Dibutyltin dichloride (DBTC, CAS 683-18-1) is a white to slightly yellowish crystalline organotin compound supplied at 96-99% main content with a tin content of 38-40%. It is an intermediate rather than an end product: it is converted into dibutyltin carboxylates and mercaptides for PVC stabilisation, used as a glass-coating precursor, and used in biocidal and analytical applications. It is also one of the more tightly regulated organotin compounds, and that regulatory position shapes who can buy it and for what.
Hazard notice. Dibutyltin dichloride is toxic and is classified as a substance of very high concern on reproductive-toxicity grounds in the EU. Organotin compounds are subject to restrictions on their use in articles and in consumer products in several markets, and biocidal uses have been withdrawn or restricted in many countries. Handle with full PPE and closed systems; the material is corrosive and the vapour is hazardous. Before ordering, confirm that your intended use and destination market permit it – some end uses that were routine twenty years ago are no longer lawful.
Specification
| Parameter | Value | Why it matters |
|---|---|---|
| Appearance | White or yellowish crystal | Colour drift suggests oxidation or hydrolysis; the material hydrolyses readily in moist air |
| Main content | 96 – 99% | The organotin content; the balance is mainly HCl-related hydrolysis products and water |
| Tin content | 38 – 40% | The analytical check that confirms the assay – theoretical tin for pure DBTC is about 39% |
| Density | About 1.4 g/mL | Used for volume-to-mass conversion in charging |
| Refractive index | About 1.4991 | Identity check, normally measured on the melt |
| Melting point | About 39 deg C | The material is a solid at room temperature and a liquid when warm – it must be handled and dosed as a melt, which is a practical constraint on drum heating |
| Boiling point | About 135 deg C at 10 mmHg | Distilled under vacuum; thermal exposure above this range risks decomposition |
| Flash point | Above 230 deg C | Not a flammability concern in normal handling, though the material must not be heated above safe limits |
| Water solubility | About 320 mg/L | Low but not negligible; hydrolysis in contact with water is the main stability consideration |
What it is used for
| Application | Role | Regulatory position to check |
|---|---|---|
| PVC heat stabiliser intermediate | Converted to dibutyltin maleate, laurate or mercaptide stabilisers | Organotin stabilisers are restricted or voluntarily withdrawn in many consumer and food-contact applications; confirm the end use is still permitted in your market |
| Glass coating precursor | Pyrolytic precursor for tin oxide coatings on glass containers and flat glass | Industrial, closed-process use; the dominant legitimate use in many regions |
| Catalyst and esterification aid | Organotin catalysis in esterification and transesterification | Some catalyst uses are restricted; confirm per market and per application |
| Biocide and preservative | Antifungal and antibacterial action | Biocidal uses have been withdrawn or restricted in many jurisdictions – this is the most tightly controlled application area |
| Analytical reagent | Reference and derivatising agent in tin analysis | Laboratory scale; disposal rules apply |
Regulatory position
| Framework | What applies | What to confirm |
|---|---|---|
| EU REACH – SVHC | Dibutyltin dichloride is identified as a substance of very high concern on reproductive toxicity grounds | Whether your use requires authorisation, and whether the article you make is subject to the organotin restrictions |
| EU REACH – restrictions | Organotin compounds are restricted in articles and consumer products above defined thresholds | The concentration limit that applies to your finished article, not just to the raw material |
| Biocidal Products Regulation | Biocidal uses require product authorisation | Whether the specific product type and use are authorised in the destination country |
| China and other Asian markets | Listed as a hazardous chemical; transport and storage requirements apply | The exact classification and any use restrictions in the destination |
| Transport | Toxic organotin; classification and packing group per the applicable regulations | Confirm with your forwarder – the class depends on packaging and concentration |
| Documentation | COA, SDS in the required language, and route-specific statements | That the SDS reflects the classification your market uses |
Handling and packaging
| Point | Requirement |
|---|---|
| Moisture | Keep dry and sealed. DBTC hydrolyses on contact with water, releasing hydrogen chloride and forming dibutyltin oxide species |
| Drum handling | Melts at about 39 deg C, so drums are usually warmed before use. Heat gently and evenly – local overheating degrades the product |
| Materials | Stainless steel or lined equipment; avoid contact with moist air in open vessels |
| PPE | Chemical-resistant gloves, face protection and closed handling – organotin compounds are absorbed and are reproductive toxicants |
| Packaging | 25 kg plastic drums; confirm the closure and liner are suitable for a material that can melt in transit in warm climates |
| Documentation | Batch COA (main content, tin content, appearance, density, refractive index) plus SDS |
For the technical background and how this compound compares with the monobutyl and tributyl analogues, see the dibutyltin dichloride technical guide and the butyltin compounds comparison.
