Tin(IV) chloride

Tin(IV) chloride
Anhydrous Tin(IV) chloride
Tin(IV) chloride pentahydrate
Names
IUPAC names
Tetrachlorostannane
Tin tetrachloride
Tin(IV) chloride
Other names
Stannic chloride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.717
EC Number 231-588-9
RTECS number XP8750000
UN number 1827
Properties
SnCl4
Molar mass 260.50 g/mol (anhydrous)
350.60 g/mol (pentahydrate)
Appearance colorless to slightly yellow fuming liquid
Odor acrid
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)
decomposes (anhydrous)
very soluble (pentahydrate)
Solubility soluble in alcohol, benzene, toluene, chloroform, acetone, kerosene, CCl4, methanol, gasoline, CS2
Vapor pressure 2.4 kPa
−115·10−6 cm3/mol
1.512
Structure
monoclinic (P21/c)
Hazards
Safety data sheet ICSC 0953
Corrosive (C)
R-phrases (outdated) R34, R52/53
S-phrases (outdated) (S1/2), S7/8, S26, S45, S61
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
0
3
1
Related compounds
Other anions
 Tin(IV) fluoride
Tin(IV) bromide
Tin(IV) iodide
Other cations
 Carbon tetrachloride
Silicon tetrachloride
Germanium tetrachloride
Tin(II) chloride
Lead(IV) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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.[1] It was first discovered by Andreas Libavius (1550–1616) and was known as spiritus fumans libavii.

Preparation

It is prepared from reaction of chlorine gas with elemental tin at 115 °C (239 °F).

Sn + 2 Cl2 → SnCl4

Structure

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.[2]

Structure of solid SnCl4.

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.[3] Although the pentahydrate is most common of the hydrates, lower hydrates have also been characterised.[4]

Reactions

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.[1]

Precursor to organotin compounds

Anhydrous tin(IV) chloride is a major precursor in organotin chemistry. Upon treatment with Grignard reagents, tin(IV) chloride gives tetraalkyltin compounds:[5]

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.[1] 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.[6]

Uses

The main application of SnCl4 is as a precursor to organotin compounds, which are used as catalysts and polymer stabilizers.[7] 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.

Safety

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.[8]

References

  1. 1 2 3 Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5
  2. ↑ Reuter, Hans; Pawlak, Rüdiger (April 2000). "Die Molekül- und Kristallstruktur von Zinn(IV)-chlorid". Zeitschrift für anorganische und allgemeine Chemie (in German). 626 (4): 925–929. doi:10.1002/(SICI)1521-3749(200004)626:4<925::AID-ZAAC925>3.0.CO;2-R.
  3. ↑ Barnes, John C.; Sampson, Hazel A.; Weakley, Timothy J. R. (1980). "Structures of di-μ-hydroxobis[aquatrichlorotin(IV)]-1,4-dioxane(1/3), di-μ-hydroxobis[aquatrichlorotin(IV)]-1,8-epoxy-p-menthane(1/4), di-m-hydroxobis[aquatribromotin(IV)]-1,8-epoxy-p-menthane(1/4), di-μ-hydroxobis[aquatrichlorotin(IV)], and cis-diaquatetrachlorotin(IV)". J. Chem. Soc., Dalton Trans. (6): 949. doi:10.1039/DT9800000949.
  4. ↑ Genge, Anthony R. J.; Levason, William; Patel, Rina; Reid, Gillian; Webster, Michael (2004). "Hydrates of tin tetrachloride". Acta Crystallographica Section C. 60 (4): i47–i49. doi:10.1107/S0108270104005633.
  5. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
  6. ↑ Thurston, David E.; Murty, Varanasi S.; Langley, David R.; Jones, Gary B. (1990). "O-Debenzylation of a Pyrrolo[2,1-c][1,4]benzodiazepine in the Presence of a Carbinolamine Functionality: Synthesis of DC-81". Synthesis. 1990: 81–84. doi:10.1055/s-1990-26795.
  7. ↑ G. G. Graf "Tin, Tin Alloys, and Tin Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005 Wiley-VCH, Weinheim. doi:10.1002/14356007.a27_049
  8. ↑ Fries, Amos A. (2008). Chemical Warfare. Read. pp. 148–49, 407. ISBN 1-4437-3840-9..
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