Alkylphosphines Trialkylphosphines

In contrast to the tertiary amines, trialkylphosphines have strong donor properties and form exceedingly stable coordination complexes with a wide variety of metal salts such as those of univalent copper and gold, and bivalent platinum, palladium, and mercury.1 Like phosphine itself, many of these tertiary alkylphosphines are highly flammable, toxic, and extremely susceptible to air oxidation. Ease of oxidation first decreases and then increases as the alkyl group becomes larger.2 3,4 5 The n-butyl compound is thus a convenient member of this group for preparation. 

One of the cleanest and most general reactions undergone by trivalent phosphorus compounds occurs with sulfur (177). For example, tri-alkylphosphines react vigorously with sulfur to yield trialkylphosphine sulfides. The analogous reaction of phosphorus esters has received considerable attention as a synthetic method, due largely to the insecticidal potency of the phosphorothioate esters. 

Finally, the dependence of the rate of oxidative addition on the choice of tri-alkylphosphine has been quantified (Table 11). Consistent with the reactivity patterns that have been observed in Pd/trialkylphosphine-catalyzed cross-coupling processes of alkyl electrophiles (e.g.. Scheme 1), Pdl2 complexes derived from P(t-Bu)2Me and PCy3 undergo relatively facile oxidative addition (entries 1 and 2), whereas those based on P(t-Bu)2Et and P(f-Bu)3 are essentially unreactive (entries 3 and 4). 

More stable and less volatile phosphines than simple trialkylphosphines are phosphabicyclononanes ( phobanes ) [43] or LIM hgands, which have been developed for the same purpose (Figure 5.11, see also Section 2.1) [44]. In addition, in 2014, Jiang and coworkers [45] suggested the use of alkylphosphines with polyethylene glycol chains for the transformation of Cj2 olefins into the corresponding alcohols in an aqueous biphasic system. 

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