1,4-Butane sultone — 1,4-BS on most route sheets — is a six-membered cyclic sulfonate ester, one of the δ-sultones. We supply it as a clear liquid, colorless to faintly yellow; held up in a glass bottle it reads water-white to a pale straw. In a plant it has one job: to attach a four-carbon sulfonate chain to another molecule. The ring opens as soon as the sultone meets a nucleophile, so an amine that will not dissolve in water, or an alcohol that carries no charge, comes out of the reaction as a water-soluble sulfonate. That single step is why the material sits near the front of so many routes for electroplating brighteners, levelers and wetting agents.
The usual charge is small — a few kilos against a batch of hundreds — so consistency between lots matters more than the drum size. Free acid, water and assay are what decide whether the sulfobutyl group lands where the route sheet says it should. Most of what we ship goes into plating intermediate work and into coating production chemicals projects; the rest goes into pharmaceutical and fine chemical routes, battery electrolyte research and photosensitive material chemistry where a charged, water-soluble group has to be built into the molecule.
| Chemical name | 1,4-Butane sultone (1,4-BS) |
| CAS number | 1633-83-6 |
| Molecular formula | C4H8O3S |
| Formula weight | 136.17 |
| Appearance | Clear liquid |
| Colour | Colorless to yellowish |
| Purity, pharmaceutical grade (%) | ≥99.5 |
| Purity, electronic grade (%) | ≥99.9 |
| Acid value, ppm (HF) | ≤100 |
| Water content, ppm (K.F.), pharmaceutical grade | ≤0.10 |
| Water content, ppm (K.F.), electronic grade | ≤200.0 |
Both grades come off the same chemistry and differ in assay and in the water limit written against them. Take the pharmaceutical grade when the sultone is charged into a pharmaceutical or fine chemical step, or when your incoming specification is written around a 99.5% minimum. It is also the grade most often ordered where the sultone becomes an intermediate for nickel plating: the sulfobetaine built from it carries the solubility and the charge of the finished brightener, so a small shift in the sultone shows up in the bath.
The electronic grade is specified at ≥99.9% assay, and it is the one to take when the derived molecule ends up inside a device — an electrolyte additive for lithium batteries, a photosensitive material, or an additive for electronic plating — and residual heavy ends in the sultone would travel all the way to the finished part. On coating production chemicals work the decision is usually made by the customer's own route sheet rather than by the catalogue: 99.5 on the sheet means pharmaceutical grade, 99.9 means electronic.
The water limit is stated separately for each grade, so match it to the water tolerance of the reaction rather than to the assay alone; a route that is dried down before the sultone is charged has more room than one that runs in a wet solvent. If the material is going into a coating chemicals programme, tell us the assay and the water figure your procedure specifies and we will match the lot to that pair of numbers.
| Property | Value |
|---|---|
| Physical form at 25 °C | Clear liquid |
| Melting range | 12–15 °C |
| State below the melting range | Solid or semi-solid |
| Density at 25 °C | approx. 1.331 g/mL |
| Boiling point at 25 mmHg | above 165 °C |
| Atmospheric boiling point | Not quoted; the figure above is measured under vacuum |
| Refractive index (nD20) | approx. 1.464 |
| Chemical class | Cyclic sulfonate ester (δ-sultone) |
| Moisture sensitivity | Hydrolyses on contact with water |
| Flash point | Stated on the SDS issued with the lot |
The chemistry is a ring-opening alkylation. Hydroxyls, amines and other nucleophiles attack the sultone and the ring opens, leaving a sulfobutyl group — four carbons ending in a sulfonate — attached to what was the nucleophile. The new group is strongly hydrophilic and carries a permanent negative charge, so a molecule that started out hydrophobic comes out water-soluble and charged. That is how a short-chain amine is turned into a surface active agent, and how a pyridine derivative becomes a sulfobetaine that dissolves freely in a plating bath while keeping an affinity for the metal surface.
Because the sultone is an alkylating agent, the reaction is run with a controlled stoichiometry or an excess of the nucleophile, and water content matters: any water present competes for the sultone and produces the hydroxy sulfonate instead of the product the route intended. Routes that build additives for an electroless plating process rely on the same clean ring-opening — the difference between a bright, even deposit and a patchy one frequently starts with how cleanly this step ran, long before the additive reaches a bath.
Every lot is released against the specification: assay, acid value and water by Karl Fischer are the three figures that decide whether the material behaves, and they are the three we test before a drum leaves. Anyone buying plating chemicals for a regulated line gets those figures for the lot they receive rather than a generic range, so incoming inspection has something to check against.
Safety and regulatory paperwork travels with the order. The SDS carries the GHS classification, and if your market needs a REACH or RoHS statement for the grade you are buying, ask for it with the enquiry and we will confirm what can be issued for that lot rather than assume it. It is the paper trail paint chemicals suppliers review before a new source goes onto an approved list.
Traceability runs both ways. The batch number links the drum back to the lot it was released from and forward to whatever it was charged into, which is what you need when a metal plating process line starts to drift and the additive package is under suspicion — the first question is always which lot went in.
The material melts between 12 and 15 °C, boils above 165 °C at 25 mmHg, and sits at a density of roughly 1.331 g/mL with a refractive index near 1.464. Those values keep its behaviour predictable through mixing, heating and storage, so existing process lines, dosing systems and reaction vessels can take it on without unexpected phase changes or handling surprises. Its clear, faint yellow appearance acts as a practical visual cue for purity — a visible shift in colour is a prompt to check the batch before charging it to a line.
Formulators usually meet this material in one of three settings: as a sultone building block in coating and paint chemical synthesis, as an electrolyte additive candidate in battery material development, or as an intermediate in surfactant and specialty chemical production. In each case the same practical questions come up — how the material behaves once heated, how it disperses into an existing formulation, and how it should be stored between batches. Buyers evaluating it for a particular line generally request a sample and run their own trials before scaling up, then confirm grade, packaging format and documentation with the supplier ahead of the first commercial order.
Choosing the right match is where most sourcing decisions stall. As a trading supplier, we keep one point of contact from first enquiry to after-sales: tell us what you are making and the conditions you work under, and we shortlist the closest matches from our supplier network, compare specifications and arrange samples before you commit to a bulk order. If something does not behave as expected, we work with the supplying partner on the cause and a practical fix, and stay with the case until it is settled. Email, WeChat or WhatsApp enquiries get a reply within 24 hours.
We supply two grades. The pharmaceutical grade is specified at ≥99.5% and the electronic grade at ≥99.9%; both are clear liquids, colorless to yellowish. Order the grade that matches the assay on your own specification — if the route sheet says 99.9, the electronic grade is the one to take, and if it says 99.5, the pharmaceutical grade covers it.
The acid value is limited to ≤100 ppm (HF) on both grades, so a standard order carries the same free-acid ceiling whichever assay you choose. It is one of the three release figures we test on every lot of plating chemicals before the drum is released.
Water is measured by Karl Fischer and the limit is stated per grade: ≤0.10 for the pharmaceutical grade and ≤200.0 for the electronic grade, both on the ppm scale. Because a sultone hydrolyses, the measured value for your lot is what matters for the reaction — a typical value is no help when the batch is moisture sensitive.
At room temperature it is a clear liquid, colorless to yellowish. The melting point is 12–15 °C, so in a cold store you may open the drum to a solid or semi-solid mass; warm it until the contents are fully liquid and mix before sampling. Density is about 1.331 g/mL at 25 °C and the refractive index is around 1.464.
Yes — that is its largest single use. Reacted with a tertiary amine or a pyridine derivative, the sultone opens and leaves a sulfobutyl group, giving a sulfobetaine that dissolves readily in the bath. Those intermediates are formulated into brightener and leveler systems for nickel plating, where the balance between solubility and surface activity is what makes the addition work.
Confirm the grade and the water limit against your own specification, the pack size against your monthly consumption, and the storage conditions at your site. If the drum will sit in an unheated area, plan for the material to solidify and for a warming step before it is charged into a metal plating process. Tell us the bath or the application it is going into and we will check the lot against it before it ships.
