Thiophosphinates

The secondary phosphine oxides oi sulfides can be oxidized to phosphinic acids oi thiophosphinic acids. 

Thermolysis of 58a in butanol affords, together with 17% of 60a (R = C4H9) which evidences the intermediacy of the thiophosphene 59 a, a variety of partly atypical products which seriously impede the desired rearrangement38. Photolysis of 58b in methanol is also found to give only 18 % 1,2-P/C shift to form the heterocumulene 59b, from which the thiophosphinic rater 60b (R = CH3) results 39). As already mentioned in connection with the photolysis of diazo compounds of type 36 (see Sect. 2.2), Wolff rearrangement (9%) and O/H insertion (6%) once again compete with thiophosphinic ester formation. Moreover, solvolysis of the P(S)/C(N2) bond 391 prevents a greater contribution of carbene products to the overall yield. 

Related to these diphosphine dichalcogenides are the triphosphine trisulfides [R2P(S)]3CH (12) which can be prepared from lithiated methylene diphosphine disulfides upon treatment with thiophosphinic chlorides (Equation 9). Deprotonation of 12 with tBuLi gives a resonance-stabilised anion 13 containing a planar central carbanion whose charge is delocalised onto the three neighbouring phosphorus and sulfur atoms.32... 

Other related compounds are the diphosphine disulfides R2P(S)P(S)R2 14, which contain a direct phosphorus-phosphorus bond, and polysulfur fe(dior-ganophosphine sulfides) R2P(S)-S -P(S)R2 in which the two phosphorus centres are connected by a chain of one of more sulfur atoms. R2P(S)P(S)R2 compounds are accessible from heating secondary phosphine sulfides with thiophosphinic chlorides (Equation 10) or by reaction of fephosphines with... 

Numerous methods have been used for the synthesis of R2P(S)-S -P(S)R2 compounds. However, probably the most convenient and generally applicable for a range of alkyl, aryl, alkoxy and aryloxy R substituents is the reaction of alkali metal dithiophosphinates with thiophosphinic bromides for n = 1 (Equation 11), or the oxidation of dithiophosphinic acids or their alkali metal salts with I2, SC12 or S2C12 for n = 2, 3 or 4 respectively (Equations 12-14).1,34... 

Numerous preparative methods have been reported for these acids and their salts and ester derivatives.1 4 Dithiophosphoric acids are accessible from the reaction of phosphorus pentasulfide with alcohols or phenols (Equation 18). Dithiophosphinic acids can be prepared from thiophosphinic chlorides and sodium hydrosulfide (Equation 19), although the phenyl derivative is better prepared using a modified Friedel-Crafts reaction in which phosphorus pentasulfide is reacted with benzene in the presence of anhydrous aluminium trichloride (Equation 20). 

Mixed chalcogen derivatives of phosphinic and phosphoric acids are also known, the most studied being the mixed sulfur-oxygen species. Thiophos-phoric acids exist in two different isomeric forms - the thiono form (18a) and the thiolo form (18b). The equilibria usually sits somewhere in between these two species, being dependent upon the nature of the R substituents, the solvent and in some cases the concentration. Thiophosphinic acids are also able to interconvert between the thiono (19a) and thiolo (19b) tautomers, although the equilibrium position usually sits well on the side of the thiono tautomer.1... 

Hence, chalcogenoamidophosphinic acids of general formula R2P(E)NHR (27) can be considered as dichalcogenophosphinic acids with one of the chalcogen atoms replaced by an amido group. These amido species are still normally referred to as acids due to their acidic amide protons. They are accessible from reaction of thiophosphinic chlorides and primary amines (Equation 43) or from reaction of aminophosphines with elemental chalcogen... 

A series of bis(thiophosphinic amido) yttrium complexes 86a-h was promising due to their high rates and enhanced control of the L-lactide polymerization activity with high polymerization rates A app = 2.2 x lO to 1.1 x 10 s at [LA]q = 1 M, [l]o = 5 mM [104]. It is worth noting that the phosphorous substituents greatly influenced the rate of the reaction, and that the rate followed the order isopropyl > phenyl > ethoxy. 

The reaction of 2-lithio-l,3-dithiane with chlorodiphenylphosphine under oxidative conditions furnished an open-chain reaction product with a formyl thioester and a thiophosphinate moiety (Equation 54) <2003TL5293>. 

Although far from exhaustive, Table 3 shows that tetracoordinated compounds as diverse as phosphonium salts, phosphinates, thiophosphinates, phosphine oxides, phos-phonium ylides and halophosphates can ail lead to P(V) derivatives by addition, substitution, or oxidoreduction reactions. 

Trialkylthiophosphates, (RO)3P=S (R = Et, Pr"), act as unidentate sulfur ligands.102 Dialkyl-thiophosphinates (33) react with some metal ions forming complexes (34), being concomitantly oxidized to bis(dialkylthiophosphoryl)disulfanes (35) as shown in equation (2).107 Dialkyldithio-phosphates, (RO)2P(S)SH, form complexes similar to (34). 

Second-order rate constants for reactions of hydroxide ion and butane-2,3-dione monoximate ion with various phosphate, phosphinate, and thiophosphinate esters pass through minima with decreasing water content of water-MeCN and water-/-BuOH mixtures. The initial inhibition is offset by stabilization of die charge-delocalized TSs.234... 

Sulfur-donor Extractants The CYANEX 301 Process. Various dialkyl-(mono/di)-thio(phosphoric/phosphinic) acids, such as di(2-ethylhexyl)-di-thiophosphoric acid (HDEHDTP), bis(2,4,4-trimethylpentyl)-thiophosphinic acid (CYANEX 272), bis(2,4,4-trimethylpentyl)-monothiophosphinic acid (CYANEX... 

Menoyo, B., Elizalde, M.R, Almela, A. 2002. Determination of the degradation compounds formed by the oxidation of thiophosphinic acids and phosphine sulfides with nitric acid. Anal. Sci. 18 799-804. 

Diphosphatricyclic compound 137 was photolyzed at 254 nm at 26 °C in MeOH to furnish retro-Diels-Alder products dihydrophosphinoline 138 and thiophosphinate 139 <2004HAC97> (Scheme 5). 

The resulting alkyl or aryl diethyl phosphates were selectively detected at the 10-25 ng level with the P-mode FPD. Similarly, Jacob et al (36) used dimethyl thiophosphinic chloride in the presence of excess triethylamine to convert primary aliphatic, aromatic and heterocyclic amines to the corresponding N-dimethyl-thiophosphinic amides. The excess reagent was easily removed by treating the reaction mixture with methanol-sodium hydrogen car-... 

Auch durch Umsetzung von Thiophosphinsauren mit Dicyclohexylcarbodiimid sind Phos-phinsaure-Thiophosphinsaure-Anhydride zuganglich348 z.B. Diethylphosphinsaure-Di-ethyl-thiophosphins dure-Anhydrid zu 78% ... 

Diphenyldisulfan setzt sich bereits bei 20° mit Diphenylphosphinigsaure-alkylestern zu Diphenyl-thiophosphin-saure-S-pheny ester (Ausbeute in Benzol 70%, in Methanol 30%) uni 4 ... 

Praparativ verbreiteter ist jedoch die Umsetzung der freien Saure oder ihrer Natriumsalze mit entsprechendenThiophosphinsaure-Derivaten. Reaktionspartner sind Thiophosphin-saure-amide919 oder -chloride920-922 ... 

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