ALKYLENE OXIDE POLYMERIZATION USING PHOSPHONIUM CATALYSTS

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

[0002] Polyethers are produced globally in large quantities. Polyether polyols, for example, are important raw materials for producing polyurethanes. Among other things, they are used to make high resiliency, molded, or rigid foams. Polyether monols are used, for example, as surfactants and industrial solvents, among other uses. Carbonate- and ester-modified alkylene oxide polymers also find uses in these and other applications.

[0003] Polyether monols and polyols are produced via alkoxylation of a starter compound, in which an active site on the starter reacts with a cyclic oxide in a ring-opening reaction. A terminal hydroxyl group is produced, which in turn can function as an active site for a subsequent alkoxylation step, thereby producing a polyether chain. The active site of the starter compound is a group containing an active hydrogen, such as a hydroxyl or thiol group. The main functions of the starter compound are to provide molecular weight control and to establish the number of hydroxyl groups the alkoxylated product will have.

[0004] A catalyst is needed to obtain economical polymerization rates. The most commonly used catalysts are alkali metal hydroxides such as potassium hydroxide and the so-called double metal cyanide (DMC) catalyst complexes, of which zinc hexacyanocobaltate catalyst complexes are the most commercially important type.

[0005] Alkali metal hydroxides provide the benefits of low catalyst costs and acceptable alkoxylation rates. They are versatile in that they effectively polymerize many alkylene oxides. Nonetheless, alkali metal hydroxides have well-known drawbacks. The alkoxylated product must be neutralized and catalyst residues scrupulously removed. These finishing steps add greatly to both capital and operating costs and produce additional waste streams that must be cleaned up and/or disposed of.

[0006] DMC catalysts provide rapid polymerization rates compared to alkali metal catalysts, even when used at very low catalyst concentrations. An important advantage of DMC catalysts over alkali metal hydroxides is no neutralization step is needed. The catalyst residues often can be left in the product, unlike the case when alkali metal hydroxides are used as the polymerization catalyst. This can result in significantly lower production costs. Nonetheless, the DMC catalysts have significant disadvantages as well. They tend to perform poorly in the presence of high concentrations of hydroxyl groups, and especially in the presence of low molecular weight starter compounds like glycerol or sorbitol that have hydroxyl groups in the 1,2- or 1,3-positions with respect to each other. Under these conditions, the catalysts are difficult to activate, perform sluggishly and often deactivate before the polymerization is completed. This represents a significant limitation on the widespread adoption of DMC catalysts. It is often necessary to produce the polyether in two or more discrete steps, in which the early stages of the polymerization are conducted in the presence of an alkali metal catalyst and, after cleaning up the resulting intermediate product, the remainder of the polymerization is performed using the DMC catalyst. This approach requires the intermediate to be neutralized and purified (because the DMC catalyst is deactivated by strong bases), thus re-introducing costs which the DMC-catalyzed polymerization is intended to avoid.

[0007] Certain Lewis acids have been evaluated as alkylene oxide polymerization catalysts. The Lewis acids require essentially no activation time but deactivate rapidly and therefore cannot produce high molecular weight polymers or high conversions of alkylene oxide to polymer. Another problem with many Lewis acid catalysts is that they deactivate at higher operating temperatures. This disqualifies them for use with certain starters that are solids, viscous, or otherwise poorly miscible with the cyclic oxide, because in those cases high operating temperatures are needed to melt the starter, 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 for use as catalysts in various reactions such as olefin isomerization, hydrosilylation, dehydrocoupling, hydrodefluorination, hydrogenation and Friedel-Crafts reactions. Angew. Chem. Int. Ed. 2014, 53, 6538-6541 describes the use of a phosphonium catalyst to polymerize tetrahydrofuran in the absence of starter to produce an 86,000 molecular weight polymer with high polydispersity.

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

wherein R¹ is a group having an unsubstituted or inertly substituted, optionally heteroatomic, aromatic five-member ring having a direct bond between an atom of the aromatic five-member ring and the phosphorus atom, each R² is independently a group having an unsubstituted or inertly substituted, optionally heteroatomic, aromatic five- or six-member ring having a direct bond between a carbon atom of the optionally heteroatomic aromatic five- or six-member 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.

[0010] The compounds of the invention are highly effective catalysts for a variety of reactions, including Friedel-Crafts reactions, hydrodeoxygenation reactions, dehydrocoupling of silanes with phenol and hydrodefluorination reactions. The compounds of the invention have been found to be particularly active alkoxylation catalysts, especially for the polymerization of cyclic oxides onto low molecular weight hydroxyl-containing initiator compounds. In this use, the catalysts have distinct advantages over the potassium hydroxide and double metal cyanide (DMC) catalysts that are most widely used at commercial scale. These catalysts can be used in very small quantities, unlike potassium hydroxide, and for that reason can be left in the product, thereby reducing or even eliminating catalyst deactivation and removal steps. Unlike DMC catalysts, these compounds are also effective ethylene oxide polymerization catalysts.

[0011] Accordingly, the invention is also an alkoxylation process, comprising (step I) forming a reaction mixture comprising a) a starter 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 of the first aspect, and (step II) reacting the cyclic oxide with the starter compound in the presence of the phosphonium catalyst to form an alkoxylated product.

[0012] R¹ includes an aromatic five-member ring. The five-member aromatic ring may be “heteroatomic”, i.e., one or more atoms of the ring are not carbon, such as oxygen, nitrogen and/or sulfur. The aromatic five-member ring of R¹ is unsubstituted or inertly substituted. Inert substituents do not react with the starter or cyclic oxide under the conditions of the alkoxylation reaction 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 and the like. The five-member ring may be fused to another ring structure, such other ring structure being aliphatic or aromatic and optionally inertly substituted. R¹ preferably does not contain active sites such as —OH, —NH, —SH or —COOH where alkoxylation can take place, and preferably does not contain cyclic oxide structures.

[0013] R¹ may be, for example:

In any of the foregoing, any ring carbon can be unsubstituted or substituted with an inert substituent.

[0014] In some embodiments, one or both R² groups is another R¹ group as described above, i.e., a group having an unsubstituted or substituted, aromatic five-member ring having a direct bond between a carbon atom of the aromatic five-member ring and the phosphorus atom. In particular embodiments, both R² groups are R¹ groups. R¹ and both R² groups all may be identical.

[0015] In other embodiments, at least one R² group and optionally both R² groups have an unsubstituted or inertly substituted, optionally heteroatomic, aromatic six-member ring having a direct bond between a carbon atom of the optionally heteroatomic aromatic six-member ring and the phosphorus atom.

[0016] In some embodiments, one or both R² 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 alkoxyl or trifluoromethyl groups. If the C_1-12 alkoxyl group has more than 2 carbon atoms, it may be linear, branched and/or cyclic. The C_1-12 alkoxyl group may be substituted with inert substituents as described above, particularly halogen and especially F, Cl or Br. A substituted phenyl group, for example may be substituted in the para-position (relative to the bond to the central phosphorus atom) with an unsubstituted or inertly substituted C_1-12 alkoxyl group and in such a case optionally contains no other substituents. R² preferably does not contain active sites such as —OH, —NH, —SH or —COOH where alkoxylation can take place, and preferably does not contain cyclic oxide structures. In specific embodiments, each R² is independently selected from phenyl, pentafluorophenyl, 3,5-trifluoromethylphenyl or 4-alkoxyphenyl wherein the alkoxy group has 1 to 4 carbon atoms, preferably 1 or 2 carbon atoms.

[0017] X is preferably, F, Cl, Br, I, OCH₃, OC₂H₅, phenoxy, CH₃, C₂H₅ or CF₃.

[0018] The anion A is a weakly coordinating anion that has a valence of n. n is preferably 1 or 2 and most preferably 1. Weakly coordinating anions are characterized in the negative charge is delocalized over a large, non-nucleophilic area. Coordination strength of an anion is conveniently determined by forming a 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 as described, for example, in J. Am. Chem Soc. 2006, 128, 8500-8508. An N—H stretching frequency of 3000 cm-1 or greater, especially 3050 cm-1 or greater, is indicative of a weakly coordinating anion.

[0019] Examples of weakly coordinating anions include tetrakis[perfluorophenyl] borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate (triflate), Al[OC(CF₃)₃]₄, B₁₂F₁₂²—, HCB₁₁H₅F₆, B(OTeF₅)₄—, Sb(OTeF₅)₆, Al[OC(CF₃)₃]₄, Al[OCH(CF₃)₂]₄— and Al[OC(CH₃)(CF₃)₂]₄.

[0020] Specific examples of the phosphonium catalyst include

and the like, where in each case A⁻ is monovalent. Analogous compounds of the form Z⁺₂A²-, where Z⁺ represents the phosphonium cation as shown in any of the foregoing structures and A²- represents a divalent weakly coordinating anion, are also useful.

[0021] The anion A in each case can be any weakly coordinating anion, including any of those mentioned before, in particular a monovalent anion such as tetrakis[perfluorophenyl]borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate and trifluoromethanesulfonate (triflate).

[0022] The phosphonium catalyst can be synthesized in several steps starting with the corresponding phosphine having the structure

wherein R¹ and R² are as defined before. Reaction with a halogenating agent yields a phosphine dihalide having the structure:

wherein Hal is F, Cl, Br or I. Examples of halogenating agents include XeF₂, perchloroethane, sulfuryl chloride, elemental bromine and elemental iodine. This reaction is conveniently performed at room temperature or at a moderately elevated temperature (such as 50 to 100° C.), using a stoichiometric amount or small excess of the halogenating agent.

[0023] The phosphine dihalide can be converted to the corresponding phosphonium salt

by reaction with a silylium compound having the general structure

wherein each R⁶ is independently hydrocarbyl (including linear, branched and/or cyclic alkyl, aryl, aryl-substituted alkyl and alkyl-substituted aryl) and A is as defined before. The silylium compound is conveniently formed, for example, by reaction of the corresponding silane

with a salt of the A⁻ anion, such as the trityl (C⁺(C₆H₅)₃) salt. This reaction is conveniently performed in solution in a suitable solvent such as toluene at a temperature of 0 to 50° C. The product can be recovered by addition of an antisolvent (such as pentane or other liquid alkane) and if desired purified by methods such as recrystallization.

[0024] 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.

[0025] The corresponding alkoxide (i.e., X in structure I is alkoxyl or inertly substituted alkoxyl), can be synthesized using methods as described by LaFortune et al., in Dalton Transactions, DOI: 10.1039/c6dt03544b.

[0026] In cases in which X is CF₃, a suitable synthetic route starts with

where R¹ and R² are as described above and Ph denotes phenyl. Reaction with trimethylsilane-CF₃ in the presence of CsF replaces the phenoxy group with CF₃. Subsequent reaction with R¹OTf (where OTf denotes triflate and R¹ is as described before) in the presence of a palladium catalyst produces

respectively, in the triflate salt form. Analogous methods are useful when X is C_1-12 alkyl or another perfluoroalkane.

[0027] The alkoxylation is performed in the presence of one or more starter compounds. The starter compound has one or more functional groups capable of being alkoxylated. The starter may contain any larger number of such functional groups. The functional groups may be, for example, primary, secondary or tertiary hydroxyl, or thiol. A preferred starter contains 1 or more such functional groups, preferably 2 or more of such functional groups, and may contain as many as 12 or more of such functional groups.

[0028] In certain embodiments, the functional groups are all hydroxyl groups. In some embodiments, the starter compound will have 2 to 8, 2 to 6, 2 to 4 or 2 to 3 hydroxyl groups.

[0029] The starter compound has an equivalent weight per functional group less than that of the polyether product. It may have an equivalent weight of 9 (in the case of water) to 6000 or more. The invention has particular advantages when the starter compound is a low equivalent weight alcohol or polyol (up to 500, up to 250, up to 125, up to 75 g/equivalent or up to 50 g/equivalent, for example) and for that reason prior to alkoxylation has a high concentration of hydroxyl groups. Equivalent weight of an alcohol or polyol is conveniently determined using titration methods such as ASTM 4274-16, which yield a hydroxyl number in mg KOH/gram of polyol that can be converted to equivalent weight using the relation equivalent weight=56, 100-hydroxyl number.

[0030] Among the suitable starters are vinyl alcohol, propenyl alcohol, allyl alcohol, acrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, a C_1-50 alkanol, especially a C_1-12 alkanol, phenol, cyclohexanol, an alkylphenol, water (considered for purposes of this invention as having two hydroxyl groups), ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butane diol, 1,6-hexane diol, 1,8-octane diol, cyclohexane dimethanol, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, sucrose, xylitol, mannitol, maltitol, sucralose, phenol, polyphenolic starters such as bisphenol A or 1,1,1-tris(hydroxyphenyl) ethane, and the like. Any two or more of the foregoing starters may be used together if desired.

[0031] The cyclic oxide is characterized in having a least one 3-, 4- or 5-member ring structure that contains an oxygen atom in the ring structure. Especially preferred cyclic oxides are oxiranes that have a three-member, oxygen-containing ring. The cyclic oxide(s) may be, for example, ethylene oxide, 1,2-propylene oxide (generally referred to herein as “propylene oxide”), oxetane, 1,2-butene oxide, 2-methyl-1,2-butene oxide, 2,3-butene oxide, tetrahydrofuran, epichlorohydrin, hexene oxide, octene oxide, styrene oxide, divinylbenzene dioxide, a glycidyl ether such as bisphenol A diglycidyl ether, epichlorohydrin or other polymerizable oxirane. In some embodiments, the alkylene oxide is 1,2-propylene oxide, ethylene oxide, or a mixture thereof, including, for example, a mixture of at least 50% (preferably at least 80%) by weight propylene oxide and correspondingly up to 50% (preferably up to 20%) by weight ethylene oxide. In some embodiments, two or more alkylene oxides are polymerized simultaneously (to form random copolymers), and or the composition of the alkylene oxide is changed one or more times, or even continuously, throughout the course of the polymerization to form block and/or random/block copolymers.

[0032] The alkoxylation is performed by combining the starter and phosphonium catalyst with the cyclic oxide(s) and optionally comonomer and subjecting the resulting reaction mixture to reaction conditions. The catalyst may be added as a solution in a solvent. Such a solvent preferably is inert under the conditions of the alkoxylation reaction. Diethyl ether, dichloromethane and hydrocarbons such as toluene or hexane are useful solvents for the phosphonium catalyst.

[0033] The alkoxylation proceeds at a wide range of temperatures from −100° C. to 250° C. or more. 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 preferably does not exceed 190° C., and more preferably does not exceed 180° C. An important advantage of the phosphonium catalysts used in the invention is that they perform well without premature deactivation at higher temperatures, especially 150° to 200° C. or 150° to 180° C. The higher temperatures promote faster reactions. Additionally, the ability to operate at these higher temperatures permits the process to be used with starters and/or cyclic oxides that have somewhat high melting temperatures (such as sorbitol, xylitol, mannitol, maltitol, sucralose) and/or which are viscous at lower temperatures, or which, like sorbitol and glycerol, have limited solubility in the cyclic oxide at lower temperatures.

[0034] The alkoxylation reaction usually is performed at a superatmospheric pressure but can be performed at atmospheric pressure or even a subatmospheric pressure.

[0035] Enough phosphonium catalyst is used to provide a commercially reasonable alkoxylation rate, but it is generally desirable to use as little thereof as possible consistent with reasonable alkoxylation rates, as this both reduces the cost for the catalyst and can eliminate the need to remove catalyst residues from the product. The amount of phosphonium catalyst may be, for example, sufficient to provide 10 to 10,000 ppm by weight of phosphonium catalyst based on the weight of the starter. In specific embodiments, the amount of phosphonium catalyst may be sufficient to provide at least 25 ppm, at least 50 ppm or at least 100 ppm catalyst on the foregoing basis, and up to 1,000 ppm or up to 500 ppm catalyst, again on the foregoing basis. The weight of the phosphonium catalyst includes the weight of both cation and associated anion.

[0036] The alkoxylation reaction can be performed batch-wise, semi-continuously (including with continuous addition of starter as described in U.S. Pat. No. 5,777,177) or continuously.

[0037] The alkoxylation reaction can be performed in any type of vessel that is suitable for the pressures and temperatures encountered. The reactor should be equipped with a means of providing and/or removing heat, so the temperature of the reaction mixture can be maintained within the required range. Suitable means include various types of jacketing for thermal fluids, various types of internal or external heaters, and the like. A cook-down step performed on continuously withdrawn product is conveniently conducted in a reactor that prevents significant back-mixing from occurring. Plug flow operation in a pipe or tubular reactor is a preferred manner of performing such a cook-down step.

[0038] The crude product obtained in any of the foregoing processes may contain unreacted cyclic oxide, small quantities of the starter compound and low molecular weight alkoxylates thereof, and small quantities of other organic impurities and/or water. Volatile impurities (including unreacted cyclic oxides) should be flashed or stripped from the product. The crude product typically contains catalyst residues. It is typical to leave these residues in the product, but these can be removed if desired. Moisture and volatiles can be removed by stripping the alkoxylated product.

[0039] The process of the invention is useful for preparing alkoxylated products that can have hydroxyl equivalent weights from as low as about 85 g/equivalent to as high as about 8,000 g/equivalent or more. Alkoxylated polyols produced in accordance with the invention are useful raw materials for producing polyurethanes and other polymers made by reacting the alkoxylated polyol with a polyisocyanate. These products include a wide variety of cellular and non-cellular materials, which may vary in physical properties from very rigid to highly flexible. Alkoxylated monols produced in accordance with the invention are useful as surfactants or as industrial solvents, among other uses. Alkoxylated polyols and monols can be aminated to produce the corresponding amine-terminated materials, which are in turn useful raw materials for making various materials including polyureas and cured epoxy resins.

[0040] In particular embodiments, the starter is a polyol having a hydroxyl equivalent weight of 125 g/equivalent or less, especially 75 g/equivalent or less or even 50 g/equivalent or less and a formula molecular weight of up to 250 g/mol, and the alkoxylation is continued to produce an alkoxylated product having 1 to 12, especially 1 to 10, 1 to 5 or 1 to 3 units of polymerized cyclic oxide per hydroxyl group on the starter. The number average molecular weight of the alkoxylated product may be, for example, 100 to 1000 g/mol, 100 to 800 g/mol, 150 to 800 g/mol or 200 to 800 g/mol as measured by GPC against polystyrene standards. In such particular 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 starter in such embodiments most preferably is one or more of glycerol, trimethylolpropane, trimethylolethane, erythritol, pentaerythritol, sorbitol and sucrose. Such products are useful raw materials for making rigid polyurethane and/or polyisocyanurate polymers, including foams.

[0041] In some embodiments the cyclic oxide is polymerized with or in the presence of one or more copolymerizable monomers that are not cyclic oxides. Examples of such copolymerizable monomers 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 copolymerizable monomers include carboxylic acid anhydrides, which copolymerize with cyclic oxides to produce ester linkages in the product.

[0042] The following examples are provided to illustrate the invention but are not intended to limit the scope thereof. All parts and percentages are by weight unless otherwise indicated.

[0043] 45 grams of glycerol are charged into a semi-batch reactor equipped with stirrer, temperature controls, nitrogen feed and monomer feed lines and a vent. The catalyst is added as a solid in an amount (based on starter) as indicated in Table 1. The reactor is purged with nitrogen and heated to the temperature indicated in Table 1 with stirring, then purged again with nitrogen to remove any solvent from the catalyst addition. While maintaining the same temperature, propylene oxide then is fed into the reactor on demand to attempt to maintain a 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 having a target number average molecular weight of about 412 g/mol; the actual amounts fed are indicated in Table 1. The time required to feed the propylene oxide (run time) is indicated in Table 1. Upon completion of monomer feed, 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 yield calculated. The product is analyzed for Mn and polydispersity by gel permeation chromatography against polystyrene standards.

[0044] The activities of the catalysts are compared by calculating a turnover frequency (TOF) in each instance. TOF reflects the number of propylene oxide molecules converted per catalytic site per unit time, as follows:

$\mathrm{TOF}=\frac{\mathrm{mmol}\mathrm{PO}\mathrm{consumed}}{\mathrm{mmol}\mathrm{catalyst}\times \mathrm{run}\mathrm{time}(\mathrm{hr})}.$

Higher values indicate greater catalyst activity.

[0045] In Table 1, KOH designates potassium hydroxide and BF₃·OEt₂ designates boron trifluoride diethyl etherate.

[0046] Catalyst P(2-F)₃F tetrakis(pentafluorophenyl) borate is P(2-F)₃F tetrakis(pentafluorophenyl) borate is made by reacting tris(2-furyl)phosphine with XeF₂ in the general manner described in Chem. Sci. 2015, 6, 2016 to produce P(2-F)₃F₂. The P(2-F)₃F₂ is suspended in toluene at room temperature. Separately, a silylium solution is produced by combining triethyl silane and trityl tetrakis(pentafluorophenyl) borate in toluene. The P(2-F)₃F₂ suspension and silylium solution are combined at room temperature and stirred for 30 minutes. The toluene is removed by evaporation to produce a slurry, which is triturated with pentane until it solidifies. The product P(2-F)₃F tetrakis(penta-fluoro-phenyl) borate is then recrystallized from dichloromethane using pentane as an antisolvent. The product is recovered and recrystallized, and its structure confirmed by ¹H, ¹³C and ³¹P NMR.

TABLE 1
				PO partial	Run	PO
		Loading	T,	press., psi	time	Fed	Yield	TOF	Mn,
Designation	Catalyst	(ppm)	° C.	(kPa)	(h)	(mL)	(g)	(hr−1)	g/mol	PDI
A*	KOH	4000	130	30 (207)	1.6	103.8	112.3	207	412	1.02
B*	BF3•OEt2	111	100	11 (76)	47.2	24.5	37.1	211	ND	ND
C*	B(C6F5)3	667	80	7 (48)	1.7	103.0	114.7	14,768	407	1.10
1	P(2-F)3F	378	160	30 (207)	0.6	102.9	112.4	134,289	412	1.09
	tetrakis
	(pentafluoro-
	phenyl) borate
*Not an example of the invention. “ND” is not done. “PO partial pressure” is the target PO partial pressure in the reactor during the polymerization. The Run time indicates the time required to feed the indicated amount of propylene oxide. “PO Fed” indicates the total amount of propylene oxide fed during the indicated run time. “TOF” is turnover frequency. PDI is the polydispersity index, i.e., weight average molecular weight divided by number average molecular weight. Molecular weights are measured by GPC against polystyrene standards.

[0047] As indicated by the data in Table 1, the catalyst of the invention is extremely active compared to the controls, the turnover frequency being almost 700 times greater than that of KOH, which is the industry workhorse propylene oxide polymerization catalyst. The greater catalytic activity leads to drastically reduced run times, effectively increasing the production capability of the manufacturing equipment proportionally. Molecular weight and polydispersity are similar to those obtained in the KOH-catalyzed run (Comp. A).