WO2023148545A1

WO2023148545A1 - Dual-task borinane-based catalysts for ring opening (co)polymerization

Info

Publication number: WO2023148545A1
Application number: PCT/IB2022/062224
Authority: WO
Inventors: Xiaoshuang FENG; Chao Chen; Yves Gnanou
Original assignee: King Abdullah University Of Science And Technology
Priority date: 2022-02-03
Filing date: 2022-12-14
Publication date: 2023-08-10

Abstract

Provided are dual-task borinane-based catalysts comprising a compound of Formula I (I) wherein Y is an alkyl, aryl, cycloalkyl, or cycloaryl spacer; Z is a nitrogen or phosphorous atom; R is an alkyl, aryl, cycloalkyl, or cycloaryl group, or a polymeric support; and a, b, and c are integers independently selected from the group consisting of 0-100, methods of making the catalyst using a monocyclic borinane. Methods of using the catalysts include producing polyethers, polycarbonates, polyesters, and polyurethanes, and obtaining primary hydroxyl-derivatives of the polyethers and polycarbonates.

Description

DUAL-TASK B ORIN ANE-BASED CATALYSTS FOR RING OPENING (CO)POLYMERIZATION

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims benefit of US Provisional Application No. 63/306,358 filed on February 3, 2022. US Provisional Application No. 63/306,358 is incorporated herein by reference. A claim of priority is made.

BACKGROUND

[0002] Trialkylborane, especially tri ethylborane (TEB), represents an exceptional Lewis acid owing to its seamless commercial availability, mild Lewis acidity, oxyphilic and non-metallic character. Since the first report on the copolymerization of CO2 with epoxides using TEB to promote the synthesis of polycarbonates, this Lewis acid has emerged as a versatile catalyst to carry out a broad range of (co)polymerizations combined with an organic Lewis base or an initiator. These systems have demonstrated their suitability and effectiveness in the homo- or copolymerizations of many oxygenated monomers (e.g., epoxides with CO2, COS, anhydrides, and isocyanates), exhibiting very high activity for the preparation of polyethers, polycarbonates, polyesters and polyurethanes with high molar masses. In contrast to organometallic catalytic system, the above (co)polymerizations are conducted through anionic polymerization approach and the molar masses of the obtained polymers are well controlled with narrow polydispersity. [0003] Preparation of low molar mass polymers, such as polyols using TEB- mediated system, requires a large amount of Lewis acid, however. The initiator controls the molar mass of the obtained polymer through the [monomer] to [initiator] ratio and one or two equivalents of TEB are needed. Yet, it is not feasible to tune the molar masses by increasing the concentration of alcohols or acids as chain transfer agent as TEB activation of monomers is sensitive to protic compounds. A specific process to recycle TEB and ammonium cations was designed. While this process reduces the production cost, it requires additional isolation and purification steps.

[0004] Inspired by the reports of remarkable increase of catalytic activity of one component (dual-task) organometallic catalysts with salen catalysts carrying multiple side arms bearing onium groups, dual-task borane-based catalysts featuring electrophilic boron centers attached within the same molecule to an ammonium cation have been reported. Their catalytic activity and robustness is significantly improved in comparison with its precursor, 9-borabicyclo[3.3.1]nonane (9-BBN) and TEB in some cases. Therefore, the need for a safer, more robust, and active organoboron catalyst than TEB for polymerizations remains.

SUMMARY

[0005] The present disclosure is predicated on the discovery of a dual-task catalyst featuring at least one monocyclic borinane attached to onium cations as a single molecule dual-task borinane-based catalysts of the present disclosure exhibit very high activities, and are capable of catalyzing homopolymerization of epoxides, oxetanes, and copolymerization of epoxides, and oxetanes with CO2, epoxides with anhydride, epoxides with isocyanates to afford polyethers, polycarbonates, polyesters and polyurethanes, respectively. Furthermore, the robustness and high activities of the dual-task borinane- based catalyst permit use of chain transfer agents to tune the molar masses of generated polymers.

[0006] Accordingly, a first aspect of the present disclosure features a dual-task borinane-based catalyst comprising a compound of formula I:

wherein Y is an alkyl, aryl, cycloalkyl, or cycloaryl spacer;

Z is a nitrogen or phosphorous atom;

R is an alkyl, aryl, cycloalkyl, or cycloaryl group, or a polymeric support; and a, b, and c are integers independently selected from the group consisting of 0-100. The R group can be an unsubstituted or substituted group selected from Ci - C30 alkyl groups, C3 - C30 cycloalkyl groups, and Ce - C30 aryls or cycloaryl groups, a can be 1-4, b can be 1 and c can be 0-3. The catalyst can further include an anion selected from the group consisting of ion selected from the group consisting of Cl", F", Br", I", OH", NCh’, N3', BF₄‘ , (CeFs^B", sulfonate, perchlorate, chlorate, phosphate, carboxylate, alkoxide, and phenoxide. The catalyst can be selected from the group consisting of:

[0007] A second aspect of the present disclosure features a method of preparing a dual-task borinane-based catalyst according to any embodiment of the first aspect, the method comprising:

where X represents unsaturated bonds, an alkene or an alkyne bond; and

Y is an alkyl, aryl, cycloalkyl, or cycloaryl spacer;

Z is a nitrogen or phosphorous atom;

R is an alkyl, aryl, cycloalkyl, or cycloaryl group, or a polymeric support; and a, b, and c are integers independently selected from the group consisting of 0- 100.

[0008] In a third aspect, the present disclosure features a method of polymer synthesis comprising ring opening polymerization or copolymerization of a cyclic monomer in the presence of a dual-task borinane-based catalyst according to any one of the embodiments of the first aspect. The cyclic monomer can be selected from the group consisting of cyclic esters, epoxides, oxetanes, anhydrides, and combinations thereof. The cyclic monomer can be copolymerized with CO2. The cyclic monomer can be an epoxide represented by the structure of formula IV:

wherein each of Ri and R2 can be independently selected from nothing, hydrogen, alkyls, heteroalkyls, cycloalkyls, alkenyls, heteroalkenyls, cycloalkenes, alkynyls, heteroalkynyls, cycloalkynyls, alkoxys, aryls, heteroaryls, aralkyls, aralkylenes, alkaryls, alkarylenes, halogens, and combinations thereof, each of which can be substituted or unsubstituted. The method can produce a polyether or a polycarbonate. The method can further comprise sequential polymerization of oxetane to derivatize a terminal secondary hydroxyl group of the polymer into a primary hydroxyl group. The epoxide can be copolymerized with an isocyanate to produce a polyurethane. The epoxide can be copolymerized with an anhydride to produce a polyester. The method can further include tuning the molecular mass of the polymer or copolymer by adding a chain transfer agent. The cyclic monomer can include an oxetane, and optionally the method can produce a polyether, or optionally the oxetane is copolymerized with CO2.

[0009] In a fourth aspect, the present disclosure features a method of preparing a poly ether having terminal primary hydroxyl groups, the method comprising polymerizing an epoxide in the presence of a dual-task borinane-based catalyst according to any one of the embodiments of the first aspect, to generate a polyether with terminal secondary hydroxyl groups; and sequentially polymerizing oxetane to derivatize the secondary hydroxyl groups into primary hydroxyl groups.

[0010] In a fifth aspect, the present disclosure features a method of preparing a polycarbonate having terminal primary hydroxyl groups, the method comprising copolymerizing an epoxide and CO2 in the presence of a dual-task borinane-based catalyst according to any embodiment of the first aspect, to generate a polycarbonate with terminal secondary hydroxyl groups; and sequentially polymerizing oxetane to derivatize the secondary hydroxyl groups into primary hydroxyl groups.

[0011] Optionally, in the method of either the fourth or fifth aspect, the epoxide can be selected from the group represented by formula IV:

wherein each of Ri and R2 can be independently selected from nothing, hydrogen, alkyls, heteroalkyls, cycloalkyls, alkenyls, heteroalkenyls, cycloalkenes, alkynyls, heteroalkynyls, cycloalkynyls, alkoxys, aryls, heteroaryls, aralkyls, aralkylenes, alkaryls, alkarylenes, halogens, and combinations thereof, each of which can be substituted or unsubstituted.

[0012] The details of one or more examples are set forth in the description below. Other features, objects, and advantages will be apparent from the description and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

[0013] The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document, in which:

[0014] FIG. 1 illustrates a tabulated comparison of catalyst activities for ringopening polymerization of propylene oxide (PO) of two dual-task borinane-based catalysts with catalysts reported in the literature, according to some embodiments.

[0015] FIG. 2 illustrates tabulated results of catalyst B4 catalyzed ring polymerization of epoxides for polyethers in the absence and presence of chain transfer agent (BzOH), a dual-task borinane-based catalyst, according to some embodiments.

[0016] FIG. 3 illustrates the catalytic activity of dual-task borinane-based catalysts for PO polymerization in the presence of different chain transfer agents, according to some embodiments.

[0017] FIG. 4 illustrates the results of copolymerization of PO with CO2 to produce poly(ether-carbonate)s in the presence of DBzOH as chain transfer agent, using a dualtask borinane-based catalyst, according to some embodiments.

[0018] FIG. 5 illustrates the results of ring-opening polymerization of oxetane catalyzed by B4, a dual-task borinane-based catalyst, according to some embodiments.

[0019] FIG. 6 illustrates the 'H NMR spectrum of borinane in CDCh, according to some embodiments.

[0020] FIG. 7 illustrates the ¹³C NMR spectrum of borinane in CDCh, according to some embodiments.

[0021] FIG. 8 illustrates the ⁿB NMR spectrum of borinane in CDCh, according to some embodiments.

[0022] FIG. 9 illustrates a 'H NMR spectrum of a dual -task borinane-based catalyst (Bl) in CDCh, according to some embodiments. [0023] FIG. 10 illustrates a ¹³C NMR spectrum of a dual-task borinane-based catalyst (Bl) in CDCh, according to some embodiments.

[0024] FIG. 11 illustrates a 'H NMR spectrum of a dual-task borinane-based catalyst (B2) in CDCh, according to some embodiments.

[0025] FIG. 12 illustrates a ¹³C NMR spectrum of a dual-task borinane-based catalyst (B2) in CDCh, according to some embodiments.

[0026] FIG. 13 illustrates a 'H NMR spectrum of a dual-task borinane-based catalyst (B3) in CDCh, according to some embodiments.

[0027] FIG. 14 illustrates a ¹³C NMR spectrum of a dual-task borinane-based catalyst (B3) in CDCh, according to some embodiments.

[0028] FIG. 15 illustrates a 'H NMR spectrum of a dual-task borinane-based catalyst (B4) in CDCh, according to some embodiments.

[0029] FIG. 16 illustrates a ¹³C NMR spectrum of a dual-task borinane-based catalyst (B4) in CDCh, according to some embodiments.

[0030] FIG. 17 illustrates a ⁿB NMR spectrum of a dual-task borinane-based catalyst (B4) in CDCh, according to some embodiments.

[0031] FIG. 18 illustrates a ¹ H NMR spectrum of PPO in CDCh, according to some embodiments.

[0032] FIG. 19 illustrates a graphical representation of size exclusion chromatography (SEC) traces of PPO copolymers with different molar masses, according to some embodiments.

[0033] FIG. 20A illustrates a spectrum of the MALDI-TOF mass spectroscopy analysis of PPO, which molar mass controlled by EhO, according to some embodiments. [0034] FIG. 20B illustrates a polymer structure analysis of PPO, according to some embodiments.

[0035] FIG. 21 illustrates a ¹ H NMR spectrum of PPC in CDCh, according to some embodiments.

[0036] FIG. 22 illustrates a H NMR spectrum of PCHC in CDCh, according to some embodiments.

[0037] FIG. 23 illustrates a ¹ H NMR spectrum of PTMO in CDCh, according to some embodiments.

[0038] FIG. 24 illustrates a 'H NMR spectrum of PTMO-b-PPO-b-PTMO in CDCh, according to some embodiments. [0039] FIG. 25 illustrates an ¹⁹F NMR spectrum of polyether polymers having different end hydroxyl groups, according to some embodiments.

DETAILED DESCRIPTION

[0040] The present disclosure features dual-task catalysts comprising monocyclic borinanes attached to onium cations in a single molecule, characterized by the chemical structure of formula I:

wherein Y is an alkyl, aryl, cycloalkyl, or cycloaryl spacer;

Z is a nitrogen or phosphorous atom;

R is an alkyl, aryl, cycloalkyl, or cycloaryl group, or a polymeric support; and a, b, and c are integers within the range of 0-100, such as 0-25, 1-15, 1-10 or 1-4. Dual -task catalysts according to Formula I exhibit very high activities imparted by the monocyclic borinane moiety.

[0041] With respect to Formula I, the term “alkyl” refers to a saturated aliphatic hydrocarbon group such as methyl, ethyl, propyl, and butyl, and may be a straight or branched chain, “aryl” refers to an aromatic hydrocarbon group such as phenyl, naphthyl and anthranil, in which the aromatic hydrogen group may be substituted or unsubstituted, and “cycloaryl” refers to a saturated or unsaturated alicyclic hydrocarbon group containing aromatic hydrocarbon group such as cyclophenyl and a tetrahydronaphthalene group, which may be substituted or unsubstituted. In one or more embodiments, R is an unsubstituted or substituted group selected from Ci - C30 alkyl groups, C3 - C30 cycloalkyl groups, and Ce - C30 aryls or cycloaryl groups, a, b and c could be any integrals from 0 to 100. For example, a dual-task borinane-based catalyst according to Formula I can be selected from the group consisting of:

[0042] Although B1-B4 include Cl" ions, other dual-task borinane-based catalysts encompassed by Formula I can include an ion selected from the group consisting of F', Br', I", OH", NCh', Ns', BFF, (CeFs^B', sulfonate, perchlorate, chlorate, phosphate, carboxylate, alkoxide, and phenoxide.

[0043] In a second aspect, the present disclosure provides methods of preparing a dual-task borinane-based catalyst. For example, embodiments of the present disclosure describe a synthetic process for preparing the dual-task borinane-based catalysts of Formula I (Scheme 1).

Scheme 1. General structures of dual-task borinane-based catalysts and their synthetic procedures.

where X represents unsaturated bonds, an alkene or an alkyne bond; and Y, Z, R, a, b, and c are as defined above for Formula I. [0044] For example, in one embodiment, the method of preparing a dual -task borinane-based catalyst includes hydroboration of an quaternary ammonium salt, quaternary phosphonium salts, phosphonitrile, or a polymeric support represented by chemical formula II:

where X represents unsaturated bonds, an alkene or an alkyne bond; and Y, Z, R, a, b, and c are as defined above for Formula I.

In some cases, the ratio of borinane to compound of Formula II, is selected to achieve a desired catalytic activity or to optimize the ratio of Lewis Base:Lewis Acid in the single molecule.

[0045] A method of preparing a dual-task borinane-based catalysts of the present disclosure can include synthesizing monocyclic borinane, e.g., according to a method of Scheme 2.

Scheme 2. Synthetic approaches of monocyclic borinane.

[0046] For example, as shown in method I of Scheme 2, pure monocyclic borinane can be obtained by combining 9-Borabicyclo[3.3. l]nonane (9-BBN (in hexane)) and 1,4- pentadiene and then adding borane dimethylsulfide complex (BMS), for 6-18 hours, or about 8-16 hours. Treatment with BMS leads to cyclization of pentadiene moiety forming borinane along with the regeneration of 2 equiv of 9-BBN.

[0047] After sufficient time for reaction of the borane mixture solution, anhydrous l,4-diazabicyclo[2.2.2]octane (DABCO) solution can be added. DABCO can be dissolved in a tetrahydrofuran, or other solvent (e.g., ether, dimethoxyethane, dioxolane, n-pentane, or n-hexane). The reaction proceeds for about 18-30 hours (e.g., 20-24 hours) with borinane forming a complex with DABCO, which complex is precipitated. Pure borinane can be separated with 9-BBN by filtration. In some cases, the 9-BBN can be recycled for further reaction. Free borinane can be generated from the DABCO complex by reaction with boron trifluoride. The free borinane solution can be concentrated (e.g., under vacuum) to yield pure borinane. This method provides a high yield of monocyclic borinane (about 95% yield). In some cases, the method includes combining 9-BBN and 1,4 -pentadiene at a ratio of about 40-50: 1, such as about 40-42: 1. Concentrating step can include removing solvent by reduced pressure evaporation or use of a rotary evaporator. [0048] As shown in Method II of Scheme 2, with pure borinane in hand, borinane can be regenerated through hydroboration of 1,4-pentadiene using borinane instead of 9- BBN. Scheme 2(11) avoids the need to separate borinane from 9-BBN, as performed in method I.

[0049] The method of preparing a dual-task borinane-based catalyst of the present disclosure can include preparing a compound represented by chemical formula II, or ammonium salt, quaternary phosphonium salts, phosphonitrile, or polymeric support thereof:

For example, a representative ammonium salt according to Formula II can be prepared by a method that includes contacting a solution of a trialkyl amine with 5-bromo-l -pentene at a ratio of 1 : 1 for 24-50 hours. The solution can be agitated and/or heated to about 80- 90° C. After removing the solvent and purifying the reaction product, a solution of the obtained bromide salt can be treated with a halide-exchange resin to provide the ammonium salt represented by chemical Formula III:

(III).

Purifying can include washing the crude reaction product one or more times with a solvent (e.g., ethyl acetate or the like). The crude, purified, and/or ion-exchanged product can be dried by low-pressure evaporation or using a rotary evaporator.

[0050] The present disclosure features methods of polymer synthesis comprising ring opening polymerization or copolymerization of a cyclic monomer in the presence of a dual-task borinane-based catalyst of formula I. The cyclic monomer can be selected from the group consisting of cyclic esters, epoxides, oxetanes, cyclic anhydrides and their combinations, and respectively with heterocumulene monomers thereof.

[0051] The robustness and high activity of the catalysts of the present disclosure permits addition of a chain transfer agent to tune the molecular masses of the generated polymers. The chain transfer agent can be selected from water, mono-alcohols (i.e., alcohols having one OH group such as diphenylphosphinic acid, 4-ethylbenzenesulfonic acid, methanol, ethanol, propanol, butanol, pentanol, hexanol, phenol, cyclohexanol, methylolbenzene (BzOH), trifluoroethanol (TFE), Propargyl alcohol (PA), 2- Hydroxyethyl acrylate (HEA)), 4-Bis(mercaptomethyl)benzene (DBzSH), diols (e.g., 1,2-ethanediol, 1,2-propanediol (PG), 1,3 -propanediol, 1,2-butanediol, 1,3 -butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-diphenol, 1,3-diphenol, 1,4- diphenol, catechol, 1,4-Dimethylolbenzene (DBzOH), and cyclohexenediol), triols (e.g., Glycerol, benzenetri ol, 1,2,4-Butanetriol, tris (methyl alcohol) propane, tris (methyl alcohol) ethane, tris (methyl alcohol) nitropropane), tetraol (e.g., calix [4] arene and 2,2- bis (Methyl alcohol)-l,3-propanediol), polyol (e.g., D-(+)-glucose, or D-sorbitol), dihydroxy-terminated polyester (e.g., polylactic acid), and dihydroxy-terminated poly ethers (e.g., poly(ethylene glycol) (PEG)), and mixtures thereof. In some cases, the chain transfer agent is selected from the group consisting of:

[0052] In one or more embodiments, the cyclic monomer is an epoxide, such as an epoxide of formula IV:

wherein each of Ri and R2 can be independently selected from nothing, hydrogen, alkyls, heteroalkyls, cycloalkyls, alkenyls, heteroalkenyls, cycloalkenes, alkynyls, heteroalkynyls, cycloalkynyls, alkoxys, aryls, heteroaryls, aralkyls, aralkylenes, alkaryls, alkarylenes, halogens, or combinations thereof, each of which can be substituted or unsubstituted. In some embodiments, Ri and R2 connect to form a fused ring having, for example, five or more carbon atoms in the ring structure, where any of the carbon atoms can optionally be replaced with a heteroatom. Ri and R2 may independently contain functional groups such as one or more of halide, vinyl, thiol, ether, ester, ketone, aldehyde, and acid. The heteroatom can be selected from a halide, N, O, P, Si, Se, or S. The N, P, S, and Se atoms can be oxidized. The N heteroatom can be quaternized. In the epoxide can be ethylene oxide (EO), propylene oxide (PO), 1 -butylene oxide (BO), 1- hexene oxide (HO), 1 -octene oxide (00), styrene oxide (SO), cyclohexene oxide (CHO), allyl glycidyl ether (AGE), and butyl glycidyl ether (BGE), 2-ethylhexyl glycidyl ether (EHGE), phenyl glycidyl ether (PGE), benzyl glycidyl ether (BGE), glycidyl azide (GA), epichlorohydrin (ECH), cyclopentene oxide (CPO), 4-vinyl-l -cyclohexene 1,2 epoxide (VCHO), or limonene oxide (LO), with structures provided below:

[0053] The cyclic ester can be selected from any cyclic compound (e.g., cycloalkanes, cycloalkenes, etc.) having one or more carbon atoms replaced by an ester unit/group of the formula — C(O)O — . Suitable cyclic esters include, but are not limited to, cyclic monoesters, cyclic diesters, cyclic triesters, and the like. For example the cyclic ester can be a lactide, trimethylene carbonate, glycolide, P -butyrolactone, 6-valerolactone, y-butyrolactone, y-valerolactone, 4-methyldihydro-2(3H)-furanone, alpha-methyl- gamma-butyrolactone, s-caprolactone, 1 ,3-dioxolan-2-one, propylene carbonate, 4- methyl-l,3-dioxan-2-one, l,3-doxepan-2-one, 5-C1-4 alkoxy-1, 3-dioxan-2-one; or derivatives thereof. In some cases, the cyclic ester is a lactide monomer. The lactide monomers can be selected from L-lactide, D-lactide, me o-lactide, and combinations thereof. The lactide monomers can further be substituted or unsubstituted. For example, the methyl groups of lactide can be replaced with one or more substituents selected from hydrogen, alkyls, heteroalkyls, cycloalkyls, alkenyls, heteroalkenyls, cycloalkenes, alkynyls, heteroalkynyls, cycloalkynyls, alkoxys, aryls, heteroaryls, aralkyls, aralkylenes, alkaryls, alkarylenes, halogens, or combinations thereof, each of which can be substituted or unsubstituted. The aforementioned substituents shall not be limiting as any substituent known in the art can be used herein.

[0054] In one or more embodiments, a cyclic anhydride is polymerized or copolymerized. The cyclic anhydride may be a saturated cyclic anhydride, an unsaturated cyclic anhydride, or a mixture thereof, according to formula V:

wherein Q is an optionally substituted group selected from the group consisting of C7-12 arylalkyl; 6-10-membered aryl; 5-10-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; 4-7-membered heterocyclic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; and a saturated or unsaturated, straight or branched, Ci- C30 aliphatic group, wherein one or more methylene units are optionally and independently replaced by — NR_y — , — N(R_V)C(O) — , — C(O)N(R_y) — , — OC(O)N(R_y)— , — N(R_y)C(O)O— , — OC(O)O— , — O— , — C(O)— , — OC(O)— , — C(O)O— , — S— , —SO—, — SO2— , — C(=S)— , — C(=NR_y)— , — C(=NOR_y)— or _ N=N— ; each occurrence of R_y is independently hydrogen or an optionally substituted Ci- 6 aliphatic group. “Saturated” anhydrides include anhydrides that contain no reactive ethylenic unsaturation, but which may have aromatic rings. In one or more embodiments, a compound of formula V has the following structure:

wherein each R¹ and R² can be independently selected from the group consisting of nothing, hydrogen, alkyls, heteroalkyls, cycloalkyls, alkenyls, heteroalkenyls, cycloalkenes, alkynyls, heteroalkynyls, cycloalkynyls, alkoxys, aryls, heteroaryls, aralkyls, aralkylenes, alkaryls, alkarylenes, halogens, or combinations thereof, each of which can be substituted or unsubstituted. R¹ and R² may independently contain functional groups such as one or more of halide, vinyl, thiol, ether, ester, ketone, aldehyde, and acid. The heteroatom can be selected from a halide, N, O, P, Si, Se, or S. The N, P, S, and Se atoms can be oxidized. The N heteroatom can be quaternized. [0055] Exemplary saturated cyclic anhydrides include succinic anhydride (SA), phthalic anhydride (PA), tetrahydrophthalic anhydride, alkyl and aryl -substituted succinic anhydrides, halogenated saturated cyclic anhydrides such as tetrabromophthalic anhydride. In some cases, the cyclic anhydride is an unsaturated cyclic anhydrides (i.e., cyclic anhydrides with ethylenic unsaturation) or a mixtures of an unsaturated cyclic anhydride and a saturated cyclic anhydride. The unsaturated cyclic anhydride can be maleic anhydride (MA), citraconic anhydride , itaconic anhydride, halogenated unsaturated cyclic anhydrides, and mixtures thereof. In one or more embodiments, the cyclic anhydride is phthalic anhydride (PA), succinic anhydride (SA), diglycolic anhydride (DGA), glutaric anhydride (GA), maleic anhydride (MA), 1,2- Cyclopropanedicarboxylic anhydride (C3SA) 1,2-cyclopentane diformic anhydride (C5SA), 2-hexenyl-succinic anhydride (C6SA), 2-hexenyl-maleic anhydride (C6MA), dimethylmaleic anhydride (DMMA), carbic anhydride (NorSA), or a mixture thereof, with structures provided below:

[0056] The oxetane can be selected from the group consisting of unsubstituted or substituted oxetane, according to formula VI.

[0057] A dual-task borinane-based catalyst of the present disclosure can be used to synthesize polyethers and polycarbonates according to Scheme 3. For example, a catalyst of the present disclosure can catalyze ring opening polymerization of epoxides to produce polyethers according to Scheme 3(1):

wherein Ri and R2 are defined as in formula IV, and R is defined above in formula I, n is any integer equal to or greater than 1 and m is 1-200. In some cases, transfer agent R-(0H)_n is not included in the reaction mixture (m is undefined).

SCHEME 3(1)

[0058] In other embodiments, a catalyst of the present disclosure can catalyze copolymerization of epoxides with CO2 to produce polycarbonate and polycarbonate polyols, according to Scheme 3(2):

wherein n, m, R, Ri and R2 are defined as in scheme 3(1).

SCHEME 3(2)

[0059] In further embodiments, a catalyst of the present disclosure can catalyze ring opening polymerization of oxetane with CO2 with derivatization of the terminal secondary hydroxyls into primary hydroxyls through sequential polymerization of oxetane, according to I and II of Scheme 3(3):

I.

wherein n, m, R, Ri and R2 are defined as in Scheme 3(1) and p can be an integer of 1-10.

SCHEMES 3(3) I-II

[0060] In one or more further embodiments, a catalyst of the present disclosure catalyze copolymerization of an epoxide with an anhydride to produce a polyester, according to Scheme 4 below:

wherein the epoxide and cyclic anhydride are selected from the compounds defined by formula (IV) and (V), respectively. The number of repeat units n can be any whole number greater than 1. SCHEME 4

[0061] In another embodiment, catalysts of the present disclosure can catalyze copolymerization of an epoxide with an isocyanate to produce a polyurethane, according to Scheme 5 below:

wherein Ri and R2 are defined as in Formula IV, R is an aromatic, aliphatic, cycloaliphatic and/or araliphatic group and n is an integer greater than or equal to 1.

SCHEME S

For example, the isocyanate can be selected from the following:

4-nltrophenyl 4-trifluorom ethylphenyl 4-fluorophenyl pentafluorophenyl Isocyanate Isocyanate Isocyanate Isocyanate bls(trlfluoromethyl)- NPI TFMPI FPI PFPI phenyl Isocyanate

BTFMPI

[0062] The following Examples are intended to illustrate the above invention and should not be construed as to narrow its scope.

EXAMPLE 1

[0063] FIG. 1 illustrates a tabulated comparison of catalyst activities for ringopening polymerization of propylene oxide (PO) of two dual-task borinane-based catalysts with catalysts reported in the literature, according to some embodiments. [0064] FIG. 2 illustrates tabulated results of catalyst B4 catalyzed ring polymerization of epoxides for polyethers in the absence and presence of chain transfer agent (BzOH), a dual-task borinane-based catalyst, according to some embodiments.

[0065] FIG. 3 illustrates the catalytic activity of dual-task borinane-based catalysts for PO polymerization in the presence of different chain transfer agents, according to some embodiments.

[0066] FIG. 4 illustrates the results of copolymerization of PO with CO2 to produce poly(ether-carbonate)s in the presence of DBzOH as chain transfer agent, using a dualtask borinane-based catalyst, according to some embodiments.

[0067] FIG. 5 illustrates the results of ring-opening polymerization of oxetane catalyzed by B4, a dual-task borinane-based catalyst, according to some embodiments.

[0068] Instead of using bicyclic borane (9-BBN) to form the dual -task borane-based catalyst, these Examples describe synthesis of dual-task catalysts with monocyclic borinanes attached to onium cations in single molecule (Scheme 1), exhibiting very high activities (e.g., TOF > 200,000 ) and robustness (e.g., TON = 10000-2.4>< 10⁶ ).

1. Synthesis of borinane.

[0069] A flame dried round bottom flask equipped with magnetic stir bar was transferred to glove box. The flask was charged with 48.5 mL 9- Borabicyclo[3.3.1]nonane (9-BBN, 0.4 M in hexane) and 1 mL of 1,4 pentadiene (9.7 mmol). The flask was stirred at room temperature in glove box overnight before adding 0.92 mL borane (borane dimethylsulfide complex). The reaction continued at room temperature for 24 h. An anhydrous l,4-diazabicyclo[2.2.2]octane (DABCO, 0.54 g) THF solution was added to the above borane mixture solution. Borinane, having formed a complex with DABCO, was precipitated. The 9-BBN does not undergo complexation with DABCO. The borinane was separated with 9-BBN by filtration, and 9-BBN can be recycled for further reaction. Free borinane was generated from the DABCO complex by reacting with boron trifluoride. The above solution was concentrated under vacuum to yield pure borinane as white solid (0.76 g, 95% yield).

[0070] With pure borinane in hand, borinane can be regenerated through hydroboration of 1,4 pentadiene with borinane as described above instead of 9-BBN and avoid separation procedure (Scheme 2, method II described above).

2. Synthesis of ammonium salts. [0071] In a flame dried round bottom flask equipped with magnetic stir bar, an anhydrous acetonitrile solution of tributyl amine (1 eq., 10 g, 54 mmol) was charged. An equivalent quantity of 5 -bromo- 1 -pentene (1 eq., 8.05 g, 54 mmol) was added and stirred at 85 °C for 48 h. The solvent was removed via rotary evaporation to afford crude products as a pale brown solid which was further purified by three times wash with ethyl acetate. The pure ammonium salt (yield 98 %) was obtained as white solid and dried under P2O5. The above bromide salt (5 g) was dissolved in methanol and eluted through a column containing Amberlite IRA-402 (Cl form) ion-exchange resin (50.0 g) at a drop rate of 1 mL/min. Solvent was removed and product was dried in vacuum at 50 °C to yield a white solid (4.1 g, 100% yield).

3. Hydroboration of ammonium salts with borinane: synthesis of dual-task catalyst Bl.

[0072] In a flame dried Schlenk tube, the anhydrous THF solution of above obtained ammonium salt (800 mg, 2.76 mmol) was charged. An equivalent quantity of borinane (230 mg, 2,76 mmol) was added and stirred at room temperature in glovebox overnight. Solvent was removed under reduced pressure to afford crude products as white solid (Bl, 1.02 g, 100% yield).

4. Polymer and copolymer synthesis

[0073] Catalytic activity of the B 1 for ring-opening polymerization of propylene oxide (PO) was compared to literature reported activities for 9-BBN and other Lewis Acids. The results show that Bl exhibited significantly higher TON and TOF values and were effective for producing higher molecular mass polymers with improved control over polymer size. a. Preparation of polyether polyol.

[0074] Dual-task borinane catalyst (B4), obtained by a method similar to B 1 above, was dissolved in THF to obtain a 1 M solution, and further diluted 100 times to afford a 0.01 M THF solution. A typical polymerization procedure which corresponds to FIG. 2 entry 3 is described as follows: A flame dried Schlenk tube was transferred to glovebox. Then the tube was charged with 1 eq. catalyst (50 pL, 0.5 pmmol), 100 eq DBzOH (6.9 mg, 0.05 mmol) and 20000 eq. PO (0.7 mL, 10 mmol). The tube was stirred at room temperature for 30 min. The crude polymer was dried in vacuum at 50 °C to yield a vicious oil (0.58 g, 100% yield). The catalytic activity of dual-task borinane catalysts Bl- B4 was assessed for PO polymerization in the presence of different chain transfer agents as shown in FIG. 3. b. Synthesis of Polycarbonates-diol.

[0075] A typical polymerization procedure which corresponding to FIG. 4, entry 9 proceeded as follows: A 50 mL Parr reactor with a magnetic stir bar and a small glass vial inside was first dried in an oven at 120 °C overnight and then immediately transferred into glove box. After the reactor cooled down, 1 eq. catalyst (50 pL, 0.5 pmmol) and 100 eq. DBzOH (6.9 mg, 0.05 mmol) was added. Then 10000 eq. of PO (0.7 mL, 10 mmol) was added into the small glass vial. Subsequently, the reactor was sealed and taken out from glove box. After charged with 15 bar CO2, the reactor was heated at 50 °C for 12 h. The reactor was cooled, unreacted CO2 was slowly released, and the polymer solution was directly precipitated in methanol to afford polycarbonate polyol. The crude polymer was dried in vacuum at 50 °C to yield a vicious oil (0.54 g, 60% yield). c. Synthesis of PTMO and PPO based polyol terminated with primary hydroxyl.

[0076] A typical polymerization procedure corresponding to FIG. 5, entry 4 proceeded as follows: A flame dried Schlenk tube was transferred to glovebox. Then the tube was charged with 1 eq. (2 pmol) catalyst, 125 eq. DBzOH (34.5 mg, 0.25 mmol) and 5000 eq. PO (0.7 mL, 10 mmol). The tube was stirred at room temperature for 30 min. Subsequently, 250 eq. oxetane was added and stirred for further 12 h. The crude polymer was dried in vacuum at 50 °C to yield a vicious oil (0.61 g, 100% yield).

Example 2

[0077] FIG. 6 illustrates the 'H NMR spectrum of borinane in CDCL, according to some embodiments. FIG. 7 illustrates the ¹³C NMR spectrum of borinane in CDCL, according to some embodiments. FIG. 8 illustrates the ⁿB NMR spectrum of borinane in CDCL, according to some embodiments.

[0078] FIG. 9 illustrates a ¹ H NMR spectrum of a dual -task borinane-based catalyst (Bl) in CDCL, according to some embodiments. FIG. 10 illustrates a ¹³C NMR spectrum of a dual-task borinane-based catalyst (Bl) in CDCL, according to some embodiments.

[0079] FIG. 11 illustrates a 'H NMR spectrum of a dual-task borinane-based catalyst (B2) in CDCL, according to some embodiments. FIG. 12 illustrates a ¹³C NMR spectrum of a dual-task borinane-based catalyst (B2) in CDCh, according to some embodiments.

[0080] FIG. 13 illustrates a ^XH NMR spectrum of a dual -task borinane-based catalyst (B3) in CDCh, according to some embodiments. FIG. 14 illustrates a ¹³C NMR. spectrum of a dual-task borinane-based catalyst (B3) in CDCh, according to some embodiments.

[0081] FIG. 15 illustrates a

NMR spectrum of a dual -task borinane-based catalyst (B4) in CDCh, according to some embodiments. FIG. 16 illustrates a ¹³C NMR spectrum of a dual-task borinane-based catalyst (B4) in CDCh, according to some embodiments. FIG. 17 illustrates a ⁿB NMR spectrum of a dual -task borinane-based catalyst (B4) in CDCh, according to some embodiments.

[0082] FIG. 18 illustrates a ³H NMR spectrum of PPO in CDCh, according to some embodiments. FIG. 19 illustrates a graphical representation of size exclusion chromatography (SEC) traces of PPO copolymers with different molar masses, according to some embodiments. FIG. 20A illustrates a spectrum of the MALDI-TOF mass spectroscopy analysis of PPO, which molar mass controlled by EhO, according to some embodiments. FIG. 20B illustrates a polymer structure analysis of PPO, according to some embodiments.

[0083] FIG. 21 illustrates a ³H NMR spectrum of PPC in CDCh, according to some embodiments.

[0084] FIG. 22 illustrates a H NMR spectrum of PCHC in CDCh, according to some embodiments.

[0085] FIG. 23 illustrates a ³H NMR spectrum of PTMO in CDCh, according to some embodiments.

[0086] FIG. 24 illustrates

spectrum of PTMO-b-PPO-b-PTMO in CDCh, according to some embodiments.

[0087] FIG. 25 illustrates an ¹⁹F NMR spectrum of polyether polymers having different end hydroxyl groups, according to some embodiments.

[0088] While the disclosure has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted for elements thereof without departing from the scope of the embodiment s). In addition, many modifications may be made to adapt a particular situation or material to the teachings of the embodiment(s) without departing from the essential scope thereof. Therefore, it is intended that the disclosure is not limited to the disclosed embodiment(s), but that the disclosure will include all embodiments falling within the scope of the appended claims. Various examples have been described. These and other examples are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A dual-task borinane-based catalyst comprising a compound of formula I:

wherein Y is an alkyl, aryl, cycloalkyl, or cycloaryl spacer;

Z is a nitrogen or phosphorous atom;

R is an alkyl, aryl, cycloalkyl, or cycloaryl group, or a polymeric support; and a, b, and c are integers independently selected from the group consisting of 0-100.

2. The catalyst of claim 1 , wherein R is an unsubstituted or substituted group selected from Ci - C30 alkyl groups, C3 - C30 cycloalkyl groups, and Ce - C30 aryls or cycloaryl groups, a is 1-4, b is 1 and c is 0-3.

3. The catalyst of claim 1 or 2, further comprising an anion selected from the group consisting of ion selected from the group consisting of Cl", F', Br', I", OH", NCb', Ns', BF₄' , (CeFsJiB; sulfonate, perchlorate, chlorate, phosphate, carboxylate, alkoxide, and phenoxide.

4. The catalyst of any one of claims 1-3, wherein the dual -task borinane-based catalyst is selected from the group consisting of

5. A method of preparing a dual -task borinane-based catalyst according to any one of claims 1-4, the method comprising:

where X represents unsaturated bonds, an alkene or an alkyne bond; and

Y is an alkyl, aryl, cycloalkyl, or cycloaryl spacer;

Z is a nitrogen or phosphorous atom;

6. A method of polymer synthesis comprising ring opening polymerization or copolymerization of a cyclic monomer in the presence of a dual-task borinane-based catalyst according to any one of claims 1-4.

7. The method of claim 6, wherein the cyclic monomer is selected from the group consisting of cyclic esters, epoxides, oxetanes, anhydrides, and combinations thereof.

8. The method of claim 6 or 7, wherein the cyclic monomer is copolymerized with CO₂

9. The method of any one of claims 6-8, wherein the cyclic monomer is an epoxide represented by the structure of formula IV:

10. The method of any one of claims 6-9, wherein the method produces a poly ether or a polycarbonate.

11. The method of any one of claims 6-10, further comprising sequential polymerization of oxetane to derivatize a terminal secondary hydroxyl group of the polymer into a primary hydroxyl group.

12. The method of claim 7 or 9, wherein the epoxide is copolymerized with an isocyanate to produce a polyurethane.

13. The method of claim 7 or 9, wherein the epoxide is copolymerized with an anhydride to produce a polyester.

14. The method of any one of claims 6-13, further comprising tuning the molecular mass of the polymer or copolymer by adding a chain transfer agent.

15. The method of claim 6, wherein the cyclic monomer includes an oxetane.

16. The method of claim 15, wherein the method produces a poly ether.

17. The method of claim 15 or 16, wherein the oxetane is copolymerized with CO2.

18. A method of preparing a poly ether having terminal primary hydroxyl groups, the method comprising: polymerizing an epoxide in the presence of a dual-task borinane-based catalyst according to any one of claims 1-4, to generate a poly ether with terminal secondary hydroxyl groups; and sequentially polymerizing oxetane to derivatize the secondary hydroxyl groups into primary hydroxyl groups.

19. A method of preparing a polycarbonate having terminal primary hydroxyl groups, the method comprising: copolymerizing an epoxide and CO2 in the presence of a dual-task borinane- based catalyst according to any one of claims 1-4, to generate a polycarbonate with terminal secondary hydroxyl groups; and sequentially polymerizing oxetane to derivatize the secondary hydroxyl groups into primary hydroxyl groups.

20. The method of claim 18 or 19, wherein the epoxide is selected from the group represented by formula IV:

O