Fuel additives, organoleads

It is interesting to mention that PbCl2 is stable whereas PbCLj is thermodynamically unstable and decomposes at room temperature to yield PbCl2 and elemental CI2. On the other hand, organolead(IV) compounds have been prepared (and have been used extensively as fuel additives, such as PbEtq) whereas species like PbEt2 have yet to be prepared and are likely not possible, as they disproportionate to the more thermodynamically stable PbEt4 and solid Pb. This tendency is also reflected in the reaction enthalpies of the methyl... 

The most important organolead compounds are tetramethyllead and tetraethyllead, both of which have been used as fuel additives because of their anti-knocking... 

Rosenberg et al. [72] used reversed-phase HPLC with atmospheric pressure chemical ionization MS to separate and measure several organotin species that had been extracted from sediments. These species were used as a fuel additive when organolead compounds were replaced. They are environmentally important because of their bioaccumulation and toxicities. 

Organolead compounds have been recently widely used. They are used in agriculture (as pesticides), in medicine, as well as in various chemical processes as catalysts for the polymerisation of vinyl monomers, chlorination of hydrocarbons, etc. Lead tetraalkyl derivatives are used as additives for engine fuels due to their antiknock properties. 

The addition of an organolead compound to motor gasolines raises octane numbers, but not uniformly. The incremental increase depends on the composition of the base stock fuel, the particular lead compound employed, the increasing amount of lead compound added, the method of testing, etc. As an extremely crude indication, it may be assumed that 2 ml of tetraethyllead per gallon will result in roughly 10 octane numbers appreciation in the fuel. 

Metallic lead is soft, bluish white, highly malleable, and ductile. It is a poor conductor of heat and electricity and resistant to corrosion. A protective film of basic carbonate is formed on the surface of lead exposed to moist air. Lead reacts with water in the presence of air to form lead hydroxide. Inorganic Pb(II) compounds are mainly insoluble or slightly soluble in water. Exceptions are lead chlorate, perchlorate, nitrate, and acetate. Lead chloride is moderately soluble (9.9 g/liter at 20°C). The most important organolead compounds are tetramethyllead and tetraethyllead used as antiknock additives in fuel. Both are colorless liquids at room temperature with boiling points 110 and 200°C, respectively. Photolytically these degrade to RaPb , R2Pb , and Pb. The different chemical forms of lead have different toxicity, so that speciation information is important [1,2]. 

For organolead compounds, demands for spedation already started with awareness of the toxicology of lead stemming from organolead additives in fuel. For gas... 

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