Polymerization of alkylene oxides using phosphonium catalysts

Abstract

The alkoxylation reaction is carried out in the presence of a phosphonium catalyst having the structure P + (XR1R2R3) A1 wherein R1 is a group having an unsubstituted or inertly substituted aromatic five-membered ring with a direct bond between the atom of the aromatic five-membered ring and the phosphorus atom, and each R2 is independently a group having an unsubstituted or inertly substituted, optionally heteroatom, aromatic five-membered or six-membered ring with a direct bond between the carbon atom and the phosphorus atom of the optionally heteroatom aromatic five-membered or six-membered ring, X is selected from fluorine, chlorine, bromine, iodine, C1-12 perfluoroalkyl, C1-12 alkyl, aryloxy and C1-12 alkoxy, and X is selected from the group consisting of fluorine, chlorine, bromine, iodine, C1-12 perfluoroalkyl, C1-12 alkyl, aryloxy and C1-12 alkoxy. And A is a weakly coordinating anion.

Description

[0001] The present invention relates to an alkoxylation process in which a cyclic oxide is added to a starter compound to produce an ether or a polyether.

[0002] Polyethers are produced in large quantities globally. For example, polyether polyols are important raw materials for the production of polyurethanes. In addition to this, they are also used in the manufacture of high resilience foams, molded foams or rigid foams. For example, polyether monools are used as surfactants and industrial solvents and so on. It has also been found that carbonate-modified alkylene oxide polymers and ester-modified alkylene oxide polymers can also be used in these and other applications.

[0003] Polyether monools and polyols are produced via the alkoxylation of starter compounds, in which the active sites on the starter compound react with the cyclic oxide in a ring-opening reaction. Terminal hydroxyl groups are produced, which can in turn act as active sites for subsequent alkoxylation steps, thereby producing a polyether chain. The active sites of the starter compound are groups containing active hydrogen, such as hydroxyl or thiol groups. The main function of the starter compound is to provide molecular weight control and to determine the number of hydroxyl groups that the alkoxylation product will have.

[0004] Catalysts are required to obtain an economic polymerization rate. The most commonly used catalysts are alkali metal hydroxides (such as potassium hydroxide) and so-called double metal cyanide (DMC) catalyst complexes, where the zinc hexacyanocobaltate catalyst complex is the most commercially important type.

[0005] Alkali metal hydroxides offer the beneficial effects of low catalyst cost and an acceptable alkoxylation rate. They are versatile because they can effectively polymerize many alkylene oxides. Nevertheless, alkali metal hydroxides still have well-known drawbacks. The alkoxylation product must be neutralized and the catalyst residues must be carefully removed. These finishing steps greatly increase the capital and operating costs and generate additional waste streams that must be cleaned up and / or disposed of.

[0006] Compared with alkali metal catalysts, DMC catalysts provide rapid polymerization rates, even when used at very low catalyst concentrations. An important advantage of DMC catalysts over alkali metal hydroxides is that no neutralization step is required. Unlike the case of using alkali metal hydroxides as polymerization catalysts, the catalyst residues can generally be left in the product. This can result in a significant reduction in production costs. Nevertheless, DMC catalysts also have significant disadvantages. In the presence of high concentrations of hydroxyl groups, especially in the presence of low molecular weight initiator compounds (such as glycerol or sorbitol) having hydroxyl groups at the 1,2- or 1,3-positions relative to each other, DMC catalysts tend to perform poorly. Under these conditions, the catalyst is difficult to activate, acts sluggishly, and often deactivates before the polymerization is complete. This poses a significant limitation to the widespread adoption of DMC catalysts. It is often necessary to produce polyethers in two or more separate steps, where the early stage of the polymerization is carried out in the presence of an alkali metal catalyst, and after cleaning the resulting intermediate product, the remaining process of the polymerization is carried out using a DMC catalyst. This method requires the neutralization and purification of the intermediate (since the DMC catalyst is deactivated by strong bases), thus reintroducing the costs that DMC-catalyzed polymerization is intended to avoid.

[0007] Certain Lewis acids have been evaluated as alkylene oxide polymerization catalysts. These Lewis acids generally do not require an activation time, but deactivate rapidly and thus cannot produce high molecular weight polymers or achieve a high conversion of alkylene oxide to polymer. Another problem with many Lewis acid catalysts is that they deactivate at higher operating temperatures. This makes them unsuitable for use with certain initiators that are solid, viscous, or have poor miscibility with cyclic oxides, since in these cases, high operating temperatures are required to melt the initiator, reduce its viscosity, or promote mixing with the cyclic oxide.

[0008] Various phosphonium compounds have been described in the literature. See, for example, Science 341 1374 (2013), Dalton Trans. 2018, 47, 11411; Chem. Eur. J. 2015, 21, 6491 - 6500, Dalton Trans. 2016, 45, 5568; Angew. Chem. Int. Ed. 2014, 53, 6538 - 6541; Chem. Sci. 2015, 6, 2016 and Chem. Commun., 2018, 54, 662 - 665. They have been described as catalysts for various reactions such as olefin isomerization, hydrosilylation, dehydrogenative coupling, hydrodefluorination, hydrogenation, and Friedel - Crafts reactions. Angew. Chem. Int. Ed. 2014, 53, 6538 - 6541 describes the polymerization of tetrahydrofuran in the absence of an initiator using a phosphonium catalyst to produce an 86,000 molecular weight polymer with a high polydispersity.

[0009] In a first aspect, the invention is a compound having the following structure:

[0010]

[0011] wherein R 1 is a group having an unsubstituted or inertly substituted aromatic five-membered ring, optionally with a heteroatom, with a direct bond between an atom of the aromatic five-membered ring and the phosphorus atom, each R 2 is independently a group having an unsubstituted or inertly substituted aromatic five-membered or six-membered ring, optionally with a heteroatom, with a direct bond between a carbon atom of the optionally heteroatom-containing aromatic five-membered or six-membered ring and the phosphorus atom, X is selected from fluorine, chlorine, bromine, iodine, C 1-12 perfluoroalkyl, C 1-12 alkyl, aryloxy and C 1-12 alkoxy, A is a weakly coordinating anion, and n is the valence of A.

[0012] The compounds of the invention are highly efficient catalysts for various reactions, including Friedel-Crafts reactions, hydrodeoxygenation reactions, dehydrogenative coupling of silanes with phenols, and hydrodefluorination reactions. It has been found that the compounds of the invention are particularly active alkoxylation catalysts, especially for polymerizing cyclic oxides onto low molecular weight hydroxy-containing initiator compounds. In this use, the catalysts have distinct advantages over potassium hydroxide and double metal cyanide (DMC) catalysts, which are most widely used on a commercial scale. Unlike potassium hydroxide, these catalysts can be used in very small amounts and can thus remain in the product, thereby reducing or even eliminating the catalyst deactivation and removal steps. Unlike DMC catalysts, these compounds are also effective ethylene oxide polymerization catalysts.

[0013] Accordingly, the invention is also an alkoxylation method, comprising (step I) forming a reaction mixture comprising a) an initiator compound having at least one hydroxy or thiol group; b) at least one cyclic oxide; and c) a catalytically effective amount of the phosphonium catalyst of the first aspect, and (step II) reacting the cyclic oxide with the initiator compound in the presence of the phosphonium catalyst to form an alkoxylated product.

[0014] R 1 includes an aromatic five-membered ring. The five-membered aromatic ring can be a "heteroatom", i.e., one or more atoms of the ring are not carbon, such as oxygen, nitrogen, and / or sulfur. R 1The aromatic five-membered ring is unsubstituted or inertly substituted. An inert substituent does not react with the initiator or cyclic oxide under alkoxylation reaction conditions and includes, for example, alkyl (linear, branched, and / or cyclic), aryl, ether (-O-), ester (-O-C(O)-), carbonate (-O-C(O)-O)), halogen (especially F, Cl, Br, and / or I), sulfide (-S-), polysulfide (-S z -, where z>1), amino, silyl, etc. The five-membered ring can be fused to another ring structure, and such another ring structure is aliphatic or aromatic and optionally inertly substituted. R 1 Preferably does not contain active sites where alkoxylation can occur, such as -OH, -NH, -SH, or -COOH, and preferably does not contain a cyclic oxide structure.

[0015] R 1 Can be, for example:

[0016]

[0017] group). In any of the foregoing, any ring carbon can be unsubstituted or substituted with an inert substituent.

[0018] In some embodiments, one or two R 2 groups are another R 1 group as described above, that is, a group having an unsubstituted or substituted aromatic five-membered ring with a direct bond between the carbon atom of the aromatic five-membered ring and the phosphorus atom. In a specific embodiment, both R 2 groups are R 1 groups. R 1 and both R 2 groups can be the same.

[0019] In other embodiments, at least one R 2 group and optionally both R 2 groups have an unsubstituted or inertly substituted, optionally heteroatom-containing aromatic six-membered ring with a direct bond between the carbon atom of the optionally heteroatom-containing aromatic six-membered ring and the phosphorus atom.

[0020] In some embodiments, one or two R 2 groups are independently selected from the group consisting of phenyl and phenyl substituted with one or more substituents selected from the group consisting of halogen, unsubstituted or inertly substituted C 1-12 alkyl, unsubstituted or inertly substituted C 1-12 alkoxy, or trifluoromethyl groups. If the C 1-12 alkoxy group has more than 2 carbon atoms, it can be linear, branched, and / or cyclic. C 1-12The alkoxy group may be substituted by inert substituents as described above, in particular by a halogen, especially F, Cl or Br. The substituted phenyl group may, for example, be unsubstituted or inertly substituted by a C 1-12 alkoxy group in the para position (relative to the bond to the central phosphorus atom) and, in such a case, optionally without further substituents. R 2 preferably does not contain active sites where alkoxylation can occur, such as -OH, -NH, -SH or -COOH, and preferably does not contain an epoxide structure. In a specific embodiment, each R 2 is independently selected from phenyl, pentafluorophenyl, 3,5-trifluoromethylphenyl or 4-alkoxyphenyl, where the alkoxy group has 1 to 4 carbon atoms, preferably 1 or 2 carbon atoms.

[0021] X is preferably F, Cl, Br, I, OCH 3 , OC 2 H 5 , phenoxy, CH 3 , C 2 H 5 or CF 3 .

[0022] The anion A is a weakly coordinating anion with a valence of n. n is preferably 1 or 2, and most preferably 1. Weakly coordinating anions are characterized by the delocalization of the negative charge over a large non-nucleophilic region. The coordination strength of the anion is conveniently determined by forming the tri-n-octylammonium salt of the anion, dissolving the salt in carbon tetrachloride, and measuring the N-H stretching frequency by infrared spectroscopy using a method such as that described in, for example, J. Am. Chem. Soc. 2006, 128, 8500 - 8508. A N-H stretching frequency of 3000 cm -1 or higher, especially 3050 cm -1 or higher indicates a weakly coordinating anion.

[0023] Examples of weakly coordinating anions include tetra[perfluorophenyl]borate, tetra[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate (triflate), Al[OC(CF 3 ) 3 4 - , B 12 F 12 2- , HCB 11 H 5 F 6 - , B(OTeF 5 ) 4 - , Sb(OTeF 5 ​) 6 - 、Al[OC(CF 3 ) 3 ] 4 - 、Al[OCH(CF 3 ) 2 ] 4 - and Al[OC(CH 3 )(CF 3 ) 2 ] 4 - .

[0024] Specific examples of phosphonium catalysts include etc., where in each case A - It is one price. + 2 A 2- Also useful are similar compounds of the form wherein Z + represents a phosphonium cation as shown in any of the preceding structures, and A 2- Represents a divalent weakly coordinating anion.

[0026] The anion A may in each case be any weakly coordinating anion, including any of those mentioned above, in particular monovalent anions such as tetrakis[perfluorophenyl]borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate (triflates).

[0027] Phosphonium catalysts can be synthesized in several steps, starting from the corresponding phosphine with the following structure: Where R 1 and R 2 As defined above. Reaction with a halogenating agent produces a dihalogenated phosphine having the following structure: wherein Hal is F, Cl, Br or I. Examples of halogenating agents include XeF 2 , perchloroethane, sulfuryl chloride, elemental bromine and elemental iodine. The reaction is conveniently carried out at room temperature or at a moderately elevated temperature (such as 50°C to 100°C) using a stoichiometric amount or a small excess of the halogenating agent.

[0028] The dihalogenated phosphine can be reacted with a phosphine having the general structure The silyl onium compound is converted into the corresponding phosphonium salt Each R 6Independently is a hydrocarbyl group (including straight-chain, branched-chain, and / or cyclic alkyl, aryl, aryl-substituted alkyl, and alkyl-substituted aryl), and A is as defined previously. The silylium compound is formed conveniently, for example, by the reaction of the corresponding silane with A - anion salts (such as trityl (C + (C 6 H 5 ) 3 ) salts). This reaction is conveniently carried out in a solution in a suitable solvent such as toluene at 0 °C to 50 °C. The product can be recovered by adding an anti-solvent (such as pentane or other liquid alkanes) and purified by methods such as recrystallization if necessary.

[0029] To produce the corresponding hydroxide (i.e., X in Structure I is OH), the phosphonium salt can be reacted with an anhydrous unsubstituted or inertly substituted C 1-12 alcohol.

[0030] The corresponding alkoxide (i.e., X in Structure I is an alkoxy or inertly substituted alkoxy) can be synthesized using the method described by LaFortune et al. in Dalton Transactions, DOI: 10.1039 / c6dt03544b.

[0031] In the case where X is CF 3 , a suitable synthetic route starts from , where R 1 and R 2 are as described above, and Ph represents phenyl. The reaction with trimethylsilyl-CF 3 in the presence of CsF replaces the phenoxy group with CF 3 . Subsequently, the reaction with R 1 OTf (where OTf represents trifluoromethanesulfonate and R 1 is as described previously) produces in the form of trifluoromethanesulfonate respectively. When X is C 1-12 alkyl or another perfluoroalkane, a similar method is useful.

[0032] Alkoxylation is carried out in the presence of one or more initiator compounds. The initiator compound has one or more functional groups capable of being alkoxylated. The initiator can contain any relatively large number of such functional groups. The functional groups can be, for example, primary hydroxyl, secondary hydroxyl, or tertiary hydroxyl or thiol. Preferred initiators contain 1 or more such functional groups, preferably contain 2 or more such functional groups, and can contain up to 12 or more such functional groups.

[0033] In some embodiments, the functional groups are all hydroxyl groups. In some embodiments, the initiator compound will have from 2 to 8, from 2 to 6, from 2 to 4, or from 2 to 3 hydroxyl groups.

[0034] The equivalent weight per functional group of the initiator compound is less than the equivalent weight per functional group of the polyether product. Its equivalent weight can be from 9 (in terms of water) to 6000 or greater. The present invention has particular advantages when the initiator compound is a low equivalent weight alcohol or polyol (e.g., up to 500 g / equivalent, up to 250 g / equivalent, up to 125 g / equivalent, up to 75 g / equivalent, or up to 50 g / equivalent) and thus has a high concentration of hydroxyl groups prior to alkoxylation. The equivalent weight of an alcohol or polyol is conveniently determined using a titration method such as ASTM 4274-16, which yields a hydroxyl number in the form of mg KOH / g polyol, and this hydroxyl number can be converted to an equivalent weight using the following relationship: equivalent weight = 56,100 ÷ hydroxyl number.

[0035] Suitable initiators include vinyl alcohol, allyl alcohol, allyl alcohol, acrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, C 1-50 alkanols (especially C 1-12 alkanols), phenol, cyclohexanol, alkylphenols, water (which has two hydroxyl groups for the purposes of the present invention), ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, cyclohexanedimethanol, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, sucrose, xylitol, mannitol, maltitol, sucralose, phenol, polyphenolic initiators (such as bisphenol A), or 1,1,1-tris(hydroxyphenyl)ethane, etc. If desired, any two or more of the foregoing initiators can be used together.

[0036] Cyclic oxides are characterized by having at least one 3-, 4-, or 5-membered ring structure containing an oxygen atom in the ring structure. Particularly preferred cyclic oxides are ethylene oxide having a three-membered oxygen-containing ring. Cyclic oxides can be, for example, ethylene oxide, 1,2-epoxypropane (commonly referred to herein as "propylene oxide"), oxetane, 1,2-epoxybutane, 2-methyl-1,2-epoxybutane, 2,3-epoxybutane, tetrahydrofuran, epichlorohydrin, epoxyhexane, epoxyoctane, styrene oxide, divinylbenzene dioxide, glycidyl ethers (such as bisphenol A diglycidyl ether), epichlorohydrin or other polymerizable ethylene oxides. In some embodiments, the alkylene oxide is 1,2-epoxypropane, ethylene oxide, or a mixture thereof, including, for example, a mixture of at least 50 wt% (preferably at least 80 wt%) propylene oxide with a corresponding at most 50 wt% (preferably at most 20 wt%) ethylene oxide. In some embodiments, two or more alkylene oxides are polymerized simultaneously (to form a random copolymer), and either the composition of the alkylene oxide is changed one or more times during the entire polymerization process, or even continuously changed, to form block copolymers and / or random / block copolymers.

[0037] Alkoxylation is carried out by combining an initiator and a phosphonium catalyst with a cyclic oxide and optionally a comonomer, and subjecting the resulting reaction mixture to reaction conditions. The catalyst can be added as a solution in a solvent. Such a solvent is preferably inert under alkoxylation reaction conditions. Diethyl ether, dichloromethane, and hydrocarbons such as toluene or hexane are useful solvents for the phosphonium catalyst.

[0038] Polymerization is carried out in the temperature range of -100 °C to 250 °C or higher. In some embodiments, the reaction temperature is at least 80 °C, at least 100 °C, at least 120 °C, at least 130 °C, or at least 150 °C. The polymerization temperature is preferably not more than 190 °C, and more preferably not more than 180 °C. An important advantage of the phosphonium catalysts used in the present invention is that they perform well at higher temperatures, especially 150 °C to 200 °C or 150 °C to 180 °C, without premature deactivation. Higher temperatures promote faster reactions. Additionally, the ability to operate at these higher temperatures allows the method to be used with initiators and / or cyclic oxides having slightly higher melting temperatures (such as sorbitol, xylitol, mannitol, maltitol, sucralose) and / or that are viscous at lower temperatures, or that have limited solubility in cyclic oxides at lower temperatures, such as sorbitol and glycerol.

[0039] The alkoxylation reaction is generally carried out under superatmospheric pressure, but can also be carried out at atmospheric pressure or even below atmospheric pressure.

[0040] Sufficient phosphonium catalyst can be used to provide a commercially reasonable alkoxylation rate, but it is generally desirable to use as little phosphonium catalyst as is consistent with a reasonable alkoxylation rate, as this both reduces the cost of the catalyst and obviates the need to remove catalyst residues from the product. Based on the weight of the initiator, the amount of phosphonium catalyst can, for example, be sufficient to provide from 10 ppm to 10,000 ppm by weight of phosphonium catalyst. In a specific embodiment, on the foregoing basis, the amount of phosphonium catalyst can be sufficient to provide at least 25 ppm, at least 50 ppm or at least 100 ppm of catalyst, and also on the foregoing basis, can be sufficient to provide at most 1,000 ppm or at most 500 ppm of catalyst. The weight of the phosphonium catalyst includes the weight of both the cation and the associated anion.

[0041] The alkoxylation reaction can be carried out batchwise, semi - continuously (including continuous addition of the initiator as described in US 5,777,177) or continuously.

[0042] The alkoxylation reaction can be carried out in any type of vessel suitable for the pressures and temperatures encountered. The reactor should be equipped with means for heating and / or removing heat, whereby the temperature of the reaction mixture can be maintained within the desired range. Suitable means include various types of jackets for heat transfer fluids, various types of internal or external heaters, etc. The cooking step on the continuously withdrawn product is conveniently carried out in a reactor that prevents significant back - mixing. Plug - flow operation in a pipe or tubular reactor is a preferred way to carry out such a cooking step.

[0043] The crude product obtained by any of the foregoing methods can contain unreacted cyclic oxide, small amounts of the initiator compound and its low - molecular - weight alkoxylates; and small amounts of other organic impurities and / or water. Volatile impurities (including unreacted cyclic oxide) should be flash - evaporated or stripped from the product. The crude product generally contains catalyst residues. These residues are usually left in the product, but can be removed if desired. Water and volatiles can be removed by stripping the alkoxylated product.

[0044] The process of the present invention can be used to prepare alkoxylated products having a hydroxyl equivalent that can range as low as about 85 g / equivalent to as high as about 8,000 g / equivalent or higher. The alkoxylated polyols produced according to the present invention are useful starting materials for the production of polyurethanes and other polymers prepared by reacting alkoxylated polyols with polyisocyanates. These products include a wide variety of porous and non - porous materials, the physical properties of which can range from very rigid to highly flexible. The alkoxylated monools produced according to the present invention can be used as surfactants or industrial solvents, among other uses. The alkoxylated polyols and monools can be aminated to produce the corresponding amine - terminated materials, which are in turn useful starting materials for the preparation of various materials including polyureas and cured epoxy resins.

[0045] In certain embodiments, the initiator is a polyol having a hydroxyl equivalent of 125 g / equivalent or less, particularly 75 g / equivalent or less or even 50 g / equivalent or less and a molecular formula molecular weight of at most 250 g / mol, and alkoxylation is continued to produce an alkoxylated product having 1 to 12, particularly 1 to 10, 1 to 5 or 1 to 3 polymerized cyclic oxide units per hydroxyl group on the initiator. The number average molecular weight of the alkoxylated product can be, for example, 100 g / mol to 1000 g / mol, 100 g / mol to 800 g / mol, 150 g / mol to 800 g / mol or 200 g / mol to 800 g / mol, as measured by GPC relative to a polystyrene standard. In such certain embodiments, the cyclic oxide is preferably 1,2-propylene oxide, ethylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, epichlorohydrin or a mixture of any two or more thereof, with 1,2-propylene oxide, ethylene oxide or a mixture thereof being particularly preferred. The initiator in such embodiments is most preferably one or more of glycerol, trimethylolpropane, trimethylolethane, erythritol, pentaerythritol, sorbitol and sucrose. Such products are useful starting materials for the preparation of rigid polyurethane and / or polyisocyanurate polymers (including foams).

[0046] In some embodiments, the cyclic oxide is polymerized with or in the presence of one or more comonomers that are not cyclic oxides. Examples of such comonomers include carbonate precursors that copolymerize with an alkylene oxide to produce carbonate linkages in the product. Examples of such carbonate precursors include carbon dioxide, phosgene, linear carbonates and cyclic carbonates. Other comonomers include carboxylic anhydrides that copolymerize with the cyclic oxide to produce ester linkages in the product.

[0047] The following examples are provided to illustrate the invention but are not intended to limit the scope of the invention. Unless otherwise indicated, all parts and percentages are by weight.

[0048] Example 1 and Comparative Samples A - C

[0049] 45 g of glycerol was charged into a semi-batch reactor equipped with a stirrer, temperature control, nitrogen feed and monomer feed lines, and an outlet. The catalyst was added as a solid in the amounts shown in Table 1 (based on the initiator). The reactor was purged with nitrogen and heated to the temperature indicated in Table 1 under stirring, and then purged again with nitrogen to remove any solvent from the catalyst addition. While maintaining the same temperature, propylene oxide was then fed into the reactor as needed to attempt to maintain the target propylene oxide partial pressure as indicated in Table 1. The target amount of propylene oxide to be added was approximately 103 g to produce a product with a target number average molecular weight of approximately 412 g / mol; the actual feed amount is indicated in Table 1. The time required for the propylene oxide feed (run time) is indicated in Table 1. After the monomer feed was complete, the reaction was digested at 160 °C for 2 h and then cooled to 50 °C under a nitrogen purge. After purging with nitrogen at 50 °C for 10 min, the product was collected and the yield was calculated. The product was analyzed for M n and polydispersity against polystyrene standards by gel permeation chromatography.

[0050] The activity of the catalysts was compared by calculating the turnover frequency (TOF) in each case. The TOF reflects the number of propylene oxide molecules converted per catalytic site per unit time, as follows:

[0051]

[0052] Higher values indicate higher catalyst activity.

[0053] In Table 1, KOH represents potassium hydroxide, and BF 3 ·OEt 2 represents boron trifluoride diethyl etherate.

[0054] Catalyst P(2-F) 3 F tetrakis(pentafluorophenyl)borate is P(2-F) 3 F tetrakis(pentafluorophenyl)borate was prepared by reacting tris(2-furyl)phosphine with XeF 2 in the general manner described in Chem. Sci. 2015, 6, 2016 to produce P(2-F) 3 F 2 . P(2-F) 3 F 2 was suspended in toluene at room temperature. Separately, a silylium solution was produced by combining triethylsilane and triphenylmethyltetrakis(pentafluorophenyl)borate in toluene. The P(2-F) 3 F 2 suspension and the silylium solution were combined and stirred at room temperature for 30 min. Toluene was removed by evaporation to produce a slurry, which was triturated with pentane until it solidified. The product P(2-F)3 The tetra(pentafluorophenyl)borate was then recrystallized from dichloromethane using pentane as an antisolvent. The product was recovered and recrystallized, and its structure was confirmed by 1 H, 13 C, and 31 P NMR.

[0055] Table 1

[0056]

[0057]

[0058] * Not an example of the present invention. "ND" is not done. "PO partial pressure" is the target PO partial pressure in the reactor during polymerization. The run time indicates the time required to feed the indicated amount of propylene oxide. "PO feed" indicates the total amount of propylene oxide fed during the indicated run time. "TOF" is the turnover frequency. PDI is the polydispersity index, i.e., the weight-average molecular weight divided by the number-average molecular weight. Molecular weights were measured by GPC relative to polystyrene standards.

[0059] As indicated by the data in Table 1, the catalyst of the present invention is extremely active compared to the control, with a turnover frequency almost 700 times that of KOH, which is the major industrial propylene oxide polymerization catalyst. The higher catalytic activity results in a significantly reduced run time, thus proportionally and effectively increasing the production capacity of the manufacturing equipment. The molecular weights and polydispersities are similar to those obtained in KOH-catalyzed runs (Comparison A).

Claims

1. A compound having the following structure: wherein R 1 is a group having an unsubstituted or substituted aromatic five-membered ring optionally containing a heteroatom, with a direct bond between an atom of said aromatic five-membered ring and the phosphorus atom, each R 2 is independently a group having an unsubstituted or substituted aromatic five-membered or six-membered ring optionally containing a heteroatom, with a direct bond between a carbon atom of said aromatic five-membered or six-membered ring optionally containing a heteroatom and the phosphorus atom, X is selected from fluorine, chlorine, bromine, iodine, C 1-12 perfluoroalkyl, C 1-12 alkyl and C 1-12 alkoxy, A is a weakly coordinating anion, and n is the valence of A.

2. The compound according to claim 2, wherein the aromatic five-membered ring of the 1 group is heteroatomic.

3. The compound according to claim 2, wherein R 1 is selected from the group consisting of furyl, benzofuryl, isobenzofuryl, thienyl, benzothienyl, benzo[c]thienyl, oxazolyl, benzoxazolyl, benzisoxazolyl, thiazolyl and benzothiazolyl, wherein in any one of the foregoing, any ring carbon is optionally unsubstituted or substituted with a straight-chain, branched-chain and / or cyclic alkyl, aryl, ether, ester, carbonate, halogen, sulfide, polysulfide or silyl group.

4. The compound according to any one of claims 1 to 3, wherein each R 2 has an unsubstituted or substituted aromatic five-membered ring having a direct bond between a carbon atom of the aromatic five-membered ring and the phosphorus atom.

5. The compound according to claim 4, wherein each R 2 is furyl, benzofuryl, isobenzofuryl, thienyl, benzothienyl, benzo[c]thienyl, oxazolyl, benzoxazolyl, benzisoxazolyl, thiazolyl, and benzothiazolyl, wherein in any one of the foregoing, any ring carbon is optionally unsubstituted or substituted with linear, branched, and / or cyclic alkyl, aryl, ether, ester, carbonate, halogen, sulfide, polysulfide, amino, or silyl.

6. The compound according to claim 4 or 5, wherein R 1 and each R 2 are the same.

7. A compound according to any one of claims 1 to 3, wherein each R 2 has an unsubstituted or inertly substituted aromatic six-membered ring, optionally containing a heteroatom, with a direct bond between a carbon atom of the optionally heteroatom-containing aromatic six-membered ring and the phosphorus atom.

8. The compound according to claim 7, wherein each R 2 is independently selected from the group consisting of phenyl and phenyl substituted with one or more substituents selected from the group consisting of halogen, unsubstituted or inertly substituted C 1-12 alkyl, unsubstituted or inertly substituted C 1-12 alkoxy or trifluoromethyl groups.

9. The compound according to any one of claims 1 to 3, wherein one R 2 has an unsubstituted or substituted aromatic five-membered ring having a direct bond between a carbon atom of the aromatic five-membered ring and the phosphorus atom, and the other R 2 has an unsubstituted or inertly substituted aromatic six-membered ring optionally having a heteroatom, having a direct bond between a carbon atom of the optionally heteroatom-containing aromatic six-membered ring and the phosphorus atom.

10. The compound according to any one of claims 1 to 3, wherein one R 2 is selected from the group consisting of furyl, benzofuryl, isobenzofuryl, thienyl, benzothienyl, benzo[c]thienyl, benzoxazolyl, oxazolyl, benzisoxazolyl, thiazolyl, and benzothiazolyl, wherein in any one of the foregoing, any ring carbon is optionally unsubstituted or substituted with a straight-chain, branched-chain, and / or cyclic alkyl, aryl, ether, ester, carbonate, halogen, sulfide, polysulfide, amino, or silyl group, and the other R 2 is selected from the group consisting of phenyl and phenyl substituted with one or more substituents selected from the group consisting of halogen, unsubstituted or inertly substituted C 1-12 alkyl, unsubstituted or inertly substituted C 1-12 alkoxy, or trifluoromethyl group.

11. A compound according to any one of the preceding claims, wherein X is F, Cl, Br, I, OCH 3 , OC 2 H 5 , phenoxy, CH 3 , C 2 H 5 or CF 3 .

12. A compound according to any one of the preceding claims, wherein A is selected from the group consisting of tetra[perfluorophenyl]borate, tetra[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate (trifluoromethanesulfonate), Al[OC(CF 3 ) 3 4 - , B 12 F 12 2- , HCB 11 H 5 F 6 - , B(OTeF 5 ) 4 - , Sb(OTeF 5 ) 6 - , Al[OC(CF 3 ) 3 4 - , Al[OCH(CF 3 ) 2 4 - and Al[OC(CH 3 )(CF 3 ) 2 4 - ;​​​​ 13. The compound according to claim 1, having any one of the following structures: And A - is a monovalent anion.

14. An alkoxylation process comprising (step I) forming a reaction mixture comprising a) an initiator compound having at least one hydroxyl group; b) at least one cyclic oxide; and c) a catalytically effective amount of a phosphonium catalyst according to any one of claims 1 to 13, and (step II) reacting the cyclic oxide with the initiator compound in the presence of the phosphonium catalyst to form an alkoxylation product.

15. The alkoxylation process according to claim 14, wherein the initiator compound has a molecular formula molecular weight of 250 g / mol or less and a hydroxyl equivalent of at most 75 g / equivalent.

16. The alkoxylation process according to claim 14 or 15, wherein the initiator compound has one or more hydroxyl groups and no primary or secondary amino groups.

17. The alkoxylation process according to any one of claims 14 to 16, wherein the cyclic oxide is ethylene oxide.

18. The alkoxylation process according to claim 17, wherein the cyclic oxide is one or more of ethylene oxide, 1,2-epoxypropane, 1,2-epoxybutane, and 2,3-epoxybutane.

19. The alkoxylation process according to any one of claims 14 to 18, wherein step II is carried out at a temperature of 150 °C to 200 °C.

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