(12) Patent Application Publication (10) Pub. No.: US 2008/0103330 A1 Liu Et Al
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US 20080 103330A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2008/0103330 A1 Liu et al. (43) Pub. Date: May 1, 2008 (54) PROCESS FOR THE PREPARATION OF Publication Classification HIGHLY PURIFIED, (51) Int. Cl. DALKYDTHOPHOSPHINC COMPOUNDS C07F 9/30 (2006.01) C07F 9/34 (2006.01) (76) Inventors: Leo Zhaoqing Liu, Shanghai (CN); (52) U.S. Cl. ............................................... 562/9:568/14 Gary Woodward, Northwich (57) ABSTRACT Cheshire (GB) An improved process for production of dialkyldithiophos phinic acid including Sulfurizing a purified dialkylphosphinic Correspondence Address: acid by: reacting a hypophosphorous acid or salt with a sto Kevin E. McVeigh ichiometric excess of an alpha olefin in the presence of a free RHODANC. radical initiator to form a reaction product comprising 8 Cedar Brook Drive monoalkylphosphinic acid and dialkylphosphinic acid; add Cranbury, NJ 08512-7500 ing Sufficient aqueous base to the reaction product to i) form the salts of the phosphinic acids, and ii) establish an aqueous phase and an organic phase, wherein a monoalkylphosphinic (21) Appl. No.: 11/977,620 acid solubilizes into an aqueous phase; separating the organic phase from the aqueous phase; acidifying the organic phase (22) Filed: Oct. 25, 2007 and removing the olefin from the organic phase; isolating the purified dialkylphosphinic acid product; and Sulfurizing the Related U.S. Application Data purified dialkylphosphinic acid product to form a dialky dithiophosphinic acid. The present invention also provides a (60) Provisional application No. 60/854.279, filed on Oct. process for preparing purified dialkylthiophosphinic chlo 25, 2006, provisional application No. 60/914,558, ride, and a process for preparing purified dialkylmonothio filed on Apr. 27, 2007. phosphinic acids. US 2008/O 103330 A1 May 1, 2008 PROCESS FOR THE PREPARATION OF bonds and, preferably, a class of compounds consisting of HIGHLY PURIFIED, compounds of the formula (I): DALKYDTHOPHOSPHINC COMPOUNDS CROSS-REFERENCE TO RELATED (I) APPLICATIONS 0001. The present application relates to US Provisional Patent Application No. 60/854.279, filed Oct. 25, 2006, incor porated herein by reference in its entirety. FIELD OF THE INVENTION wherein Z represents a monovalent hydrocarbon radical free ofaliphatic multiple bonds, or a monovalent inorganic cation, 0002 The present invention generally relates to an and Y represents a hydrogenatom, a monovalent hydrocarbon improved process for the economical production of dialky radical free of aliphatic multiple bonds, or the group —OZ in ldithiophosphinic acid compounds, preferably branched which Z is defined as above. Among the phosphorous classes dialkyldithiophosphinic acid compounds. The process and compounds that Stiles et al. Suggest as reactants are the enables a single phase separation which realizes a high purity salts of hypophosphorous acid, hydrocarbyl esters of hypo dialkylphosphinic acid product which is then converted to a phosphorous acid, hydrocarbyl esters of organic phosphinic dialkyldithiophosphinic acid. The present invention also pro acids and mono- and di-hydrocarbyl esters of phosphorous vides a process for the preparation of highly purified dialky acid. A particularly preferred Subclass comprises the alkali lthiophosphinic halide and products therein, thereby produc metal salts of hypophosphorous acid Such as sodium hypo ing a dialkylthiophosphinic compound having one Sulfur phosphite which Stiles et al. found to be able to be directly atom and one halide atom. The present invention also pro added to olefins containing up to 14 carbonatoms “to produce vides a process for the preparation of highly purified dialky in a single, operational step a water soluble detergent in lmonothiophosphinic acids and products therein, thereby substantially quantitative yields.” producing a dialkylmonothiophosphinic acid having one 0008 Stiles et al. also noted that 1-olefins exhibit a some oxygen and one Sulfur. what higher rate of reaction in these processes than do other olefins. The Stiles et al. addition reaction is initiated by the BACKGROUND OF THE INVENTION presence of free radicals in intimate contact with the reac 0003) Numerous derivatives of organic phosphinic and tants. Neither the reaction temperature nor the reaction pres dithiophosphinic acids are known to exist and to have con sure is taught to be critical by Stiles et al. siderable commercial value as well as a great variety of useful 0009 Stiles et al. teach that where a mole to mole addition applications. For example, organic phosphinates and dithio is desired, it is generally preferable to employ the reactants in phosphinates as well as their acids are effective wetting about equimolar proportions or with the phosphorous com agents and detergents; plasticizers for many plastics and res pound in excess; and, where it is desirable to cause more than ins; bonding agents for asphalt and similar compositions; one mole of the olefinic compound to be incorporated in the color stabilizers and oxidation inhibitors for greases and product. lubricants (U.S. Pat. No. 3,001,938); corrosion inhibitors: 0010 Dialkyldithiophosphinic acids have also been used flame proofing agents; flotation auxiliaries; metal extractants; to extract metals (U.S. Pat. No. 5,447.552). In the general setting retarders for gypsum; and textile auxiliaries such as procedure employed for the separation of metal elements filament stabilizers (U.S. Pat. No. 3,374.288). from solutions thereof, especially acidic solutions, the feed 0004 Highly purified, highly branched dialkyldithiophos Solution generally contains nickel and/or cobalt ions. The phinic acids have been especially recognized as being very extract containing the extracted metal(s) is usually sent to a important and much desired precursors, intermediate prod scrubber wherein it is scrubbed with dilute acid and then sent ucts, and end products in numerous specialized fields, includ to a stopper where it is stripped with more concentrated acid ing mining. For example, branched dialkyldithiophosphinic to separate the metals. Hydrochloric acid and Sulfuric acid are acids act as metal extractants and froth flotation agents. the preferred acids of the prior art to scrub and strip the 0005. As a result of the above listed numerous possibilities extract. Bis-(2,4,4-trimethylpentyl)dithiophosphinic acid is of practical application, a demand has been created for a said to be a preferred extractant, especially for the separation simple industrial synthesis for the production of dialky of cobalt from nickel. ldithiophosphinic acids in a highly purified State. 0011. The currently commercialized method to manufac 0006 Because of the above described great commercial ture dialkyldithiophosphinic acids is by direct sulfurisation of value, many methods of preparing organic phosphinic acids the corresponding dialkyl phosphines, these are in turn manu have been advanced. Although the methods vary widely in factured from phosphine gas and olefins under pressure. their individual steps, a great many employ the reactions of Phosphine is highly toxic and flammable and the addition of phosphorous-halogen compounds to attain carbon-to-phos an olefin to phosphine gas often yields a mixture of primary, phorous bonds. While it has long been known to be possible secondary and tertiary phosphines. In particular when a to form Such bonds by reacting alkylhalides with phosphine, dialkyl phosphine is the desired product the process also or by the use of Grignard reagents, such methods are not produces undesirable amounts of trialkyl phosphines which practical in commercial scale operations. unlike primary phosphines, cannot be recycled and, on Sul 0007 Stiles et al. (U.S. Pat. No. 2,724,718) discloses a furisation, produce trialkylphosphine Sulfides as an impurity, process for the production of phosphinates employing the which must be removed by extraction from the dialkyldithio reaction between a compound containing olefinic double phosphinic acids. US 2008/O 103330 A1 May 1, 2008 0012. This art-recognized problem of producing high lphosphinic acid is significantly more soluble in the aqueous purity dialkyldithiophosphinic acids by a practical reaction phase than in the organic phase, i.e., the excess olefin reactant process which is applicable to the production of compounds phase, than the dialkylphosphinic acid ester product. having a variety of structures, especially highly branched 0020. In another respect, the present invention provides an dialkyl structures, has heretofore remained unsolved. efficient process to convert dialkylphosphinic acid into 0013 Phosphinic acid was converted by reacting with dialkyithiophosphoryl halide, preferably dialkylthiophos thiophosphoryl chloride into thiophosphinic chloride at very phoryl chloride, comprising the step of reacting dialkylphos low yield (33-54%, Fedorova, G. Ketal Zhurnal Obshchei Khimi (1982), 52(1) 214 Chem Abst. 96:181355. phinic acid with a halogenating agent and a Sulfurizing agent 0014. Alternatively, thiophosphinic halides can be pre to form dialkylthiophosphinic halide. For example, the pared from other starting materials such as phosphines present invention converts dialkylphosphinic acid into (Kaushik, M.P. etal Indian J. Chem. Sect B: Org. Chem. Med. dialkylthiophosphinic chloride in a one-pot process without Chem. (1991), 20B(10), 932), thiophosphonous anhydride additional purification by reacting dialkylphosphinic acid (Bliznyuk, N. K. et al SU347332), alkaryl halide