COMPOUNDS WITH PHOSPHINE OXIDE AND AMINE FUNCTIONS, USEFUL AS URANIUM (VI) LIGANDS, AND USES THEREOF, IN PARTICULAR FOR EXTRACTING URANIUM(VI) FROM AQUEOUS SOLUTIONS OF SULPHURIC ACID

Abstract

The invention relates to compounds which correspond to the general formula (I) below:

##STR00001##

in which: R.sup.1 and R.sup.2 represent, independently of one another, a C.sub.4 to C.sub.12 acyclic hydrocarbon group; R.sup.3 represents H; a C.sub.1 to C.sub.12 acyclic hydrocarbon group with optionally one or more heteroatoms; a C.sub.5 or C.sub.6 cyclic hydrocarbon group; or a 5- or 6-membered heterocyclic group; R.sup.4 represents H or a C.sub.1 to C.sub.12 acyclic hydrocarbon group with optionally one or more heteroatoms; R.sup.5 and R.sup.6 represent, independently of one another, H; a C.sub.1 to C.sub.12 acyclic hydrocarbon group with optionally one or more heteroatoms; a C.sub.5 or C.sub.6 cyclic hydrocarbon group; or a 5- or 6-membered heterocyclic group; on the condition however that R.sup.5 and R.sup.6 do not each represent H.

Claims

1-21. (canceled)

22. A method for extracting uranium(VI) from an aqueous solution of sulphuric acid, comprising contacting the aqueous solution with an organic solution comprising a compound of formula (I): ##STR00009## in which: R.sup.1 and R.sup.2 represent, independently of one another, a saturated or unsaturated, acyclic hydrocarbon group comprising 4 to 12 carbon atoms; R.sup.3 represents a hydrogen atom; a saturated or unsaturated, acyclic hydrocarbon group comprising 1 to 12 carbon atoms and optionally one or more heteroatoms; a saturated or unsaturated, cyclic hydrocarbon group with 5 or 6 carbon atoms; or a saturated or unsaturated, 5- or 6-membered heterocyclic group; R.sup.4 represents a hydrogen atom or a saturated or unsaturated, acyclic hydrocarbon group comprising 1 to 12 carbon atoms and optionally one or more heteroatoms; R.sup.5 and R.sup.6 represent, independently of one another, a hydrogen atom; a saturated or unsaturated, acyclic hydrocarbon group comprising 1 to 12 carbon atoms and optionally one or more heteroatoms; a saturated or unsaturated, cyclic hydrocarbon group with 5 or 6 carbon atoms; or a saturated or unsaturated, 5- or 6-membered heterocyclic group; on the condition however that R.sup.5 and R.sup.6 do not each represent a hydrogen atom; and then separating the aqueous solution from the organic solution.

23. The method of claim 22, in which R.sup.1 and R.sup.2 each represent a linear or branched alkyl group comprising 6 to 12 carbon atoms.

24. The method of claim 23, in which R.sup.1 and R.sup.2 are identical to each other and each represent a linear or branched alkyl group comprising 8 to 10 carbon atoms

25. The method of claim 22, in which R.sup.3 represents a linear or branched alkyl group comprising 1 to 12 carbon atoms.

26. The method of claim 22, in which R.sup.4 represents a hydrogen atom or a linear or branched alkyl group comprising 1 to 12 carbon atoms.

27. The method of claim 22, in which R.sup.5 and R.sup.6 each represent a linear or branched alkyl group comprising 1 to 12 carbon atoms, or a cycloalkyl group.

28. The method of claim 22, in which: R.sup.1, R.sup.2 and R.sup.3 each represent an n-octyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent a 2-ethylhexyl group; or R.sup.1 and R.sup.2 each represent a 2-ethylhexyl group, R.sup.3 represents an n-octyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent a 2-ethylhexyl group; or R.sup.1, R.sup.2 and R.sup.3 each represent an n-octyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent an n-octyl group; or R.sup.1 and R.sup.2 each represent an n-octyl group, R.sup.3 represents a 2,4,4-trimethylpentyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent an n-octyl group; or R.sup.1 and R.sup.2 each represent an n-octyl group, R.sup.3 represents a 2,4,4-trimethylpentyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent a 2-ethylhexyl group.

29. The method of claim 22, in which the aqueous solution comprises 0.01 mol/L to 2 mol/L of sulphuric acid.

30. The method of claim 22, in which the organic solution comprises 0.01 mol/L to 0.25 mol/L of the compound in an organic diluent.

31. The method of claim 22, in which the aqueous solution is derived from the lixiviation of a uranium ore by sulphuric acid.

32. A method for recovering the uranium present in an aqueous solution of sulphuric acid derived from the lixiviation of a uranium ore by sulphuric acid, comprising: a) an extraction of uranium, in oxidation state VI, from the aqueous solution, the extraction comprising contacting the aqueous solution in contact with an organic phase comprising a compound of formula (I): ##STR00010## in which: R.sup.1 and R.sup.2 represent, independently of one another, a saturated or unsaturated, acyclic hydrocarbon group comprising 4 to 12 carbon atoms; R.sup.3 represents a hydrogen atom; a saturated or unsaturated, acyclic hydrocarbon group comprising 1 to 12 carbon atoms and optionally one or more heteroatoms; a saturated or unsaturated, cyclic hydrocarbon group with 5 or 6 carbon atoms; or a saturated or unsaturated, 5- or 6-membered heterocyclic group; R.sup.4 represents a hydrogen atom or a saturated or unsaturated, acyclic hydrocarbon group comprising 1 to 12 carbon atoms and optionally one or more heteroatoms; R.sup.5 and R.sup.6 represent, independently of one another, a hydrogen atom; a saturated or unsaturated, acyclic hydrocarbon group comprising 1 to 12 carbon atoms and optionally one or more heteroatoms; a saturated or unsaturated, cyclic hydrocarbon group with 5 or 6 carbon atoms; or a saturated or unsaturated, 5- or 6-membered heterocyclic group; on the condition however that R.sup.5 and R.sup.6 do not each represent a hydrogen atom; then separating the aqueous solution from the organic phase; and b) a stripping of uranium(VI) from the organic phase obtained at the end of a), the stripping comprising contacting the organic phase with an aqueous solution comprising at least one carbonate, then separating the organic phase from the aqueous solution.

33. The method of claim 32, in which the organic phase of a) comprises 0.01 mol/L to 0.25 mol/L of the compound in solution in an organic diluent.

34. The method of claim 32, in which the aqueous solution of sulphuric acid comprises 0.1 g/L to 8 g/L of uranium, 0.1 mol/L to 2 mol/L of sulphate ions and 0.01 mol/L to 2 mol/L of sulphuric acid.

35. The method of claim 32, in which: a volumetric ratio between the organic phase and the aqueous solution of sulphuric acid less than or equal to 1 is used at a); and/or a volumetric ratio between the organic phase and the aqueous solution of carbonate greater than or equal to 1 is used at b).

36. A compound of formula (I): ##STR00011## in which: R.sup.1 and R.sup.2 represent, independently of one another, a saturated or unsaturated, acyclic hydrocarbon group comprising 4 to 12 carbon atoms; R.sup.3 represents a saturated or unsaturated, acyclic hydrocarbon group comprising 1 to 12 carbon atoms and optionally one or more heteroatoms; a saturated or unsaturated, cyclic hydrocarbon group with 5 or 6 carbon atoms; or a saturated or unsaturated, 5- or 6-membered heterocyclic group; R.sup.4 represents a hydrogen atom or a saturated or unsaturated, acyclic hydrocarbon comprising 1 to 12 carbon atoms and optionally one or more heteroatoms; R.sup.5 and R.sup.6 represent, independently of one another, a hydrogen atom; a saturated or unsaturated, acyclic hydrocarbon group comprising 1 to 12 carbon atoms and optionally one or more heteroatoms; a saturated or unsaturated, cyclic hydrocarbon group with 5 or 6 carbon atoms; or a saturated or unsaturated, 5- or 6-membered heterocyclic group; on the condition however that R.sup.5 and R.sup.6 do not each represent a hydrogen atom.

37. The compound of claim 36, in which R.sup.1 and R.sup.2 each represent a linear or branched alkyl group comprising 6 to 12 carbon atoms.

38. The compound of claim 37, in which R.sup.1 and R.sup.2 are identical to each other and each represent a linear or branched alkyl group comprising 8 to 10 carbon atoms.

39. The compound of claim 36, in which R.sup.3 represents a linear or branched alkyl group comprising 1 to 12 carbon atoms.

40. The compound of claim 36, in which R.sup.4 represents a hydrogen atom or a linear or branched alkyl group comprising 1 to 12 carbon atoms.

41. The compound of claim 36, in which R.sup.5 and R.sup.6 each represent a linear or branched alkyl group comprising 1 to 12 carbon atoms, or a cycloalkyl group.

42. The compound of claim 36, in which: R.sup.1, R.sup.2 and R.sup.3 each represent an n-octyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent a 2-ethylhexyl group; or R.sup.1 and R.sup.2 each represent a 2-ethylhexyl group, R.sup.3 represents an n-octyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent a 2-ethylhexyl group; or R.sup.1, R.sup.2 and R.sup.3 each represent an n-octyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent an n-octyl group; or R.sup.1 and R.sup.2 each represent an n-octyl group, R.sup.3 represents a 2,4,4-trimethylpentyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent an n-octyl group; or R.sup.1 and R.sup.2 each represent an n-octyl group, R.sup.3 represents a 2,4,4-trimethylpentyl group, R.sup.4 represents a hydrogen atom and R.sup.5 and R.sup.6 each represent a 2-ethylhexyl group.

Description

BRIEF DESCRIPTION OF THE FIGURE

[0068] FIG. 1 illustrates the different synthesis routes by which the compounds according to the invention may be synthesised.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

Example I: Synthesis of Compounds According to the Invention

[0069] The compounds according to the invention may be synthesised by different synthesis routes as a function of the significations of R.sup.3 and R.sup.4.

[0070] These synthesis routes are illustrated in FIG. 1.

[0071] As this figure shows, the compounds, which correspond to the general formula (I) in which one of R.sup.3 and R.sup.4 is different from a hydrogen atom whereas the other of R.sup.3 and R.sup.4 represents a hydrogen atom and which correspond to the compounds 4 and 4 of FIG. 1, may be obtained by a Kabachnik-Fields reaction which consists in condensing a dialkylphosphite oxide 1, of formula R.sup.1R.sup.2P(O)H, with, on the one hand, an aldehyde 2 of formula R.sup.3CHO in which R.sup.3 is different from a hydrogen atom (reaction A in FIG. 1) or an aldehyde 2 of formula R.sup.4CHO in which R.sup.4 is different from a hydrogen atom (reaction A in FIG. 1) and, on the other hand, an amine 3 of formula HNR.sup.5R.sup.6, in the presence of para-toluene sulfonic acid in catalytic quantity in toluene.

[0072] Reactions A and A are, for example, carried out by heating to reflux a mixture comprising n mmol of oxide 1, 1.2n mmol of aldehyde 2 (reaction A) or aldehyde 2 (reaction A) and 1.2n mmol of amine 3 in toluene (10n mL+50n mL to complete the Dean-Stark) with approximately 25n mg of para-toluene sulfonic acid (catalytic quantity) until at least 90% of oxide 1 are consumed, which is controlled by .sup.31P NMR. The solvent is next evaporated and the residue is purified by flash chromatography (Agilent Intelliflash 971-FP) on silica gel (eluent: cyclohexane/ethyl acetate 100-0/80-20, v/v) with monitoring by thin layer chromatography (TLCMerck TLC Silica Gel 60 F.sub.254) using phosphomolybdic acid in ethanol solution as stain.

[0073] The compounds, which correspond to the general formula (I) in which R.sup.3 and R.sup.4 are each a hydrogen atom and which correspond to the compounds 5(a) of FIG. 1, may be obtained by a reaction, also Kabachnik-Fields, noted A in this figure, that is carried out in the same manner as reactions A and A but by replacing the aldehyde 2 or 2 by formaldehyde (compound 2(a) of FIG. 1) which is introduced into the reaction medium in the form of paraformaldehyde.

[0074] Finally, the compounds, which correspond to the general formula (I) in which R.sup.3 and R.sup.4 are both different from a hydrogen atom and which correspond to the compounds 5(b) of FIG. 1, may be obtained: [0075] either by a C-alkylation reaction of the compound 4, noted B in this figure, that is carried out by means of a strong base such as sodium hydride, and a halide of formula R.sup.4X in which R.sup.4 is different from a hydrogen atom, for example an iodide R.sup.4I; [0076] or by a C-alkylation reaction of the compound 4, noted B in FIG. 1, that is also carried out by means of a strong base but by using a halide of formula R.sup.3X in which R.sup.3 is different from a hydrogen atom, for example an iodide R.sup.31; [0077] or instead by the aforesaid reaction A but which is carried out using a ketone of formula R.sup.3C(O)R.sup.4 in which R.sup.3 and R.sup.4 are both different from a hydrogen atom (compound 2(b) of FIG. 1) instead of formaldehyde.

[0078] Reactions B and B are typically carried out by adding to a solution comprising (n mmol) of compound 4 (reaction B) or compound 4 (reaction B) in 1 M dimethylformamide (10n mL), under nitrogen and under stirring, a solution comprising 1.3n mmol of sodium hydride followed, 10 minutes after, by a solution comprising 1.5n mmol of the halide R.sup.4X (reaction B) or the halide R.sup.3X (reaction B). The mixture is left to react for 18 hours under stirring then 25n mL of a solution of 1 M hydrochloric acid are added. The mixture is next extracted with 225n mL of ethyl ether. The organic phases are combined, washed successively with saturated (25n mL) sodium bicarbonate (NaHCO.sub.3), with water (25n mL) and with brine (25n mL), then dried on magnesium sulphate (MgSO.sub.4). After filtration and evaporation, the product is optionally purified by flash chromatography on silica gel.

[0079] The following compounds are thus synthesised.

[0080] I.2Compound ODODEHANP:

[0081] The title compound, which corresponds to the general formula (I) in which R.sup.1R.sup.2R.sup.3=n-octyl, R.sup.4H, R.sup.5R.sup.6=2-ethylhexyl, is synthesised by implementing step A, from di-n-octylphosphine oxide (4.4 mmol), n-nonanal and di(2-ethylhexyl)amine (reflux for 24 hours at 140 C.).

[0082] Yield: 69% (3.2 mmol)

[0083] .sup.31P NMR (162 MHz, CDCl.sub.3, 25 C.) (ppm): 53.0

[0084] .sup.1H NMR (400 MHz, CDCl.sub.3, 25 C.) (ppm): 2.44 (m, J.sub.P-H=8.4 Hz, 1H, PCH(Oct)-N); 2.58 (m, 2H, NCH.sub.2CH); 2.37 (m, 2H, NCH.sub.2CH); 1.90 (m, 2H); 1.86-1.50 (m, 10H); 1.42-1.11 (m, 48H); 0.91-0.78 (m, 21H, CH.sub.3)

[0085] .sup.13C NMR (100 MHz, CDCl.sub.3, 25 C.) (ppm): 60.3 & 59.7 (d, J.sub.C-P=66.7 Hz, PCHN); 57.2 (NCH.sub.2); 38.2 (CHCH.sub.2N); 31.9; 31.4; 31.3; 31.2; 31.1; 29.9; 29.6; 29.5; 29.3; 29.1; 25.6; 24.5; 24.3; 24.1; 23.3; 23.1; 22.7; 22.1; 21.9 (CH.sub.2); 14.1; 10.9; 10.7 (CH.sub.3)

[0086] HR-ESI-MS: calculated for C.sub.41H.sub.87NOP.sup.+=640.6525. found=640.6495.

[0087] I.3Compound ODEHDEHANP:

[0088] The title compound, which corresponds to the general formula (I) in which R.sup.1R.sup.2=2-ethylhexyl, R.sup.3=n-octyl, R.sup.4H, R.sup.5R.sup.6=2-ethylhexyl, is synthesised by implementing step A, from di(2-ethylhexyl)phosphine oxide (2.7 mmol), n-nonanal and di(2-ethylhexyl)amine (reflux for 8 hours at 140 C.).

[0089] Yield: 27% (0.65 mmol)

[0090] .sup.31P NMR (162 MHz, CDCl.sub.3, 25 C.) (ppm): 51.6

[0091] .sup.1H NMR (400 MHz, CDCl.sub.3, 25 C.) (ppm): 2.84 (m, 2H, PCH(CH(C.sub.2H.sub.5)C.sub.6H.sub.13)N); 2.34 (m, 2H); 1.88-1.07 (m, 55H); 0.92-0.78 (m, 27H, CH.sub.3) HR-ESI-MS: calculated for C.sub.41H.sub.87NOP.sup.+=640.6525. found=640.6513.

[0092] I.4Compound ODODOANP:

[0093] The title compound, which corresponds to the general formula (I) in which R.sup.1R.sup.2R.sup.3=n-octyl, R.sup.4H, R.sup.5R.sup.6=n-octyl, is synthesised by implementing step A, from di-n-octylphosphine oxide (7.7 mmol), n-nonanal and di-n-octylamine (reflux for 24 hours at 140 C.).

[0094] Yield: 57% (4.4 mmol)

[0095] .sup.31P NMR (162 MHz, CDCl.sub.3, 25 C.) (ppm): 53

[0096] .sup.1H NMR (400 MHz, CDCl.sub.3, 25 C.) (ppm): 2.75 (m, J.sub.P-H=7.6 Hz, 1H, PCH(Oct)-N); 2.64 (m, 2H, NCH.sub.2); 2.49 (m, 2H, NCH.sub.2); 1.82-1.14 (m, 66H); 0.92-0.78 (m, 15H, CH.sub.3)

[0097] .sup.13C NMR (100 MHz, CDCl.sub.3, 25 C.) (ppm): 60.7 & 60.0 (d, J.sub.C-P=66.7 Hz, PCHN); 53.2 (NCH.sub.2); 32.1; 31.7, 31.6; 31.5; 30.1; 29.9; 29.8; 29.6; 29.5; 29.3; 27.6; 27.1; 27.0; 26.3; 25.3; 22.9; 22.2 (CH.sub.2); 14.3 (CH.sub.3)

[0098] HR-ESI-MS: calculated for C.sub.41H.sub.87NOP.sup.+=640.6525. found=640.6523.

[0099] I.5Compound ODODEHATMHP:

[0100] The title compound, which corresponds to the general formula (I) in which R.sup.1R.sup.2=n-octyl, R.sup.3=2,4,4-trimethylpentyl, R.sup.4H, R.sup.5R.sup.6=2-ethylhexyl, is synthesised by implementing step A, from di-n-octylphosphine oxide (7.6 mmol), 3,5,5-trimethylhexanal and di(2-ethylhexyl)amine (reflux for 72 hours at 140 C.).

[0101] Yield: 72% (5.5 mmol)

[0102] .sup.31P NMR (162 MHz, CDCl.sub.3, 25 C.) (ppm): 52.9

[0103] .sup.1H NMR (400 MHz, CDCl.sub.3, 25 C.) (ppm): 2.87 (m, JP-H=8.4 Hz, 1H, PCH(Oct)-N); 2.68 (m, 2H, NCH.sub.2CH); 2.38 (m, 2H, NCH.sub.2CH); 1.87-1.51 (m, 10H); 1.48-1.08 (m, 41H); 0.96-0.79 (m, 30H, CH.sub.3)

[0104] .sup.13C NMR (100 MHz, CDCl.sub.3, 25 C.) (ppm): 57.6 & 56.9 (d, J.sub.C-P=65.3 Hz, PCHN); 52.5; 52.2 (NCH.sub.2); 39.1; 38.5; 38.4; 38.2; 28.0; 27.5; 22.4 (CH); 36.8; 36.5; 35.9; 34.9; 32.0; 31.8; 31.4; 31.2; 28.0; 27.5; 24.7; 24.4; 23.5; 22.8; 22.1 (CH.sub.2); 30.6; 30.5; 21.8; 21.7; 14.3; 14.2; 11.1; 11.0; 10.9 (CH.sub.3)

[0105] HR-ESI-MS: calculated for C.sub.41H.sub.87NOP.sup.+=640.6525. found=640.6517.

[0106] I.6Compound ODODOATMHP:

[0107] The title compound, which corresponds to the general formula (I) in which R.sup.1R.sup.2=n-octyl, R.sup.3=2,4,4-trimethylpentyl, R.sup.4H, R.sup.5R.sup.6=n-octyl, is synthesised by implementing step A, from di-n-octylphosphine oxide (7.5 mmol), 3,5,5-trimethylhexanal and di-n-octylamine (reflux for 72 hours at 140 C.).

[0108] Yield: 65% (4.92 mmol)

[0109] .sup.31P NMR (162 MHz, CDCl.sub.3, 25 C.) (ppm): 53.5

[0110] .sup.1H NMR (400 MHz, CDCl.sub.3, 25 C.) (ppm): 2.89-2.39 (m, 5H); 1.88-1.51 (m, 10H); 1.45-1.18 (m, 47H); 0.95-0.80 (m, 24H, CH.sub.3)

[0111] .sup.13C NMR (100 MHz, CDCl.sub.3, 25 C.) (ppm): 58.1 & 57.3; 57.7 & 57.0 (d, J.sub.C-P=75.4 Hz, PCHN); 53.1 (NCH.sub.2); 52.5; 51.6 (CH.sub.2P); 27.9; 27.3; 22.1 (CH) 35.8; 34.7, 32.1; 31.7; 31.6; 31.5; 30.1; 29.9; 29.6; 29.4; 29.3; 27.6; 22.8; 22.2 (CH.sub.2); 30.6; 30.3; 22.7; 14.3 (CH.sub.3)

[0112] HR-ESI-MS: calculated for C.sub.41H.sub.87NOP.sup.+=640.6525. found=640.6526.

[0113] I.7Compound ODCHDOANP:

[0114] The title compound, which corresponds to the general formula (I) in which R.sup.1R.sup.2=n-octyl, R.sup.3=2,4,4-trimethylpentyl, R.sup.4H, R.sup.5R.sup.6=cyclohexyl, is synthesised by implementing step A, from di-n-octylphosphine oxide (7.6 mmol), 3,5,5-trimethylhexanal and dicyclohexylamine (reflux for 96 hours at 140 C.).

[0115] Yield: 24% (1.9 mmol)

[0116] .sup.31P NMR (162 MHz, CDCl.sub.3, 25 C.) (ppm): 53.5 & 50.4

[0117] .sup.1H NMR (400 MHz, CDCl.sub.3, 25 C.) (ppm): 3.17-3.03 (m, J.sub.P-H=12 Hz, 1H, PCH(triMePent)-N); 2.68 (m, 2H, NCHCH.sub.2); 1.97 (m, 1H); 1.85 (m, 2H); 1.77-1.53 (m, 18H); 1.39-1.15 (m, 32H); 0.92-0.82 (m, 18H, CH.sub.3)

[0118] .sup.13C NMR (100 MHz, CDCl.sub.3, 25 C.) (ppm): 57.1 & 56.2 (broad d, J.sub.C-P=86 Hz, PCHN); 54.2; 54.1; 53.6; 53.5 (NCH); 53.1; 53.0 (CH.sub.2P); 27.3; 22.4 (CH); 41.5; 41.4; 39.2; 39.1; 35.1; 34.8; 34.4; 32.0; 31.5; 31.4; 29.9; 28.5; 27.6; 27.5; 27.3; 27.1; 26.9; 26.7; 26.1; 22.8; 22.5; 22.3 (CH.sub.2); 30.5; 22.2; 14.2 (CH.sub.3)

[0119] HR-ESI-MS: calculated for C.sub.37H.sub.75NOP.sup.+=580.5586. found=580.5582.

Example II: Properties of the Compounds According to the Invention

[0120] II.1Capacity of the Compounds According to the Invention to Extract Uranium(VI) from a Synthetic Aqueous Solution with 10 Metal Elements in Sulphuric Acid:

[0121] The capacity of the compounds according to the invention to extract uranium(VI) from an aqueous solution of sulphuric acid is firstly tested on a synthetic aqueous solution, which comprises 10 metal elements (to keep as close as possible to the conditions encountered during the extraction of uranium(VI) from the liquor of lixiviation of uranium ores by sulphuric acid), and compared to that which exhibits, under the same experimental conditions, tri-n-octylamine (which is one of the two tertiary amines constituting the Alamine 336 used in the AMEX method) one the one, and HDEHP (which is one of the two extractants of the synergic mixture used in the DAPEX method) on the other hand).

[0122] The synthetic aqueous solution used within the scope of these tests comprises 250 mg/L of each of the following metal elements: uranium(VI), iron(III), molybdenum(VI), cerium(III), lanthanum(III), gadolinium(III), ytterbium(III), neodymium(III), titanium(IV) and zirconium(IV), 1 mol/L of H.sub.2SO.sub.4 and 1 mol/L of Li.sub.2SO.sub.4.

[0123] The compounds according to the invention tested are ODODEHANP, ODODOANP, ODODEHATMHP and ODODOATMHP.

[0124] The extraction tests are carried out, in tubes, by placing a volume of 1 to 2 mL of the synthetic aqueous solution in contact with an identical volume of an organic solution comprising either one of the tested compounds according to the invention or tri-n-octylamine or instead HDEHP at a level of 0.1 mol/L in n-dodecane, for 1 hour, under stirring and at a temperature of 21-22 C. After which, the aqueous and organic phases are separated from each other by gravity decantation in less than 3 minutes.

[0125] The concentrations of uranium and the other metal elements are measured by inductively coupled plasma optical emission spectrometry (ICP-OES): [0126] in the synthetic solution before it is placed in contact with the organic solutions but after dilution to bring its uranium and iron concentrations to measurable values (0 to 20 ppm); and [0127] in the aqueous phases once separated from the organic phases, also after dilution of said aqueous phases.

[0128] The results of these tests are shown in table I below, in which are indicated the chemical structures of the different compounds tested, the distribution coefficients of uranium, iron, molybdenum, cerium, lanthanum, gadolinium, ytterbium, neodymium, titanium and zirconium, respectively noted D.sub.U, D.sub.Fe, D.sub.Mo, D.sub.Ce, D.sub.La, D.sub.Gd, D.sub.Yb, D.sub.Nd, D.sub.Zr and D.sub.Ti, obtained with the extraction for tri-n-octylamine (for which the values of the distribution coefficients are given in italics and for information purposes, given the appearance of a third phase), HDEHP and for each of the tested compounds according to the invention as well as the potential formation of a third phase at extraction.

TABLE-US-00001 TABLE I Compounds tested D.sub.u D.sub.Fe D.sub.Mo D.sub.Ce D.sub.La D.sub.Gd D.sub.Yb D.sub.Nd D.sub.Zr D.sub.Ti PRIOR ART [00003] 0.7 0 7 0 0 0 0 0 0.5 0 Third phase at extraction [00004] 6 0.2 70 0 0 0 2.4 0 120 14 COMPOUNDS ACCORDING TO THE INVENTION [00005] 90 0 1.4 0 0 0 0 0 0.3 0.1 [00006] >200 0 2.2 0 0 0 0 0 1.2 0.1 [00007] >200 0 0.6 0 0 0 0 0 0.1 0 [00008] >200 0 2.2 0 0 0 0 0 1.0 0.1 Oct = n-octyl; EtHex = 2-ethylhexyl; (2,4,4)triMePent = 2,4,4-trimethylpentyl

[0129] This table shows that the compounds according to the invention have a capacity to extract uranium(VI) from an aqueous solution of sulphuric acid distinctly higher that that exhibited by the reference extractants of the prior art.

[0130] It also shows that the compounds according to the invention exhibit in addition a selectivity for uranium(VI) with regard to the other metal elements much greater than that exhibited by the reference extractants of the prior art. Thus, iron, cerium, lanthanum, gadolinium, ytterbium and neodymium are not at all extracted whereas molybdenum, zirconium and titanium are only extracted very weakly.

[0131] As an example, table II below presents the improvements obtained in terms of D.sub.U, separation factor of uranium and iron, noted FS.sub.U/Fe, separation factor of uranium and molybdenum, noted FS.sub.U/Mo, separation factor of uranium and zirconium, noted FS.sub.U/Zr, and separation factor of uranium and titanium, noted FS.sub.U/Ti, with the compound ODODEHATMHP compared to the reference extractants of the prior art (for tri-n-octylamine, the values are, here again, given in italics and for information purposes, given the appearance of a third phase).

TABLE-US-00002 TABLE II D.sub.U FS.sub.U/Fe FS.sub.U/Mo FS.sub.U/Zr FS.sub.U/Ti Compounds tested ODODEHATMHP >200 9000 3300 1600 5400 NOct.sub.3 0.7 1300 0.1 1.5 1200 Improvement >250 7 >10000 1000 4.5 HDEHP 6 36 0.09 0.04 0.5 Improvement >30 250 >10000 >10000 >10000

[0132] This table shows that the improvements obtained are very high.

[0133] The possibility of recovering quantitatively in aqueous phase the uranium(VI) having been extracted by the compounds according to the invention is also tested.

[0134] To do so, the organic phases obtained at the end of the extraction tests are placed in contact, in tubes, volume to volume, with an aqueous solution comprising 0.5 mol/L of ammonium carbonate (NH.sub.4).sub.2CO.sub.3 and/or 0.5 mol/L of ammonium oxalate ((NH.sub.4).sub.2C.sub.2O.sub.4). Contact is maintained for 1 hour, under stirring and at a temperature of 21-22 C. After which, the aqueous and organic phases are separated from each other by gravity decantation in less than 3 minutes and the aqueous phases are subjected to an analysis by plasma torch optical emission spectroscopy (ICP-OES) to measure the uranium concentration thereof.

[0135] These stripping tests show that an aqueous solution of a carbonate, such as ammonium carbonate, makes it possible to strip from an organic phase comprising a compound according to the invention the totality of the uranium(VI) having been extracted in this phase. It is thus possible to recover quantitatively in aqueous phase the uranium having been extracted using a compound according to the invention as extractant.

[0136] II.2Comparison of the Extractant Properties of a Compound According to the Invention with Those of the Compound DEHCNPB of Reference [3]:

[0137] An extraction test is carried out to compare the extractant properties of a compound according to the invention, namely the compound ODODEHATMPH given its performances, with those exhibited by the compound DEHCNPB described in reference [3].

[0138] This test is carried out using: [0139] as aqueous phase: a synthetic aqueous solution comprising 200 mg/L of each of the following 7 metal elements: uranium(VI), iron(III), molybdenum(VI), gadolinium(III), neodymium(III), titanium(IV) and zirconium(IV), 1 mol/L of H.sub.2SO.sub.4 and 1 mol/L of Li.sub.2SO.sub.4; and [0140] as organic phases: solutions comprising 0.1 mol/L of the compound ODODEHATMPH or the compound DEHCNPB in n-dodecane.

[0141] A volume of the aqueous phase is placed in contact with an identical volume of each of the organic phases for 1 hour, under stirring and at a temperature of 21-22 C., then separated from this phase by gravity decantation.

[0142] The concentrations of uranium and other metal elements are measured by inductively coupled plasma atomic emission spectroscopy (ICP-OES) in the aqueous phase before and after contact with the organic phases.

[0143] The results of this test are presented in table III below, in which are indicated the distribution coefficients, noted D.sub.M, of uranium, iron, molybdenum, gadolinium, neodymium, titanium and zirconium, as well as the separation factors, noted FS.sub.U/M, obtained for each of the two compounds tested.

TABLE-US-00003 TABLE III Compounds tested ODODEHATMHP DEHCNPB Metal elements D.sub.M FS.sub.U/M D.sub.M FS.sub.U/M Uranium >200 >200 Iron 0 0 Molybdenum 0.6 >300 80 >2.5 Gadolinium 0 0 Neodymium 0 0 Zirconium 0.1 >2000 80 >2.5 Titanium 0 15 >13

[0144] This table shows that the objective pursued by the Inventors is indeed attained by the invention since the compounds according to the invention, while having an affinity for uranium(VI) comparable to that of the compound DEHCNPB (D.sub.U>200), have a selectivity for uranium(VI) with regard to molybdenum, titanium and zirconiumwhich represent the main metal impurities capable of being extracted, jointly with uranium(VI), from an aqueous solution of sulphuric acid derived from the lixiviation of a uranium ore by sulphuric acidvery significantly greater than that shown by the compound DEHCNPB.

REFERENCES CITED

[0145] [1] Coleman et al., Ind. Eng. Chem. 1958, 50, 1756-1762 [0146] [2] Blake et al., Oak Ridge National Laboratory Report, 18 Dec. 1956 [0147] [3] WO-A-2014/139869