Tin(IV) chloride

Tin(IV) chloride, also known as tin tetrachloride or stannic chloride, is an inorganic compound of tin and chlorine with the formula SnCl₄. It is a colorless hygroscopic liquid, which fumes on contact with air. 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.

Tin(IV) chloride

Tin (IV) chloride Anhydrous Tin(IV) chloride Tin(IV) chloride pentahydrate.jpg Tin(IV) chloride pentahydrate
Names
IUPAC names Tetrachlorostannane Tin tetrachloride Tin(IV) chloride
Other names Stannic chloride
Identifiers
CAS Number	7646-78-8 Y 10026-06-9 (pentahydrate) N
3D model (JSmol)	anhydrous: Interactive image pentahydrate: Interactive image
ChemSpider	22707 Y
ECHA InfoCard	100.028.717
EC Number	231-588-9
PubChem CID	24287
RTECS number	XP8750000
UNII	67H76LFL3V Y
UN number	1827
CompTox Dashboard (EPA)	DTXSID1029679
InChI InChI=1S/4ClH.Sn/h4*1H;/q;;;;+4/p-4 Y Key: HPGGPRDJHPYFRM-UHFFFAOYSA-J Y InChI=1/4ClH.Sn/h4*1H;/q;;;;+4/p-4 Key: HPGGPRDJHPYFRM-XBHQNQODAC
SMILES anhydrous: Cl[Sn](Cl)(Cl)Cl pentahydrate: Cl[Sn-2](Cl)(Cl)([OH2+])([OH2+])Cl.O.O.O
Properties
Chemical formula	SnCl4
Molar mass	260.50 g/mol (anhydrous) 350.60 g/mol (pentahydrate)
Appearance	Colorless 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)
Solubility in water	hydrolysis,very hygroscopic (anhydrous) very soluble (pentahydrate)
Solubility	soluble in alcohol, benzene, toluene, chloroform, acetone, kerosene, CCl4, methanol, gasoline, CS2
Vapor pressure	2.4 kPa
Magnetic susceptibility (χ)	−115·10−6 cm3/mol
Refractive index (nD)	1.512
Structure
Crystal structure	monoclinic (P21/c)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314, H412
Precautionary statements	P260, P264, P273, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
NFPA 704 (fire diamond)	3 0 1
Safety data sheet (SDS)	ICSC 0953
Related compounds
Other anions	Tin(IV) fluoride Tin(IV) bromide Tin(IV) iodide
Other cations	Carbon tetrachloride Silicon tetrachloride Germanium tetrachloride Lead(IV) chloride
Related compounds	Tin(II) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Preparation

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

Sn + 2Cl
₂ → SnCl
₄

Structure

Anhydrous tin(IV) chloride solidifies at −33 °C to give monoclinic crystals with the P21/c space group. It is isostructural with SnBr₄. The molecules adopt near-perfect tetrahedral symmetry with average Sn–Cl distances of 227.9(3) pm.^[2]

Space-filling model of anhydrous SnCl₄.

Structure of solid SnCl₄.

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 [SnCl₄(H₂O)₂] molecules together with varying amounts of water of crystallization. The additional water molecules link together the molecules of [SnCl₄(H₂O)₂] through hydrogen bonds.^[3] Although the pentahydrate is the most common hydrate, lower hydrates have also been characterised.^[4]

Aside from water, other Lewis bases form adducts with SnCl₄. These include ammonia and organophosphines. The complex [SnCl₆]²⁻ is formed with hydrochloric acid making hexachlorostannic acid.^[1]

Applications

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 useful precursors to catalysts (e.g., dibutyltin dilaurate) and polymer stabilizers.^[6]

Organic synthesis

SnCl₄ is used in Friedel–Crafts reactions as a Lewis acid catalyst.^[1] For example, the acetylation of thiophene to give 2-acetylthiophene is promoted by tin(IV) chloride.^[7] Similarly, tin(IV) chloride is useful for the nitrations.^[8]

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 supplanted by a mixture of silicon tetrachloride and titanium tetrachloride near the end of the war due to shortages of tin.^[9]

References

1. Egon Wiberg, Nils Wiberg, Arnold Frederick Holleman (2001). Inorganic Chemistry. Elsevier. ISBN 0-12-352651-5.{{cite book}}: CS1 maint: multiple names: authors list (link)
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; et al. (2004). "Hydrates of tin tetrachloride". Acta Crystallographica Section C. 60 (4): i47–i49. doi:10.1107/S0108270104005633. PMID 15071197.
5. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
6. 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
7. John R. Johnson, G. E. May (1938). "2-Acetothienone". Organic Syntheses. 18: 1. doi:10.15227/orgsyn.018.0001.
8. 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. S2CID 98109571.
9. Fries, Amos A. (2008). Chemical Warfare. Read. pp. 148–49, 407. ISBN 978-1-4437-3840-8..

External links

• International Chemical Safety Card 0953
• tinchemical.com/products (industrial uses) at the Wayback Machine (archived 2005-02-28)