3D model (JSmol)
|Molar mass||260.50 g/mol (anhydrous)
350.60 g/mol (pentahydrate)
|Appearance||colorless to slightly yellow fuming liquid|
|Density||2.226 g/cm3 (anhydrous)
2.04 g/cm3 (pentahydrate)
|Melting point||−34.07 °C (−29.33 °F; 239.08 K) (anhydrous)
56 °C (133 °F; 329 K) (pentahydrate)
|Boiling point||114.15 °C (237.47 °F; 387.30 K)|
very soluble (pentahydrate)
|Solubility||soluble in alcohol, benzene, toluene, chloroform, acetone, kerosene, CCl4, methanol, gasoline, CS2|
|Vapor pressure||2.4 kPa|
Refractive index (nD)
|Safety data sheet||ICSC 0953|
|R-phrases (outdated)||R34, R52/53|
|S-phrases (outdated)||(S1/2), S7/8, S26, S45, S61|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Tin(IV) chloride, also known as tin tetrachloride or stannic chloride, is a inorganic compound with the formula SnCl4. At room temperature it is a colourless liquid, which fumes on contact with air, giving a stinging odor. It is used as a precursor to other tin compounds. It was first discovered by Andreas Libavius (1550–1616) and was known as spiritus fumans libavii.
- Sn + 2 Cl2 → SnCl4
Anhydrous tin(IV) chloride solidifies at −33 °C to give monoclinic crystals with the P21/c space group; making it isostructural to solidified SnBr4. Within this the molecules adopt near-perfect tetrahedral symmetry with average Sn–Cl distances of 227.9(3) pm.
Several forms of hydrated tin tetrachloride are known. They all consist of [SnCl4(H2O)2] molecules together with varying amouts of water of crystallization. The additional water molecules link together the molecules of [SnCl4(H2O)2] through hydrogen bonds. Although the pentahydrate is most common of the hydrates, lower hydrates have also been characterised.
Anhydrous tin(IV) chloride is a Lewis acid. It forms adducts with ammonia, organophosphines, and other Lewis bases. When mixed with a small amount of water a semi-solid crystalline mass of the pentahydrate, SnCl4·5H2O is formed. This solid was formerly known as butter of tin. With hydrochloric acid the complex [SnCl6]2− is formed making the so-called hexachlorostannic acid.
Precursor to organotin compounds
- SnCl4 + 4 RMgCl → SnR4 + 4 MgCl2
Anhydrous tin(IV) chloride reacts with tetraorganotin compounds in redistribution reactions:
- SnCl4 + SnR4 → 2 SnCl2R2
These organotin halides are more useful than the tetraorganotin derivatives.
Applications in high organic synthesis
Although a specialized application, SnCl4 is used in Friedel-Crafts reactions as a Lewis acidic catalyst for alkylation and cyclisation. Stannic chloride is used in chemical reactions with fuming (90%) nitric acid for the selective nitration of activated aromatic rings in the presence of inactivated ones.
The main application of SnCl4 is as a precursor to organotin compounds, which are used as catalysts and polymer stabilizers. It can be used in a sol-gel process to prepare SnO2 coatings (for example for toughening glass); nanocrystals of SnO2 can be produced by refinements of this method.
Stannic chloride was used as a chemical weapon in World War I, as it formed an irritating (but non-deadly) dense smoke on contact with air: it was substituted for by a mixture of silicon tetrachloride and titanium tetrachloride near the end of the War due to shortages of tin.
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