Alkoxylation process using mono-and dicationic cyclopentadienyl phosphorus catalysts

Abstract

The alkoxylation is carried out by reacting a cyclic oxide with an initiator in the presence of certain cyclopentadienyl phosphorus catalysts. The cyclopentadienyl phosphorus catalyst is highly active and effective at such small amounts such that generally no catalyst residue is required to be removed from the product. The cyclopentadienyl phosphorus catalyst is 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 worldwide. For example, polyether polyols are important raw materials for the production of polyurethanes. In addition to this, they are 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 in turn can 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 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 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 widespread 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 (since 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] A variety of Lewis acidic phosphorus 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 being used 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 is an alkoxylation method, which alkoxylation method 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 phosphorus catalyst having any of the following structures: (Cp*PX) + n A n- or (Cp*P) 2+ (A n- ) 2 / n , where Cp* represents an optionally substituted cyclopentadienyl ligand, X represents 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 is the absolute value of the valence of A, and (Step II) reacting the cyclic oxide with the initiator compound in the presence of the cationic phosphorus catalyst to form an alkoxylated product.

[0010] An advantage of the method of the present invention is that a very high alkoxylation rate is obtained using a very small amount of the cationic phosphorus catalyst, and 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 very effective in polymerizing oxirane onto very low molecular weight initiators and are also effective ethylene oxide polymerization catalysts. The cationic phosphorus catalysts described herein are particularly useful for alkoxylating low molecular weight initiators having 1 to 12 alkylene oxide units per active site.

[0011] The Cp* ligand has the structure Each R is independently hydrogen or an inert substituent. 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, alkyl-substituted aryl, aryl-substituted alkyl, halogen (especially F, Cl, Br), alkoxy, aryloxy, etc. For example, the R group can be selected from hydrogen, F, Cl, C 1-4 alkyl, phenyl, methoxy, or ethoxy. In some embodiments, all R groups are the same. Any two R groups, especially any two adjacent R groups, can together form a cyclic structure at the carbon atoms of the cyclopentadienyl ring to which the R groups are bonded. Such cyclic structures can be aliphatic or aromatic. In a specific embodiment, Cp* is cyclopentadienyl, pentafluorocyclopentadienyl, pentachlorocyclopentadienyl, pentamethylcyclopentadienyl, pentaethylcyclopentadienyl, or pentaphenylcyclopentadienyl, indenyl, or fluorenyl.

[0012] (Cp*PX) + n The cation is monocationic and can exist in the δη 2 -Cp* configuration. (Cp*P) 2+ The cation is dicationic and can exist in the δη 5 -Cp* configuration. Corresponding to the structure (Cp*P) 2+ (A n- ) 2 / n The dicationic phosphorus catalyst can additionally have one or more solvent ligands coordinated to this structure.

[0013] X, when present, is one or more of the following: F, Cl, Br, I, unsubstituted or inertly substituted C 1-12 alkyl, unsubstituted or inertly substituted alkoxy, unsubstituted or inertly substituted aryl, or unsubstituted or inertly substituted aryloxy. The inert substituents of the X group include, for example, alkyl (linear, branched, and / or cyclic), aryl, alkyl-substituted aryl, aryl-substituted alkyl, halogen (especially F, Cl, Br), alkoxy, aryloxy, 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. X, when present, is preferably F, Cl, Br, methoxy, ethoxy, methyl, ethyl, phenoxy, phenyl, or -CF3. The X group preferably does not contain reactive sites where alkoxylation can occur, such as -OH, -NH, -SH, or -COOH, and preferably does not contain a cyclic oxide structure.

[0014] The anion A is a weakly coordinating anion with a valence of n-, where n is 1 or 2. 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, for example, J. Am. Chem. Soc. 2006, 128, 8500 - 8508. A N-H stretching frequency of 3000 cm -1 or higher, particularly 3050 cm -1 or higher, indicates a weakly coordinating anion.

[0015] Examples of weakly coordinating anions include tetrakis(pentafluorophenyl)borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate (triflate), Al[OC(CF3)3]4 - , HCB 11 Me5F6 - , B 12 F 12 2- , HCB 11 H5F6 - , B(OTeF5)4 - , B(OTeF5)6 - , Sb(OTeF5)4 - , Sb(OTeF5)6 - , Al[OC(CF3)3]4 - , Al[OCH(CF3)2]4 - and Al[OC(CH3)(CF3)2]4 - .

[0016] Specific examples of the phosphorus catalyst include: Cp*P 2+ (A - )2, Cp*PF + A - , Cp*PCl + A - , Cp*PBr + A - , Cp*POMe + A - , Cp*POEt + A - and Cp*POPh + A -, where Cp* is as described above, in particular unsubstituted cyclopentadienyl, pentafluorocyclopentadienyl, pentachlorocyclopentadienyl, pentamethylcyclopentadienyl, pentaethylcyclopentadienyl, pentaphenylcyclopentadienyl, indenyl or fluorenyl, OMe represents methoxy, OEt represents ethoxy, OPh represents phenoxy, and A — is monovalent in each case. Similar compounds in which A represents a divalent weakly coordinating anion are also useful. A is most preferably a monovalent anion such as tetrakis[perfluorophenyl]borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate and trifluoromethanesulfonate (triflate).

[0017] Particularly preferred phosphorus catalysts are Cp*P 2+ , Cp*PF +1 and Cp*PCl +1 tetrakis[perfluorophenyl]borates, where Cp* is as described above and is preferably cyclopentadienyl, pentafluorocyclopentadienyl, pentachlorocyclopentadienyl, pentamethylcyclopentadienyl, pentaethylcyclopentadienyl or pentaphenylcyclopentadienyl, indenyl or fluorenyl.

[0018] Methods for preparing phosphorus catalysts are generally described, for example, in Chem. 2018, pages 2699 - 2708.

[0019] 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 may contain any larger number of such functional groups. In some embodiments, the initiator has one or more hydroxyl groups and no primary or secondary amino groups. The functional group may be, for example, a primary hydroxyl, secondary hydroxyl or tertiary hydroxyl or a thiol. Preferred initiators contain 1 or more such functional groups, preferably 2 or more such functional groups, and may contain up to 12 or more such functional groups.

[0020] In certain embodiments, all of the functional groups are hydroxyl groups. In some embodiments, the initiator compound will have 2 to 8, 2 to 6, 2 to 4 or 2 to 3 hydroxyl groups.

[0021] The equivalent weight per functional group of the initiator compound is less than that of the polyether product. Its equivalent weight can be from 9 g / equivalent (in the case of water) to 6000 g / equivalent or greater. The present invention has particular advantages when the initiator compound is a low-equivalent 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 before alkoxylation. The equivalent 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 mgKOH / gram of polyol, and this hydroxyl number can be converted to the equivalent using the following relationship: equivalent = 56,100 ÷ hydroxyl number.

[0022] 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, polyphenol 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.

[0023] The cyclic oxide is characterized by having at least one 3-membered, 4-membered or 5-membered ring structure containing an oxygen atom in the ring structure. Particularly preferred cyclic oxides are alkylene oxides having a three-membered oxygen-containing ring. The cyclic oxide can be, for example, ethylene oxide, 1,2-propylene oxide (commonly referred to herein as "propylene oxide"), oxetane, 1,2-butylene oxide, 2-methyl-1,2-butylene oxide, 2,3-butylene oxide, tetrahydrofuran, epichlorohydrin, epoxyhexane, epoxyoctane, styrene oxide, divinylbenzene dioxide, glycidyl ethers (such as bisphenol A diglycidyl ether), epichlorohydrin or other polymerizable alkylene oxides. 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 wt% (preferably at least 80 wt%) of propylene oxide and correspondingly at most 50 wt% (preferably at most 20 wt%) of 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 oxides 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.

[0024] The alkoxylation is carried out by combining the initiator and the phosphorus catalyst with the cyclic oxide and optionally the comonomer and subjecting the resulting reaction mixture to the reaction conditions. The catalyst may be added as a solution in a solvent. Such a solvent is preferably inert under the alkoxylation reaction conditions. Diethyl ether, methylene chloride and hydrocarbons such as toluene or hexane are useful solvents for the phosphorus catalyst.

[0025] The alkoxylation is carried out in a 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 no more than 190°C, and more preferably no more than 180°C. An important advantage of the phosphorus catalysts used in the present invention is that they perform well at higher temperatures, particularly 150°C to 200°C or 150°C to 180°C without premature deactivation. Higher temperatures promote faster reactions. In addition, the ability to operate at these higher temperatures allows the method to be used with initiators and / or cyclic oxides that have slightly higher melting temperatures (such as sorbitol, xylitol, mannitol, maltitol, sucralose) and / or are viscous at lower temperatures, or have limited solubility in the cyclic oxide at lower temperatures like sorbitol and glycerol.

[0026] The alkoxylation reaction is generally carried out under superatmospheric pressure, but can also be carried out at atmospheric pressure or even subatmospheric pressure.

[0027] Sufficient phosphorus catalyst is used to provide a commercially reasonable alkoxylation rate, but it is generally desirable to use as little phosphorus catalyst as possible consistent with a reasonable alkoxylation rate because this reduces the cost of the catalyst and eliminates the need to remove catalyst residues from the product. The amount of phosphorus catalyst may be, for example, sufficient to provide 10 ppm to 10,000 ppm of phosphorus catalyst by weight based on the weight of the initiator. In specific embodiments, the amount of phosphorus catalyst may be sufficient to provide at least 25 ppm, at least 50 ppm, or at least 100 ppm of catalyst on the aforementioned basis, and may be sufficient to provide up to 1,000 ppm or up to 500 ppm of catalyst on the aforementioned basis as well. The weight of the phosphorus catalyst includes the weight of both the cation and the associated anion.

[0028] The alkoxylation reaction can be carried out batchwise, semi-continuously (including continuous addition of starter, as described in US Pat. No. 5,777,177), or continuously.

[0029] 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 heating 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 backmixing. Plug flow operation in a pipe or tubular reactor is a preferred way to carry out such a cooking step.

[0030] The crude product obtained in any of the foregoing methods may contain unreacted cyclic oxide, small amounts 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.

[0031] The process of the present invention can be used to prepare alkoxylated products having a hydroxyl equivalent weight that can be as low as about 85 g / equivalent to as high as about 8,000 g / equivalent or higher, in each case greater than the hydroxyl equivalent weight of the initiator. 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 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.

[0032] 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 alkoxylation is continued to produce an alkoxylated product having from 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, in each case greater than the number average molecular weight of the initiator. 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.

[0033] 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.

[0034] 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.

[0035] Catalyst preparation procedure

[0036] PMCp*PF + , PMCp*PCl + and PMCp*P 2+ tetrakis(pentafluorophenyl)borates, where PMCp* is pentamethylcyclopentadienyl in each case, and are prepared in the general manner described on pages 2699 - 2708 of Chem. 4. PMCp*P 2+ The divalent cation can have one or more toluene ligands coordinated to the structure.

[0037] Examples 1 to 4 and Comparative Samples A to C

[0038] Forty-five grams of an initiator (monopropylene glycol in Example 4 and sorbitol in Example 5, glycerol in all other cases) were charged into a semi-batch reactor equipped with a stirrer, a temperature controller, a nitrogen feed line, a monomer feed line, and a vent. A catalyst was added as a solid. The type and amount of the catalyst are indicated in Table 1. The reactor was purged with nitrogen and heated to the temperature indicated in Table 1 with 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 indicated in Table 1. The target amount of propylene oxide to be added was approximately 103 g; 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 was completed, the reaction was 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 was collected and the yield was calculated. The M n and polydispersity of the product were analyzed by gel permeation chromatography against polystyrene standards.

[0039] 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:

[0040]

[0041] Higher values indicate higher catalyst activity.

[0042] The phosphorus catalysts are as indicated in Table 1.

[0043] In Table 1, KOH represents potassium hydroxide, and BF3·OEt2 represents boron trifluoride diethyl etherate.

[0044] Table 1

[0045]

[0046] * Not an example of the present invention. ND—not determined. **Monopropylene glycol is the initiator in Example 4, and sorbitol is the initiator in Example 5; glycerol is the initiator in all other cases. 1"PMCp*" is a pentamethylcyclopentadienyl ligand. The catalysts used in Examples 1 to 5 are all tetra(pentafluorophenyl)borates of the indicated cations. "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, which is the weight-average molecular weight divided by the number-average molecular weight. The molecular weight is measured by GPC relative to a polystyrene standard.

[0047] As indicated by the data in Table 1, the catalysts of the present invention are extremely active compared to the control. When glycerol is present in the initiator, the turnover frequency ranges from about 470 to 820 times the turnover frequency range of KOH, which is an industrial main material for 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 weight and polydispersity are similar to those obtained in the KOH-catalyzed runs (Comparison A).

Claims

1. An alkoxylation method, the alkoxylation method comprising: (Step I) Form 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 phosphorus catalyst having any one of the following structures: (Cp*PX) + n A n- or (Cp*P) 2+ (A n- ) 2 / n , where Cp* represents an optionally substituted cyclopentadienyl ligand, X represents 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 is the absolute value of the valence of A, and (step II) reacting the cyclic oxide with the initiator compound in the presence of the phosphorus catalyst to form an alkoxylated product.

2. The alkoxylation process according to claim 1, wherein Cp* is cyclopentadienyl, pentafluorocyclopentadienyl, pentachlorocyclopentadienyl, pentamethylcyclopentadienyl, pentaethylcyclopentadienyl, pentaphenylcyclopentadienyl, indenyl or fluorenyl.

3. The alkoxylation process according to claim 1 or 2, wherein the phosphorus catalyst has the structure (Cp*P) 2+ (A n- ) 2 / n .

4. The alkoxylation process according to claim 1 or 2, wherein the phosphorus catalyst has the structure (Cp*PX) + n A n- .

5. The alkoxylation process according to claim 4, wherein X is F, Cl, Br, I, methoxy, ethoxy, methyl, ethyl, phenoxy, phenyl or -CF3.

6. The alkoxylation process according to claim 5, wherein X is F, Cl, Br or I.

7. The alkoxylation process according to claim 5, wherein X is F or Cl.

8. 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(CF3)3]4 - , HCB 11 H5F6 - , B(OTeF5)4 - , B(OTeF5)6 - , Sb(OTeF5)4 - , Sb(OTeF5)6 - , Al[OC(CF3)3]4 - , Al[OCH(CF3)2]4 - and Al[OC(CH3)(CF3)2]4 - .

9. The alkoxylation process according to claim 8, wherein A is tetrakis(pentafluorophenyl)borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate or trifluoromethanesulfonate.

10. 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- .

11. The alkoxylation process according to any one of the preceding claims, wherein the initiator compound has a hydroxyl equivalent weight of at most 80 g / equivalent.

12. 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.

13. The alkoxylation process according to any one of the preceding claims, wherein the cyclic oxide is an alkylene oxide.

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

15. 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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