Tin(IV) chloride, also known as tin tetrachloride or stannic chloride, is an inorganic compound with the formula Sn Cl₄. It is a colorless hygroscopic liquid, which fumes on contact with air. It is used as a precursor to other tin compounds. It was first discovered by

Andreas Libavius Andreas Libavius or Andrew Libavius was born in Halle, Germany c. 1550 and died in July 1616. Libavius was a renaissance man who spent time as a professor at the University of Jena teaching history and poetry. After which he became a physician a ...

(1550–1616) and was known as ''spiritus fumans libavii''.

Preparation

It is prepared from reaction of

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...

gas with tin at . : Sn + 2 Cl₂ → SnCl₄

Structure

Anhydrous tin(IV) chloride solidifies at −33 °C to give

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

crystals with the P21/c

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...

. It is isostructural with SnBr₄. The molecules adopt near-perfect tetrahedral symmetry with average Sn–Cl distances of 227.9(3) pm. SnCl4-xtal-down-b-axis-2005-CM-3D-polyhedra

SnCl4-xtal-down-b-axis-2005-CM-3D-polyhedra

Reactions

Tin(IV) chloride is well known as a Lewis acid. Thus it forms hydrates. The pentahydrate SnCl₄·5H₂O was formerly known as butter of tin. They all consist of nCl₄(H₂O)₂molecules together with varying amounts of water of crystallization. The additional water molecules link together the molecules of nCl₄(H₂O)₂through hydrogen bonds. Although the pentahydrate is the most common hydrate, lower hydrates have also been characterised. Aside from water, other Lewis bases form adducts with SnCl₄. These include

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

and organo phosphines. The complex nCl₆sup>2− is formed with hydrochloric acid making hexachlorostannic acid.

Applications

Precursor to organotin compounds

Anhydrous tin(IV) chloride is a major precursor in

organotin chemistry Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Organotin chemistry is part of the wider field of organometallic chemistry. The first organotin compound was diethyltin diiodide (), discovered b ...

. Upon treatment with Grignard reagents, tin(IV) chloride gives tetraalkyltin 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 useful precursors to catalysts (e.g.,

dibutyltin dilaurate Dibutyltin dilaurate (abbreviated DBTDL), also called dibutyltindilaurate or butynorate, is an organotin compound that is used as a catalyst. It is a colourless oily liquid. In terms of its structure, the molecule consists of two laurate groups ...

) and polymer stabilizers.G. G. Graf "Tin, Tin Alloys, and Tin Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005 Wiley-VCH, Weinheim.

Organic synthesis

SnCl₄ is used in Friedel-Crafts reactions as a Lewis acid

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

. For example, the acetylation of thiophene to give 2-acetylthiophene is promoted by tin(IV) chloride. Similarly, tin(IV) chloride is useful for the nitrations.

Safety

Stannic chloride was used as a

chemical weapon A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as a ...

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, as it formed an irritating (but non-deadly) dense smoke on contact with air: it was substituted for by a mixture of

silicon tetrachloride Silicon tetrachloride or tetrachlorosilane is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications. Preparation Silic ...

and

titanium tetrachloride Titanium tetrachloride is the inorganic compound with the formula . It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. is a volatile liquid. Upon contact with humid air, it forms thick clouds ...

near the end of the war due to shortages of tin..

References

External links

International Chemical Safety Card 0953
{{Chlorides Chlorides Tin(IV) compounds Metal halides