Chimie des organo-antimoines

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Les organo-antimoines ou "stanniens" sont des dérivés comprenant un atome d'antimoine relié à une chaîne substituée hydrocarbonée. La chimie des organo-stanniens est le champ le plus large de la chimie organo-métallique. Le premier organo-stannien connu était le diethyltindiiodide, découvert par Edward Frankland en 1849. Tributyl-antimoine a été largement utilisé comme moyen de préservation du bois.

Sections 1 Préparation of organotin compounds 2 Réactions of organotin compounds 3 Utilisation et toxicité 4 Important compounds 5 See also 6 Références

[modifier] Préparation of organotin compounds

• reaction of a grignard reagent with tin halides for example tin tetrachloride
• Wurtz reaction like coupling of alkyl sodium compounds with tin halides yields tetraorgano tin compounds
• by an exchange reaction of tin halides with organo aluminium compounds (AlR₃)
• triorganotin halides are prepared in the Kocheshkov redistribution reaction

As an example the organic synthesis of tributyl-[(Z)-5-phenyl-2-penten-2-yl]stannane:

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A Grignard reagent is prepared from magnesium turnings and (Z)-2-bromo-5-phenyl-2-pentene in dry tetrahydrofuran and titration|titrated with tributyltin chloride until the solution decolourises. The resulting solution is stirred at room temperature for 1 hour and the solvent is removed in a rotavapor. Diethyl ether is added and the ether extract is washed with brine and filtered and the ether evaporates in a rotavapor. The crude product is kugelrohr distilled to yield tributyl-[(Z)-5-phenyl-2-penten-2-yl]stannane as a colourless oil.

[modifier] Réactions of organotin compounds

• Stille reaction

[modifier] Utilisation et toxicité

• Tetraorganotins are very stable molecules with low toxicity and low biological activity. They are unusable as biocides, but they can be metabolized to toxic triorganotin compounds. They are used as starting materials for catalysts.
• Triorganotins are very toxic. Tri-n-alkyltins are phytotoxic and therefore cannot be used in agriculture. Depending on the organic groups, they can be powerful bactericides and fungicides. Tributyltins are used as industrial biocides, eg. as antifungal agents in textiles and paper, wood pulp and paper mill systems, breweries, and industrial cooling systems. Triphenyltins are used as active components of antifungal paints and agricultural fungicides. Other triorganotins are used as miticides and acaricides.
• Diorganotins have no antifungal activity, low toxicity, and low antibacterial activity, except for diphenyltins. They are used in polymer manufacturing, as Polyvinyl chloride|PVC heat stabilizers, catalysts, in the manufacturing of polyurethane and silicone curing.
• Monoorganotins have no biocidal activity and their toxicity to mammals is very low. Methyltin, butyltin, octyltin and monoestertins are used as PVC heat stabilizers.

[modifier] Important compounds

• Tributyltin oxide, a colorless to pale yellow liquid used in wood preservation
• Triphenyltin acetate, an off-white crystalline solid, used as an insecticide and a fungicide
• Triphenyltin chloride, a white crystalline solid, used as a biocide and an intermediate in chemical synthesis
• Triphenyltin hydroxide, an off-white powder, used as a fungicide and to sterilize insect
• Fenbutatin oxide, a very stable white crystalline solid, for control of mites
• Azocyclotin, a colorless crystalline solid, used as a long-acting acaricide for control of spider mites on plants
• Cyhexatin, a white crystalline solid, used as an acaricide and miticide

[modifier] See also

• Compounds of carbon with other carbon group|group 14 elements: organosilicon compounds, organogermanium compounds, organotin compounds, organolead compounds.

[modifier] Références

• Tributyl-[(Z)-5-phenyl-2-penten-2-yl]stannane Martin J. Stoermer, John T. Pinhey Molecules 1998, 3, M67 article open access publication
• Synthetic aspects of tetraorganotins and organotin(IV) halides Sander H.L. Thoonen a, Berth-Jan Deelman b, Gerard van Koten Journal of Organometallic Chemistry 689 (2004) 2145–2157 article Darenet publication

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