Alkoxylation process using bipyridinium catalysts

Abstract

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

Description

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

[0002] Polyethers are produced in large quantities globally. For example, polyether polyols are an important raw material for the production of polyurethane. In addition, they are used to manufacture highly elastic foams, molded foams, or rigid foams. For example, polyether monools are used as surfactants and industrial solvents. Carbonate-modified and ester-modified epoxy polymers have also been found to be used in these and other applications.

[0003] Polyether monohydric and polyhydric alcohols are produced via alkoxylation of an initiator compound, wherein the active site on the initiator compound reacts with a cyclic oxide in a ring-opening reaction. The active site of the initiator compound is a group containing an active hydrogen, such as a hydroxyl or thiol group. The primary function of the initiator compound is to provide molecular weight control and determine the number of hydroxyl groups that the alkoxylated product will have.

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

[0005] Alkali metal hydroxides offer the advantages of low catalyst cost and acceptable alkoxylation rates. They are widely used because they can efficiently polymerize many epoxides. Nevertheless, alkali metal hydroxides still have well-known drawbacks. Alkoxylation products must be neutralized, and catalyst residues must be carefully removed. These finishing steps significantly increase capital and operating costs and generate additional waste streams that must be cleaned up and / or disposed of.

[0006] Compared to alkali metal catalysts, DMC catalysts offer rapid polymerization rates, even when used at very low concentrations. A significant advantage of DMC catalysts over alkali metal hydroxides is the elimination of the need for a neutralization step. Unlike the use of alkali metal hydroxides as polymerization catalysts, catalyst residues can typically remain in the product. This can significantly reduce production costs. Nevertheless, DMC catalysts also have significant drawbacks. They tend to perform poorly in the presence of high concentrations of hydroxyl groups, especially in the presence of low molecular weight initiator compounds (such as glycerol or sorbitol) with hydroxyl groups at the 1,2- or 1,3-positions relative to each other. Under these conditions, the catalyst is difficult to activate, acts sluggishly, and often deactivates before polymerization is complete. This greatly limits the widespread adoption of DMC catalysts.

[0007] DE 4103906A1 and DE 4102546A describe N-alkoxyquinolineonium or N-alkoxypyridinonium salts as room-temperature photocatalysts for epoxide polymerization. The polymerization is carried out at room temperature using a strong UV light source.

[0008] This invention relates to an alkoxylation method comprising: (step I) forming a reaction mixture comprising a) an initiator compound having at least one hydroxyl or thiol group and a molecular weight of 62 g / mol to 250 g / mol; b) at least one cyclic oxide; and c) a catalytically effective amount of a dipyridinium catalyst having one of the following structures:

[0009] (I) and (II)

[0010] Each A - Each R independently represents a weakly coordinating anion, and each R is independently a hydrocarbon group bonded to a carbon atom of a pyridinium group or an inertly substituted hydrocarbon group, provided that any two R groups can form a divalent moiety together. Each x is a number from 0 to 4. 1 It is a linking group, each R 1 It is a divalent linker, each R 2 Independently, it is hydrogen, alkyl, inertly substituted alkyl, phenyl, or inertly substituted phenyl, z is a number from 1 to 4, and each R 3 Independently, it is a hydrocarbon group bonded to a carbon atom of a pyridinium group or an inertly substituted hydrocarbon group; and (step II) reacting the cyclic oxide with the initiator compound at a temperature of 80°C to 220°C in the presence of a dipyridinium catalyst to form an alkoxylated product.

[0011] The advantage of the method of the present invention is that it achieves very high alkoxylation rates using very small amounts of dipyridinium catalyst, and for this reason, catalyst residues can remain in the product (unlike alkali metal hydroxides), thereby reducing or even eliminating catalyst deactivation and removal steps. Unlike DMC catalysts, these compounds are very effective in adding alkyl oxidants to very low molecular weight initiators and are also effective in alkoxylation of initiators with ethylene oxide. The dipyridinium catalysts described herein are particularly suitable for alkoxylation of low molecular weight initiators having 1 to 12 alkylene oxide units per active site.

[0012] Each R (if present) can independently be an alkyl group (especially C10). 1-4 Alkyl groups, inertly substituted alkyl groups, aryl groups, or inertly substituted aryl groups. Any two R groups can form a divalent moiety, which, together with the pyridinium group to which the R groups are bonded, forms a ring structure. Such a ring structure can form a conjugated aromatic ring system together with the pyridinium group.

[0013] R 1 It can be, for example, having a structure -(CR) 4 2) q -or-O-(CR) 4 2) q -O- divalent groups, where each R 4 Independently, it is hydrogen, alkyl, inertly substituted alkyl, phenyl, or inertly substituted phenyl, and q is at least one, preferably from 1 to 4, and most preferably 2. Each R 4 Preferably, it is either hydrogen or methyl. R 1 Specific examples of the groups include methylene (-CH2-), ethylene (-CH2CH2-), -CH(CH3)-CH2-, -CH(CH3)-CH(CH3)-, -O-CH2-O-, -O-CH2CH2-O-, and -O-CH(CH3)-CH 2- O-、-O-CH(CH3)-CH(CH3)-O-、

[0014] Each R 2 Preferably, it is hydrogen or methyl. Z is preferably 1 or 2, and most preferably 2. CR 2 Specific examples of the two groups include methylene (-CH2-), ethylene (-CH2CH2-), -CH(CH3)CH2- and -CH(CH3)-CH(CH3)-.

[0015] Each R 3 (If present) can be independently an alkyl group (especially C10). 1-4 Alkyl), inertly substituted alkyl, aryl or inertly substituted aryl.

[0016] An inert substituent is a substituent that does not react with the initiator compound or cyclic oxide under the conditions of the alkoxylation reaction (step II). Examples of inert substituents include acyclic ethers (such as methoxy, ethoxy, isopropoxy, n-butoxy, tert-butoxy, etc.), esters, alkyl groups (including straight-chain, branched, and / or cyclic alkyl groups), aryl, alkenyl, nitro (-NO2), and halogens.

[0017] Anion A is a weakly coordinating anion with a valence of n, where n is 1 or 2. Weakly coordinating anions are those whose coordination with the associated cation is weaker than that with the surrounding solvent molecules. The coordination strength of the anion can be conveniently determined by: forming a tri-n-octylammonium salt of the anion, dissolving the salt in carbon tetrachloride, and measuring the NH stretching frequency by infrared spectroscopy using, for example, the method described in J. Am. Chem Soc. 2006, 128, 8500-8508. 3000 cm⁻¹ -1 Or even higher, especially 3050cm-1 Or a higher NH stretching frequency indicates a weakly coordinated anion.

[0018] Examples of weakly coordinating anions include tetra(perfluorophenyl)borate, tetra[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate / triflate, and Al[OC(CF3)3]4. — HCB 11 Me5F6 — B 12 F 12 2— HCB 11 H5F6 — B(OTeF5)4 — Sb(OTeF5)6 — Al[OC(CF3)3]4 — Al[OCH(CF3)2]4 — and Al[OC(CH3)(CF3)2]4 — .

[0019] Specific examples of dipyridinium catalysts include: and .

[0020] A — In each case, it is monovalent. Similar compounds in which A represents a divalent weakly coordinating anion are also useful. A is most preferably a monovalent anion, such as tetra[perfluorophenyl]borate, tetra[3,5-bis(trifluoromethyl)phenyl]borate, and trifluoromethanesulfonate.

[0021] Methods for preparing dipyridinium catalysts are typically described, for example, in Chem. Eur. J. 2021, 11730. The starting dihalide salt of the dipyridinium compound is obtained by reacting with C... + (PH)3A - or Si + (CH3) A -The compound reacts readily to convert [A] into its constituent form. - ]2 Salt. This can be conveniently carried out in a suitable solvent or diluent (such as toluene or acetonitrile) and can be carried out at approximately room temperature (such as 0°C to 40°C).

[0022] Having structure The starting dipyridinium dihalide salt (where Hal represents halogen) can be in a structure The starting bipyridine compound and the Hal-R structure 1 -Hal dihalides (where Hal is a halogen, preferably bromine) are prepared by reaction at elevated temperatures, for example, from 80°C to 150°C. This reaction can be carried out in a suitable solvent, such as toluene or acetonitrile.

[0023] Having structure The starting dipyridinium dihalide salt can be in a structure N-oxide compounds and those with the structure Hal-(CR) 2 2) z -Hal dihalides (where Hal is a halogen, preferably bromine) are prepared by reaction at elevated temperatures, for example, from 50°C to 100°C. This reaction can be carried out in a suitable solvent, such as toluene or acetonitrile.

[0024] Alkoxylation is carried out in the presence of one or more initiator compounds. The initiator compounds have one or more hydroxyl and / or thiol groups. The hydroxyl groups can be, for example, primary, secondary, or tertiary hydroxyl groups. Preferred initiators contain one or more hydroxyl and / or thiol groups, preferably two or more hydroxyl and / or thiol groups, and may contain up to 12 or more hydroxyl and / or thiol groups.

[0025] In some embodiments, the functional groups are all hydroxyl groups. In some embodiments, the initiator compound will have 1 to 8, 2 to 8, 2 to 6, 2 to 4, or 2 to 3 hydroxyl groups, which are most preferably primary hydroxyl groups and / or secondary hydroxyl groups.

[0026] The equivalent weight per functional group of this initiator compound is less than that of the polyether product. It has a molecular weight ranging from 62 g / mol to 250 g / mol.

[0027] Suitable initiators include vinyl alcohol, propenol, allyl alcohol, acrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, and C. 1-16 Alkyl alcohols (especially C) 1-12Alkyl alcohols, phenol, cyclohexanol, alkylphenols, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, cyclohexanediol, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, sucrose, xylitol, mannitol, maltitol, sucralose, phenol, and polyphenolic initiators (such as bisphenol A or 1,1,1-tris(hydroxyphenyl)ethane), etc. If desired, any two or more of the aforementioned initiators may be used together.

[0028] 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 alkyl epoxides having a ternary oxygen-containing ring. Cyclic oxides can be, for example, ethylene oxide, 1,2-epoxypropane (generally referred to herein as "propylene oxide"), oxacyclobutane, 1,2-epoxybutane, 2-methyl-1,2-epoxybutane, 2,3-epoxybutane, tetrahydrofuran, epichlorohydrin, epihexane, epioctane, epiphenylene oxide, divinylbenzene dioxide, glycidyl ethers (such as bisphenol A diglycidyl ether), epichlorohydrin, or other polymerizable alkyl epoxides. In some embodiments, the alkyl epoxide is 1,2-epoxypropane, ethylene oxide, or mixtures thereof, comprising, for example, a mixture of at least 50% by weight (preferably at least 80% by weight) of propylene oxide and a correspondingly maximum of 50% by weight (preferably at most 20% by weight) of ethylene oxide. In some embodiments, two or more epoxides are polymerized simultaneously (to form random copolymers), and / or the composition of the epoxides is changed once or more, or even continuously, throughout the polymerization process to form block copolymers and / or random / block copolymers.

[0029] Alkoxylation is carried out by combining an initiator and a dipyridinium catalyst with a cyclic oxide and optionally a comonomer, and subjecting the resulting reaction mixture to 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, dichloromethane, and hydrocarbons such as toluene or hexane are useful solvents for the dipyridinium catalyst.

[0030] Alkoxylation is carried out at reaction temperatures of at least 80°C, at least 100°C, at least 120°C, at least 130°C, or at least 150°C, and up to 220°C. The polymerization temperature preferably does not exceed 190°C, and more preferably does not exceed 180°C. A significant advantage of the dipyridinium catalysts used in this invention is their good performance at higher temperatures, particularly 150°C to 200°C or 150°C to 180°C. Higher temperatures promote faster reactions. Furthermore, 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, like sorbitol and glycerol, have limited solubility in cyclic oxides at lower temperatures.

[0031] Alkoxylation reactions are typically carried out at atmospheric pressure, but can also be performed at atmospheric pressure or even below. Alkoxylation reactions can be carried out without exposing the reactants to electromagnetic radiation in the ultraviolet and visible spectra (such as radiation with wavelengths from 100 nm to 750 nm). Alkoxylation can be carried out, for example, in a closed reactor that does not allow electromagnetic radiation in the ultraviolet and visible spectra to enter and does not contain internal ultraviolet and visible radiation sources.

[0032] Sufficient dipyridinium catalyst is used to provide a commercially reasonable alkoxylation rate, but it is generally desirable to use as little dipyridinium catalyst as possible that corresponds to a reasonable alkoxylation rate, as this reduces both the cost of the catalyst and eliminates the need to remove catalyst residues from the product. Based on the weight of the initiator, the amount of dipyridinium catalyst can be, for example, sufficient to provide 10 ppm to 10,000 ppm by weight. In specific embodiments, based on the foregoing, the amount of dipyridinium catalyst can be sufficient to provide at least 25 ppm, at least 50 ppm, or at least 100 ppm of catalyst, and also on the foregoing, sufficient to provide up to 1,000 ppm or up to 500 ppm of catalyst. The weight of the dipyridinium catalyst includes the weight of both the cation and the associated anion.

[0033] Alkoxylation reactions can be carried out intermittently, semi-continuously (including continuous addition of initiators, as described in US 5,777,177), or continuously.

[0034] Alkoxylation reactions can be carried out in any type of vessel suitable for the pressure and temperature encountered. The reactor should be equipped with heating and / or deheating devices to maintain the temperature of the reaction mixture within the desired range. Suitable devices include various types of jackets for hot fluids, various types of internal or external heaters, etc. A cooking step of continuously extracted products is conveniently performed in a reactor that prevents significant backmixing. Plug flow operation in a tubular or pneumatic reactor is the preferred method for carrying out this cooking step.

[0035] The crude product obtained from the alkoxylation process may contain unreacted cyclic oxides, small amounts of initiator compounds, and small amounts of other organic impurities and / or water. Volatile impurities (including water and unreacted cyclic oxides) should be flash-evaporated or vaporized from the alkoxylation product. The crude product typically contains catalyst residues. These residues are usually left in the product, but can be removed if necessary.

[0036] The method of this invention can be used to prepare alkoxylated products with a hydroxyl equivalent weight of 85 g / equivalent or higher, particularly 85 g / equivalent to 350 g / equivalent, 85 g / equivalent to 300 g / equivalent, 85 g / equivalent to 250 g / equivalent, or 85 g / equivalent to 175 g / equivalent. The hydroxyl equivalent weight of the alkoxylated product is conveniently determined using a titration method such as ASTM 4274-21, which produces a number of hydroxyl groups in mg KOH / g polyol, which can be converted to equivalent weight using the following relationship: Equivalent weight = 56,100 ÷ Number of hydroxyl groups.

[0037] The alkoxylated polyols produced according to the present invention are useful raw materials for the production of polyurethanes and other polymers prepared by reacting alkoxylated polyols with polyisocyanates. These products comprise a wide variety of porous and non-porous materials with physical properties ranging from very rigid to highly flexible. The alkoxylated products are particularly useful for the preparation of rigid polyurethanes and polyurethane-isocyanurate foams. The alkoxylated monools produced according to the present invention can be used as surfactants or industrial solvents, among other applications. Alkoxylated polyols and monohydric alcohols can be amination to produce corresponding amine-terminated materials, which are then useful raw materials for the preparation of various materials, including polyureas and cured epoxy resins.

[0038] In a particular embodiment, the initiator is a polyol with a hydroxyl equivalent weight of 125 g / mol or less, particularly 75 g / mol or less, or even 50 g / mol or less, and alkoxylation continues until one to 12, particularly one to 10, one to 7, or one to 4 cyclic oxide units are added to each hydroxyl group on the initiator. The number average molecular weight of the alkoxylated product can be, for example, 100 g / mol to 1000 g / mol, 100 g / mol to 800 g / mol, 150 g / mol to 800 g / mol, or 200 g / mol to 800 g / mol, as measured relative to a polyether standard by gel permeation chromatography. In such a particular embodiment, the cyclic oxide is preferably 1,2-epoxypropane, ethylene oxide, 1,2-epoxybutane, 2,3-epoxybutane, epichlorohydrin, or any two or more mixtures thereof, wherein 1,2-epoxypropane, ethylene oxide, or mixtures thereof are 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 raw materials for the preparation of rigid polyurethane and / or polyisocyanurate polymers (including foams).

[0039] 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 epoxides to form carbonate bonds in the product. Examples of such carbonate precursors include carbon dioxide, phosgene, linear carbonates, and cyclic carbonates. Other copolymerizable monomers include carboxylic anhydrides that copolymerize with cyclic oxides to form ester bonds in the product.

[0040] The following examples are provided to illustrate the invention, but are not intended to limit the scope of the invention. Unless otherwise specified, all parts and percentages are by weight.

[0041] Catalyst preparation process

[0042] Having structure The catalyst named "Phen-2OTf" (where each A — (It is trifluoromethanesulfonate ion) is prepared according to the method described in the following literature: Chem.Eur.J. 2021, 11730.

[0043] Having structure The catalyst named "Phen-2BarF" (where each A — It is B(C6F5)3 - (Ions) were prepared according to the method described in the following literature: Chem. Eur. J. 2021, 11730.

[0044] Having structure The catalyst named "BiPy-2BarF" (where each A — It is B(C6F5)3 - (Ions) were prepared according to the method described in the following literature: Chem. Eur. J. 2021, 11730.

[0045] Having structure The catalyst named "(PyrO)2ET-2OTf" (where each A — (Trifluoromethanesulfonate ion) was prepared by combining pyridine N-oxide and 1,2-dibromoethane in an equivalent ratio of 2:5:1 in acetonitrile and heating to 70°C overnight. The resulting dihalide salt was recovered and combined with trimethylsilyl trifluoromethanesulfonate in acetonitrile, and stirred at room temperature for 30 minutes to produce the final product.

[0046] Having structure The catalyst named "(Pyr)2ET-2OTf" (where each A — (trifluoromethanesulfonate) is prepared by combining pyridine and 1,2-dibromoethane in an equivalent ratio of 2:5:1 in acetonitrile and heating to 70°C overnight. The resulting dihalide salt is recovered and combined with trimethylsilyl trifluoromethanesulfonate in acetonitrile, and stirred at room temperature for 30 minutes to produce the final product.

[0047] Examples 1 to 6 and Comparative Samples A to E

[0048] 45 g of initiator (sorbitol in Example 5, glycerol in all other cases) was charged into a stainless steel semi-batch reactor equipped with a stirrer, temperature control, nitrogen feed and monomer feed lines, and an exhaust port. A catalyst was added as a solid. The type and amount of catalyst are indicated in Table 1. The reactor was purged with nitrogen and heated with stirring to the temperature indicated in Table 1, then purged again with nitrogen to remove any solvent from the catalyst addition. While maintaining the same temperature, propylene oxide was then fed into the reactor as needed to attempt to maintain the target propylene oxide partial pressure as indicated in Table 1. The target amount of propylene oxide to be added for glycerol alkoxylation was approximately 103 g, and for sorbitol alkoxylation, 155 g; the actual feed amounts are indicated in Table 1. The time required for propylene oxide feeding (run time) is indicated in Table 1. After the monomer feed was complete, the reaction was digested at 160 °C for 2 hours, then cooled to 50 °C under nitrogen purging. After purging with nitrogen at 50°C for 10 minutes, the product was collected and the yield was calculated. The M of the product was analyzed by gel permeation chromatography against a polystyrene standard. n And polydispersity.

[0049] The catalyst activity was compared by calculating the turnover frequency (TOF) for each case. TOF reflects the number of propylene oxide molecules converted per catalytic site per unit time, as follows: .

[0050] A higher value indicates higher catalyst activity.

[0051] Dipyridinium catalysts are indicated in Table 1.

[0052] In Table 1, KH represents potassium hydride, and BF3·OEt2 represents boron trifluoride diethyl ether compound.

[0053]

[0054] As indicated by the data in Table 1, the catalyst of the present invention exhibits extremely high activity compared to the control. When glycerol is in the initiator, the turnover frequency range is approximately 270 to 400 times higher than that of KH. This higher catalytic activity results in a significantly reduced run time, thereby proportionally and effectively increasing the production capacity of manufacturing equipment. The molecular weight and polydispersity are similar to those obtained in KH catalytic runs (Comparative Sample A).

[0055] The excellent activity of (PyrO)₂Et-2OTf is significant because ultraviolet and visible light radiation is excluded from the stainless steel reactor. (PyrO)₂Et-2OTf is previously known as a photoinitiator when exposed to UV light; Example 6 shows that this catalyst can efficiently polymerize propylene oxide at elevated temperatures even in the absence of UV and visible light radiation.

[0056] Comparison with sample E shows that not all dipyridinium compounds are effective alkoxylation catalysts.

[0057] All catalysts of this invention produce alkoxylated products in which 70% to 80% of the hydroxyl groups are primary hydroxyl groups. In contrast, the KH catalyst produces products in which only 28% of the hydroxyl groups are primary hydroxyl groups. The higher proportion of primary hydroxyl groups is associated with significantly higher reactivity with polyisocyanates; therefore, this invention not only provides rapid and efficient alkoxylation but also produces alkoxylated products with significantly higher reactivity.

[0058] When Bipy-2BarF and Phen-2BarF catalysts were used for the alkoxylation of a 700 molecular weight triol under the same general conditions as in Examples 1 to 3, the alkoxylation proceeded slowly and the catalysts appeared to be deactivated.

[0059] Examples 7 and 8

[0060] Ethylene oxide polymerization was carried out using a 48-well Symyx Technologies parallel pressure reactor (PPR). Each of the 48 wells was equipped with an individually weighed glass insert containing approximately 5 mL of internal working fluid. Each well contained a top-mounted paddle stirrer.

[0061] A 0.7 mL glycerol / catalyst mixture (containing approximately 0.72 g of initiator) was loaded into each of the multiple inserts. Based on the combined weight of the initiator and ethylene oxide used in the polymerization run, this mixture provided approximately 500 ppm by weight of catalyst. Each well was pressurized with nitrogen at 50 psig (344.7 kPa) and subsequently heated to the polymerization temperature of 160 °C. Upon reaching the polymerization temperature, 0.67 mL of ethylene oxide was injected into each well, where it reacted with the initiator in the glass insert.

[0062] The internal pressure in the headspace of each well was monitored individually throughout the polymerization process. After the initial injection of ethylene oxide, the internal pressure was observed hourly, and if the pressure in any particular well had dropped below 190 psig (1.31 MPa), 0.67 mL of ethylene oxide was injected again. This was repeated after the second hour of polymerization. Four hours after the initial ethylene oxide injection, the wells were allowed to cool to room temperature and vented. The glass inserts were then allowed to stand overnight at 40–50 °C under nitrogen to allow residual ethylene oxide to evaporate; afterwards, the inserts were weighed to determine the amount of product.

[0063] The molecular weight and polydispersity (Mn) of the obtained product were analyzed by gel permeation chromatography, using polystyrene standards as a reference. w / M n ).

[0064] For Example 7, the catalyst was Phen-2OTf. 60% of ethylene oxide was converted into a polymer, producing a product with a number-average molecular weight of 285 and a polydispersity of 1.02.

[0065] For Example 8, the catalyst was Bypy-2BarF. 70% of ethylene oxide was converted into a polymer, producing a product with a number-average molecular weight of 268 and a polydispersity of 1.02.

Claims

1. A method of alkoxylating comprising: (Step I) forming a reaction mixture comprising a) a starter compound having at least one hydroxyl or thiol group and a molecular weight of 62 g / mol to 250 g / mol; b) at least one cyclic oxide; and c) a catalytically effective amount of a dipyridinium catalyst having one of the following structures: (I) and (II) wherein each A - independently represents a weakly coordinating anion, each R is independently a hydrocarbyl or inertly substituted hydrocarbyl group bonded to a carbon atom of the pyridinium group, with the proviso that any two R groups can together form a divalent moiety, each x is a number from 0 to 4, each R 1 is a divalent linking group, each R 2 is independently hydrogen, alkyl or inertly substituted alkyl, z is a number from 1 to 4, and each R 3 is independently a hydrocarbyl or inertly substituted hydrocarbyl group bonded to a carbon atom of the pyridinium group; and (step II) reacting the cyclic oxide with the starter compound in the presence of the dipyridinium catalyst at a temperature from 80 °C to 220 °C to form an alkoxylated product.

2. The alkoxylation process of claim 1, wherein the dipyridinium catalyst is selected from the group consisting of having the structure and compounds, or mixtures of any two or more of them, wherein each A - represents a monovalent anion.

3. The alkoxylation process of claim 1 or 2, wherein each A - is selected from the group consisting of tetra[perfluorophenyl]borate, tetra[3,5- bis(trifluoromethyl)phenyl]borate, and trifluoromethanesulfonate.

4. The alkoxylation process of any preceding claim, wherein the starter compound has neither a primary amino group nor a secondary amino group.

5. The alkoxylation process of any preceding claim, wherein the starter compound has from 1 to 8 hydroxyl groups.

6. The alkoxylation process of any preceding claim, wherein the starter compound is one or more of glycerol, trimethylolpropane, trihydroxyethylpropane, sucrose, and sorbitol.

7. The alkoxylation process of any preceding claim, wherein the cyclic oxide is an alkylene oxide.

8. The alkoxylation process of claim 7, wherein the alkylene oxide is one or more of ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, and 2,3-butylene oxide.

9. The alkoxylation process of any preceding claim, wherein Step II is conducted at a temperature of 150 °C to 200 °C.

10. The alkoxylation process of any preceding claim, which is conducted without exposing the reaction mixture to electromagnetic radiation in the ultraviolet and visible spectrum.

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