Tetraalkyl compounds

Tetraalkyl Compounds of the Group 14 Elements, the Case of SnBu4... 

Recently, we have demonstrated that hydrogen preadsorbed on pla tinum or nickel can react with tin or lead tetraalkyl compounds re suiting in the formation of bimetallic surface entities with metal -metal interaction [5-8]. CSRs leading to the formation of bimetal lie surface species can be written as follows ... 

A classical study on the fate of tetraalkyl compounds in the atmosphere249 shows the effect of photochemical oxidation on the breakdown of R4Pb. Direct ozonolysis of Me Pb (equation 53) presumably proceeds by analogy to the process in tetraethyltin250. 

The use of sodium amide proved to be very successful in the synthesis of nonstabilized ylides free from lithium salts. - The reaction is usually carried out in liquid ammonia, but also a suspension of sodium amide in benzene or THF can be used. Whereas alkyltriarylphosphonium salts are deprotonated in liquid ammonia, in the case of the corresponding tetraalkyl compounds boiling THF is necessary. Mixtures of dry phosphonium salt and powdered sodium amide can be stored indefinitely and hence provide instant ylide mixtures. Upon addition of an ethereal solvent the ylide is quantitatively generated. 

The only other derivatives of this ring system to be reported are the tetraalkyl compounds 2 which were obtained by reaction of the dioxo furans 5 with ethylenediamine. ... 

Prior to their separation by GC, organolead compounds need to be extracted from the sample matrix and, if necessary, derivatized into a volatile and thermally stable form. Volatile nonpolar tetraalkyl compounds can be extracted from environmental samples with nonpolar solvents such as benzene or hexane and injected directly onto the gas chromatograph. The case of nonvolatile, ionic alkyl compounds (R2Pb and RsPb ) is more complex. They should first be extracted and preconcentrated in the presence of NaCl and sodium diethyldithiocarbamate and then derivatized into a volatile form. The most widespread derivatization methods are of two distinct types those based on the use of tetraalkylborates that can be directly performed in the aqueous solution (ethylation and propylation) and those applying... 

In the presence of excess Vi4Pb, vinyl bromide is also formed, proving that the Pb—C bond is cleaved before bromination of the C=C double bond takes place. Hydrochloric acid in the presence of a twofold excess of Vi4Pb cleaves only one vinyl substituent at — 78°C with saturated lead tetraalkyl compounds this reaction takes place only at much higher temperatures. A comparison of the reactivities with vinyltin compounds is interesting bromine and hydrochloric acid cleave from dibutyldivinyltin not more than one vinyl substituent (238, 248). 

An estimation of AH 298.15 gaseous Pb(C2H5)4 on the basis of triatomic additivity appears in [657]. A AH value of 10.57 kcal/mol was calculated by the MNDO method [722] see also [725]. A method for calculating AH for tetraalkyl compounds of group 14 elements... 

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