Functionalised Compounds

Abstract

A substantially insoluble compound having a polysaccharide backbone which is derivatised at one or more of its hydroxyl groups with a ligand (L) bound to the sugar moiety by a sulphur atom which may be tailored according to a wide range of applications. The compound is useful as a catalyst and in removal of contaminants from a feed containing particularly metal ions.

Claims

1. A compound comprising a substantially insoluble polysaccharide compound selected from cellulose and starch having a backbone comprising more than 20 sugar moieties wherein at least one of the sugar moieties is derivatised at one or more of its hydroxyl groups with a ligand (L) bound to the sugar moiety by a sulphur atom wherein the ligand L is of formula:
—S(O).sub.a(C R.sup.1 R.sup.2).sub.nX wherein: independently in each occurrence, R.sup.1 and R.sup.2 are selected from hydrogen, an optionally substituted, linear or branched C.sub.1-40-alkyl, C.sub.2-40-alkenyl or C.sub.2-40-alkynyl group, an aryl and a C.sub.1-40-alkylaryl group; a is, independently in each occurrence from 0 to 2; n is independently an integer from 1 to 22: X is selected from: —CR.sup.1R.sup.2R.sup.3; a divalent group linking two sugar moieties; —CR.sup.1R.sup.2 (CR.sup.1R.sup.2).sub.nC(═W)R; —CR.sup.1R.sup.2 (CR.sup.1Z).sub.i Q.sub.h CHR.sup.1Z; —CR.sup.1R.sup.2(CR.sup.1Z).sub.i Q.sub.h [(CHR.sup.1).sub.nW].sub.tR.sup.1; —(CR.sup.1Z).sub.i Q.sub.h C(═W)R.sup.1 —CR.sup.1R.sup.2(CR.sup.1Z).sub.i Q.sub.h R.sup.3 —OC(═W)R; wherein R is independently selected from H, R.sup.1, —OR.sup.1, —NR.sup.1R.sup.2, —NHNR.sup.1R.sup.2 and —SR.sup.1; R.sup.3 is an optionally substituted, linear or branched C.sub.1-40-alkyl, C.sub.2-40-alkenyl or C.sub.2-40-alkynyl group, an aryl and a C.sub.1-40-alkylaryl group; Q is independently selected from —C(═W.sup.1)W.sup.2— and —W.sup.2 C(═W.sup.1)—; W, W.sup.1 and W.sup.2 are independently selected from oxygen, sulfur, —N(R.sup.1)— and —N(NR.sup.1 R.sup.2); Z is independently selected from —OR.sup.1, —NR.sup.1R.sup.2 and —SR.sup.1; h is independently 0 or 1; i is independently from 0 to 6; t is independently an integer from 1 to 20; —[C(═W)].sub.h(W(C R.sup.1R.sup.2).sub.m).sub.nZ; and —S(O).sub.a—Y wherein Y is a monovalent terminal group.

2. A compound according to claim 1 has a solubility of less than 5% and desirably less than 1% in water at standard temperature and pressure.

3. A compound according to claim 1 wherein the polysaccharide comprises cellulose.

4. A compound according to claim 1 wherein the sugar moieties are derivatised at the hydroxyl substituent on the “6” carbon atom of the sugar moiety.

5. A compound according to claim 1 wherein a first proportion of the sugar moieties are derivatised by the ligand L and a second proportion of the sugar moieties are derivatised by a different substituent L′ at any one or more hydroxyl groups on the sugar moiety wherein L′ is selected from group X, R.sup.1, —Z, —(W(C R.sup.1 R.sup.2).sub.m).sub.nZ and a divalent group which forms a cross-linking bridge between two or more sugar moieties.

6. A compound according to claim 1 wherein R.sup.1 and R.sup.2 are independently selected from hydrogen, a linear or branched C.sub.1-40-alkyl, C.sub.2-40-alkenyl or C.sub.2-40-alkynyl group, an aryl and a C.sub.1-40-alkylaryl group, m is from 1 to 20, a is from 0 to 2 and b is from 0 to 2.

7. (canceled)

8. A compound according to claim 1 at least a proportion of the groups X are a divalent group selected from —[CO.sub.2(CH.sub.2).sub.mCO.sub.2]— and —[CH.sub.2(CH.sub.2).sub.mCH.sub.2]— linking two sugar moieties and m is independently from 1 to 10.

9.-10. (canceled)

11. A compound according to claim 1 wherein the functional group X is selected from: —S(O).sub.a(C R.sup.1 R.sup.2).sub.n C R.sup.1 R.sup.2R.sup.3; —S(O).sub.a(C R.sup.1 R.sup.2).sub.n S—Y; —S(O).sub.a(C R.sup.1 R.sup.2).sub.n—(C═W).sub.h(W(C R.sup.1 R.sup.2).sub.m).sub.nZ; —S(O).sub.a(C R.sup.1 R.sup.2).sub.n (CR.sup.1Z).sub.i Q.sub.hC(═W)R.sup.1; —S(O).sub.a(C R.sup.1 R.sup.2).sub.n C R.sup.1 R.sup.2 (CR.sup.1Z).sub.iQ.sub.hCHR.sup.1Z; —S(O).sub.a(C R.sup.1 R.sup.2).sub.n C R.sup.1 R.sup.2 (CR.sup.1Z)Q.sub.h [(CHR.sup.1).sub.nW].sub.t R.sup.1 —S(O).sub.a(C R.sup.1 R.sup.2).sub.n C R.sup.1 R.sup.2 (CR.sup.1Z).sub.iQ.sub.h R.sup.3; and —S(O).sub.a(C R.sup.1 R.sup.2).sub.n OC(═W)R.sup.1 wherein: Q is independently selected from —C(═W.sup.1)W.sup.2—, —W.sup.2 C(═W.sup.1)—; W, W.sup.1 and W.sup.2 are independently selected from oxygen, sulfur, NR′; Z is independently selected from —R.sup.1, —OR.sup.1, —NR.sup.1R.sup.2 and —SR.sup.t; and R.sup.1 and R.sup.2 are independently selected from hydrogen, a linear or branched C.sub.1-22-alkyl, C.sub.2-22-alkenyl and C.sub.2-22-alkynyl group, an optionally substituted aryl and an optionally substituted C.sub.1-22-alkylaryl group; R.sup.3 is an optionally substituted, linear or branched C.sub.1-22-alkyl, C.sub.2-22-alkenyl or C.sub.2-22-alkynyl group, an aryl and a C.sub.1-22-alkylaryl group a is independently 0 to 2 h is independently 0 or 1; i is independently from 0 to 6; m is independently from 1 to 6; n is independently from 1 to 6; t is independently from 1 to 20.

12. A compound according to claim 1 wherein X is selected from —S(CH.sub.2).sub.n—CR.sup.1R.sup.2R.sup.3; —S(CH.sub.2).sub.n SH; —S(CH.sub.2).sub.n C(O)(NR.sup.1(CH.sub.2).sub.m).sub.n NR.sup.1 R.sup.2 and —S(CH.sub.2).sub.n (S(CH.sub.2).sub.m).sub.n SH.

13. A compound according to claim 1 wherein X is selected from —S(CH.sub.2).sub.n SH; —S(CH.sub.2).sub.n C(O)(NR.sup.1(CH.sub.2).sub.m).sub.n NR.sup.1 R.sup.2 and —S(CH.sub.2).sub.n (S(CH.sub.2).sub.m).sub.n SH.

14. A compound according to claim 10 wherein n is independently in each occurrence, 2 or 3.

15. A process for treating a feed comprising contacting a compound claim 1 with a feed: i) to effect a chemical reaction by catalytic transformation of a component of the feed to produce a desired product; or ii) to remove or reduce the level of a component of the feed so as to produce a feed depleted in the removed component.

16. (canceled)

17. A process according to claim 12 wherein the component is selected from palladium, platinum, rhodium, iridium, ruthenium, gold, nickel, copper, silver, mercury, iron, lead, chromium, cadmium, arsenic, cobalt arsenates, chromates, permanganates, borates and perchlorates.

18. A process according to claim 12 wherein the level of the component in the feed depleted in the removed component is at least 10% less than the level of the component in the feed by weight based on the level of the component in the feed.

19. A process according to claim 12 wherein the component is a metal species and it is reduced to a level below 500 ppm in the feed depleted in the component.

20.-21. (canceled)

22. A process according to claim 12 wherein the feed is an aqueous stream, an industrial process stream, a mining process stream, a chemical synthesis process stream or a process stream in the production of electronic components wherein the compound reduces the level of metal species in the stream.

23. (canceled)

24. A method of producing a derivatised polysaccharide compound which is substantially insoluble in water comprising providing a polysaccharide compound selected from cellulose and starch having a backbone comprising more than 20 sugar moieties, derivatising at least one hydroxyl substituent and reacting the derivatised hydroxyl substituent with a compound to provide a ligand (L) of formula:
—S(O).sub.a(C R.sup.1 R.sup.2).sub.nX such that the ligand is bound to the sugar moiety by the sulphur atom of the ligand wherein: independently in each occurrence, R.sup.1 and R.sup.2 are selected from hydrogen, an optionally substituted, linear or branched C.sub.1-40-alkyl, C.sub.2-40-alkenyl or C.sub.2-40-alkynyl group, an aryl and a C.sub.1-40-alkylaryl group; a is, independently in each occurrence from 0 to 2; n is independently an integer from 1 to 22, preferably 1 to 12, especially from 1 to 6, for example 1, 2 or 3: X is selected from: —CR.sup.1 R.sup.2R.sup.3; a divalent group, preferably —[CO.sub.2(CH.sub.2).sub.mCO.sub.2]— or —[CH.sub.2(CH.sub.2).sub.mCH.sub.2]— linking two sugar moieties and m independently being 1 to 10, preferably 1 to 6, for example 1, 2, or 4; —CR.sup.1R.sup.2 (CR.sup.1 R.sup.2).sub.nC(═W)R; —CR.sup.1R.sup.2 (CR.sup.1Z).sub.i Q.sub.h CHR.sup.1Z; —CR.sup.1R.sup.2(CR.sup.1Z).sub.i Q.sub.h [(CHR.sup.1).sub.nW].sub.tR.sup.1; —(CR.sup.1Z).sub.i Q.sub.h C(═W)R.sup.1 —CR.sup.1R.sup.2(CR.sup.1Z).sub.i Q.sub.h R.sup.3 —OC(═W)R; wherein R is independently selected from H, R.sup.1, —OR.sup.1, —NR.sup.1R.sup.2, —NHNR.sup.1R.sup.2 and —SR′; R.sup.3 is an optionally substituted, linear or branched C.sub.1-40-alkyl, C.sub.2-40-alkenyl or C.sub.2-40-alkynyl group, an aryl and a C.sub.1-40-alkylaryl group; Q is independently selected from —C(═W.sup.1)W.sup.2— and —W.sup.2 C(═W.sup.1)—; W, W.sup.1 and W.sup.2 are independently selected from oxygen, sulfur, —N(R.sup.1)— and —N(NR.sup.1 R.sup.2); Z is independently selected from —OR.sup.1, —NR.sup.1R.sup.2 and —SR′; h is independently 0 or 1; i is independently from 0 to 6; t is independently an integer from 1 to 20, preferably 1 to 3. —[C(═W)].sub.h(W(C R.sup.1R.sup.2).sub.m).sub.nZ, and preferably in this case R.sup.1 and R.sup.2 are H and Z is OH or NH.sub.2; and —S(O).sub.a—Y wherein Y is a monovalent terminal group, preferably selected from H and the options for X, excluding —S(O).sub.a—Y.

25. A method according to claim 17 wherein the polysaccharide compound is cellulose.

26. (canceled)

27. A method according to claim 17 wherein the polysaccharide compound is contacted with tetrabutyl phosphonium hydroxide solution to produce a an aqueous solution or dispersion comprising at least 10% by weight of dissolved polysaccharide which is then subjected to the said derivatisation step.

28.-29. (canceled)

30. A scavenging product comprising a compound as defined in claim 1 in the form of a bead, microcrystalline material, nanofibers or a membrane.

Description

EXAMPLE 1

[0145] Synthesis of Cellulose Tosylate

[0146] Cellulose tosylate may be prepared by the following reaction procedure as set out in Green Chem., 2012, 14, 3126-3131. Suspend dried cellulose (1 g) in water (26.9 mL) then add NaOH (2.5 g) and stir/shake until dissolved. Freeze to a solid (salt/ice bath) then thaw to a gel at room temperature. Once thawed add more water (20.6 mL) then add NEt.sub.3 and TsCl, then stir overnight at room temperature. Filter off the solid then wash with hot water (300 mL) then hot EtOH (150 mL). The tosylated cellulose is dried in a vacuum oven at 75-80° C., preferably overnight, before use to remove any residual water.

[0147] Synthesis of Cellulose Tosylate—Removal of Et.sub.3N and Addition of Toluene

[0148] An aqueous NaOH solution (2.3 M, 7.6 g) was added to microcrystalline cellulose (0.26 g) before freezing to a solid (−18° C. freezer, typically overnight). Thaw to room temperature then add toluene (6 mL) and tosyl chloride (1.2 g). Stir the mixture vigorously for 3 hours, before adding ethanol (30 mL). Filter off the solid material then wash with water (30 mL), ethanol (20 mL), toluene (20 mL), ethanol (20 mL), and water (20 mL). The resulting solid is dried overnight in a vacuum oven at 75° C. The degree of substitution (moles of tosyl per anhydroglucose unit) can be determined using ICP-OES analysis. Inclusion of toluene in the procedure allows lower amounts of tosyl chloride to be used compared to the above procedure, additionally under these conditions the triethylamine used in the above procedure was found to be unnecessary (neither beneficial nor detrimental) to the degree of substitution obtained.

[0149] Synthesis of Cellulose Tosylate—Removal of Complete Freezing Step

[0150] A solution of NaOH (40.1 g) in water (430 mL) is prepared and cooled to 0° C. To this solution add microcrystalline cellulose (30 g) and stir for 6 hours at 0° C. to disperse. The mixture is then left at 0° C. overnight without stirring before stirring is recommenced and toluene (360 mL) is added. Cool the mixture back to 0° C. before adding tosyl chloride (141 g) and stirring at 0° C. for 5 hours. Methanol (800 mL) is then added and the reaction mixture stirred for 30 minutes before filtering off the solid. The solid is washed with methanol (500 mL), water (500 mL), methanol (500 mL), water (500 mL), and methanol (500 mL). The resulting solid is dried overnight in a vacuum oven at 55° C.

[0151] Synthesis of Cellulose Tosylate in Dimethylacetamide and Lithium Chloride

[0152] Cellulose tosylate can also be prepared following non-aqueous reaction protocols, for example as described in Carbohydrate Research, 1990, 208, 183-191. To a stirred suspension of microcrystalline cellulose (1 g) and dimethylacetamide (50 mL) is added lithium chloride (4.2 g). This is then stirred overnight before triethylamine (30.1 mL) is added and the reaction cooled to 10° C. A solution of tosyl chloride (10.3 g) in dimethylacetamide is then dropped into the reaction and then left to stir at 10° C. for 24 hours. The solids were filtered off and then to the filtrate ice water is added to precipitate. The precipitated solid is filtered and washed with water before drying.

[0153] During the preparation the tosylated cellulose may be soluble in highly polar non-aqueous solvents for example DMSO, DMF or DMAC with or without added LiCl, depending on the degree of tosylation and in ionic liquids.

[0154] Synthesis of Cellulose Tosylate Using Tetrabutyl Phosphonium Hydroxide

[0155] Cellulose tosylate may also be prepared using tetrabutyl phosphonium hydroxide

[0156] to dissolve cellulose at room temperature to provide a solution having a high level of cellulose. Dried cellulose (0.5 g) was suspended in a tetrabutylphosphonium hydroxide solution (60% wt/wt aqueous, 3 g) and stirred until dissolved. The concentration of cellulose was 14% which is higher than typically achievable using sodium hydroxide solution and may be carried out at room temperature rather than at 0° C.

[0157] A solution of tosylchloride in toluene was added and stirred vigorously for 5 hours at room temperature. Methanol (30 mL) was added to precipitate solid material which was then filtered. The solid material was washed with methanol before drying the solid obtained overnight using a vacuum oven (65-70° C.).

EXAMPLE 2: SYNTHESIS OF CELLULOSE THIOL

[0158] Dissolve (or suspend) cellulose tosylate prepared in accordance with Example 1 or from another source in dry DMF under an atmosphere of argon, heating to ≥30° C. depending on the degree of tosylation. Add 10 equiv. of 1,3-propanedithiol and base (diisopropyltriethylamine or trimethylamine) and agitate by stirring or shaking at 80-100° C. for 24 h. Precipitate into ice cold water (150 mL), isolate by filtration (use filter with arm for vacuum, into single-necked RBF) then wash with acetone or MeOH and dry in a vacuum oven for at least 4 h at 65° C. The dithiol replaces the tosylate to produce a cellulose thiol with the —OH position at the 6 carbon being substituted by —S(CH.sub.2).sub.3SH.

EXAMPLE 3: RECOVERY OF PALLADIUM FROM AN ORGANIC STREAM

[0159] The product of Example 2 was used to recover palladium from an organic process stream. The functional group loadings of the thiol substituent on the cellulose backbone were calculated (by ICP-OES). The compound according to the invention with 1 mole equivalent was then contacted with a 200 ppm model palladium solution (in DCM). The percentage recovery of Palladium was calculated from measurements on the treated stream and Pd loading on the scavengers (i.e. maximum metal loading on functionalised cellulose, g/kg) were measured from the solids (Table 1). The highest removal of palladium from a model stream was measured at 99%.

EXAMPLE 4: RECOVERY OF PALLADIUM FROM AN AQUEOUS STREAM

[0160] A 200 ppm Pd solution was prepared from a 10,000 ppm ICP standard. 10 ME of scavenger produced in Example 2 was tested to measure the average recovery of Pd from an aqueous stream. The results (Table 1) show very effective removal (99%). Cellulose and cellulose-tosylate were also tested and removed 0% Pd

EXAMPLE 5: RECOVERY OF GOLD FROM A BASIC AQUEOUS STREAM

[0161] An industrial aqueous waste stream containing 40 ppm Au (pH>12) was tested using scavenger produced in Example 2 to measure the average recovery of Au from an aqueous stream. Under conditions with 20 mole equivalents of scavenger at 80° C. for 22 hours the results show very effective removal (94%).

EXAMPLE 6: RECOVERY OF RUTHENIUM FROM A BASIC AQUEOUS STREAM

[0162] An industrial aqueous waste stream containing 29 ppm Ru was tested using scavenger produced in Example 2 to measure the average recovery of Ru from an aqueous stream. Under conditions with 20 mole equivalents of scavenger at either 25° C. or 80° C. for 22 hours the results show very effective removal (93-97%).

TABLE-US-00001 TABLE 1 Average Pd Loading on recovery cellulosic scavenger ME (%) (g/kg) Stream type  1 40 32 Org model Pd 18 90 — Org model Pd 10 99 — Aq model Pd