ALKYLENE OXIDE POLYMERIZATION USING PHOSPHONIUM CATALYSTS

Abstract

Alkoxylation reactions are performed in the presence of a phosphonium catalyst having the structure P.sup.+(XR.sup.1R.sup.2R.sup.3)A.sup.1 wherein R.sup.1 is a group having an unsubstituted or inertly substituted aromatic five-member ring having a direct bond between an atom of the aromatic five-member ring and the phosphorus atom, and each R.sup.2 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.sub.1-12 perfluoroalkyl, C.sub.1-12 alkyl, aryloxy and C.sub.1-12 alkoxy, and A is a weakly coordinating anion.

Claims

1. A compound having the structure: ##STR00014## wherein R.sup.1 is a group having an unsubstituted or 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 R.sup.2 is independently a group having an unsubstituted or 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.sub.1-12 perfluoroalkyl, C.sub.1-12 alkyl and C.sub.1-12 alkoxy, A is a weakly coordinating anion and n is the valence of A.

2. The compound of claim 1, wherein the aromatic five-member ring of the R.sup.1 group is heteroatomic.

3. The compound of claim 2, wherein R.sup.1 is selected from the group consisting of furanyl, benzofuranyl, isobenzofuranyl, thiophenyl, benzothiophenyl, benzo[c]thiophenyl, oxazolyl, benzoxazolyl, benzisoxazolyl, thiozolyl, and benzothiazolyl and wherein, in any of the foregoing, any ring carbon is optionally unsubstituted or substituted with linear, branched and/or cyclic alkyl, aryl, ether, ester, carbonate, halogen, sulfide, polysulfide, or silyl.

4. The compound of claim 1, wherein each R.sup.2 has 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.

5. The compound of claim 4, wherein each R.sup.2 is furanyl, benzofuranyl, isobenzofuranyl, thiophenyl, benzothiophenyl, benzo[c]thiophenyl, oxazolyl, benzoxazolyl, benzisoxazolyl, thiozolyl, and benzothiazolyl and wherein, in any of the foregoing, any ring carbon is optionally unsubstituted or substituted with linear, branched and/or cyclic alkyl, aryl, ether, ester, carbonate, halogen, sulfide, polysulfide, amino or silyl.

6. The compound of claim 4, wherein R.sup.1 and each R.sup.2 are identical.

7. The compound of claim 1, wherein each R.sup.2 has 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.

8. The compound of claim 7, wherein each R.sup.2 is 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.sub.1-12 alkyl, unsubstituted or inertly substituted C.sub.1-12 alkoxyl or trifluoromethyl groups.

9. The compound of claim 1, wherein one R.sup.2 has 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, and the other R.sup.2 has 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.

10. The compound of claim 1, wherein one R.sup.2 is selected from the group consisting of furanyl, benzofuranyl, isobenzofuranyl, thiophenyl, benzothiophenyl, benzo[c]thiophenyl, benzoxazolyl, oxazolyl, benzisoxazolyl, thiozolyl, and benzothiazolyl and wherein, in any of the foregoing, any ring carbon is optionally unsubstituted or substituted with linear, branched and/or cyclic alkyl, aryl, ether, ester, carbonate, halogen, sulfide, polysulfide, amino or silyl, and the other R.sup.2 is 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.sub.1-12 alkyl, unsubstituted or inertly substituted C.sub.1-12 alkoxyl or trifluoromethyl groups.

11. The compound of claim 1, wherein X is F, Cl, Br, I, OCH.sub.3, OC.sub.2H.sub.5, phenoxy, CH.sub.3, C.sub.2H.sub.5 or CF.sub.3.

12. The compound of claim 1, wherein A is selected from the group consisting of tetrakis[perfluorophenyl]borate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, trifluoromethanesulfonate (triflate), Al[OC(CF.sub.3).sub.3].sub.4, B.sub.12F.sub.12.sup.2, HCB.sub.11H.sub.5F.sub.6, B(OTeF.sub.5).sub.4, Sb(OTeF.sub.5).sub.6, Al[OC(CF.sub.3).sub.3].sub.4, Al[OCH(CF.sub.3).sub.2].sub.4 and Al[OC(CH.sub.3)(CF.sub.3).sub.2].sub.4.

13. The compound of claim 1, having any one of the structures: ##STR00015## ##STR00016## and where A.sup. is a monovalent anion.

14. An alkoxylation process, comprising: (step I) forming a reaction mixture comprising; a) a starter compound having at least one hydroxyl group, b) at least one cyclic oxide, and c) a catalytically effective amount of the compound of claim 1; and (step II) reacting the cyclic oxide b) with the starter compound a) in the presence of the compound c) to form an alkoxylated product.

15. The alkoxylation process of claim 14, wherein the starter compound a) has a formula molecular weight of 250 g/mol or less and a hydroxyl equivalent weight of up to 75 g/equivalent.

16. The alkoxylation process of claim 14, wherein the starter compound a) has one or more hydroxyl groups and no primary amino and secondary amino groups.

17. The alkoxylation process of claim 14, wherein the cyclic oxide b) is an oxirane.

18. The alkoxylation process of claim 17, 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.

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

Description

EXAMPLE 1 AND COMPARATIVE SAMPLES A-C

[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:

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

Higher values indicate greater catalyst activity.

[0045] In Table 1, KOH designates potassium hydroxide and BF.sub.3.Math.OEt.sub.2 designates boron trifluoride diethyl etherate.

##STR00013##

[0046] Catalyst P(2-F).sub.3F tetrakis(pentafluorophenyl) borate is P(2-F).sub.3F tetrakis(pentafluorophenyl) borate is made by reacting tris(2-furyl)phosphine with XeF.sub.2 in the general manner described in Chem. Sci. 2015, 6, 2016 to produce P(2-F).sub.3F.sub.2. The P(2-F).sub.3F.sub.2 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).sub.3F.sub.2 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).sub.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 .sup.1H, .sup.13C and .sup.31P NMR.

TABLE-US-00001 TABLE 1 PO partial Run PO Loading T, press., 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 ND ND 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(2-F).sub.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).