Bis (tributyltin) oxide
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| General | ||||||||||||||||
| Surname | Bis (tributyltin) oxide | |||||||||||||||
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| Molecular formula | C 24 H 54 OSn 2 | |||||||||||||||
| Brief description |
colorless liquid |
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| properties | ||||||||||||||||
| Molar mass | 596.08 g mol −1 | |||||||||||||||
| Physical state |
liquid |
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| density |
1.17 g cm −3 |
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| Melting point |
<−45 ° C |
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| boiling point |
220–230 ° C (10 h Pa ) |
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| solubility |
very bad in water (71.2 mg l −1 at 20 ° C) |
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| safety instructions | ||||||||||||||||
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| Authorization procedure under REACH |
of particular concern : persistent, bioaccumulative and toxic ( PBT ) |
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| MAK |
0.02 mg m −3 |
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| Toxicological data | ||||||||||||||||
| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||||||||
Tributyltin Oxide (TBTO) is a chemical compound that belongs to the organometallic compounds and was mainly used as an underwater paint ( fungicide ) in shipbuilding. Due to its solubility in sea water and its high toxicity (influence on the hormonal system of humans and animals), the substance led to a disruption of the ecosystem in the sea (e.g. in marine snails: hermaphroditic formation with a high risk of extinction).
history
TBTO was used extensively from 1980. However, use in the EU for boats under 25 meters in length has been banned since 1989. This was followed by a ban on the use of all non-chemically bound organotin-containing, fouling-preventing paints for any application within the EU from the year 2000. A worldwide ban on the use of the compound (and all organotin compounds) was sought by various environmental organizations for 2008/2009. Even today, many older ships with such a coating contribute to the spread of the TBTO in the environment during operation or scrapping.
Extraction and presentation
To obtain bis (tributyltin) oxide, tin tetrachloride SnCl 4 and tri- n -butylaluminum nBu 3 Al are first converted to tri- n -butyltin monochloride (nBu 3 Sn-Cl).
- Bis (tributyltin) oxide can be produced by partial hydrolysis with water and a base . Pyridine , triethylamine or anhydrous potassium carbonate , for example , serve as the base .
- ( nBu = CH 3 -CH 2 -CH 2 -CH 2 -; B = base).
From the intermediate product tri- n -butyltin monochloride, other compounds, which earlier v. a. when biocides ( fungicides and bactericides ) were used (e.g. tributyltin benzoate). Today, however, these compounds are only used to a limited extent due to their toxicity.
Chemical properties
TBTO belongs to the group of substances called tributyltin compounds (TBT), a subgroup of organotin compounds that are particularly toxic. This is again a subgroup of the organometallic compounds.
use
TBTO is mainly used as an underwater protective paint (antifouling paint) on ships and cooling towers. In contact with seawater, tributyltin chloride and tributyltin hydroxide are formed , which can also be found in sediment today. This means that it is largely detectable in seawater.
Furthermore, TBTO is used as a fungus poison in wood preservatives (active ingredient content up to approx. 2.5%) and as a preservative in water-thinnable paints.
All tributyltin compounds are disinfectants and are used against fungal attack in textiles, leather, paper, wood and the like. They are also used as seed dressings in crop protection. Some also act as feeding inhibitors on insects.
Organotin compounds are increasingly being used as stabilizers for PCP and PVC to remove hydrogen chloride that has formed. This prevents internal erosion of the materials.
It is also sometimes found as a contaminant in PVC floor coverings, textiles and everyday objects as well as the sportswear of brand manufacturers.
safety instructions
In humans, in addition to symptoms of poisoning, inflammation reactions occur at the contact points after long-term contact. The substance affects the immune system and creates disorders of the endocrine system .
literature
- US EPA (United States Environmental Protection Agency) (1997) Toxicological review: Tributyltin oxide. Integrated Risk Information System (IRIS) and Documentation and Review of the Oral RfD: Tributyltin oxide (TBTO), Source Document US Environmental Protection Agency, Washington, DC.
- M. Hümpel, G. Kühne, U. Täuber, PE Schulze: Studies on the kinetics of TBTO. Toxicology and Analytics of the Tributyltins: The Present Status. ORTEP Assoc., The Hague, NL 1986, pp. 122-142.
Individual evidence
- ↑ a b c d e f data sheet bis (tributyltin) oxide (PDF) from Merck , accessed on January 18, 2011.
- ↑ a b Entry on bis (tributyltin) oxide in the GESTIS substance database of the IFA , accessed on July 23, 2016(JavaScript required) .
- ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry tributyltin compounds, unless specifically listed in this appendix in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on January 9, 2017. Manufacturers or distributors can extend the harmonized classification and labeling .
- ↑ Data sheet bis (tributyltin) oxide from Sigma-Aldrich , accessed on September 12, 2015 ( PDF ).
- ↑ Entry in the SVHC list of the European Chemicals Agency , accessed on July 17, 2014.