Organolead stability

There is very little information about the stabilities of lead species in aqueous solution containing less than lOngdm-3 lead. No changes in concentrations of ionic organolead species in water occurred over a period of 3 months when samples were stored at 4°C in the dark (Van Cleuvenbergen et al., 1992). Freezing is probably the best means of preserving soils and sediments. 

Organolead-alkali compounds are the least stable of the group-IVB-alkali compounds. They are thermolabile and air and moisture sensitive but are stabilized in such donor solvents as Et O, tetrahydrofuran (THF) or NHj. Information on their isolation is sparse and no physical properties of pure R PbM (M = alkali metal) or R2PbM2 are available. Nevertheless, RjPbM in situ is a powerful tool for synthesizing unsymmetrical RjPbR tetraorganoleads ... 

T, must be taken. Stability decreases with increasing atomic number of the group-IIA element and aryl are more stable than alkyl. Donors exert a stabilizing effect and, therefore, solvents such as tetrahydrofuran (THE) or pyridine (PY) are expedient for preparation and handling them. Diethyl ether is not sufficiently basic to impart adequate stability. The reactivity can be correlated with ionic character in the Pb-group-IIA element bond, the organolead moiety being anionic. 

In addition to organotin compounds, the survey work [199] mentions organolead compounds, recommended as stabilizers of chlorine-containing high-molecular compounds - hydroxides of triallqrl- and tri-aryllead, allq/ 1- and aryllead salts of aliphatic acids, and triethyllead hexylmaleate. Alkyl- and arylplumbanes have not foimd wide use in the plastics industry on account of their high toxicity. 

Organic derivatives of Group IV find applications in diverse areas. Especially important are the silicone polymers, organotin compounds as stabilizers for plastics and as biocides and organolead antiknock agents for petrol. 

Radical formers as catalysts were of no help they mostly accelerated the decomposition of Bu3PbH. Also catalysis by aluminum alkyls 189,201), used for the addition of organotin hydrides to olefins, is not useful because the transfer of an alkyl group to RjPbH depends upon the necessary addition of R2AIH to the olefin 189, 284) at 20° C (which is the limit for the stability of the organolead compounds used) and this does not take place. 

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