Sulphonated phosphines

Earlier, reference was made to the potential third mechanism associated with nucleophilic displacements at phosphoryl phosphorus, namely that which might involve the participation of a phosphaacylium cation. Mixed sulphonic-phosphonic or sulphonic-phosphinic anhydrides 645 (Z = O, R = Me or 4-methylphenyl) have been obtained from the free phosphorus(V) acid and the 1,2,4-triazole 646 in the presence of trifluoromethanesulphonic acid, or 645 (Z = O, R = CF3) from the imidazolides 647 and trifluoromethanesulphonic acid and / r/-butylphenylphosphinothioic acid with trifluoromethanesulphonic anhydride yield the mixed 0-anhydride 648 (R = CF3), some reactions of which are illustrated in Scheme 76 ". Of those reactions, the formation of the iodide 649, albeit in low yield when the reaction is carried out in MeOH, with stereochemical retention of configuration at phosphorus, contrasts with the inversion of configuration observed for the remainder, and which is normally encountered for Sn2(P) displacements. The reaction of648 with methoxybenzene to yield the phosphine sulphide 650 in a solvent of high ionizing power (1,1,1,3,3,3-hexafluoropropan-2-ol a lower yield was obtained in a... 

Finally a variety of 1-alkenes were hydroformylated with a highly water-soluble tris-sulphonated ligand, P(m-PhS03Na). Some more effective catalysts involving the use of other sulphonated phosphine ligands have also been developed. ... 

The preparation of (silyloxy)rhodium complexes of the type [Rh2(fi-OSiR3)2(Ti -COD)2l (R = Me, Ph), which could serve as models of rhodium complexes bound to silica, has been reported238. The synthesis of the water-soluble complex [Rh(Ti -COD)(DPPETS)]+[Cl]" (DPPETS = l,2-bis bis(m-sodiosulfonatophenyl)phosphino ethane) has been reported and its catalytic activity in two-phase hydroformylation reactions investigated. The mechanism of the homogeneous reduction of (Z)-a-acetamido and (Z)-a-benzamidocinnamic acid methyl ester and a-acetamidoacrylic acid methyl ester in an organic-water medium in the presence of catalysts derived from [Rh2(lt-Cl)2(Ti -COD)2] and chiral sulphonated phosphines has been investigated W. ... 

A differential vapour-pressure technique has been used to determine the molecular weights of phosphonic and phosphinic acids in 95% ethanol. Cryoscopic and n.m.r. studies have been made on solutions of phosphinic acids in sulphuric acid and oleum. Mass spectrometry has indicated the ready formation of phosphinylium ions after electron bombardment of phosphonic and phosphinic acids and their derivatives. However, the cryoscopic results in sulphuric acid indicated that reaction did not proceed beyond protonation, and the n.m.r. study on oleum solutions suggested that sulphonation occurred. 

Miscellaneous Reactions of Phosphines.- The role of chiral phosphines as ligands in the catalysis of reactions leading to the formation of chiral products has been reviewed.1111 A procedure for the determination of the enantiomeric excess in chiral phosphines has been developed, based on 13C n.m.r. studies of the diastereoisomeric complexes formed by phosphines with the chiral pinenyl nickel bromide complex. 111 Studies of the sulphonation of triphenylphosphine and of chiral arylphosphines have been reported in attempts to prepare water soluble ligands which aid... 

Sulphuric and sulphurous acids are dibasic. Sulphonic and sulphinic acids are monobasic. With them we are at the end of the series of acids generated by replacing OH by H. In the phosphorus series the basicity is always one unit higher, so that having passed from phosphoric and phosphorous adds, which are tribasic, to phosphonic and phosphinic acids, which are dibasic, we can proceed a further step to two monobasic acids, for which the recommended names are very naturally phosphonous and phosphinous acids ... 

Generically phosphin- fits in with the parent phosphine, and phosphon with phosphine oxide or phosphone (cf. sulphone). 

The activity of water-soluble catalysts based on the hydrophilic biden-tate phosphines is also significantly influenced by the nature of the anion [94-100]. Thus for example, using the catalyst formed in situ from [Pd(TsO)2(NCMe)2] and the mef/za-sulphonated analogue of dppp under conditions close to the ones reported above, but in water as solvent and with an excess of acid (acid/Pd = 500/1), the productivity is ca. 3900, 3600 or 2250 g polymer(gPd h)-1, when the acid is TsOH, TFA or AcOH, respectively, under usual conditions [96]. If one considers that the monomers are a little soluble in H20, very high productivity and molecular weight are obtained using [Pd(CH3)(NCCH3)(dapp-s)](OTf) (dapp-s =... 

The rates of dehalogenation of a-bromo- and a-iodo-m-cyanobenzylphenyl-sulphones (89) by a number of sterically hindered phosphines in aqueous DMF have... 

Hydrophilic molecules are composed of ions (such as sulphonate, sulphate, carboxylate, phosphate and quaternary ammonium), polar groups (such as primary amines, amine oxides, sulphoxides and phosphine oxide) and non-polar groups with electronegative atoms (such as oxygen atom in ethers, aldehydes, amides, esters and ketones and nitrogen atoms in amides, nitroalkanes and amines). These molecules associate with the hydrogen bonding network in water. 

A breakthrough occurred in the mid-seventies when Union Carbide and Celanese introduced Rh/phosphine catalysts in commercial processes. This catalyst is based on the work by Wilkinson s group he received the Nobel prize for his work in 1973. Rhodium-based catalysts are much more active than cobalt catalysts and, under certain conditions, at least for 1-alkenes, they are also more selective. The processes for the hydroformylation of higher alkenes (detergent alcohols) still rely on cobalt catalysis. A new development is the use of water-soluble complexes obtained through sulphonation of the Ligands (Ruhrchemie). 

Examples of phosphine ligands that are used to make water-soluble complexes are sulphonated triphenylphosphines, e.g., Ph2P(m-S03C6H4) and l,3,5-triaza-7-phosphaadamantane, TP A82 (10-LXII). 

Similar mass-spectral rearrangements have been observed in sulphon-amides (66, 67), sulphonimides (68), and phosphine oxides (69, 70). 

Thiols and sulphides quench triplet carbonyl compounds. Evidence (including that from CIDNP studies) indicates that these reactions occur by a radical rather than an electron-transfer pathway (Cohen et al., 1979 Ver-meesch et al., 1978). It is interesting to note that sulphides will deoxygenate ketones producing sulphoxides, sulphones and presumably carbenes (Fox et al., 1979). Phosphines quench triplet carbonyl compounds (Davidson and Lambeth, 1969). They also deoxygenate carbonyl compounds to produce phosphine oxides and carbenes, and in this case, the reaction was proposed as occurring by an electron-transfer process (Fox, 1979). 

Fig. 7 Phosphate, phosphonate, phosphinate, sulphate and sulphonate anions...

Scheme 8 Direct alkylation via sulphonates, phosphonates and phosphinates...

Triarylphosphines with formyl or acetyl groups substituted into the aromatic rings can be prepared by a Grignard reaction using ethylene keta derivatives. The resulting phosphines (1) are treated with toluene-p-sulphonic acid. The acetyl derivatives may also be prepared by oxidation of the ethyl derivatives (2) followed by reduction with trichlorosilane. ... 

It should be finally noted that hydroxyphosphines can be converted under very smooth conditions into sulfonated phosphines by acylation with o-sulfobenzoic anhydride, as shown by Borner et al. (Eq. 5) [26]. With this methodology in hand the severe conditions commonly used for the incorporation of sulphonate groups in phosphines can be avoided. Acid-labile functional groups like acetals survive under these conditions. In comparison to the parent hydroxyphosphines the water solubility of the relevant Rh catalysts was strongly enhanced [27]. In the asymmetric hydrogenation of prochiral olefins, moderate enantioselectivities were achieved. 

Reference has already been made to properties of mixed phosphinic-sulphonic anhydrides. / rr-Butylphenylphosphinothioic trifluoromethanesulphonic anhydride (101) was prepared, in both racemic and optically active forms, from the phosphinothioic acid and trifluoromethanesulphonic anhydride in dichloromethane at -50 °C... 

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