Macromolecular compositions for binding small molecules

Abstract

The present invention relates to a method for preparing a macromolecular composition comprising phenylglyoxaldehyde-derivatives. The invention also relates to the macromolecular compositions per se, and to methods of using the macromolecular compositions. The macromolecular compositions are useful for undergoing subsequent reactions with small molecules, for instance to remove such small molecules from a solution.

Claims

1. Method for producing a phenylglyoxaldehyde (PGA)-type sorbent, comprising the steps of: i) providing monomers of general formula (I): ##STR00040## wherein: Q is H or —CH.sub.3; h.sup.1, h.sup.2, and h.sup.3 are each independently chosen from H, halogen, —OH, —O(C.sub.1-6 hydrocarbon), —S(C.sub.1-6 hydrocarbon), —NH(C.sub.1-6 hydrocarbon), or —N(C.sub.1-6 hydrocarbon).sub.2; or h.sup.1 and h.sup.2 together form ═O; or h.sup.1 and h.sup.2 together form -o.sup.1—(C.sub.1-4 hydrocarbon)-o.sup.2- wherein of o.sup.1 and o.sup.2 are independently O, S, NH, or N(C.sub.1-4 hydrocarbon); and X is O, S, or NH; ii) polymerizing the provided monomers to obtain a polymer; and iii) converting polymerized monomers of general formula (I) that are not PGA-type monomers into PGA-type monomers.

2. The method according to claim 1, wherein the monomers of general formula (I) comprise monomers selected from: 1-(4-ethenylphenyl)ethan-1-one, 1-(3-ethenylphenyl)ethan-1-one, 1-(4-isopropenylphenyl)ethan-1-one, 1-(3-isopropenylphenyl)ethan-1-one, 2-bromo-1-(4-ethenylphenyl)ethan-1-one, 2-bromo-1-(3-ethenylphenyl)ethan-1-one, 2-bromo-1-(4-isopropenylphenyl)ethan-1-one, 2-bromo-1-(3-isopropenylphenyl)ethan-1-one, 2-chloro-1-(4-ethenylphenyl)ethan-1-one, 2-chloro-1-(3-ethenylphenyl)ethan-1-one, 2-chloro-1-(4-isopropenylphenyl)ethan-1-one, 2-chloro-1-(3-isopropenylphenyl)ethan-1-one, 1-(4-ethenylphenyl)ethan-1,2-dione, 1-(3-ethenylphenyl)ethan-1,2-dione, 1-(4-isopropenylphenyl)ethan-1,2-dione, 1-(3-isopropenylphenyl)ethan-1,2-dione, 2,2-dihydroxy-1-(4-ethenylphenyl)ethan-1-one, 2,2-dihydroxy-1-(3-ethenylphenyl)ethan-1-one, 2,2-dihydroxy-1-(4-isopropenylphenyl)ethan-1-one, and 2,2-dihydroxy-1-(3-isopropenylphenyl)ethan-1-one.

3. The method according to claim 1, wherein the monomer is of general formula (II-p): ##STR00041## wherein h.sup.1, h.sup.2, and h.sup.3 are each independently chosen from H, halogen, —OH, —O(C.sub.1-6 hydrocarbon), —S(C.sub.1-6 hydrocarbon), —NH(C.sub.1-6 hydrocarbon), or —N(C.sub.1-6 hydrocarbon).sub.2; or h.sup.1 and h.sup.2 together form ═O; or h.sup.1 and h.sup.2 together form -o.sup.1—(C.sub.1-4 hydrocarbon)-o.sup.2- wherein of o.sup.1 and o.sup.2 are independently O, S, NH, or N(C.sub.1-4 hydrocarbon).

4. The method according to claim 1, wherein comonomers are provided along with the monomers of general formula (I).

5. The method according to claim 1, wherein the polymer is crosslinked after polymerization or during polymerization.

6. The method according to claim 1, wherein conversion in step iii) comprises: a) optional halogenation, preferably using halohydric acid; and b) oxidation, preferably using dimethyl sulfoxide (DMSO).

7. The method according to claim 1, wherein in step iii) more than 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% of the monomers of general formula (I) are converted into PGA-type monomers.

8. The method according to claim 1, wherein wherein: Q is H; and/or h.sup.1 and h.sup.2 are each independently chosen from H, halogen, —OH, and —O(C.sub.1-4 hydrocarbon); or together form ═O; preferably h.sup.1 and h.sup.2 are both H, or are both —OH, or together form ═O; and/or h.sup.3 is H; and/or X is O.

9.-12. (canceled)

13. Method for removing nucleophilic waste solutes from a fluid, comprising the steps of: i) providing a fluid comprising nucleophilic waste solutes, and iia) contacting said fluid with a PGA-type sorbent as defined in claim 9, or alternately iib) contacting said fluid with a dialysis fluid through a membrane, wherein the dialysis fluid is in contact with a PGA-type sorbent as defined in claim 9, and iii) optionally, recovering the fluid.

14.-15. (canceled)

16. The method according to claim 4, wherein the comonomers are selected from the group consisting of styrene, isopropenylbenzene, divinylbenzene, vinylbenzenesulfonic acid, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, 2-hydroxyethyl 2-methylprop-2-enoate (HEMA), 2-hydroxypropyl 2-methylprop-2-enotate, 2-hydroxyethyl prop-2-enoate, 2-hydroxypropyl prop-2-enotate, N-(2-hydroxyethyl)methacrylamide, N-(2-hydroxypropyl)methacrylamide (HPMA), N-(2-hydroxyethyl)acrylamide, N-(2-hydroxypropyl)acrylamide, a telechelic N,N′-alkylenebisacrylamide such as N,N′-methylenebisacrylamide (NMAA), N-isopropylacrylamide (NIPAm), divinyl sulfone, butadiene, acrylonitrile, methacrylonitrile, vinylsulfonamide, N-alkyl vinylsulfonamide such as N-methyl vinylsulfonamide, and N,N-dialkyl vinylsulfonamide such as N,N-dimethyl vinylsulfonamide.

Description

DESCRIPTION OF DRAWINGS

[0171] FIG. 1—Reaction of the PGA/PGAH-derivatives with urea. In the case of a PGA-type sorbent, R can be a polymeric backbone.

[0172] FIG. 2A—Synthesis of PGA-type sorbents from styrene. R.sup.1=optional crosslinker, R.sup.2=unmodified styrene, R.sup.3=side product of conversion reaction.

[0173] FIG. 2B—Synthesis of PGA-type sorbents from a precursor monomer (VPE). R.sup.1=optional crosslinker, R.sup.2=optional side product of conversion reaction.

[0174] FIG. 3—Oxidation of PS-Ac or of pVPE using HBr and DMSO. PGA=Phenylglyoxaldehyde, PGAH=phenylglyoxaldehyde hydrate, PGOA=phenylglyoxilic acid.

[0175] FIG. 4—The urea binding capacity of pVPE beads (table 2 entry 2) as a function of oxidation time of pVPE. Conditions for oxidation: pVPE (500 mg) in DMSO (5.0 mL) and 48% aqueous HBr (1.45 mL) stirred with a Teflon blade stirrer at 80° C. for 4-12 hours. Per timepoint ±150 mg beads were removed from the suspension and tested for urea binding.

[0176] FIG. 5—IR spectra of PGAH, PS-AC-Ox@urea, pVPE-Ox-(4)@urea and the 2:1 addition product of PGAH and urea. The adduct, indicated as 3′a, was synthesized as described in Jong, J. A. W. et al., ACS Omega 2019, 4 (7), 11928-11937.

[0177] FIG. 6A—Urea binding of PS—Ac-Ox and pVPE-Ox-(4) in time. Expressed in mmol urea/g sorbent.

[0178] FIG. 6B—Relative urea binding (percentage of the maximum binding capacity). Conditions: sorbent (10 mg/mL) in 30 mM urea solution in PBS at 37° C. (N=4). Triangles represent pVPE-Ox, squares represent PS—Ac-Ox.

EXAMPLES

Example 1—Materials and Methods

1.1 NMR, UV and IR Spectroscopy

[0179] NMR spectra were recorded on a Bruker 600 MHz with a BBI probe at room temperature (RT). Residual solvent signals were used as internal standard (1H: δ 7.26 ppm, 13C (1H): δ 77.16 ppm for CDCl3). Chemical shifts (δ) are given in ppm and coupling constants (J) are given in hertz (Hz). Resonances are reported as s (singlet), d (doublet), t (triplet), q (quartet), bs (broad singlet) and m (multiplet) or combinations thereof. UV absorption spectra were recorded in triplicate with a BMG LABTECH SpectroStar Nano plate reader using a UV-Star Microplate 96 well obtained from Greiner Bio-One (Alphen aan de Rijn, the Netherlands). Infrared (IR) spectra were recorded neat using a Perkin Elmer ATRU Spectrum 2.

1.2 Determination of Pseudo-First Order Rate Constants

[0180] ##STR00030##

[0181] PGAH (1a) and two PGAH derivatives (1b and 1c) (0.3 mmol, 1.0 eq.) were dissolved in 1:1 v/v mixture of PBS:dimethylsulfoxide (DMSO) (10 mL). Urea (901 mg, 15 mmol, 50 eq.) was dissolved in the PGAH solution which was subsequently magnetically stirred at 50° C. Samples (50 μL) from the reaction mixture were taken at different time points, diluted 10 (1a) or 15 (1b and 1c) times with 1:1 v/v DMSO:PBS (500 or 700 μL) and subsequently diluted another 10× using the same solvent mixture (thus resulting in a final 100 or 150 times dilution, respectively). The concentrations of the PGAH (derivatives) 1a-c in the 100 or 150 times diluted samples were determined by UV spectroscopy (260, 263 and 270 nm, for 1a, 1b and 1c, respectively). A calibration curve was prepared using a dilution series in 1:1 v/v mixture of PBS:DMSO (final concentrations varied from 0.030-0.360 mM) from a stock solution of the PGAH (derivatives) (30 mM) in 1:1 (v/v) DMSO:PBS. The k.sub.PFO-values for the PGAH analogues were determined from the slopes of the plots of log [PGAH] versus time.

1.3 Preparation of 10% Polymethacrylic Acid Sodium Salt Solution in Water

[0182] In a glass reactor equipped with mechanical stirrer, polymethacrylic acid (10 grams) was dissolved in water (84 mL) by heating to 80° C. and stirring for 30 minutes. Next an aqueous 50% NaOH (2.67 mL; 68 mmol NaOH) solution was added and stirring was continued for 60 minutes at the same temperature. The obtained viscous solution was transferred into a Falcon tube and stored at 4° C. for later use as thickening agent of the aqueous phase in suspension polymerization.

1.4 Suspension Polymerization of Styrene

[0183] For the suspension polymerization of styrene we essentially used a method as described by Jong (Jong, G. J. D. Ion exchangers from poly(aminostyrene) and ethylene imine. 1971). However, ShellSolTD and a poly(methacrylic acid) sodium salt solution were used instead of hexane and polyacrylic acid sodium salt.

[0184] The detailed procedure was as follows: the aqueous phase was prepared by addition of NaCl (340 mg), poly(methacrylic acid) sodium salt solution (8.32 g of a 10% solution in water) and CaHPO.sub.4 (3.06 g) to water (540 mL) in a glass reactor equipped with a teflon blade stirrer. The aqueous phase was stirred for 30 minutes at RT and the pH was 6.9. The organic phase was prepared by mixing styrene (229 mL, 2.0 mol), ShellSolTD (276 mL) and toluene (27 mL) in a beaker. Next, 55% technical grade divinylbenzene (DVB) (13 mL, 50 mmol, 2.5 mol %) and a 50% benzoylperoxide blend with dicyclohexyl phthalate (6.0 g, 12.4 mmol, 0.6 mol %) was added to the organic phase and stirred until the initiator was dissolved and a homogeneous solution was formed at room temperature (RT). The organic phase was subsequently added to the aqueous phase in the glass reactor under continuous mechanical stirring at 180 rpm, by which an o/w emulsion was formed, and oxygen was removed by flushing with nitrogen gas for 20 minutes. Next, the emulsion was heated at 73° C. in an oil bath for 16 hours under mechanical stirring. The resulting suspension was allowed to cool to RT and was poured over a sieve (cut-off 200 μm, Veco B. V.) and washed with acetone and water. The white beads were collected and dried over P.sub.2O.sub.5 under vacuum, resulting in 216 g polystyrene (PS) beads. TGA analysis showed ˜14% volatiles present, indicating a yield of solid material of ˜186 gram (86%).

[0185] Macroporous polystyrene beads (PS) were thus synthesized by suspension co-polymerization of styrene and a low content of divinylbenzene (DVB, 2.5%) in a cylindrical reactor with mechanical stirrer. A mixture of toluene and ShellSolTD@ (9:91 v/v) was used as a non-solvating porogen and spherical beads were obtained in a 97% yield. The average diameter of the beads as determined by light microscopy was 0.49±0.18 mm. Scanning Electron Microscopy (SEM) analysis showed that pores are clearly visible on the surface of the beads. The surface area (S.sub.BET) and pore volume of the beads as determined by nitrogen physisorption were 36.3 m.sup.2/g and 0.32 mL/g, respectively. The plot of the pore volume versus the pore diameter showed that the pores present in the material were mainly in the range of 50-100 nm, demonstrating that the obtained beads are indeed macroporous.

1.5 Friedel-Crafts Acetylation of Polystyrene

[0186] In a glass reactor equipped with a teflon blade stirrer, PS beads (80.9 g, 0.77 mol aromatic groups, 1.0 eq.) were swollen in 1,2-dichloroethane (DCE, 750 mL) for 30 minutes under mechanical stirring. Anhydrous AlCl.sub.3 (156 g, 1.17 mol, 1.5 eq.) was added portion wise (3-5 gram) to the suspension over the course of 15 minutes. After all AlCl.sub.3 was added, acetyl chloride (66 mL, 0.94 mol, 1.2 eq.) was added slowly and the suspension was heated to 50° C. in an oil bath for 5 hours, after which the formation of HCl-gas (caused by the reaction of aromatic group and acetyl chloride) stopped. The suspension was allowed to cool to RT, after which the suspension was filtered (cut-off 200 μm). The residue was suspended in a 500 mL of 6 M HCl solution at 0° C. in an ice bath and stirred for 30 minutes to remove aluminum salts; this step was repeated twice. The suspension was filtered (cut-off 200 μm, Veco B. V.) and washed with acetone and water until the pH of the filtrate was >5. The residue was dried over P.sub.2O.sub.5 under vacuum, resulting in acetylated polystyrene (PS-Ac, 71.6 g).

1.6 Halogenation and Kurnblum Oxidation of Acetylated Polystyrene

[0187] In a glass reactor equipped with a teflon blade stirrer, PS-Ac beads (60.0 g) were swollen in DMSO (600 mL, 8.45 mol) for 30 minutes under continuous stirring, after which an aqueous solution of 48% HBr (175 mL, 1.55 mol) was slowly added. One of the outlets of the reactor was capped with a septum containing a needle allowing escape of the formed Me.sub.2S. The suspension was stirred at 80° C. for 8 hours, after which the reaction mixture was filtered (cut-off 200 μm, Veco B. V.). The residue was washed with water until the pH of the filtrate was >5. The residue was dried over P.sub.2O.sub.5 under vacuum, resulting in PS—Ac-Ox (55.2 grams).

1.7 Scanning Electron Microscopy Analysis of Sorbent Particles

[0188] The morphology of the beads was analyzed by scanning electron microscopy (SEM, Phenom, FEI Company, the Netherlands). Dried beads were transferred onto 12-mm diameter aluminum specimen stubs (Agar Scientific Ltd., England) using double-sided adhesive tape. Prior to analysis, the beads were coated with platinum using an ion coater under vacuum. The samples were imaged using a 5 kV electron beam.

1.8 Determination of the Size of the Beads by Light Microscopy

[0189] The diameters of the beads were measured using optical microscopy, utilizing a size calibrated Nikon eclipse TE2000-U microscope equipped with a digital camera (Nikon DS-2Mv camera and Nikon DS-U1 digital adapter, with a 4× magnification) and the NIS-elements basic research software package. Images of the beads were taken in the dry state and for 30 arbitrary beads 3 points on the perimeter of the beads were identified to allow calculation of circular diameter by the program. The average diameters and standard deviations are reported.

1.9 Quantitative .SUP.13.C Solid State NMR Analysis of the Different Beads

[0190] For solid-state .sup.13C NMR measurements, beads were crushed and transferred into a 3.2 mm rotor for the magic-angle spinning (MAS) solid-state NMR analysis. The analysis of the samples was performed either on a Bruker 700 MHz wide-bore magnet with an AVANCE-III console or on a Bruker 400 MHz spectrometer. The spectra were recorded at room temperature (298 K) and using Magic Angle Spinning (MAS) frequency between 10 and 14 kHz, chosen to minimize the overlap of the signal with spinning sidebands. For the .sup.13C direct excitation spectra, 300 pulses were applied with field strength of 55 kHz and 80 kHz SPINAL64. .sup.1H decoupling was applied during acquisition. The .sup.13C T1 relaxation time for each sample was determined using inverse recovery and used to establish the repetition time for the different samples, set to 2*T1. Except for the pVPE-Ox-(4) sample, which showed a very short relaxation time of 1 s, for the other samples the T1 varied from 40 to 80 s. The NMR spectra were processed with 200 Hz line-broadening and analyzed with Bruker Topspin3.5.

1.10 Determination of Surface Area of the Beads Using Nitrogen Physisorption

[0191] N.sub.2 physisorption isotherms were measured at −196° C. using a Micromeritics TriStar 3000 and TriStar II Plus apparatus. Prior to analysis, the samples were dried under vacuum for 16 hours at RT. Surface areas of the beads were determined using the Brunauer-Emmett-Teller (BET) method and the total pore volumes were derived from the amount of N.sub.2 adsorbed at p/p.sub.0=0.995. A Barrett-Joyner-Halenda (BJH) analysis was employed to determine pore size/volume distributions of the samples with the use of a Harkins-Jura thickness curve. Due to the shrinking of the porous polymeric beads and collapsing of the pores with increasing pressure, and subsequent expansion and with decreasing pressure, the correction of the dead volume is incorrect, as by default it assumes that the solid fraction of the sample does not change in volume with pressure. As the dead volume was determined at p/p.sub.0≈0 and assumed constant during the measurement, the default dead volume-corrected isotherms decrease slightly with increasing pressures, which is physically meaningless. The relative deviation is largest for materials with low surface areas (<5 m.sup.2/g) and high materials volume fractions in the measurement tubes, such as for pVPE-Ox. A correction for this deformation i.e. change in dead volume with pressure was applied to these isotherms by a linear swelling function (V.sub.adjusted=a.Math.(p/p.sub.0)+V.sub.original), in which a represents the swelling factor relative to the material's volume at p/p.sub.0≈0, until dV/d (p/p.sub.0)>0 was achieved for all pressures. Values for a were between 1.2 and 7.2, indicating a significant deformation of these materials. The S.sub.BET surface areas of the pVPE-Ox beads were calculated from the isotherms that were corrected for these volume changes as a function of pressure.

1.11 Determination of Urea Binding

[0192] The sorbent beads (15 mg) were dispersed with urea solution (1.5 mL, 30 mM) in PBS in Eppendorf tubes. The samples were placed in an oven at 37° C. on a rotating device. After 1, 2, 4, 8, 16 and 24 hours, two Eppendorf tubes per time point were taken and the beads were allowed to settle and the supernatant was removed. To determine the maximum binding capacity, the sorbent beads (50 mg per vial) were incubated for 24 hours at 70° C. with a urea solution (5 mL, 30 or 50 mM) in PBS in two glass vials, after which the beads were allowed to settle and the urea concentrations in the supernatants were determined with an AU 5800 routine chemistry analyzer (Beckman Coulter, Brea, Calif.) using a coupled enzyme reaction, which results in a colorimetric (570 nm) product proportional to the urea concentration.

1.12 Thermal Analysis of Monomer and Beads

[0193] Thermographic analysis (TGA) was done as follows. In a platinum pan the beads were heated at a rate of 10° C./minute. The weight loss during the ramp heating (and thereby the decomposition temperature) was determined on a TA Instruments TGA Q50. Differential scanning calorimetry (DSC) analysis of the different samples was done as follows. In an open aluminum pan the monomer or beads were heated from −50 till 250° C. at a rate of 10° C./minute and the heat flow was monitored. Next, the sample was quench cooled from 250 to −50° C. and subsequently heated again to 250° C. at a rate of 10° C./min. The T.sub.9 or melting point was determined with a TA instruments Discovery DSC. For the beads, residual solvent evaporated during the first run and therefore the results of the second run are reported. For the monomer (VPE) events of the first run are reported.

Example 2—Provision of Monomers

2.1 Design of Monomers of General Formula (I)

[0194] First, we investigated whether reactivity of a phenylglyoxaldehyde hydrate (PGAH)-based sorbent could be increased by appropriate substituents. The kinetics of the reaction of urea with para-methyl-PGAH (1b), a PGAH-derivative with an electron donating group (EDG), and with para-nitro-PGAH (1c), a PGAH-derivative with an electron withdrawing group (EWG) were analyzed and compared to the kinetics of unsubstituted PGAH (1a) with urea. Substituents on the meta-position were not investigated because for substituent effects on the reaction of ninhydrin-analogues with urea it is found that the position of the EDG has a marginal effect on the overall reactivity of ninhydrin-derivatives with urea (Jong, J. A. W. et al., ChemistrySelect 2018, 3 (4), 1224-1229). An excess (50 equivalents) of urea was used to limit the formation of an 1:2 urea-PGA adduct. Because the urea concentration is much higher than the PGAH concentration, its concentration stays almost constant, and thus pseudo-first order conditions are valid, making the reaction rate (−d[PGAH]/dt) dependent on the PGAH concentration only. The pseudo-first order kinetics of the reaction of PGAH (and its derivatives) with urea were analyzed by determining the concentrations of 1a-c in time using UV spectroscopy. The solvent for this reaction was a 1:1 (v/v) PBS/DMSO mixture due to the very low solubility of 1b and 1c in PBS only. The pseudo-first order rate constants (k.sub.PFO) correspond with the negative slopes in the plot of the logarithm of the PGAH-(derivatives) concentration divided by log (e) versus time and are reported in table 1. It follows that PGA-analogues without NO.sub.2 substituents are preferred.

TABLE-US-00002 TABLE 1 reaction rate of PGA-type molecules with urea Entry Substituent k.sub.PFO (min.sup.−1) 1a H 0.085 ± 0.003 1b p-Me 0.061 ± 0.005 1c p-NO.sub.2 0.006 ± 0.002

2.2 General Method for Providing Monomers of General Formula (I)

[0195] Monomers can be purchased from commercial suppliers when available, or can be prepared by chemical synthesis. For this, acylation reactions are suitable, starting from styrene or isopropenylbenzene or other derivatives that are generally commercially available. Ethynylbenzene is another suitable starting material, from which a vinyl analogue can be obtained after acylation by partial hydrogenation of the triple bond.

2.3 Synthesis of p-(Vinylphenyl)Ethenone (VPE)

[0196] ##STR00031##

[0197] In a 3-neck round bottom flask p-(ethynylphenyl)ethenone (10.0 g, 69.4 mmol) was suspended in EtOH (350 mL) and Lindlar's catalyst (300 mg, 3 w %) was added. Air was replaced by H.sub.2 and the suspension was stirred at RT for 2-16 hours. To monitor the conversion (and thus preventing over-reduction of VPE into the alkane), samples were frequently taken from the reaction mixture and, after evaporation of EtOH under reduced pressure, the conversion was determined by .sup.1H-NMR (CDCl.sub.3). After the conversion was >90%, the H.sub.2-filled balloon was removed and the reaction mixture was concentrated under reduced pressure. The crude product was re-dissolved in CH.sub.2Cl.sub.2 and purified by filtration over Hyflo. The filtrate was concentrated under reduced pressure, giving crude VPE as a yellow liquid in a 99% yield (10.1 g, 69.0 mmol). Melting point 29° C., melt enthalpy 90.6 J/g. .sup.1H-NMR (CDCl.sub.3, 600 MHz) δ 7.92 (d, J=8.3 Hz, 2H), 7.48 (d, J=8.2 Hz, 2H), 6.75 (dd, J=17.6 Hz, 10.9 Hz, 1H), 5.87 (d, J=17.6 Hz, 1H), 5.39 (d, J=10.9 Hz, 1H), 2.59 (s, 3H).

2.4 Synthesis of 2-bromo-1-(4-ethenylphenyl)ethan-1-one

[0198] ##STR00032##

[0199] In a round bottom flask p-(ethynylphenyl)bromo-ethenone (15.5 g, 69.4 mmol) is suspended in EtOH (350 mL) and Lindlar's catalyst (300 mg, 3 w %) is added. Br Air is replaced by H.sub.2 and the suspension is then stirred at RT for 2-16 hours. Further following the procedure described in example 2.3, the crude precursor 0 monomer can be obtained as a yellow/brownish liquid.

2.5 Synthesis of 2,2-dihydroxy-1-(4-ethenylphenyl)ethan-1-one

[0200] ##STR00033##

[0201] VPE (146 mg, 1.0 mmol, 1.0 eq.) is dissolved in a 10:1 mixture of dioxane (3 mL) and H.sub.2O (0.3 mL) in a microwave tube equipped with a magnetic stirrer. Selenium dioxide (2.0 mmol, 2.0 eq.) is added and the tube sealed. The mixture is shaken vigorously until selenium dioxide is completely dissolved and the tube placed in the microwave in which it is heated for 5 minutes at 180° C. The crude reaction mixture is impregnated on silica and purified over silica (EtOAc:hexane) to give pure 2,2-dihydroxy-1-(4-ethenylphenyl)ethan-1-one.

##STR00034##

2.6 Synthesis of 1-(4-ethenylphenyl)ethan-1,2-dione

[0202] 2,2-dihydroxy-1-(4-ethenylphenyl)ethan-1-one is dried under vacuum (>1 mbar) over anhydrous P.sub.2O.sub.5 for 24 hours at RT, resulting in 1-(4-ethenylphenyl)ethan-1,2-dione.

2.7 Synthesis of (4-ethenylphenyl)(2-dioxolanyl)methanone

[0203] 2,2-dihydroxy-1-(4-ethenylphenyl)ethan-1-one (1 mmol, 1 eq.) is dissolved in ethylene glycol and 1 vol.-% AcOH (5 mL) and stirred at RT overnight. CH.sub.2Cl.sub.2 is then added and the mixture transferred to a separation funnel. The organic layer is washed with water three times to remove ethylene glycol and AcOH. Concentration of the organic layer then yields (4-ethenylphenyl)(2-dioxolanyl)methanone.

##STR00035##

Example 3—Polymerization

General Method for Polymerization

[0204] Polymerization of monomers of general formula (I) can be performed using any known polymerization method, such as ionic polymerization (anionic, cationic), free radical polymerization, or controlled radical polymerization (RAFT, ATRP). Any sufficiently inert dissolving solvent can be used. Suspension polymerization is an attractive method because it can lead to granulated material. When a crosslinked sorbent is desired, up to 10% crosslinker can be added to the monomer mixture prior to polymerization, such as a divinylbenzene or butadiene. A skilled person can select suitable crosslinkers, which generally have more than one polymerizable moiety. Using about 0.5% to about 4% crosslinker gave good results. When a more hydrophilic sorbent is desired, hydrophilic comonomers can be added to the monomer mixture prior to polymerization, such as vinylbenzenesulfonic acid or acrylic acid. A skilled person can select suitable hydrophilic comonomers, which generally have a single polymerizable moiety and which also comprise a very polar group such as a carboxylic acid or a sulfonic acid. Because the polydispersity of the sorbent is not of high importance, it is efficient to let the polymerization run to completion, for example by letting it react overnight. This achieves high monomer economy and reduces the need for reaction monitoring. Purification can be done by precipitation in any solvent in which unreacted substances will dissolve, such as methanol. Alternately, the polymerization mixture can be used in the conversion as a crude mixture.

3.1 General Solution Polymerisation Method

[0205] Monomer (0.5 mmol) was dissolved in EtOH (2-10 mL) and divinylbenzene (1-4 eq.) and AIBN (1-3 mol %) were added. The flask was sealed and nitrogen was bubbled through the solution for 20 minutes. The solution was heated to 60° C. for 24 hours. The mixture was allowed to cool to room temperature and was centrifuged and the supernatant was removed. The resulting sorbent was washed and centrifuged with the EtOH 3 times and the last time washed with water. After centrifugation, the polymer was dried overnight over P.sub.2O.sub.5 under vacuum.

3.2 General Suspension Polymerisation Method

[0206] NaCl (10.5 mg), polyacrylic acid sodium salt (468 mg of a 10 w % gel in water), and Ca.sub.3(PO.sub.4).sub.2 (86 mg) were added to water (15 mL) in a glass reactor with mechanical stirrer, and stirred for 30 minutes. Monomer (15 mmol), porogen (2-3 mL of a non-water-miscible liquid), 80% divinylbenzene (1-6 mol %) and 50% benzoylperoxide blend with dicyclohexyl phthalate (1 mol %) were mixed separately and, after the initiator was dissolved, added to the aqueous phase. The mixture was stirred with a mechanical stirrer until an emulsion was obtained. Air was displaced by nitrogen in the glass reactor. The mixture was stirred at 73° C. for 16 hours, after which the suspension was filtered over a 200 μm filter. The resulting powder or beads in the residue were washed with acetone and water and dried over P.sub.2O.sub.5 under vacuum.

3.3 Preparation of Poly[(p-vinylphenyl)ethenone])-co-(divinylbenzene)]

[0207] The same procedure as for the preparation of polystyrene beads was employed, with some minor modifications. In brief, the aqueous phase was prepared by addition of NaCl (11 mg), polymethacrylic acid sodium salt solution (452 mg of a 10% gel in water) and CaHPO.sub.4 (84 mg) to water (15 mL). The organic phase was composed of VPE (2.1 g, 14.4 mmol, 2 mL), porogen (2.9 mL, composition see table 2), 80% technical grade DVB (3-6 mol %) and a 50% benzoylperoxide blend with dicyclohexyl phthalate (174 mg, 0.36 mmol, 2.5 mol %). After mixing and polymerization (same procedure followed as for ‘Suspension Polymerization of Styrene’), the resulting suspension was allowed to cool to RT and poured over a filter (cut-off 200 μm, Veco B. V.). The residue was washed with acetone and water, and finally dried over P.sub.2O.sub.5 under vacuum, resulting in pVPE (1.1-1.9 grams, yield 52-90%).

TABLE-US-00003 TABLE 2 different p(VPE) polymers that were prepared Porogen Bead diameter Yield S.sub.BET surface # Porogen ratio DVB (mm) (%) area (m.sup.2/g)  1.sup.A heptane/toluene 75:25 3% 0.62 ± 0.22 93% <0.05 2 heptane/toluene 50:50 3% 0.40 ± 0.28 99% <0.05 3 heptane/toluene 40:60 3% 0.48 ± 0.14 65% 0.1 4 heptane/toluene 30:70 3% 0.61 ± 0.23 75% 2.0 (1.9.sup.b) 5 heptane/toluene 20:80 3% 0.66 ± 0.21 66% 0.2 6 heptane/toluene 10:90 3% 0.47 ± 0.10 70% <0.05 7 toluene — 6% 0.71 ± 0.23 69% 0.2  8.sup.A toluene/ 90:10 3% 0.57 ± 0.34 52% <0.05 nitrobenzene 9 toluene/ 80:20 6% 0.55 ± 0.19 82% <0.05 nitrobenzene .sup.aAggregated particles were obtained, .sup.bSurface area after oxidation of pVPE.

Example 4—Conversion of Polymerized Monomers

General Methods for Conversion of Monomers of General Formula (I)

[0208] Table 3 shows suitable conversion methods for different monomers of general formula (I). Purification can be done by precipitation in any solvent in which unreacted substances will dissolve, such as methanol.

TABLE-US-00004 TABLE 3 suitable conversion methods for different monomers of general formula (1) Monomer type Conversion method [00036] when either or both of h.sup.1 and h.sup.2 are halogen, oxidation will lead to a PGA- type moiety. Oxidation using DMSO at elevated temperatures is convenient. when h.sup.2 and h.sup.1 together form an acetal, hemiacetal, or a thio- or amino-version thereof, hydrolysis, preferably under mild acidic conditions, leads to a PGA-type moiety. [00037] i) halogenation (at acetyl), followed by ii) oxidation; The above is conveniently performed using hydrohalic acid in DMSO; direct oxidation at acetyl is also an option. [00038] None required [00039] None required *Q, X, h.sup.1, and h.sup.2 are as defined elsewhere

4.1 Preparation of PGA-Type Sorbent Based on Poly-VPE

[0209] The different mixtures obtained in example 3.3 were converted to PGA-type sorbents. Being VPE-type material prior to conversion, conversion was performed using halogenation and Kurnblum Oxidation of the pVPE. The same procedure as for the halogenation and Kurnblum oxidation of acetylated polystyrene beads was employed (see Example 1.6) for 12 hours, downscaled to 600 mg pVPE per batch. After washing, 606 mg of yellow beads (pVPE-Ox) was obtained.

[0210] The acetyl aromatic groups in pVPE beads were thus halogenated and subsequently converted into PGAH-groups by a Kornblum oxidation in a one-pot procedure. To establish the optimal reaction time for these oxidizing conditions to obtain the highest PGA/PGAH-density, beads were taken from the reaction mixture at different time points, and their urea binding capacity was determined (see example 4). Urea binding capacity of the beads increased with oxidation time during the first 8 hours to over 2 mmol/g, demonstrating successful oxidation of the acetyl group into PGAH/PGA. For comparison, oxidation of acetylated PS-beads (not using precursor monomers) could not achieve this binding capacity (see example 4).

[0211] At longer reaction times, the binding capacity decreased. IR analysis (FIG. 5) of the sorbent obtained after 8 h of oxidation showed a single carbonyl peak at 1675 cm.sup.−1 with a minor shoulder peak at 1740 cm.sup.−1, whereas the sorbent obtained after 48 hours of oxidation showed two carbonyl peaks at 1675 cm.sup.−1 and 1740 cm-1. This is likely due to over-oxidation (see FIG. 3). The shoulder peak at 1740 cm.sup.−1 in the 8 h sample indicates that the over-oxidation of PGA/PGAH into PGOA already occurred during the first 8 hours, but it is slower than the oxidation of the acetyl group into the PGA/PGAH group. To avoid this over-oxidation reduced presence of HBr, or reduced reaction time is desirable. For oxidation, the reaction time is preferably at most 32 hours, more preferably at most 24 hours, even more preferably at most 16 hours, most preferably at most about 8 hours.

4.2 Preparation of PGA-Type Sorbent Based on Poly(VPE-Br)

[0212] Essentially, this material can be treated as poly-VPE without the need for halogenation. Polymer resin obtained via the general suspension polymerisation method described above (500 mg) is swollen in DMSO and stirred with a mechanical stirrer. Trimethylamine is used as a base for the DMSO-oxidation, which takes place once the suspension is heated to 80° C. for 8 hours. Washing is done as for example 1.6, after which PGA-type sorbent is obtained.

4.3 Preparation of PGA-Type Sorbent Based on Poly(Protected PGA)

[0213] Essentially this material, which is polymerized (4-ethenylphenyl) (2-dioxolanyl) methanone (see Example 2.7), is a protected PGA-type sorbent, i.e. a PGA-type sorbent wherein the glyoxal moiety is acetal-protected. Resin is swollen in THF, after which catalytic acetic acid and 5 vol.-% water is added to deprotect the glyoxal moiety. The solvents are filtered off two times, after which a new batch of THF, water, and acetic acid is added. Then the sorbent is washed with water twice, and dried as described in example 1.6, leading to a PGA-type solvent.

Example 5—Analysis of Sorbents

General Methods for Determining Urea Binding Capacity

[0214] Sorbent (10 mg or 15 mg) was suspended in urea-enriched PBS (30 mM, 1 mL or 1.5 mL) in a 1.5 mL microcentrifuge tube (Eppendorf, individual tube for each timepoint) and placed at 37° C. for a set amount of time. The sorbent was spun down in the tube (12.000 rpm in a conventional benchtop centrifuge, 5 min) and the urea concentration was determined in the supernatant using a commercially available urease assay (Urea CT*FS** colorimetric test purchased at DiaSys Diagnostic Systems GmbH, Holzheim, Germany). In brief, this test determines urea concentrations via a coupled enzyme reaction, which results in a colorimetric (570 nm) product in a concentration proportional to the urea concentration. To determine the maximum urea binding capacity a sample was placed at 70° C. for 24 hours and the urea concentration was determined in the supernatant. In an alternate method, sorbent (15 mg) was suspended in a solution of urea in PBS (1.5 mL, 30 mM or 50 mM) in a 1.5 mL Eppendorf and were placed in a rotation oven at 70° C. After 24 hours the sample was allowed to cool to RT and the urea concentration was determined in the supernatant by a standard urease assay (a urea stock solution kept for 24 hours at 70° C. was used as a negative control). The urea binding capacity of the sorbent was calculated based on the difference in urea concentration of the supernatant of the sorbent and the control solution.

5.1 Analysis of Beads Derived from Styrene

[0215] PS-based sorbents were analyzed by quantitative .sup.13C-solid state NMR to quantify the amount of PGAH groups in Ps-Ac-Ox. The CH.sub.3 peak of the acetyl group detected in .sup.13C-NMR spectrum of PS-Ac had disappeared, indicating that all acetyl groups had been converted. Comparison of the area under the hydrate carbon peak (80-100 ppm) with that of the aromatic peaks (110-160 ppm) and the aliphatic peaks (10-50 ppm) showed that ˜40% of the aromatic groups (thus ˜67% of the acetyl groups) had been converted into PGAH groups. In addition, a minor peak around 165 ppm was detected, which is assigned to the carboxylic acid carbonyl peak from PGOA.

[0216] PS-Ac beads were oxidized for 8 hours on a 60 gram scale and the obtained beads (Ps-Ac-Ox) were characterized by SEM, light microscopy and nitrogen physisorption. PS—Ac-Ox showed similar size (0.54±0.11 mm), surface area (37.0 m.sup.2/g) and pore volume and pore size/volume distribution as PS and PS-Ac. This confirms that the oxidation reaction neither affects the macroporosity nor degrades the beads, likely because the reaction temperature (80° C.) was below the glass transition temperatures (T.sub.9) of both the PS-Ac and PS—Ac-Ox beads (T.sub.9 of dry beads were 184° C. and >230° C., respectively). The PGAH content of the sorbent according to .sup.13C-NMR was similar to the sorbent prepared at small scale. The urea binding capacity of Ps-Ac-Ox was 1.4 mmol/g. Table 4 shows properties of these sorbents.

TABLE-US-00005 TABLE 4 properties of reference materials Urea Surf. Pore Binding Diameter Area Vol. Cap. Beads (mm) (m.sup.2/g) (mL/g) Functionalization (mmol/g) PS 0.49 ± 0.18 36.3 0.32 — — PS-Ac 0.61 ± 0.17 43.4 0.31 ~60% acetylation — Ps-Ac-Ox 0.54 ± 0.11 37.0 0.31 ~40% PGAH 1.4

5.2 Analysis of Beads Derived from a Precursor Monomer

[0217] Beads of table 2, entry 2 (S.sub.BET<0.05 m.sup.2/g) and entry 4 (S.sub.BET=2.0 m.sup.2/g) were selected for conversion. The beads of low surface area (entry 2) were oxidized for 4-12 hours under the same conditions as applied for PS-Ac. The urea binding capacities of the resulting oxidized pVPE beads (pVPE-Ox-(2) were 1.8-2.2 mmol/g, of which the highest binding capacity (2.2 mmol/g) was obtained after 12 hours of oxidation (see FIG. 4). The pVPE beads with the highest surface area (entry 4) were therefore oxidized for 12 hours and the urea binding capacity of these beads (pVPE-Ox-(4)) was 1.8 mmol/g. The surface area of the pVPE-Ox-(4) determined by nitrogen physisorption was similar to that of the corresponding pVPE beads (1.9 vs 2.0 m.sup.2/g), most likely because the reaction temperature of the oxidation reaction (80° C.) is much lower than the T.sub.9 of pVPE beads (147° C.) and the beads therefore remain dimensionally stable under these oxidizing reaction conditions.

[0218] The VPE-based materials showed a higher urea binding capacity than the styrene-based materials which may be because of the increase in the density of acetyl groups and therefore a higher PGAH content after oxidation (1.4 vs. 1.8-2.2 mmol/g). Surprisingly, the surface area of pVPE beads had no influence on the urea binding capacity (1.8-2.2 and 1.8 mmol/g for pVPE-Ox-(2) and pVPE-Ox-(4) respectively). This shows that PGAH groups are accessible for urea also in materials without macroporosity, possibly because the sorbents swell to a minor but sufficient extent in water due to the polar and hydrophilic carbonyl groups and optionally the carboxylic acid groups of PGOA (FIG. 3). In addition, upon urea binding the beads become more hydrophilic further enhancing accessibility for water and urea thereby further improving urea binding kinetics. The average size of pVPE-Ox-(4) beads determined by light microscopy was slightly larger than that of the pVPE beads (0.77±0.20 and 0.61±0.23 mm, respectively). Due to the swelling/deswelling of the beads during nitrogen physisorption experiments, the pore/volume distribution for these materials was not determined. The pVPE-Ox-(4) and corresponding pVPE beads were analyzed by SEM and appeared to be hollow (deflated after drying under vacuum, which suggests core-shell phase separation during the polymerization reaction).

[0219] To determine the density of PGAH-groups in pVPE-Ox-(2) and pVPE-Ox-(4), these materials were analyzed by .sup.13C solid state NMR spectroscopy. Comparison of the hydrate peak integral (80-100 ppm) with the backbone peak integral (10-50 ppm) demonstrates a PGAH-content of ˜50% for both pVPE-Ox-(2) and pVPE-Ox-(4), which confirms that higher PGAH contents are obtained using the VPE instead of the styrene route (˜50 and ˜40% respectively).

5.3 Analysis of Urea Binding Behaviour

[0220] It was found that the pVPE-Ox sorbent beads, which were for ˜50% functionalized with PGAH groups, had a urea binding capacity of ˜2 mmol/g. However, a 100% functionalized sorbent contains 5.5 mmol/g PGAH groups (including 3% crosslinker) based on molecular weight of the monomer (178 g/mol), which implies that a sorbent with ˜50% PGAH groups would have a urea binding capacity of 2.8 mmol/g at most. There are two reasons why the actual urea binding capacity for a sorbent functionalized with PGAH groups is lower than theoretical urea binding capacity based on a 1:1 reaction of urea with PGAH. First, some of the PGAH groups might be inaccessible for urea. Second, PGAH can react with urea in both a 1:1 and a 2:1 ratio (see FIG. 5 structure 3′a) and therefore one potential binding site is lost when PGAH reacts with urea in a 2:1 ratio. Quantification of the inaccessible and therefore unreacted PGAH groups in beads with ˜2 mmol urea per gram sorbent with .sup.13C-NMR spectroscopy is not possible because unreacted PGAH and reacted PGAH give rise to signals in the same region of the spectrum. Therefore the sorbent beads which had reacted with urea (PS-AC-Ox@urea and pVPE-Ox-(4)@urea) were analyzed with IR spectroscopy, along with PGAH, and the 2:1 adduct of PGAH and urea (3′a) (FIG. 5). PGAH shows a clear ketone-carbonyl stretching vibration at 1700 cm-1 and a C—O stretching vibration at 1210 cm-1. However, these peaks have a lower intensity in the IR spectra of PS—Ac-Ox@urea and pVPE-Ox-(4)@urea, and the main carbonyl peak is clearly shifted (from 1700 to 1740 cm-1). Based on these observations it is concluded that the majority of the PGAH groups were indeed accessible for reaction with urea and had reacted. This agrees with the observation that the surface area does not influence the urea binding capacity. Moreover, the IR spectra of PS-AC-Ox@urea and pVPE-Ox-(4)@urea are more similar to the IR spectrum of the isolated 2:1 addition product 3′a. The several peaks arising from the carbonyl stretching vibration in the region of 1650-1800 cm-1 of 3′a are also present in the spectra of PS-AC-Ox@urea and pVPE-Ox-(4)@urea. Therefore it could be concluded that reaction of the 1:1 PGAH:urea adduct with a second PGA group takes place in the sorbent beads at least to some extent, explaining the difference between the urea binding capacity of the sorbents (˜2.0 mmol/g) and the theoretical capacity based on the actual PGAH content (2.8 mmol/g).

[0221] The kinetics of the urea binding of the two different types of PGA-type sorbents was investigated by incubating them in a 30 mM urea solution in phosphate buffered saline (PBS) at 37° C., conditions representative for the regeneration of dialysate. The urea binding was determined by measuring the urea concentration in the solution at different time points (FIG. 6A). The PS—Ac-Ox sorbent only showed a binding of 0.5-0.6 mmol/g after 24 hours. The sorbent pVPE-Ox-(4) had already bound 0.5-0.6 mmol per gram in 8 hours which increased to 0.8-0.9 mmol/g after 24 hours, reaching around 50% of its maximum binding capacity. FIG. 6B shows that both materials reached ˜45% of the maximum binding capacity after 24 hours.

5.4 Maximum Binding Capacity of Various Sorbents

[0222] Maximum urea binding capacities were determined for different sorbents, either PS-based or precursor-based. Table 5 shows urea binding capacities of sorbent beads in urea solution in PBS (10 mg/mL) at 70° C. for 24 hours under static conditions.

TABLE-US-00006 TABLE 5 urea binding for various PGA-type sorbents [Urea].sub.t=0 (mM) [Urea].sub.t=24 h (mM) Max capacity Sorbent #1 #2 #1 #2 (mmol/g) PS- Ac-Ox-1h 30.5 30.4 28.1 27.3 0.28 ± 0.06 PS-Ac-Ox-4h 30.5 30.4 17.4 17.6 1.30 ± 0.01 PS-Ac-Ox-8h (60 g) 46.1 43.4 30.6 30.8 1.41 ± 0.01 PS-Ac-Ox-24h 30.5 30.4 16.2 16.6 1.41 ± 0.03 PS-Ac-Ox-32h 30.5 30.4 21.6 20.8 0.93 ± 0.06 PS-Ac-Ox-48h 30.5 30.4 27.0 27.5 0.32 ± 0.04 pVPE-Ox-(2)-4h 49.8 50.0 32.1 31.6 1.81 ± 0.04 pVPE-Ox-(2)-8h 49.8 50.0 29.0 29.2 2.08 ± 0.01 pVPE-Ox-(2)-12h 49.8 50.0 27.3 27.9 2.23 ± 0.04 pVPE-Ox-(4) 46.1 43.4 28.0 26.4 1.76 ± 0.11

5.5 Conclusion

[0223] PGA-type sorbent beads containing phenylglyoxaldehyde hydrate (PGAH) groups were successfully prepared via a precursor monomer using suspension polymerization followed by monomer conversion of the precursor into PGA (here: oxidation). The VPE route outperformed known routes using styrene, and also saves one post polymerization modification step, importantly resulting in a sorbent with higher PGAH content (˜50%, vs ˜40% for PS-based sorbents) and concomitantly higher binding capacity (over 1.8 mmol/g, vs 1.4 mmol/g for PS-based sorbents). The accessibility of the PGAH groups in the VPE-based sorbents is not dependent on the surface area of the material, possibly because the beads swell to a minor extent. The kinetics of urea sorption from simulated dialysate showed that ˜30% of the binding capacity is reached after 8 hours at 37° C. The best sorbent developed (pVPE-Ox-(4)) bound ˜0.5-0.6 mmol/g in 8 hours, which demonstrates that ˜700 grams of this PGAH-type sorbent is needed to remove the daily urea production of 400 mmol of end-stage kidney disease patients during a dialysis session of 8 hours.

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