Phosphinodithioates

Flotation Reagents. Only one sulfide mineral flotation collector is manufactured from phosphine, ie, the sodium salt of bis(2-methylpropyl)phosphinodithioic acid [13360-78-6]. It is available commercially from Cytec Industries Inc. as a 50% aqueous solution and is sold as AEROPHINE 3418A promoter. The compound is synthesized by reaction of 2-methyl-1-propene [115-11-7] with phosphine to form an iatermediate dialkylphosphine which is subsequently treated with elemental sulfur [7704-34-9] and sodium hydroxide [1310-73-2] to form the final product (14). The reactions described ia equations 10 and 11... 

Optically active secondary and tertiary phosphine sulphides have been prepared by the reaction of optically active phosphinodithioates (12) with butyllithium followed by treatment with electrophiles. Compounds (13, R=t-Bu, E=H) and (13, R=1-naphthyl, E=H) prepared in this study are claimed to be the first reported examples of optically active secondary phosphine sulphides. 

PRhC32H38, Rhodium, (l,4-butanediyi)(Ti -pentamethylcyclopentadienyI)(tri-phenylphosphine)-, 22 173 PS2C4H11, Phosphinodithioic acid, diethyl-molybdenum complexes, 23 120, 121 PS3C,2H27, Phosphorotrithious acid tributyl ester, 22 131... 

In the acid-catalyzed thiolysis of nitriles (73) HaS is commonly replaced by appropriate precursors or equivalents. Thus, thioacids, RCOSH, have been used together with HC1 or SnCU. Thioacetamide (77) is a very convenient source of HaS as shown in equation (36), an equilibrium is established which is shifted to the right, if the liberated MeCN is removed by distillation. Alternative sources of HaS are di-thiophosphoric, HSP(=S) (OR)a with R = Et or Pr, " or phosphinodithioic acid derivatives, HSPPha(= S). ° The last mentioned approach allows the elegant synthesis of a-hydroxythioamides (78) in Scheme 11. ... 

This section deals with a series of phosphor-1,1-dithiolates, which includes dithiophosphinates, M(S2PR2) , dithiophosphates, M[S2P(OR)2] , and dithiophosphonates, MIS R OR2)] Alternative names are phosphinodithioates, phosphorodithioates, and phosphonodithioates, respectively. The parent acids (proligands), (l)-(3) are shown in Scheme 1. ... 

Phosphinodithioic acids Phosphorodithioic acid 0,0-diesters Phosphonodithioic acid O-esters... 

Both (R)-(-t-)- and (S)-(-)-tertiarybutylphenylphosphine sulphides (6) have been synthesised in high optical purity from (S)-(-)- and (R)-(+)-tertiarybutylphosphinothioic acids, respectively, by formation of the mixed anhydride (5) followed by borohydride reduction (Scheme 2). Reactions of the product (6) have been used to provide routes to optically active phosphinothioic iodides, phosphinodithioates and thioselenophosphinic acids of known configurations. A new method for the asymmetric synthesis of tertiary phosphine oxides has been reported.5 An Arbusov reaction of the optically active 1,3,2-... 

Phosphinodithioic acids add to p-benzoquinones, and to (1,2-alkadiene)phosphonic acid derivatives, although... 

Phosphinodithioic acids react with stannic chloride at - 25° C to substitute one of the chlorine atoms/ but the related phosphono-chloridothioate gives (122) with the same reagent, The bis(phosphino-dithioic) acid (123) forms polymeric complexes with transition-metal ions... 

The addition of sulphur to a stoichiometric amount of a secondary phosphine, R2PH, in a solvent and in a non-oxidizing atmosphere, affords the phosphine sulphide, R2P(S)H The further addition of sulphur (a less than stoichiometric amount is recommended ) which, in principle should provide the phosphinodithioic acid, R2P(S)SH, was the method used originally in 1871 by Hofmann, without published details, for the preparation of diethylphosphinodithioic acid, and remains, following modifications, one of the more important means of obtaining such compounds. 

The two principle products from the addition of sulphur to Et2P(S)H are the phosphin-odithoic acid, Et2PSSH, and the trisulphane, 174 (R = Et, Z = Z = S, = 3)(Scheme 48), which can be separated wthout too much difficulty. In many cases, the phosphinodithioic acids may be isolated as the salt of a heavy metal such as nickel, but a better synthesis procedure consists in the addition of the sulphur to the secondary phosphine sulphide in aqueous alkali (ammonia solution provides better yields than sodium hydroxide), when the polysulphane—the principle by-product—is broken down under the influence of the alkali metal sulphide. A phosphinodiselenoic acid may be obtained in essentially the same... 

In common with simple thiols and (9, (9-dialkyl phosphorodithioates, phosphinodithioic acids add to alkenes according to the Markovnikoff rule (propenenitrile is a possible exception to this behaviour) and even in the absence of a catalyst (equation 44). In the presence of sodium methoxide, anti-Markovnikoff behaviour is often observed as the result of Michael addition of the acid anion (equation 45). Addition of the acids to otherwise saturated nitriles leads, following acidolysis of intermediate species, to thiocarboxamides and the phosphinothioyl halide (Scheme. 50). 

TABLE 2. Relative rate data for the alkaline hydrolysis of phosphinate, phosphinoth-ioate and phosphinodithioate esters influence of the alkyl substituents on phosphorus. Reproduced, with modifications, by permission of the Research Council of Canada... 

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