Alkoxylation process using phosphonium catalysts

Abstract

The alkoxylation is carried out by reacting a cyclic oxide with a starter in the presence of certain phosphonium catalysts. The phosphonium catalyst is highly active and effective at such small amounts such that generally no catalyst residue needs to be removed from the product. The phosphonium catalysts are very effective in alkoxylation even in low molecular weight initiators such as glycerol and sorbitol.

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 monoalcohols 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 monoalcohols and polyols are produced via alkoxylation of a starter compound, 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 on 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 zinc hexacyanocobaltate catalyst complexes are the most commercially important type.

[0005] Alkali metal hydroxides offer the benefit 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 disadvantages. 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. Different from the case of using alkali metal hydroxides as polymerization catalysts, the catalyst residues can usually be left in the product. This can greatly reduce the production cost. 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 completed. This poses a great limitation to the wide adoption of DMC catalysts. It is usually necessary to produce polyethers in two or more independent 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 (because the DMC catalyst is deactivated by strong bases), thus reintroducing the costs that DMC-catalyzed polymerization aims to avoid.

[0007] Certain Lewis acids have been evaluated as alkylene oxide polymerization catalysts. These Lewis acids basically do not require an activation time, but deactivate rapidly and thus cannot produce high molecular weight polymers or cannot highly convert alkylene oxides into polymers. Another problem with many Lewis acid catalysts is that they deactivate at higher operating temperatures. This makes them unable to be used with certain initiators that are solid, viscous, or have poor miscibility with cyclic oxides, because 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 in 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] The present invention relates to an alkoxylation process, which comprises: (Step I) forming a reaction mixture comprising a) an initiator compound having at least one hydroxyl or thiol group; b) at least one cyclic oxide; and c) a catalytically effective amount of a phosphonium catalyst having the following structure:

[0010]

[0011] wherein R 1 、R 2 and R 3 are independently groups having an unsubstituted or substituted, optionally heteroatom-containing aromatic six-membered ring, with a direct bond between a carbon atom of the optionally heteroatom-containing aromatic six-membered ring and the phosphorus atom, X is a halogen, a hydroxyl group, an unsubstituted or inertly substituted alkyl group, an unsubstituted or inertly substituted alkoxy group, or an unsubstituted or inertly substituted aryloxy group, A represents a weakly coordinating anion and n represents the valence of A; and (Step II) reacting the cyclic oxide with the initiator compound in the presence of the phosphonium catalyst to form an alkoxylated product.

[0012] The advantage of the process of the present invention is that a very high alkoxylation rate is obtained using a very small amount of the phosphonium catalyst. For this reason, the catalyst residue can remain in the product (unlike potassium hydroxide), thereby reducing or even eliminating the catalyst deactivation and removal steps. Different from DMC catalysts, these compounds are highly effective in polymerizing ethylene oxide onto very low molecular weight initiators. They are also effective catalysts for polymerizing ethylene oxide onto initiator compounds. The phosphonium catalysts described herein are particularly useful for alkoxylating low molecular weight initiators having from 1 to 12 alkylene oxide units per active site.

[0013] In Structure I, R 1 、R 2 and R 3 can all be the same. Any two of R 1 、R 2 and R 3 can be the same and the other can be different. R 1 、R 2 and R 3 can all be different.

[0014] R 1 、R 2 and R 3The inert substituents on the group do not react with the initiator or cyclic oxide under the alkoxylation reaction conditions and include, 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. R 1 , R 2 and R 3 preferably do not contain active sites where alkoxylation can occur (such as -OH, -NH, -SH, or -COOH) and preferably do not contain a cyclic oxide structure.

[0015] In some embodiments, R 1 , R 2 and R 3 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. If the C 1-12 alkyl or C 1-12 alkoxy group has more than 2 carbon atoms, it can be linear, branched, and / or cyclic. The C 1-12 alkyl or C 1-12 alkoxy group can be substituted with an inert substituent as described above, especially halogen, particularly F, Cl, or Br. The substituted phenyl group can, for example, be substituted at the para position (relative to the bond with the central phosphorus atom) with an unsubstituted or inertly substituted C 1-12 alkoxy group and, in such a case, optionally does not contain other substituents. In a specific embodiment, R 1 , R 2 and R 3 are independently selected from phenyl, pentafluorophenyl, 3,5-bis(trifluoromethyl)phenyl, or 4-alkoxyphenyl, where the alkoxy group has 1 to 4 carbon atoms, preferably 1 or 2 carbon atoms.

[0016] X is preferably F, Cl, Br, I, OH, OCH 3 , OC 2 H 5 , phenoxy, and CF 3 . When it is OH, the alkanol, especially the C 1-12 alkanol used as a reagent during the synthesis, can be the hydrogen bonded to the OH group. When combined with the initiator and / or during the alkoxylation reaction, the alkanol group (when present) can dissociate from the OH group.

[0017] 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 those that coordinate with the associated cation less strongly than the surrounding solvent molecules. 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 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.

[0018] Examples of weakly coordinating anions include tetrakis(pentafluorophenyl)borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate (triflate), Al[OC(CF 3 ) 3 4 — , HCB 11 Me 5 F 6 - , 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 — .

[0019] Specific examples of the phosphonium catalyst include:

[0020]

[0021] ​​​​

[0022]

[0023]

[0024]

[0025]

[0026]

[0027] etc., where in each case A — is monovalent. Z + 2 A 2- Similar compounds of the A + form are also useful, where Z 2- represents a phosphonium cation as shown by any one of Structures II-XXX and A

[0028] In any structure in Structure II-XXX, A — and A 2— can be any of the weakly coordinating anions mentioned above, especially monovalent anions such as tetra[perfluorophenyl]borate, tetra[3,5-bis(trifluoromethyl)phenyl]borate, and trifluoromethanesulfonate (triflate).

[0029] Methods for preparing phosphonium catalysts are generally described, for example, in Angew. Chem. Int. Ed. 2014, 53, 6538 - 6541; Chem. Sci. 2015, 6, 2016, and Chem. Commun., 2018, 54, 662 - 665.

[0030] The phosphonium catalyst can be synthesized in several steps starting from the corresponding phosphine having the following structure: where R 1 、R 2 and R 3 are as defined above. Reaction with a halogenating agent yields a phosphonium dihalide having the following structure: where Hal is F, Cl, Br, or I. Examples of halogenating agents include XeF 2 、perchloroethane, sulfuryl chloride, elemental bromine, and elemental iodine. This 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.

[0031] The phosphonium dihalide can be reacted with a compound having the general formula structure is converted into the corresponding phosphonium salt by reaction with a silylium compound wherein each R 6 is independently a hydrocarbyl group (including linear, branched 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 reaction of the corresponding silane with a salt of A n— anion (such as a trityl (C + (C 6 H 5 ) 3 ) salt). The reaction is conveniently carried out at 0 °C to 50 °C in a solution in a suitable solvent such as toluene. The product can be recovered by addition of an anti-solvent (such as pentane or other liquid alkane) and purified by methods such as recrystallization if desired.

[0032] 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.

[0033] 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.

[0034] 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 . Subsequent reaction with R 3 OTf (where OTf represents trifluoromethanesulfonate and R 3 is as described previously) yields

[0035] 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 larger number of such functional groups. The functional group can be, for example, a primary, secondary or tertiary hydroxyl group or a 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.

[0036] In certain 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.

[0037] 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 g / equivalent (in terms of water) to 6000 g / equivalent 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, and especially up to 80 g / equivalent) and thus has a high concentration of hydroxyl groups prior to alkoxylation. The equivalent weight of an alcohol or polyol can be conveniently determined using a titration method such as ASTM 4274-21, which gives the hydroxyl number in the form of mg KOH / gram of polyol, and this hydroxyl number can be converted to equivalent weight using the following relationship: equivalent weight = 56,100 ÷ hydroxyl number.

[0038] Suitable initiators include vinyl 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.

[0039] 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 propylene oxide, ethylene oxide or a mixture thereof, including, for example, a mixture of at least 50 wt% (preferably at least 80 wt%) propylene oxide and correspondingly 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 a block copolymer and / or a random / block copolymer.

[0040] 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.

[0041] Alkoxylation is carried out in the temperature range from -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 in the range of 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 process to be used with initiators and / or cyclic oxides having slightly higher melting temperatures (such as sorbitol, xylitol, mannitol, maltitol and sucralose) and / or being viscous at lower temperatures, or having limited solubility in cyclic oxides at lower temperatures like sorbitol and glycerol.

[0042] The alkoxylation reaction is generally carried out under superatmospheric pressure, but can also be carried out at atmospheric pressure or even below atmospheric pressure.

[0043] Use a sufficient amount of phosphonium catalyst to provide a commercially reasonable alkoxylation rate. However, 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, again 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.

[0044] 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.

[0045] 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 stripping 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 stripping step.

[0046] The crude product obtained by any of the foregoing methods can contain unreacted cyclic oxide, a small amount of the initiator compound and its low - molecular - weight alkoxylates; as well as small amounts of other organic impurities and / or water. Volatile impurities (including unreacted cyclic oxide) should be flash - vaporized or stripped from the product. The crude product usually 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.

[0047] The process of the present invention can be used to prepare alkoxylated products having a hydroxyl equivalent that can be 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 the 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 monols produced according to the present invention can be used as surfactants or industrial solvents, among other uses. The alkoxylated polyols and monols 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.

[0048] In certain embodiments, the initiator is a polyol having a hydroxyl equivalent weight of 125 g / equivalent or less, particularly 75 g / equivalent or less or even 50 g / equivalent or less, and alkoxylation is continued to produce an alkoxylated product having from 1 to 12, particularly from 1 to 10, from 1 to 5 or from 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, from 100 g / mol to 1000 g / mol, from 100 g / mol to 800 g / mol, from 150 g / mol to 800 g / mol or from 200 g / mol to 800 g / mol. 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.

[0049] 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.

[0050] The following examples are provided to illustrate the invention but are not intended to limit the scope of the invention. All parts and percentages are by weight unless otherwise indicated.

[0051] Catalyst preparation procedure

[0052] P(PFP) 3 F tetrakis(pentafluorophenyl)borate is prepared by reacting tris(perfluorophenyl)phosphine (P(PFP) 3 ) with XeF 2 in the general manner described in Science 341, 1374 (2013) to produce P(PFP) 3 F 2 . The product is recovered and recrystallized, and its structure is confirmed by 1 H, 13 C and 31 P NMR. P(PFP) 3 F is at room temperature2 Suspended in toluene. Separately, a silylium solution is produced by combining triethylsilane and triphenylmethyltetrakis(pentafluorophenyl)borate in toluene. The P(PFP) 3 F 2 suspension and the silylium solution are combined and stirred at room temperature for 30 minutes. Toluene is removed by evaporation to produce a slurry, which is ground with pentane until it solidifies. The product is then recrystallized from dichloromethane using pentane as an antisolvent.

[0053] P(PFP) 3 Cl tetrakis(pentafluorophenyl)borate is prepared by reacting P(PFP) 3 with thionyl chloride to produce P(PFP) 3 Cl 2 as described above. P(PFP) 3 Cl 2 is converted to the product by reaction with the silylium solution. The starting P(PFP) 3 is brominated using elemental bromine, and P(PFP) 3 Br tetrakis(perfluorophenyl)borate is prepared in a similar manner.

[0054] PPh 3 F tetrakis(pentafluorophenyl)borate is prepared according to the general procedure described in: Chem. Sci. 2015, 6, 2016. PPh 3 is reacted with XeF 2 to produce the corresponding difluoride (PPh 3 F 2 ), which is then reacted with the silylium solution as described above to form the product.

[0055] PPh 3 F-OTf is formed by the reaction of PPh 3 F 2 with trimethylsilyl trifluoromethanesulfonate in dichloromethane at room temperature, followed by concentration under vacuum and recrystallization.

[0056] PPh 3 Cl tetrakis(pentafluoropentyl)borate is prepared in the same general manner as P(PFP) 3 Cl tetrakis(pentafluoropentyl)borate, using triphenylphosphine (PPh 3 ) as the starting material instead of P(PFP) 3 and hexachloroethane as the chlorine source.

[0057] PPh 3 Br tetrakis(pentafluorophenyl)borate and PPh 3Tetrakis(pentafluorophenyl)borate is prepared by reacting the corresponding dibromide or diiodide with the silylium solution as described above.

[0058] Tris(p - methoxy)phenylphosphine (P(PMP)) 3 is used as the starting material instead of P(PFP) 3 ), and P(PMP) 3 Cl tetrakis(pentafluorophenyl)borate is prepared in the same general manner as P(PFP) 3 Cl tetrakis(pentafluorophenyl)borate.

[0059] PPh 3 CF 3 ·OTf is prepared in the general manner described in Chem. Commun., 2018, 54, 662 - 665. Reacts with trimethylsilyl - CF 3 in the presence of CsF to produce diphenyl(trifluoromethyl)phosphine, which then reacts with phenyl trifluoromethanesulfonate in the presence of a palladium catalyst to produce the product.

[0060] PPh 3 OH tetrakis(pentafluorophenyl)borate is prepared by reacting FPPh 3 tetrakis(pentafluorophenyl)borate with absolute ethanol at 70 °C for 3 hours. The synthesized PPh 3 OH has ethanol hydrogen - bonded to the OH group; this is thought to dissociate from the catalyst when the catalyst binds to the initiator and / or during alkoxylation.

[0061] Examples 1-11 and Comparative Samples A-C

[0062] Forty - five grams of glycerol is charged into a semi - batch reactor equipped with a stirrer, temperature control, nitrogen feed, monomer feed line, and vent. The catalyst is added as a solid. The type and amount of the catalyst (based on the initiator) are as indicated in Table 1. The reactor is purged with nitrogen and heated with stirring to the temperature indicated in Table 1, and then purged again with nitrogen to remove any solvent from the catalyst addition. While maintaining the same temperature, propylene oxide is 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 is 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 propylene oxide feeding (run time) is indicated in Table 1. After the monomer feed is complete, the reaction is digested at 160 °C for 2 hours and then cooled to 50 °C under nitrogen purge. After purging with nitrogen at 50 °C for 10 minutes, the product is collected and the yield is calculated. The M of the product is analyzed by gel permeation chromatography against polystyrene standards. nAnd polydispersity.

[0063] 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:

[0064]

[0065] Higher values indicate higher catalyst activity.

[0066] The phosphonium catalysts are shown in Table 1. All are tetra(pentafluorophenyl)borates unless otherwise stated. Those designated with the name "OTf" (Ex. 5, 10) are trifluoromethanesulfonates.

[0067] In Table 1, KOH represents potassium hydroxide, and BF 3 ·OEt 2 represents boron trifluoride diethyl etherate.

[0068] Table 1

[0069]

[0070] *Not an example of the present invention. "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. The molecular weight was measured by GPC relative to a polystyrene standard. "OTf" indicates that the phosphonium catalyst is a trifluoromethanesulfonate.

[0071] As indicated by the data in Table 1, the catalysts of the present invention have extremely high activity compared to the control. Even when using low operating temperatures and pressures, the turnover frequency range is approximately 100 to 1000 times larger than that of KOH, which is the industrial main catalyst for propylene oxide polymerization (e.g., Ex. 1 and 8). The higher catalytic activity results in a significantly reduced run time, thereby proportionally and effectively increasing the production capacity of the manufacturing equipment. The molecular weight and polydispersity are similar to those obtained in the KOH-catalyzed runs (Comparison A).

[0072] Parallel Pressure Reactor (PPR) polymerization procedure

[0073] Ethylene oxide polymerization was carried out using a 48-well Symyx Technologies parallel pressure reactor (PPR). Each of these 48 wells was equipped with a separately weighed glass insert with an internal working liquid volume of approximately 5 mL. Each of these wells contained an overhead paddle stirrer.

[0074] Charge 0.7 mL of glycerol / PPh 3 F mixture (containing approximately 0.72 g of initiator) into each of a plurality of inserts. Based on the combined weight of the initiator and ethylene oxide used in the polymerization run, the mixture provides approximately 500 ppm by weight of catalyst. Pressurize each pore with nitrogen at 50 psig (344.7 kPa) and then heat it to a polymerization temperature of 160 °C (Ex. 12) or 130 °C (Ex. 13). When the polymerization temperature is reached, inject 0.67 mL of ethylene oxide into each pore, where the ethylene oxide reacts with the initiator in the glass insert.

[0075] Monitor the internal pressure in the headspace of each pore individually throughout the polymerization. After the first injection of ethylene oxide, observe the internal pressure hourly and, if the pressure in any particular pore has dropped below 190 psig (1.31 MPa), inject an additional 0.67 mL of ethylene oxide. This is done again after the second hour of polymerization. Four hours after the first injection of ethylene oxide, cool the pores to room temperature and vent. Allow the glass inserts to stand overnight under nitrogen at 40 °C - 50 °C to volatilize residual ethylene oxide, after which the inserts are weighed to determine the amount of product.

[0076] Analyze the molecular weight and polydispersity (M w / M n ) of the resulting product by gel permeation chromatography against polystyrene standards.

[0077] In Example 12, polymerization at 160 °C resulted in a 75% conversion of ethylene oxide to polymer. The number average molecular weight of the product was 370 and the polydispersity was 1.08. In Example 13, polymerization at 130 °C resulted in a 94% conversion of ethylene oxide to polymer. The number average molecular weight of the product was 412 and the polydispersity was 1.09. These molecular weights and polydispersities are within the expected values.

Claims

1. An alkoxylation process, the alkoxylation process comprises: (Step I) forming a reaction mixture comprising a) an initiator compound having at least one hydroxyl or thiol group; b) at least one cyclic oxide; and c) a catalytically effective amount of a phosphonium catalyst having the following structure: wherein R 1 , R 2 and R 3 are each independently a group having an unsubstituted or substituted, optionally heteroatom-containing aromatic six-membered ring, having a direct bond between a carbon atom of the optionally heteroatom-containing aromatic six-membered ring and the phosphorus atom, X is halogen, hydroxy, unsubstituted or inertly substituted alkyl, unsubstituted or inertly substituted alkoxy, or unsubstituted or inertly substituted aryloxy, A represents a weakly coordinating anion and n represents the valence of A; and (Step II) reacting the cyclic oxide with the initiator compound in the presence of the phosphonium catalyst to form an alkoxylated product.

2. The alkoxylation method according to claim 1, wherein R 1 , R 2 and R 3 are independently selected from phenyl or phenyl substituted with one or more substituents, and the one or more substituents are selected from the group consisting of halogen, C 1-12 alkoxy or trifluoromethyl groups.

3. The alkoxylation process according to claim 1, wherein R 1 , R 2 and R 3 are independently selected from phenyl, pentafluorophenyl, 3,5-bis(trifluoromethyl)phenyl or 4-alkoxyphenyl, wherein the alkoxy group has 1 to 4 carbon atoms.

4. The alkoxylation process according to any one of claims 1 to 3, wherein R 1 , R 2 and R 3 are the same.

5. The alkoxylation process according to any one of the preceding claims, wherein X is fluorine, chlorine, bromine or iodine.

6. The alkoxylation process according to any one of claims 1 to 4, wherein X is a straight-chain or branched alkoxy group having 2 to 4 carbon atoms.

7. The alkoxylation process according to any one of the preceding claims, wherein A is selected from the group consisting of: tetrakis[perfluorophenyl]borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate, Al[OC(CF 3 ) 3 4 — , 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 — .​​​​ 8. The alkoxylation process according to claim 7, wherein A is tetrakis(pentafluorophenyl)borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate or trifluoromethanesulfonate.

9. The alkoxylation process according to claim 1, wherein A is selected from the group consisting of: B 12 F 12 2— , B 12 Cl 12 2— and B 12 Br 12 2— , and n is 2.

10. The alkoxylation process according to any one of the preceding claims, wherein the initiator compound has a molecular formula weight of 250 g / mol or less.

11. The alkoxylation process according to any one of the preceding claims, wherein the initiator compound has one or more hydroxyl groups and no primary or secondary amino groups.

12. The alkoxylation process according to any one of the preceding claims, wherein the cyclic oxide is ethylene oxide.

13. The alkoxylation process according to claim 12, wherein the cyclic oxide is one or more of ethylene oxide, 1,2-epoxypropane, 1,2-epoxybutane and 2,3-epoxybutane.

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

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