. Batch values are always confirmed on the COA.
Identity
EC 201-058-1. Also sold as dimethyl sulphate, DMS or sulphuric acid dimethyl ester. UN 1595.
A central sulphur with two S=O bonds and two methoxy (–OCH₃) groups.
Appearance
Colourless, oily liquid with a faint onion-like odour. Density about 1.33 g/cm³. Boils near 188 °C.
Toxicity
Fatal if inhaled, corrosive and a probable carcinogen. Symptoms can be delayed for hours. Closed handling only.
Technical Data
Reference data for Dimethyl Sulfate, useful when writing a specification, checking an SDS or planning storage and transport.
| Property | Value |
|---|---|
| IUPAC name | Dimethyl sulfate (dimethyl sulphate) |
| Synonyms | DMS, sulphuric acid dimethyl ester, methyl sulphate, dimethyl monosulphate |
| CAS number | 77-78-1 |
| EC number | 201-058-1 |
| PubChem CID | 6497 |
| Molecular formula | C2H6O4S, (CH3O)2SO2 |
| Molar mass | 126.13 g/mol |
| Appearance | Colourless, oily liquid |
| Odour | Faint, onion-like; gives no reliable warning of harmful exposure |
| Melting point | About −32 °C |
| Boiling point | About 188 °C at 1013 hPa, with decomposition |
| Density | About 1.33 g/cm³ at 20 °C |
| Vapour pressure | Low, about 0.1–0.4 hPa at 20 °C |
| Flash point | About 83 °C (closed cup) |
| Solubility in water | About 28 g/L at 18–20 °C, with hydrolysis to methyl hydrogen sulphate, methanol and sulphuric acid |
| Other solvents | Soluble in methanol, acetone, dichloromethane, diethyl ether and aromatic solvents |
| HS code | Heading 2920; Indian tariff item 2920 29 10 (dimethyl sulphate) |
| Transport | UN 1595, Dimethyl sulphate, Class 6.1 (subsidiary 8), Packing Group I; check the batch SDS |
Literature values for reference. Supplied material is tested batch-wise and reported on the COA.
Applications
It methylates oxygen, nitrogen and sulphur atoms on scale, which makes it a workhorse for drug, crop-protection, colour, fragrance and fabric-softener chemistry.
Used for O-methylation of phenols and N-methylation of amines and heterocycles in API and intermediate routes, for example converting gallic acid into 3,4,5-trimethoxybenzoic acid. Residual dimethyl sulfate is treated as a potential genotoxic impurity and controlled in the final API.
O- and N-methylation
Quaternising tertiary amines and fatty esteramines with dimethyl sulfate gives methyl sulphate (methosulphate) quats. These cationic surfactants are the active ingredients of many fabric softeners and hair conditioners, and are also used as antistatic agents and phase-transfer catalysts.
Methosulphate quats
Methyl ether and N-methyl groups are common in herbicides, insecticides and fungicides. Dimethyl sulfate is one of the methylating agents used for such steps, for example in routes to the herbicide dicamba, which is a methoxy-substituted benzoic acid made by methylating a salicylic acid derivative.
Crop-protection chemistry
Used to methylate dye intermediates and to quaternise dye bases into cationic (basic) dyes, which colour acrylic fibres brightly. Methylation can shift shade and improve fastness or solubility, so dye makers specify a clean, high-assay grade for consistent results.
Cationic dyes
Methylating phenols gives aromatic methyl ethers valued in perfumery, such as anisole, veratrole and 2-methoxynaphthalene (nerolin), which has an orange-blossom note. The finished aroma chemical is purified so that no reagent remains in the fragrance material.
Aromatic methyl ethers
Quality & Compliance
Every supply is backed by the documents your QA, regulatory and stores teams expect.
COA, batch-wise
Tests, limits and results for the exact batch you receive, shared before dispatch.
SDS / MSDS
Hazards, safe handling, storage, transport and first-aid measures for Dimethyl Sulfate.
Technical data
Typical properties and the specification we supply against, to match with your in-house spec.
On request
Additional documents for vendor approval and audits can be arranged on request.
Safety & Handling
A short summary for stores, production and EHS teams. It does not replace the Safety Data Sheet supplied with every batch.
Harmonised EU classification: toxic if swallowed, fatal if inhaled, causes severe skin burns and eye damage, may cause an allergic skin reaction, suspected of causing genetic defects and may cause cancer (Carc. 1B; IARC Group 2A). Signal word: Danger. Effects can be delayed 6–24 hours. Check the SDS of the batch.
H301H314H317H330H341H350
Handle only in closed systems or a fume hood with efficient exhaust. Wear chemical goggles and a face shield, gloves rated for dimethyl sulfate (for example butyl rubber or laminate film), impervious clothing, and a suitable respirator wherever vapour may escape. Anyone exposed needs prompt medical observation, even without symptoms.
Store in tightly closed original containers in a cool, dry, well-ventilated, locked store with access limited to trained staff. Keep away from water and moist air, ammonia, amines, strong bases, oxidisers and heat sources, and use secondary containment under drums.
Regulated as UN 1595, Dimethyl sulphate, Class 6.1 (toxic) with subsidiary hazard Class 8 (corrosive), Packing Group I for road and sea. Air transport is generally forbidden. Ship only in UN-approved packing with licensed dangerous-goods transporters.
Evacuate the area and approach upwind only with full protection, including respiratory protection. Absorb with dry sand or another inert absorbent, collect into closed containers, and treat small residues with dilute alkali or ammonia solution. Keep it out of drains, soil and water courses.
PAN India Delivery
From our centralized sales office in Mumbai, we supply Dimethyl Sulfate to buyers in every major manufacturing cluster.
MumbaiMumbai, Thane, Navi Mumbai, Tarapur, Boisar, Pune and Aurangabad.
AhmedabadAhmedabad, Vadodara, Ankleshwar and Vapi.
HyderabadHyderabad and Visakhapatnam.
BaddiBaddi and Haridwar.
GoaPharma and chemical units across Goa.
BengaluruBengaluru and Chennai.
IndoreIndore, Pithampur and Sikkim.
Specification
A typical specification for synthesis-grade dimethyl sulfate (assay ≥ 99%). Share your in-house specification and we quote against it.
The Chemistry
Made
Dimethyl ether reacts with sulphur trioxide in a continuous, closed process to give dimethyl sulfate directly. The crude ester is then distilled under reduced pressure to remove acidic by-products and colour, reaching the assay of about 99% that synthesis users expect.
Used
A phenoxide, amine or thiolate attacks a methyl carbon and displaces methyl sulphate, giving ArO–CH₃, R₃N⁺–CH₃ or RS–CH₃. Base is added to soak up the acid formed, and any excess reagent is destroyed with aqueous alkali or ammonia before work-up.
Tested
Each batch is reported on a COA covering appearance, identification, GC assay and the agreed limits for free acidity, colour and water. Samples are drawn and sealed in closed, compatible containers, so your QC team can check them safely and release the lot quickly.
Stored
Moisture slowly turns it into acidic products that build pressure and corrode containers. Keep drums tightly closed in a cool, dry, ventilated and locked store, away from water, ammonia, amines, alkalis and oxidisers, with spill kits and a decontamination solution ready.
Glossary
Terms you will meet on quotations, specifications and documents for Dimethyl Sulfate.
FAQ
Anything else, call +91 98191 11179 or write to source@chelorapharmachem.com.
Request a QuoteDimethyl sulfate (CAS 77-78-1) is a methylating agent. It adds methyl groups to phenols, amines and thiols in API, agrochemical, dye and fragrance synthesis, and it quaternises amines to make methyl sulphate quats used in fabric softeners, conditioners and other cationic surfactants.
The CAS number is 77-78-1, and the EC number is 201-058-1. Its formula is C₂H₆O₄S, written (CH₃O)₂SO₂, and its molar mass is 126.13 g/mol. Quoting the CAS number avoids confusion with diethyl sulphate and with dimethyl sulphide, which is also abbreviated DMS.
Yes. Dimethyl sulphate is the British and Indian spelling and dimethyl sulfate the American one. DMS, sulphuric acid dimethyl ester and methyl sulphate are other names for the same substance, CAS 77-78-1. Note that dimethyl sulphide (CAS 75-18-3) and dimethyl sulphoxide (DMSO) are completely different chemicals.
Dimethyl sulfate (CAS 77-78-1) transfers a methyl group, while diethyl sulfate (CAS 64-67-5) transfers an ethyl group, so they give different products and are not interchangeable. Diethyl sulfate is a less volatile, slightly less reactive liquid; both are toxic, corrosive alkylating agents that need careful handling.
Both are strong methylating agents. Methyl iodide (CAS 74-88-4) boils at about 42 °C and is far more expensive, so it is mostly used in laboratories and small batches. Dimethyl sulfate is cheaper and less volatile, which is why industry prefers it for large-scale methylation, but it is extremely toxic and must be handled in closed systems.
We supply technical and synthesis grades, typically with a GC assay of 99% or more, subject to availability. Tell us your application, assay, acidity and colour limits and preferred packing when you enquire, so we can quote against your specification.
Keep it in tightly closed original containers in a cool, dry, well-ventilated and locked store, with access limited to trained staff. Keep it away from water, ammonia, amines, alkalis, oxidisers and heat, use secondary containment, and follow the storage section of the SDS supplied with the batch.
Dimethyl sulphate falls under HS heading 2920, esters of other inorganic acids of non-metals. The Indian customs tariff lists it at 2920 29 10. Confirm the full national tariff code with your customs broker before import or export.
Yes, it is very hazardous. It is fatal if inhaled, toxic if swallowed, causes severe burns, may cause skin allergy, and is a suspected mutagen and presumed carcinogen. Symptoms can appear hours after exposure and its faint odour gives no warning. Read the SDS before handling and use closed systems with full protection.
Yes. It is regulated as UN 1595, Dimethyl sulphate, Class 6.1 (toxic) with subsidiary Class 8 (corrosive), Packing Group I for road and sea, and air transport is generally forbidden. Always check the transport section of the SDS supplied with the batch.
We provide a batch-wise Certificate of Analysis (COA), SDS/MSDS and specifications. Additional documents for vendor qualification can be arranged on request.
Yes. We handle requirements from samples and trial lots for R&D, process development and vendor approval up to regular bulk supply for commercial production, subject to product availability and dangerous-goods packing rules.
We supply buyers across India, including Maharashtra, Gujarat, Telangana, Andhra Pradesh, Himachal Pradesh, Goa, Karnataka, Tamil Nadu, Madhya Pradesh, Uttarakhand and Sikkim, from our centralized sales office in Mumbai.
Email source@chelorapharmachem.com or source@cheloragroup.com, call +91 98191 11179, or use the enquiry form on this page. Include the quantity, grade, delivery location and target date.
Request a Quote
Tell us the quantity, grade and delivery location. Our centralized sales team replies with competitive pricing, lead time and documentation.
