Previous - Next
Lead and its organic compounds
DESIGNATIONS
Registry name |
Lead compounds - organic |
|
Note: |
As lead tetraethyl and lead tetramethyl are the only commercially important organic lead compounds, the following data will refer to these substances. |
|
| CAS No.: | 78-00-2 | 75-74-1 |
| Chemical name: | Lead tetraethyl | Lead tetramethyl |
| Synonyms, Trade names: | Tetraethyllead, TEL, | Tetramethyllead, TML, |
| Tetraethyl plumbum, Ethyl fluid | ||
| Tetramethylplumbum, Methyl fluid | ||
| Chemical name (German): | Bleitetraethyl | Bleitetramethyl |
| Chemical name (French): | Plomb tétraéthyle | Plomb tétraméthyle |
| Appearance: | colourless oily liquid | colourless liquid |
| sweet odour when highly diluted | sweet odour when highly diluted | |
BASIC CHEMICAL AND PHYSICAL DATA
Empirical formula: |
C8H20Pb |
C4H12Pb |
Rel. molecular mass: |
322.4 g |
267.33 g |
Density: |
1.653 g/cm3 |
1.995 g/cm3 |
Relative gas density: |
11.2 |
9.23 |
Boiling point: |
>100°C decomposition |
>110°C decomposition |
Melting point: |
-136.8°C |
-27.5°C |
Vapour pressure: |
0.3 hPa at 20°C 3.0 hPa at 50°C |
32 hPa at 20°C 128 hPa at 50°C |
Flash point: |
» 80°C |
<21°C |
Ignition temperature: |
220°C |
|
Explosion limits: |
1.8 vol.% (lower explosion limit) |
1.8 vol.% (lower explosion limit) |
Solvolysis/solubility: |
in water: virtually insoluble soluble in organic solvents and fat |
in water: virtually insoluble soluble in organic solvents and fat |
Conversion factors: |
1 ppm = 13.4 mg/m3 1 mg/m3 = 0.07 ppm |
1 ppm = 11.1 mg/m3 1 mg/m3 = 0.09 ppm |
ORIGIN AND USE
Usage:
Tetraethyllead and tetramethyllead were added to motor-vehicle fuels as anti-knock agents.
Origin/derivation:
TEL is produced either via radical reaction of lead alloys (Na/Mg) with ethylchloride
at about 70°C or via reaction of triethylaluminium with lead acetate in non polar
solvents.
Toxicity
Humans: |
LDLo 1.70 µg/kg (estimated), (TEL) |
acc. UBA, 1986 |
Mammals: |
||
Rat |
LDLo 17 mg/kg, oral, (TEL) |
acc. UBA, 1986 |
LC50 850 mg/m3, inhalation (60 min), (TEL) |
acc. UBA, 1986 |
|
LDLo 31 mg/kg, intravenous, (TEL) |
acc. UBA, 1986 |
|
TDLo 11 mg/kg, oral, (6.-16. day of pregnancy), (TEL) |
acc. UBA, 1986 |
|
TDLo 7,500 µg/kg, oral, (4.-14. day of pregnancy), (TEL) |
acc. UBA, 1986 |
|
LD50 15 mg/kg, parenteral, (TEL) |
acc. UBA, 1986 |
|
LD50 109 mg/kg, oral, (TML) |
acc. UBA, 1986 |
|
LDLo 73 mg/kg, intraperitoneal, (TML) |
acc. UBA, 1986 |
|
TDLo 80 mg/kg, oral, (9.-11. day of pregnancy), (TML) |
acc. UBA, 1986 |
|
LD50 105 mg/kg, parenteral, (TML) |
acc. UBA, 1986 |
|
Mouse |
LCLo 650 mg/m3, inhalation (7h), (TEL) |
acc. UBA, 1986 |
LDLo 86 mg/kg, subcutaneous, (TEL) |
acc. UBA, 1986 |
|
TDLo 100mg/kg, subcutaneous (21d), intermittent, (TEL) |
acc. UBA, 1986 |
|
Rabbit |
LDLo 24 mg/kg, oral, (TML) |
acc. UBA, 1986 |
LDLo 3,391 mg/kg, dermal, (TML) |
acc. UBA, 1986 |
|
LDLo 90 mg/kg, intravenous, (TML) |
acc. UBA, 1986 |
|
Guinea pig |
LDLo 995 mg/kg, dermal, (TEL) |
acc. UBA, 1986 |
Aquatic organisms: |
||
Fish |
1.4 mg/l fatal |
acc. UBA, 1986 |
Plankton |
0.5 mg/l toxic |
acc. UBA, 1986 |
Characteristic effects:
Humans/mammals: TEL/TML are highly toxic lead compounds. Because of their lipophilic properties they are readily absorbed through the skin. TEL/TML primarily act on the central nervous system causing excitation, epileptic spasms and delirium. Paralysis and Parkinson´s Disease may appear as a retarded effect. The toxicity is mainly due to the triethyl lead ion which forms at decomposition. When alkylated they may have a carcinogenic effect. Chronic exposure may result in lead poisoning.
(Refer also to Lead and its inorganic compounds)
ENVIRONMENTAL BEHAVIOUR
Water:
Surface water forms an accumulation sink for organic lead compounds. As TEL/TML are
not readily soluble in water, they sink and accumulate in the sediment or they are
adsorbed on suspended particles.
Air:
Large quantities of lead are released into the atmosphere from combustion processes. There
is a major difference between urban and rural areas. Lead compounds may be transported
over a considerable area depending on wind speed, wind direction, precipitation and
humidity. The majority is however directly sedimented or removed from the air by way of
precipitation. Lead is adsorbed on small particles of dust in the air and these in turn
are deposited on vegetation and soil. The accumulation of lead from motor-vehicle
emissions takes place in the immediate vicinity of roads.
Soil:
All types of lead compounds accumulate in soil.
(Refer also to Lead and its inorganic compounds)
ENVIRONMENTAL STANDARDS
Medium/ acceptor |
Sector |
Country/ organ. |
Status |
Value |
Cat. |
Remarks |
Source |
| Air: | Workp | D | L | 0.075 mg/m3 | MAK | Skin, calculated as Pb |
DFG, 1989 |
| Workp | SU | (L) | 0.005 mg/m3 | PDK | Skin, calculated as Pb |
acc. KETTNER, 1979 | |
| Workp | USA | (L) | 0.1 mg/m3 | TWA | Skin, TEL, calculated as Pb |
ACGIH, 1986 | |
| Workp | USA | (L) | 0.15 mg/m3 | TWA | Skin, TML, calculated as Pb |
acc. AUER TECHNIKUM 1988 |
Comparison/reference values
(Refer also to Lead and its inorganic compounds)
Assessment/comments
As TEL and TML are highly toxic, their use as an anti-knock agent in fuels has been considerably restricted in industrial nations. Vapour inhalation and skin contact are to be avoided at all costs.
(Refer also to Lead and its inorganic compounds)