PHOSPHINE OXIDES REDUCTION

Abstract

Provided is a process for the conversion of a tertiary phosphine oxide to the corresponding tertiary phosphine, comprising at least reacting said tertiary phosphine oxide with a phosphite compound, in the presence of at least a catalyst. Furthermore, provided is a composition comprising at least a tertiary phosphine oxide and a phosphite compound, and optionally a catalyst.

Claims

1. A process for the conversion of a tertiary phosphine oxide to the corresponding tertiary phosphine, comprising at least reacting said tertiary phosphine oxide with a phosphite compound, in the presence of at least a catalyst.

2. The process according to claim 1 wherein the tertiary phosphine oxide is a compound of formula (I) as follows: ##STR00009## wherein R.sup.1, R.sup.2 and R.sup.3 are each independently selected from the group consisting of substituted or unsubstituted, branched or linear hydrocarbyl; and substituted or unsubstituted carbocyclyl or heterocyclyl; A is a linking moiety; m is an integer of 0 to 2.

3. (canceled)

4. The process according to claim 2 wherein each R.sup.1, R.sup.2 and R.sup.3 is independently selected from the group consisting of substituted or unsubstituted C.sub.6-C.sub.20 aryl-C.sub.o-C.sub.20 alkyl and C.sub.5-C.sub.20 heteroaryl-C.sub.o-C.sub.20 alkyl.

5. The process according to claim 2 wherein R.sup.1, R.sup.2 and R.sup.3 are all substituted or unsubstituted phenyl.

6. The process according to claim 2 wherein the linking moiety A comprises substituted or unsubstituted hydrocarbylene or substituted or unsubstituted monocyclic or polycyclic carbocyclylene or heterocyclylene, and optionally one or several functional groups.

7. The process according to claim 1 wherein the tertiary phosphine oxide is selected from the group consisting of: triphenylphosphine oxide, trioctylphosphine oxide, tris(4-methoxyphenyl)phosphine oxide, tris(4-methylphenyl)phosphine oxide, tris(4-fluorophenyl)phosphine oxide, cyclohexyldiphenylphosphine oxide, 1,2-bis(diphenylphosphinoyl)ethane dioxide, 2,2-bis(diphenyloxyphosphino)-1,1-binaphthyl, bis(2-(diphenyloxyphosphino) phenyl ether, 9,9-dimethyl-4,6-bis(dipheny loxyphosphino) xanthene, 1,1-bis(diphenyloxyphosphino) ferrocene, (azanediylbis(ethane-2,1-diyl))bis(diphenylphosphine oxide), tris(4-chlorophenyl) phosphineoxide, bis(2-methylphenyl) phenylphosphineoxide, bis(2-methylphenyl) phenylphosphineoxide, (4-cyanophenyl)diphenylphosphine oxide, and any of these compounds attached to a solid and/or polymeric support.

8. The process according to claim 1 wherein the phosphorus atom of each phosphite function of phosphite compound is linked to groups selected from substituted or unsubstituted, branched or linear hydrocarbyl; and substituted or unsubstituted carbocyclyl or heterocyclyl.

9. The process according to claim 1 wherein the phosphite compound is represented by the formula (II) as follows: ##STR00010## wherein R.sup.4, R.sup.5 and R.sup.6 are each independently selected from the group consisting of hydrogen, substituted or unsubstituted, branched or linear hydrocarbyl; and substituted or unsubstituted, aliphatic or aromatic carbocyclyl or heterocyclyl; B is a linking moiety; and n is an integer of from 0 to 2.

10. (canceled)

11. The process according to claim 9 wherein R.sup.4, R.sup.5 and R.sup.6 is independently selected from the group consisting of hydrogen atom, substituted or unsubstituted C.sub.6-C.sub.20 aryl-C.sub.0-C.sub.20 alkyl.

12. The process according to claim 1 wherein the phosphite compound is selected from the group consisting of: phosphorous acid, triphenylphosphite, diphenylphosphite, phenylphosphite, diisodecylphenylphosphite, diphenylisodecylphosphite, disooctyloctylphenylphosphite, phenyldiisodecylphosphite, tris(4-methoxyphenyl)phosphite, tri(o-tolyl)phosphite, tris (nonylphenyl)phosphite, tetraphenyl dipropyleneglycol diphosphite, and 4,4-isopropylidenediphenol C.sub.12-.sub.15 alcohol phosphite.

13. The process according to claim 1 wherein the phosphite compound is present in an amount comprised between 1 and 10 molar equivalent phosphite of the phosphite compound to the phosphine oxide of the tertiary phosphine oxide.

14. (canceled)

15. The process according to claim 1 wherein the catalyst is selected from the group consisting of fluorine (F.sub.2), chlorine (Cl.sub.2), bromine (Br.sub.2), iodine (I.sub.2), iodine monochloride (ICl), iodine monobromide (IBr), heterocyclyl halides, haloalkanes, phosphine dihalides, and any trialkyl, cycloalkyl or aryl analogues thereof.

16. The process according to claim 1 wherein the catalyst loading is comprised between 0.1 and 1 molar equivalents of the tertiary phosphine oxide.

17. The process according to claim 1 wherein either the tertiary phosphine oxide and/or the phosphite compound are attached to a solid support.

18. The process according to claim 1 wherein the process is carried out in presence of a non-polar solvent or an anhydrous aprotic polar solvent.

19. The process according to claim 1 wherein the reaction medium comprises water.

20. The process according to claim 19 wherein the reaction medium comprises water with a molar ratio of water to tertiary phosphine oxide comprised between 1/1 and 10/1.

21. The process according to claim 1 wherein the process is carried out in the presence of a base.

22. The process according to claim 21 wherein the base is present in an amount comprised between 0.1 and 2 molar equivalents of the tertiary phosphine oxide.

23. (canceled)

24. A composition comprising at least: a tertiary phosphine oxide and a phosphite compound, and optionally a catalyst.

Description

DETAILS OF THE INVENTION

The Tertiary Phosphine Oxide and the Tertiary Phosphine Product

[0028] It should be realized that the process of the invention is not limited to any particular tertiary phosphine oxide and in fact, it is contemplated that any tertiary phosphine oxide may be reduced by the inventive process, notably by a proper selection of the phosphite compound.

[0029] The tertiary phosphine oxide of the invention may contain any number of phosphine oxide functions to be reduced. For example, the tertiary phosphine oxide may contain from 1 to 3, e.g. 1 or 2 phosphine oxide functions. In one embodiment, the tertiary phosphine oxide contains 1 phosphine oxide function. In another embodiment, the tertiary phosphine oxide contains 2 phosphine oxide functions.

[0030] Furthermore, it is contemplated that the phosphine oxide may additionally contain other functional groups, such as halogen, nitro, amino, cyano, ether, thioether, or alkylene group.

[0031] The tertiary phosphine oxide of the invention may notably be a compound of formula (I) as follows:

##STR00001##

wherein R.sup.1, R.sup.2 and R.sup.3 are each independently selected from the group comprising substituted or unsubstituted, branched or linear hydrocarbyl; and substituted or unsubstituted carbocyclyl or heterocyclyl; A is a linking moiety; m is an integer of 0 to 2, preferably 0, 1 or 2.

[0032] For example, each R.sup.1, R.sup.2 and R.sup.3 may be independently selected from the group comprising C.sub.1-C.sub.20 alkyl, C.sub.6-C.sub.20 aryl-C.sub.o-C.sub.20 alkyl, C.sub.3-C.sub.20 cycloalkyl-C.sub.oC.sub.20 alkyl, 5-20 membered heterocyclyl-C.sub.0-C.sub.20 alkyl; 5-20 membered heteroaryl-C.sub.0-C.sub.20 alkyl wherein any alkyl, cycloalkyl and heterocyclyl moiety may be saturated or unsaturated, any alkyl moiety may be branched or linear, and any alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl moiety is optionally substituted with one or several substituents.

[0033] In one embodiment, in a compound of formula (I), any C.sub.1-C.sub.20 alkyl may more particularly be a C.sub.1-C.sub.10 alkyl; any C.sub.o-C.sub.20 alkyl may more particularly be a C.sub.o-C.sub.10 alkyl; any C.sub.6-C.sub.20 aryl may more particularly be a C.sub.6-C.sub.14 aryl; any 5-20 membered heterocyclyl may more particularly be a 5-14 membered heterocyclyl; and any 5-20 membered heteroaryl may more particularly be a 5-14 membered heteroaryl.

[0034] In one embodiment, in a compound of formula (I), any C.sub.1-C.sub.20 alkyl may more particularly be a C.sub.1-C.sub.6 alkyl; any C.sub.o-C.sub.20 alkyl may more particularly be a C.sub.o-C.sub.6 alkyl; any C.sub.6-C.sub.20 aryl may more particularly be a C.sub.6-C.sub.10 aryl; any 5-20 membered heterocyclyl may more particularly be a 5-10 membered heterocyclyl; and any 5-20 membered heteroaryl may more particularly be a 5-10 membered heteroaryl.

[0035] For example, R.sup.1, R.sup.2 and R.sup.3 may be each independently selected from the group comprising substituted or unsubstituted C.sub.6-C.sub.20 aryl-C.sub.o-C.sub.20 alkyl and C.sub.5-C.sub.20 heteroaryl-C.sub.o-C.sub.20 alkyl, e.g. substituted or unsubstituted C.sub.6-C.sub.20 aryl and C.sub.5-C.sub.20 heteroaryl, such as substituted or unsubstituted phenyl, naphthyl and furyl, in particular substituted or unsubstituted phenyl.

[0036] More particularly, R.sup.1, R.sup.2 and R.sup.3 may be each independently selected from the group comprising substituted or unsubstituted C.sub.6-C.sub.20 aryl-C.sub.0-C.sub.20 alkyl, e.g. substituted or unsubstituted C.sub.6-C.sub.20 aryl, such as substituted or unsubstituted phenyl or naphthyl, in particular substituted or unsubstituted phenyl.

[0037] In one embodiment, R.sup.1, R.sup.2 and R.sup.3 are all substituted or unsubstituted phenyl.

[0038] The linking moiety A may be any diradical capable of attaching the two phosphorous atoms of the phosphine (oxide) functions to each other, through any number of intervening bonds. The linking moiety A may comprise substituted or unsubstituted hydrocarbylene or substituted or unsubstituted monocyclic or polycyclic carbocyclylene or heterocyclylene, and optionally one or several functional groups, such as ether or thioether function.

[0039] When m in formula (I) is more than 1, A is independently selected at each occurrence.

[0040] In one embodiment, A is a polycyclic diradical, such as a diradical comprising 2 to 8 ring moieties, e.g. 2 to 6, or 2 to 4 ring moieties, wherein each ring moiety is independently selected from 5- or 6-membered, saturated or unsaturated, aromatic or non-aromatic carbocycles and hetercycles, and wherein the ring moieties are either fused to each other or attached to each other through one or several intervening bonds of e.g. covalent type or metallocene type, such as a covalent bond, an ether function, a thioether function, an optionally substituted alkylene group, e.g. a methylene or ethylene group, or a ferrocene type bond. In this embodiment, the two phosphine oxide functions preferably are attached to different ring moieties.

[0041] In another embodiment, A may be a substituted or unsubstituted hydrocarbylene, carbocyclylene, or heterocyclylene. The linking moiety A also may be a substituted or unsubstituted metallocenylene, i.e. a diradical derived from a metallocene, i.e. a compound with the general formula (C.sub.5H.sub.5).sub.2M consisting of two cyclopentadienyl anions bound to a positively charged metal centre (M). As an example, A may be a substituted or unsubstituted ferrocenylene.

[0042] In one embodiment, A is an unsubstituted or substituted diradical selected from the group of substituted or unsubstituted, saturated or unsaturated, branched or linear C.sub.1-C.sub.20 alkylene, C.sub.3-C.sub.20 carbocyclylene, e.g. C.sub.6-C.sub.20 arylene, 5-20 membered heterocyclylene, e.g. 5-20 membered heteroarylene, C.sub.6-C.sub.40 bicyclylene, e.g. C.sub.12-C.sub.40 biarylene, 10-40 membered biheterocyclylene, e.g. 10-40 membered biheteroarylene, and C.sub.10-C.sub.30 ferrocenylene.

[0043] For example, A may be an unsubstituted or substituted diradical selected from the group of C.sub.6-C.sub.20 arylene, 5-20 membered heterocyclylene, 5-20 membered heteroarylene, C.sub.12-C.sub.40 biarylene, 10-40 membered biheterocyclylene, 10-40 membered biheteroarylene, and C.sub.10-C.sub.30 ferrocenylene.

[0044] In one embodiment, A is an unsubstituted or substituted diradical selected from the group of C.sub.12-C.sub.40 biarylene, 5-20 membered heterocyclylene and C.sub.10-C.sub.30 ferrocenylene, e.g. binaphthyl, such as 2,2-binaphthyl; xanthenylene, e.g. 4,5-xanthenylene; and (C.sub.10) ferrocenylene, e.g. 1,1-ferrocenylene.

[0045] Examples of tertiary phosphine oxides that may be reduced according to the invention are triphenylphosphine oxide, trioctylphosphine oxide, tris(4-methoxyphenyl)phosphine oxide, tris(4-methylphenyl)phosphine oxide, tris(4-fluorophenyl)phosphine oxide, cyclohexyldiphenylphosphine oxide, 1,2-bis(diphenylphosphinoyl)ethane dioxide, 2,2-bis(diphenyloxyphosphino)-1,1-binaphthyl, bis(2-(diphenyloxyphosphino) phenyl ether, 9,9-dimethyl-4,6-bis(dipheny loxyphosphino) xanthene, 1,1-bis(diphenyloxyphosphino) ferrocene, (azanediylbis(ethane-2,1-diyl))bis(diphenylphosphine oxide), tris(4-chlorophenyl) phosphineoxide, bis(2-methylphenyl) phenylphosphineoxide, bis(2-methylphenyl) phenylphosphineoxide, (4-cyanophenyl)diphenylphosphine oxide, or any of these compounds attached to a solid and/or polymeric support.

[0046] It has to be outlined that the compounds of the invention may include one or several atoms having an (R) form and (S) form, in which case all forms and combinations thereof are contemplated as included within the scope of the invention, as well as any mixture of any isomers.

The Reducing Phosphite Compound

[0047] The reducing phosphite compound may comprise at least one phosphite function, such as for instance a secondary phosphite function and/or a tertiary phosphite function. The phosphite compound of the invention may comprise at least one or several secondary phosphite function and/or one or several tertiary phosphite functions. The phosphorus atom of each phosphite function may be linked to groups selected from substituted or unsubstituted, branched or linear hydrocarbyl; and substituted or unsubstituted carbocyclyl or heterocyclyl, as defined herein above.

[0048] For example, the phosphite compound may contain from 1 to 3 phosphite functions. In one embodiment, the phosphite compound contains 1 or 2 phosphite functions. In one particular embodiment, the phosphite compound is a tertiary phosphite that contains 1 phosphite function.

[0049] Furthermore, it is contemplated that the phosphite compound may additionally contain other functional groups, such as for instance halogen, nitro, amino, cyano, ether, thioether or alkylene group.

[0050] In one embodiment, the phosphite compound is represented by the formula (II) as follows:

##STR00002##

wherein R.sup.4, R.sup.5 and R.sup.6 are each independently selected from the group comprising: hydrogen, substituted or unsubstituted, branched or linear hydrocarbyl; and substituted or unsubstituted, aliphatic or aromatic carbocyclyl or heterocyclyl; B is a linking moiety; and n is an integer of from 0 to 2, such as 0 or 1.

[0051] Preferably, at least one of the R.sup.4, R.sup.5 and R.sup.6 group is not a hydrogen atom.

[0052] For example, R.sup.4, R.sup.5 and R.sup.6 may be independently selected from the group comprising: hydrogen atom, substituted or unsubstituted, branched or linear C.sub.1-C.sub.20 hydrocarbyl, e.g. C.sub.1-C.sub.10 hydrocarbyl, e.g. C.sub.1-C.sub.6 hydrocarbyl; and substituted or unsubstituted, aliphatic or aromatic C.sub.3-C.sub.20 carbocyclyl, e.g. C.sub.3-C.sub.10 carbocyclyl, or C.sub.3-C.sub.6 carbocyclyl, or 5-20 membered heterocyclyl, e.g. 5-10 membered heterocyclyl, or 5-6 membered heterocyclyl.

[0053] In one embodiment, R.sup.4, R.sup.5 and R.sup.6 are independently selected from the group comprising: hydrogen atom, substituted or unsubstituted, branched or linear C.sub.1-C.sub.20 hydrocarbyl, e.g. C.sub.1-C.sub.10 hydrocarbyl, e.g. C.sub.1-C.sub.6 hydrocarbyl; and substituted or unsubstituted, aliphatic C.sub.3-C.sub.20 carbocyclyl, e.g. C.sub.3-C.sub.10 carbocyclyl, or C.sub.3-C.sub.6 carbocyclyl. For example, any hydrocarbyl moiety may be an alkyl and any carbocyclyl moiety may be a cycloalkyl.

[0054] More particularly, R.sup.4, R.sup.5 and R.sup.6 may be each independently selected from the group comprising: hydrogen atom, substituted or unsubstituted C.sub.6-C.sub.20 aryl-C.sub.0-C.sub.20 alkyl, e.g. substituted or unsubstituted C.sub.6-C.sub.20 aryl, such as substituted or unsubstituted phenyl or naphthyl, in particular substituted or unsubstituted phenyl.

[0055] Preferably, the phosphite compounds are chosen in the group consisting of: phosphorous acid, triphenylphosphite, diphenylphosphite, phenylphosphite, diisodecylphenylphosphite, diphenylisodecylphosphite, disooctyloctylphenylphosphite, phenyldiisodecylphosphite, tris(4-methoxyphenyl)phosphite, tri(o-tolyl)phosphite, tris (nonylphenyl)phosphite, tetraphenyl dipropyleneglycol diphosphite, 4,4-isopropylidenediphenol C.sub.12-.sub.15 alcohol phosphite and the like.

[0056] The phosphite compound is preferably present in an amount comprised between 1 and 10 molar equivalent phosphite of the phosphite compound to the phosphine oxide of the tertiary phosphine oxide, preferably between 2 and 6 molar equivalent phosphite.

[0057] For example, the phosphite compound may suitably be present in an amount such as the molar ratio of the phosphite function(s) of the phosphite compound to the phosphine oxide function(s) of the tertiary phosphine oxide to be reduced is from 1 to 10, e.g. from 1.5 to 8, e.g. from 2 to 6.

[0058] In one embodiment, the phosphite compound is attached to a solid support. In this embodiment, the phosphite compound may be regenerated after use, e.g. by reacting it with a reduction agent, such as H.sub.2, LiAlH.sub.4 and the like.

The Catalyst

[0059] The catalyst to be used in the present invention is a catalyst that catalyzes the conversion of a tertiary phosphine oxide to the corresponding tertiary phosphine. In accordance with the invention, the catalyst can be any type of chemical species capable of catalyzing the reaction of the invention. Preferably the catalyst comprises at least one halogen atom such as Cl, Br, I and F.

[0060] The catalyst may be selected from the group comprising fluorine (F.sub.2), chlorine (Cl.sub.2), bromine (Br.sub.2), iodine (I.sub.2), iodine monochloride (ICl), iodine monobromide (IBr), heterocyclyl halides, such as N-halosuccinimide, 1,3-dihalo-5,5-dimethylhydantoin, haloalkanes, in particular tetrahalomethanes, such as tetrachloromethane, tetrabromomethane, tetraiodomethane, tetrafluoromethane, phosphine dihalides, as tertiary phosphine dihalides, such as triphenylphosphine dichloride, triphenylphosphine dibromide, triphenylphosphine diiodide, triphenylphosphine difluoride, triphenylphosphine dichloride, and/or any trialkyl, cycloalkyl or aryl analogues thereof.

[0061] The catalyst loading may be comprised between 0.1 and 1 molar equivalents of the tertiary phosphine oxide to be reduced, in particular 0.2 and 0.6 molar equivalents, more preferably 0.3 and 0.5 molar equivalents.

[0062] In fact, increasing the amount of catalyst above the indicated ranges does not appear to have any significant effect on the reaction. However, depending on the utilized catalyst, higher/lower molar equivalents may be relevant, and increasing/decreasing the amount of catalyst is thus also within the scope of the present invention.

[0063] The catalyst may be present in any physical form, but suitable forms known to a person skilled in the art for a particular combination of reagents and/or reaction conditions are naturally preferable.

The Solid Support

[0064] Either the tertiary phosphine oxide and/or the phosphite compound may be attached to a solid support. An example of such a solid support is a polystyrene material, such as sold under the trade name JandaJel, by Sigma-Aldrich Co. Other possible solid phase supports are e.g. silica gel, Ring-Opening Olefin Metathesis Polymerization (ROMP) gel etc.

[0065] The person of ordinary skill in the art will now of various other possible solid supports, such as those described e.g. in U.S. Pat. No. 7,491,779 to Steinke, et al., the contents of which are incorporated by reference.

The Reaction Medium

[0066] The process of converting the tertiary phosphine oxide into the corresponding phosphine may be performed under solvent-free conditions, in order to further reduce the environmental impact of the process. The process of the present invention has, by virtue of the selection of reagents and conditions under which the reaction is taking place, a remarkably low environmental impact, but the possibility to utilize solvent-free reaction conditions further optimizes the eco-friendly characteristics of the present invention.

[0067] The process may also be carried out in the presence of a non-polar solvent or an anhydrous aprotic polar solvent.

[0068] Anhydrous aprotic solvent(s) may be chosen in the group consisting of toluene, hexane, tetrahydrofuran (THF), 2-methyltetrahydrofuran, acetonitrile, diethylether, dioxane, propionitrile, benzonitrile, ethyl acetate and mixtures of these.

[0069] The reaction medium may also comprise water, notably with a molar ratio of water to tertiary phosphine oxide comprised between 1/1 and 10/1, preferably comprised between 1/1 and 2/1.

[0070] The process may also be carried out in the presence of a base. Said base is not particularly limited and could be organic or inorganic base. Organic base may notably be tertiary amine chosen from a group consisting of pyridine, trimethylamine, triethylamine, DIPEA(N,N-diisopropylethylamine) and DBU(1,8-diazabicyclo[5.4.0]undec-7-ene), DABCO (1,4-diazabicyclo[2.2.2]octane), DMP(2,5-dimethylpyridine). Inorganic base may be alkali metal hydroxide, such as sodium hydroxide, potassium hydroxide and alkali metal salt chosen from a group consisting of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.

[0071] The bases mentioned above could be used solely or in the form of a mixture.

[0072] The base might be preferably present in an amount comprised between 0.1 and 2 molar equivalents of the tertiary phosphine oxide to be reduced, in particular 0.2 and 1.0 molar equivalents, more preferably 0.3 and 0.8 molar equivalents.

[0073] Further, the process can be carried out in virtually any type of reaction vessel, additionally increasing the versatility, specifically from an industrial perspective, of the invention.

Other Features of the Inventive Process

[0074] The process of the invention very advantageously may be carried out at low reaction temperature, notably between 15 and 30 C. The process may be carried out under air or under an inert atmosphere, such as a nitrogen atmosphere. Very advantageously, the reaction time may be kept very short, notably between 2 and 6 hours.

[0075] The mixture may be stirred for the appropriate amount of time.

[0076] The reaction mixture may be quenched, notably by H.sub.2O, brine or preferably saturated NaHCO.sub.3.

[0077] The product may be then purified by an appropriate method known in the prior art such as extraction, crystallization, or filtration.

[0078] For example, in one embodiment, at the completion of the reaction, the reaction medium is diluted, if necessary, and washed with portions of a weak basic buffer solution, such as saturated NaHCO.sub.3. The solution is dried, e.g. with Na.sub.2SO.sub.4 and filtered, whereafter the solvent is evaporated. The evaporation residue is redissolved in a hot solvent, e.g. EtOH, and made to crystallize, e.g. by keeping in a refrigerator. The product crystals then are filtered off, washed and dried.

[0079] The following examples are included to illustrate embodiments of the invention. Needless to say, the invention is not limited to described examples.

EXPERIMENTAL PART

Example 1

[0080] To a 100 mL three-necked flask was added 1.39 g (5 mmol) of triphenylphosphine oxide, 6.20 g (20 mmol) of triphenyl phosphite and 20 mL of anhydrous THF. 1.26 g (5 mmol) of I.sub.2 was then introduced to the mixture. The mixture was stirred for 24 h at room temperature under nitrogen atmosphere provided by a nitrogen balloon. Reaction is expressed as follows:

##STR00003##

[0081] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0082] Conversion of triphenylphosphine oxide: 69%

[0083] Yield of triphenylphosphine: 66%

Example 2

[0084] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 6.20 g (20 mmol) of triphenyl phosphite, 20 mL of anhydrous THF, 0.63 g (2.5 mmol) of I.sub.2 and 0.18 g of H.sub.20 (10 mmol) respectively. The mixture was stirred at room temperature overnight.

[0085] Reaction is expressed as follows:

##STR00004##

[0086] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0087] Conversion of triphenylphosphine oxide: 75%

[0088] Yield of triphenylphosphine: 66%

Example 3

[0089] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 4.68 g (20 mmol) of diphenyl phosphite, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 18 h.

[0090] Reaction is expressed as follows:

##STR00005##

[0091] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0092] Conversion of triphenylphosphine oxide: 82%

[0093] Yield of triphenylphosphine: 67%

Example 4

[0094] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.77 g (2.5 mmol) of triphenylphosphite, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 18 h.

[0095] Reaction is expressed as follows:

##STR00006##

[0096] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0097] Conversion of triphenylphosphine oxide: 91%

[0098] Yield of triphenylphosphine: 88%

Example 5

[0099] In a glove box, a 50 mL flask vial containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.46 g (1.5 mmol) of triphenylphosphite, 20 mL of anhydrous THF and 0.38 g (1.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 20 h. Reaction is expressed as follows:

##STR00007##

[0100] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0101] Conversion of triphenylphosphine oxide: 86%

[0102] Yield of triphenylphosphine: 80%

Example 6

[0103] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.77 g (2.5 mmol) of triphenylphosphite, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 5 h before it was quenched with 0.2 g of H.sub.2O. The yield of triphenylphosphine was 89% in the mixture based on .sup.31P NMR spectroscopy. 5.7 g of colorless oil was obtained after concentrated under vacuum, which was further purified by flash chromatography to afford 1.06 g of a white solid (4.04 mmol, 81%).

[0104] Reaction is expressed as follows:

##STR00008##

Example 7

[0105] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.323 g (2.5 mmol) of N,N-diisopropylethylamine, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 5 h before it was quenched with 0.2 g of H.sub.2O.

[0106] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0107] Conversion of triphenylphosphine oxide: 87%.

[0108] Yield of triphenylphosphine: 85%.

Example 8

[0109] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.253 g (2.5 mmol) of triethylamine, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 5 h before it was quenched with 0.2 g of H.sub.2O.

[0110] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0111] Conversion of triphenylphosphine oxide: 83%.

[0112] Yield of triphenylphosphine: 76%.

Example 9

[0113] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.190 g (1.25 mmol) of 1,8-diazabicyclo[5.4.0]undec-7-ene, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 5 h before it was quenched with 0.2 g of H.sub.2O.

[0114] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0115] Conversion of triphenylphosphine oxide: 75%.

[0116] Yield of triphenylphosphine: 72%.

Example 10

[0117] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 20 mL of anhydrous THF and 0.562 g (2.5 mmol) of N-iodosuccinimide respectively. The mixture was stirred at room temperature for 6 h before it was quenched with 0.2 g of H.sub.2O.

[0118] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0119] Conversion of triphenylphosphine oxide: 83%.

[0120] Yield of triphenylphosphine: 77%.

Example 11

[0121] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.77 g (2.5 mmol) of triphenylphosphite, 20 mL of anhydrous THF and 0.562 g (2.5 mmol) of N-iodosuccinimide respectively. The mixture was stirred at room temperature for 5 h before it was quenched with 0.2 g of H.sub.2O.

[0122] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0123] Conversion of triphenylphosphine oxide: 92%.

[0124] Yield of triphenylphosphine: 91%.

Example 12

[0125] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.39 g (5 mmol) of triphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.77 g (2.5 mmol) of triphenylphosphite, 0.253 g (2.5 mmol) of triethylamine, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 5 h before it was quenched with 0.2 g of H.sub.2O.

[0126] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0127] Conversion of triphenylphosphine oxide: 95%.

[0128] Yield of triphenylphosphine: 94%.

Example 13

[0129] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.84 g (5 mmol) of tris(4-methoxyphenyl)phosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.77 g (2.5 mmol) of triphenylphosphite, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 18 h.

[0130] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0131] Conversion of triphenylphosphine oxide: 74%.

[0132] Yield of triphenylphosphine: 73%.

Example 14

[0133] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.60 g (5 mmol) of tris(4-methylphenyl)phosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.77 g (2.5 mmol) of triphenylphosphite, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 6 h.

[0134] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0135] Conversion of triphenylphosphine oxide: 88%.

[0136] Yield of triphenylphosphine: 80%.

Example 15

[0137] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.66 g (5 mmol) of tris(4-fluorophenyl)phosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.77 g (2.5 mmol) of triphenylphosphite, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 5 h.

[0138] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0139] Conversion of triphenylphosphine oxide: 94%.

[0140] Yield of triphenylphosphine: 90%.

Example 16

[0141] In a glove box, a 50 mL flask containing a stirring bar was charged with 1.42 g (5 mmol) of cyclohexyldiphenylphosphine oxide, 2.34 g (10 mmol) of diphenylphosphite, 0.77 g (2.5 mmol) of triphenylphosphite, 20 mL of anhydrous THF and 0.63 g (2.5 mmol) of I.sub.2 respectively. The mixture was stirred at room temperature for 5 h.

[0142] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0143] Conversion of triphenylphosphine oxide: 80%.

[0144] Yield of triphenylphosphine: 75%.

Example 17

[0145] In a glove box, a 50 mL flask containing a stirring bar was charged with 2.15 g (5 mmol) of 1,2-bis(diphenylphosphinoyl)ethane dioxide, 2.34 g (10 mmol) of diphenylphosphite, 0.77 g (2.5 mmol) of triphenylphosphite, 20 mL of anhydrous THF and 0.562 g (2.5 mmol) of N-iodosuccinimide respectively. The mixture was stirred at 50 C. for 18 h.

[0146] The reaction mixture was characterized by .sup.31P NMR spectroscopy and the conversion and yield were calculated based on the integrals.

[0147] Conversion of triphenylphosphine oxide: 90%.

[0148] Yield of triphenylphosphine: 60%.