Tetramethyl lead
Structural formula | ||||||||||||||||
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General | ||||||||||||||||
Surname | Tetramethyl lead | |||||||||||||||
other names |
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Molecular formula | C 4 H 12 Pb | |||||||||||||||
Brief description |
flammable, volatile, colorless liquid |
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External identifiers / databases | ||||||||||||||||
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properties | ||||||||||||||||
Molar mass | 267.33 g mol −1 | |||||||||||||||
Physical state |
liquid |
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density |
2.00 g cm −3 |
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Melting point |
−28 ° C |
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boiling point |
110 ° C |
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Vapor pressure |
32 mbar (20 ° C) |
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solubility | ||||||||||||||||
Refractive index |
1.512 (20 ° C) |
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safety instructions | ||||||||||||||||
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MAK |
0.05 mg m −3 (calculated as lead) |
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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 . Refractive index: Na-D line , 20 ° C |
Tetramethyl lead , with the constitutional formula Pb (CH 3 ) 4 , is a chemical compound from the group of organic lead compounds .
Extraction and presentation
Tetramethyl lead can be obtained by reacting lead (II) chloride with methyl magnesium chloride (which is itself produced by reacting magnesium with methyl chloride ).
Alternatively, it can be obtained by reacting lead (II) iodide with methyllithium and methyl iodide .
Technically TML mainly by reaction of a lead sodium - alloy prepared with methylene chloride.
properties
Tetramethyl lead is a flammable, volatile, colorless, highly refractive liquid with a sweetish odor, which is very sparingly soluble in water. It decomposes explosively from a temperature above 90 ° C, with lead smoke being produced.
use
Tetramethyl lead is added to gasoline for gasoline engines (especially for aircraft engines) as an anti-knock agent.
safety instructions
The vapors of tetramethyl lead can form an explosive mixture with air ( flash point 38 ° C).
Individual evidence
- ↑ a b c d e f g h i j Entry on tetramethyl lead in the GESTIS substance database of the IFA , accessed on July 23, 2016(JavaScript required) .
- ↑ a b c d e f Georg Brauer (Ed.), With the collaboration of Marianne Baudler u. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 781.
- ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry lead alkyls in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on December 14, 2016. Distributors can expand the harmonized classification and labeling .
- ↑ Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 75-74-1 or tetramethyl lead ), accessed on November 2, 2015.
- ^ Dodd S. Carr: Lead Compounds . In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH, Weinheim 2005, doi : 10.1002 / 14356007.a15_249 .
- ↑ Prof. Blum's educational server for chemistry: lead (quote: "This is no longer added to gasoline for gasoline engines. However, there is still plenty of it in gasoline for piston-powered aircraft engines.")