A direct approach to selective sulfonation of triarylphosphines

A practical and convenient synthesis of mono-, di- and a trisulfonated phosphines from triphenylphosphine analogs, (2,4-dimethylphenyl)3−n-(phenyl)n-phosphine and (4-methoxyphenyl)3−n-(phenyl)n-phosphine (n=0–2), is described, respectively. This represents an easy way to prepare water-soluble phosphines with complete selectivity, and with essentially no phosphine oxide formation.