ALKOXYLATION PROCESSES USING PHOSPHONIUM CATALYSTS

Abstract

Alkoxylations are performed by reacting a cyclic oxide with a starter in the presence of certain phosphonium catalysts. The phosphonium catalysts are highly active and effective in such small quantities that it is often unnecessary to remove catalyst residues from the product. The phosphonium catalysts are very effective in alkoxylating even low molecular weight starters such as glycerol and sorbitol.

Claims

1. 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 having the structure: ##STR00014## wherein the R.sup.1, R.sup.2 and R.sup.3 independently are groups having an unsubstituted or 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, X is halogen, hydroxyl, 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 b) with the starter compound a) in the presence of the phosphonium catalyst c) to form an alkoxylated product.

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

3. The alkoxylation process of claim 1, wherein R.sup.1, R.sup.2 and R.sup.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 of claim 1, wherein R.sup.1, R.sup.2 and R.sup.3 are identical.

5. The alkoxylation process of claim 1, wherein X is fluorine, chlorine, bromine or iodine.

6. The alkoxylation process of claim 1, wherein X is a linear or branched alkoxy group containing 2-4 carbon atoms.

7. The alkoxylation process of claim 1, wherein A is selected from the group consisting of tetrakis[perfluorophenyl] borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate, Al[OC(CF.sub.3).sub.3].sub.4, HCB.sub.11H.sub.5F.sub.6, B(OTeF.sub.5).sub.4.sup., Sb(OTeF.sub.5).sub.6.sup., Al[OC(CF.sub.3).sub.3].sub.4.sup., Al[OCH(CF.sub.3).sub.2].sub.4.sup. and Al[OC(CH.sub.3)(CF.sub.3).sub.2].sub.4.sup..

8. The alkoxylation process of claim 7, wherein A is tetrakis(perfluorophenyl)borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate or trifluoromethanesulfonate.

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

10. The alkoxylation process of claim 1, wherein the starter compound a) has a formula molecular weight of 250 g/mol or less.

11. The alkoxylation process of claim 1, wherein the starter compound a) has one or more hydroxyl groups and no primary amino and secondary amino groups.

12. The alkoxylation process of claim 1, wherein the cyclic oxide b) is an oxirane.

13. The alkoxylation process of claim 12, wherein the cyclic oxide b) is one or more of ethylene oxide, 1,2-propylene oxide, 1,2-butene oxide and 2,3-butene oxide.

14. The alkoxylation process of claim 1, wherein step II is performed at a temperature of 150 to 200 C.

Description

EXAMPLES 1-11 AND COMPARATIVE SAMPLES A-C

[0051] 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. Catalyst is added as a solid. The type and amount of catalyst (based on starter) are 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 is calculated. The product is analyzed for M.sub.n and polydispersity by gel permeation chromatography against polystyrene standards.

[0052] 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:

[00001]$\mathrm{TOF}=\frac{\mathrm{mmol}\mathrm{PO}\mathrm{consumed}}{\mathrm{mmol}\mathrm{catalyst}\mathrm{run}\mathrm{time}\left(\mathrm{hr}\right)}.$

Higher values indicate greater catalyst activity.

[0053] The phosphonium catalysts are as indicated in Table 1. All are tetrakis(pentafluorophenyl)borate salts except as indicated. Those indicated with OTf designations (Ex. 5, 10) are triflate salts.

[0054] In Table 1, KOH designates potassium hydroxide and BF.sub.3.Math.OEt.sub.2 designates boron trifluoride diethyl etherate.

TABLE-US-00001 TABLE 1 PO partial pressure, Run PO Loading T, psi time Fed Yield TOF M.sub.n, Designation Catalyst (ppm) C. (kPa) (h) (mL) (g) (hr.sup.1) g/mol PDI A* KOH 4000 130 30 (207) 1.6 103.8 112.3 207 412 1.02 B* BF.sub.3OEt.sub.2 111 100 11 (76) 47.2 24.5 37.1 211 N.D. N.D. C* B(C.sub.6F.sub.5).sub.3 667 80 7 (48) 1.7 103.0 114.7 14,768 407 1.10 1 P(PFP).sub.3F 467 100 11 (76) 1.0 103.1 117.6 86,245 411 1.09 2 P(PFP).sub.3Cl 489 160 30 (207) 0.6 102.9 117.1 138,799 441 1.06 3 P(PFP).sub.3Br 489 160 30 (207) 0.6 103.1 113.4 144,077 461 1.07 4 PPh.sub.3F 378 160 30 (207) 0.6 102.9 113.8 138,367 410 1.09 5 PPh.sub.3FOTf 178 160 30 (207) 0.6 103.5 113.3 132,424 413 1.09 6 PPh.sub.3Cl 378 160 30 (207) 0.6 103.0 116.0 140,860 415 1.08 7 PPh.sub.3Br 400 160 30 (207) 0.6 102.9 115.3 139,050 442 1.06 8 PPh.sub.3I 422 100 11 (76) 3.9 103.3 114.5 21,293 410 1.09 9 P(PMP).sub.3Cl 420 160 30 (207) 0.9 102.9 113.5 92,226 395 1.10 10 PPh.sub.3CF.sub.3OTf 200 100 11 (76) 2.5 103.0 114.7 31,425 379 1.11 11 PPh.sub.3OH 400 160 30 (207) 0.6 103.1 113.5 134,566 392 1.09 *Not an example of the invention. 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. OTf indicates the phosphonium catalyst is the triflate salt.

[0055] As indicated by the data in Table 1, the catalysts of the invention are extremely active compared to the controls. Turnover frequencies range are approximately 100 to 1000 times greater than that of KOH, which is the industry workhorse propylene oxide polymerization catalyst, even when low operating temperatures and pressures are employed (e.g., Ex. 1 and 8). 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).

Parallel Pressure Reactor (PPR) Polymerization Procedure

[0056] Ethylene oxide polymerizations are performed using a 48-well Symyx Technologies Parallel Pressure Reactor (PPR). Each of the 48 wells is equipped with an individually weighed glass insert having an internal working liquid volume of approximately 5 mL. The wells each contain an overhead paddle stirrer.

[0057] 0.7 mL of a glycerol/PPh.sub.3F mixture (containing approximately 0.72 g of the starter) is charged to each of multiple inserts. This mixture provides about 500 ppm by weight of catalyst based on the combined weight of starter and ethylene oxide used in the polymerization run. Each well is pressurized with 50 psig (344.7 kPa) nitrogen and then heated to the polymerization temperature of 160 C. (Ex. 12) or 130 C. (Ex. 13). Upon reaching the polymerization temperature, 0.67 mL of ethylene oxide are injected into each well, where it reacts with the starter in the glass insert.

[0058] The internal pressure in the headspace of each well is monitored individually throughout the polymerization. Each hour after the first injection of ethylene oxide, the internal pressure is observed, and if the pressure in any particular well has fallen below 190 psig (1.31 MPa), another 0.67 mL of the ethylene oxide is injected. This is done again after the second hour of polymerization. 4 hours after the first ethylene oxide injection, the wells are allowed to cool to room temperature and vented. The glass inserts are allowed to stand under nitrogen at 40-50 C. overnight to allow residual ethylene oxide to volatilize, after which the inserts are weighed to determine the amount of product.

[0059] The resulting products are analyzed for molecular weight and polydispersity (M.sub.w/M.sub.n) by gel permeation chromatography against a polystyrene standard.

[0060] In Example 12, polymerization at 160 C. results in 75% conversion of ethylene oxide to polymer. The number average molecular weight of the product is 370 and polydispersity is 1.08. In Example 13, polymerization at 130 C. results in 94% conversion of ethylene oxide to polymer. The number average molecular weight of the product is 412 and polydispersity is 1.09. These molecular weights and polydispersities are within expected values.