Alkane thiols, synthesis

In this chapter, two new approaches for the synthesis of metal-polymer nanocomposite materials have been described. The first method allows the preparation of contact-free dispersions of passivated gold clusters in polystyrene, and it is based on a traditional technique for the colloidal gold synthesis—that is, the alcoholic reduction of tetrachloroauric acid in presence of poly(vinyl pyrrolidone) as polymeric stabilizer. The primary function of the stabilizer is to avoid cluster sintering, but it also allows us to isolate clusters by co-precipitation. It has been found that the obtained polymer-protected nanometric gold particles can be dissolved in alkane-thiol alcoholic solutions to yield thiol-derivatized gold clusters by thiol absorbtion on the metal surface. Differently from other approaches for thioaurite synthesis available in the literature, this method allows complete control over the passivated gold cluster structure since a number of thiol molecules can be equivalently used and the... 

M. Tanaka, T. Sawaguchi, Y. Sato, K. Yoshioka, O. Niwa, Synthesis of phosphorylcholine-oligoethylene glycol-alkane thiols and their suppressive effect on non-specific adsorption of proteins. Tetrahedron Lett. 50 (2009) 4092 095. 

Matsuno R, Takami K, Ishihara K. Simple synthesis of a library of zwitterionic surfactants via Michael-type addition of methacrylate and alkane thiol compounds. Langmuir 2010 26(16) 13028-32. 

We describe here the synthesis of Au nanoparticles under controlled conditions to prevent their aggregation and its uniform dispersion in the polymer matrix, which forms the sensing element. Synthesis of Au nanoparticles is based on two-phase reduction of gold salt by borohydride in the presence of alkane thiol [16] as shown in Fig.l. 

Further reports on asymmetric synthesis in the presence of Cinchona alkaloids have been made.142 " For example, hydrogenation of methyl pyruvate with a platinum-alumina catalyst containing quinine gives (+)-(/ )-methyl lactate in 87% optical yield.1426 Asymmetric induction with optical yields up to 36 and 26% has been observed in the Michael addition of thiols and nitro-alkanes to ct/ -unsaturated ketones in the presence of quaternary salts derived from the Cinchona alkaloids.142"... 

Thiols and thioethers are the most commonly encountered sulphur derivatives which can be directly reduced to alkanes. For this purpose, Raney Ni has been traditionally used. An example of its use is the synthesis of let- and 7j5-eremophilanes from a tricyclic thiophene precursor (equation 29) However, more recently nickel complex reducing agents ( NiCRA ) have been profitably and effectively used for this purpose, as indicated by the reduction of dodecanethiol to dodecane (equation 30)". Similarly, nickelocene in the presence of LAH has been used to effect desulphurization of thiols . A combination of NaEtaBH and FeCl2 also achieves the thiol-to-alkane transformation quite satisfactorily The increasing utility of nickel boride has also been exploited for the transformation of sulphides to alkanes as indicated in equation 31. ... 

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