ALKYLENE OXIDE POLYMERIZATION USING ALUMINUM COMPOUNDS AND CYCLIC AMIDINES

Abstract

Polyethers are prepared by polymerizing an alkylene oxide in the presence of a starter, an aluminum compound that has at least one hydrocarbyl substituent, and a cyclic amidine. The phosphorus-nitrogen base is present in only a small molar ratio relative to the amount of starter. The presence of such small amounts of cyclic amidine greatly increases the catalytic activity of the system, compared to the case in which the aluminum compound is used by itself. The product polyethers have low amounts of unsaturated polyether impurities and little or no unwanted high molecular weight fraction. Polymers of propylene oxide have very low proportions of primary hydroxyl groups.

Claims

1. A method for producing an alkylene oxide polymer or copolymer, comprising combining (i) at least one aluminum compound containing at least one trisubstituted aluminum atom, wherein at least one of the substituents of at least one trisubstituted aluminum atom is hydrocarbyl; (2) at least one cyclic amidine; (3) at least one starter; (4) at least one alkylene oxide and optionally (5) at least one comonomer that is not an oxirane, and polymerizing the alkylene oxide(s) or copolymerizing the alkylene oxide(s) and optionally the comonomer to form the alkylene oxide polymer or copolymer.

2. The method of claim 1 wherein at least one aluminum atom of the aluminum compound is substituted with one or two hydrocarbyl groups, and is substituted with one or two halogen, oxo, ether or hydride groups.

3. The method of claim 1 wherein the aluminum compound includes one or more of trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, tri-n-propyl aluminum, triisobutyl aluminum, tri-n-butyl aluminum, tri-t-butylaluminum and trioctadecylaluminum.

4. The method of claim 1 wherein the aluminum compound includes one or more of dimethyl aluminum chloride, methyl aluminum dichloride, diethyl aluminum chloride, ethyl aluminum dichloride, diisobutyl aluminum chloride, isobutyl aluminum dichloride, methyl aluminum di[(2,6-di-t-butyl-4-methyl)phenoxide] (Al(BHT).sub.2Me), dimethyl 2,6-di-t-butyl-4-methylphenoxide (AlBHTMe.sub.2) methyl aluminum di(2,6-diisopropyl)phenoxide, dimethyl aluminum (2,6-diisopropyl)phenoxide methyl aluminum di [(2,6-diphenyl) phenoxide], dimethyl aluminum (2,6-diphenyl) phenoxide, methyl aluminum di[(2,4,6-trimethyl)phenoxide], dimethyl aluminum (2,4,6-trimethyl)phenoxide, tetraethylaluminane, tetramethylaluminane, diisobutyl aluminum hydride, isobutyl aluminum dihydride, dimethyl alumimum hydride, methyl aluminum dihydride, diethyl aluminum hydride, ethyl aluminum dihydride, diisopropyl aluminum hydride, isopropyl aluminum dihydride, diethyl aluminum ethoxide, ethyl aluminum diethoxide, dimethyl aluminum ethoxide, methyl aluminum diethoxide, dimethyl aluminum fluoride, methyl aluminum difluoride, diethyl aluminum fluoride, ethyl aluminum difluoride, diisobutyl aluminum fluoride, isobutyl aluminum difluoride, dimethyl aluminum bromide, methyl aluminum dibromide, diethyl aluminum bromide, ethyl aluminum dibromide, diisobutyl aluminum bromide, isobutyl aluminum dibromide, dimethyl aluminum iodide, methyl aluminum diiodide, diethyl aluminum iodide, ethyl aluminum diiodide, diisobutyl aluminum iodide and isobutyl aluminum iodide.

5. The method of claim 1 wherein the aluminum compound includes a tetraalkylaluminoxane in which each alkyl group independently contains 1 to 6 carbon atoms.

6. The method of claim 1 wherein the cyclic amidine is a bicyclic amidine.

7. The method of claim 6 wherein the bicyclic amidine is those represented by the structure: ##STR00007## wherein X is CHR or NR.sup.1, wherein each R is independently hydrogen, unsubstituted or inertly substituted alkyl (including cycloalkyl), unsubstituted or inertly substituted phenyl or a non-protic nucleophilic group and each R.sup.1 is independently hydrogen, hydrocarbyl or inertly substituted hydrocarbyl, and m and n are each independently a positive integer.

8. The method of claim 6 wherein the bicyclic amidine is one or more of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 5-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (Me-TBD) 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU) and 6-(dibutylamino)-1,8-diazabicyclo[5.4.0]undec-7-ene, where the butyl groups are independently n-butyl, sec-butyl or t-butyl groups.

9. The method of claim 1 wherein the cyclic amidine is imidazole or an imidazole derivative corresponding to the structure: ##STR00008## wherein R.sup.3 and each R.sup.4 is independently hydrogen, unsubstituted hydrocarbyl or inertly substituted hydrocarbyl.

10. The method of claim 9 wherein the cyclic amidine is one or more of imidazole, N-methyl imidazole, N-ethyl imidazole, N-phenyl imidazole, 1,2-dimethyl imidazole, 1,2-diethyl imidazole, 1,2-diphenyl imidazole, 4,5-dimethyl imidazole, 4,5-diethylimidazole, 4,5-diphenyl imidazole, 1,4,5-trimethyl imidazole, 1,4,5-triethyl imidazole, 1,4,5-triphenyl imidazole and the like.

11. The method of claim 1 wherein the aluminum compound is present in an amount sufficient to provide 100 to 2,500 parts by weight of aluminum per million parts by weight of the alkylene oxide polymer or copolymer.

12. The method of claim 1 wherein the aluminum compound and starter are combined at a mole ratio of 0.00005 to 0.05 moles of aluminum provided by the aluminum compound per mole of starter.

13. (canceled)

14. The method of claim 1 wherein the aluminum compound and cyclic amidine are combined at a mole ratio of 1:2 to 4:1.

15. The method of claim 1 wherein: the aluminum compound is diethylaluminum chloride and the cyclic amidine is DBU, Me-TBD or TBD, and the mole ratio of the aluminum compound to the cyclic amidine is 2:3 to 2:1; the aluminum compound is diethylaluminum chloride and the cyclic amidine is DBN, and the mole ratio of the aluminum compound to the cyclic amidine is >1:1 to 2:1; the aluminum compound is ethylaluminum dichloride and the cyclic amidine is DBU or DEM, and the mole ratio of the aluminum compound to the cyclic amidine is >1:1 to 2:1; the aluminum compound is ethylaluminum dichloride and the cyclic amidine is Me-TBD or TBD, and the mole ratio of the aluminum compound to the cyclic amidine is 2:3 to 2:1; the aluminum compound is DIBAL and the cyclic amidine is DBU, Me-TBD or DBN, and the mole ratio of the aluminum compound to the cyclic amidine is 2:3 to 2:1; the aluminum compound is DIBAL and the cyclic amidine is TBD, and the mole ratio of the aluminum compound to the cyclic amidine is 1:2 to 4:1; the aluminum compound is (iBu).sub.2AlCl or Al(BHT).sub.2Me and the cyclic amidine is DBU, Me-TBD, DBN or TBD, and the mole ratio of the aluminum compound to the cyclic amidine is 1:2 to 4:1; the aluminum compound is TEDA and the cyclic amidine is DBU, Me-TBD or DBN, and the mole ratio of the aluminum compound to the cyclic amidine is 2:3 to 2:1; the aluminum compound is TEDA and the cyclic amidine is TBD, and the mole ratio of the aluminum compound to the cyclic amidine is 1:5 to 3:1 or the aluminum compound is one or more of trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, tri(n-propyl) aluminum, triisobutyl aluminum, tri(n-butyl)aluminum, tri(t-butyl) aluminum, tri(octadecyl)aluminum, and the cyclic amidine is one or more of DBU, Me-TBD, DBN or TBD and the mole ratio of the aluminum compound to the cyclic amidine is 2:3 to 4:1.

16. (canceled)

17. The method of claim 1 wherein the starter contains 2 to 8 hydroxyl groups and has an equivalent weight of 30 to 250.

18. The method of claim 1 wherein the alkylene oxide is propylene oxide, ethylene oxide or a mixture of propylene oxide and ethylene oxide.

19. The method of claim 1 wherein the starter is a homopolymer of propylene oxide and/or a random or block copolymer of propylene oxide in which no more than 25% of the hydroxyl groups are primary, which starter has a hydroxyl equivalent weight of at least 125 up to 1000 g/equivalent, and the alkylene oxide is ethylene oxide.

20. A polyether polyol being a homopolymer of propylene oxide or random copolymer of propylene oxide and ethylene oxide, the polyether polyol being prepared by homopolymerizing propylene oxide or a mixture of at least 70% by weight propylene oxide and correspondingly up to 30% by weight ethylene oxide, based on the weight of alkylene oxides polymerized, in the absence of any comonomer that is not an oxirane, to form the polyether polyol, characterized in that a) the polyether has a hydroxyl equivalent weight of at least 500 up to 4000 g/equivalent; b) the polyether has a nominal hydroxyl functionality of 2 to 8; c) the polyether has no more than 0.01 meq/g of terminal unsaturation; d) the polyether has a polydispersity (M.sub.w/M.sub.n) by gel permeation chromatography of no more than 1.10; e) the polyether contains no more than 2000 parts by million by weight (ppm) based on polyether polyol weight, of a fraction having a molecular weight by GPC of 40,000 g/mol or more; and f) no more than 12% of the hydroxyl groups of the polyether are primary hydroxyl groups as determined by ASTM D-4273 or equivalent method, wherein at least 90% of the weight of the polyether is oxypropylene and/or oxyethylene units.

21. A polyether polyol being a propylene oxide homopolymer or random copolymer of propylene oxide and ethylene oxide, the polyether polyol being prepared by homopolymerizing propylene oxide or a mixture of at least 90% by weight propylene oxide and correspondingly up to 10% by weight ethylene oxide, based on the weight of alkylene oxides polymerized, in the absence of any comonomer that is not an oxirane, to form the polyether polyol, the polyether polyol being further characterized in a) having a hydroxyl equivalent weight of 1000 to 2500 g/equivalent, b) having a nominal functionality of 2 to 8; c) having no more than 0.007 meq/g of terminal unsaturation; d) having a polydispersity (M.sub.w/M.sub.n) of no more than 1.07; and e) containing no more than 1200 ppm, of a fraction having a molecular weight by GPC of 40,000 g/mol or more, wherein at least 90% of the weight of the polyether is oxypropylene and/or oxyethylene units.

22. The polyether polyol of claim 21 wherein no more than 8% of the hydroxyl groups are primary hydroxyl groups.

Description

EXAMPLES 1-6 AND COMPARATIVE SAMPLE A

[0104] In these polymerizations, the starter is a 700 molecular weight, trifunctional poly(propylene oxide) and the aluminum compound is diethylaluminum chloride (Et.sub.2AlCl). The amount of aluminum compound in each case is 2000 parts per million based on the weight of the starter (ppm). The mole ratio of aluminum compound to the cyclic amidine initially present is as indicated in Table 1; this ratio is also the mole ratio of aluminum atoms to cyclic amidine. The polymerization temperature is 160° C. The cyclic amidine is diazabicycloundecene (DBU), methyl-triazabicyclodecene (Me-TBD), 1,8-diazabicyclo-7-undecene (DBN) or triazabicyclodecene (TBD), as indicated in Table 1, as are the amount of product produced, the % of hydroxyl groups that are primary, the number average molecular weight and the polydispersity (PDI, M.sub.w/M.sub.n).

TABLE-US-00001 TABLE 1 PO Polymerizations with Et.sub.2AlCl Al:cyclic ppm Al Cyclic amidine Yield, %1° Sample compound amidine ratio.sup.1 g OH PDI M.sub.n Comp. 2000 None N/A 1.50 7 1.08 1636 A* Ex. 1 2000 DBU 1:1 3.09 4 1.03 3865 Ex. 2 2000 Me- 1:1 2.67 5 1.03 3233 TBD Ex. 3 2000 DBN 1:1 0.99 5 1.03 1064 Ex. 4 2000 TBD 1:2 0.80 8 1.03 942 Ex. 5 2000 TBD 1:1 3.04 5 1.03 3829 Ex. 6 2000 TBD 2:1 2.39 4 1.04 2761 *Comparative. .sup.1Mole ratio, aluminum compound to cyclic amidine.

[0105] DBU and Me-TBD, at a mole ratio of 1:1 relative to the aluminum compound, provides a large increase in polymerization rate and product molecular weight, compared with the control which lacks any cyclic amidine compound. DBN at the same level provides no such increase at this particular ratio of Et.sub.2AlCl:DBN; better results are expected at a higher ratio, as suggested by the results with TBD (Examples 4-6). Examples 4-6 demonstrate the effect of Al:cyclic amidine ratio with TBD. A lower ratio (i.e., high relative amount of TBD), as in Ex. 4, appears to suppress catalytic activity, leading to a lower yield. Ratios of 1:1 and 2:1 lead to very large increases in both yield and product molecular weight.

EXAMPLES 7-13 AND COMPARATIVE SAMPLE B

[0106] In these polymerizations, the starter is a 700 molecular weight, trifunctional polypropylene oxide), the alkylene oxide is propylene oxide and the aluminum compound is ethylaluminum dichloride (EtAlCl.sub.2). The amount of aluminum compound in each case is as indicated in Table 2. The mole ratio of aluminum compound to the cyclic amidine in each case is as indicated in Table 2; this ratio is also the mole ratio of aluminum atoms to cyclic amidine in each case. The polymerization temperature is 160° C. The cyclic amidine is as indicated in Table 2, as are the amount of product produced, the % of hydroxyl groups that are primary, the number average molecular weight and the polydispersity (PDI, M.sub.w/M.sub.n).

TABLE-US-00002 TABLE 2 PO Polymerizations with EtAlCl.sub.2 Al:cyclic ppm Al Cyclic amidine Yield, %1° Sample compound amidine ratio.sup.1 g OH PDI M.sub.n Comp. 2000 None N/A 1.41 33  1.06 1669 B* Ex. 7 2000 DBU 1:1 1.29 5 1.04 1570 Ex. 8 2100 DBN 1:1 0.88 4 1.03 1029 Ex. 9 2100 Me- 1:1 2.98 5 1.03 3145 TBD Ex. 10 2100 TBD 1:2 0.82 ND ND ND Ex. 11 2100 TBD 1:1 2.84 5 1.03 3404 Ex. 12 2100 TBD 2:1 2.99 5 1.08 3544 Ex. 13 2100 TBD 4:1 0.73 4 1.07  871 *Comparative. ND—not done. .sup.1Mole ratio, aluminum atoms to cyclic amidine.

[0107] At a mole ratio of 1:1, DBU and DBN do not increase yield or product molecular weight compared to the case in which no cyclic amidine compound is present. The data using TBD (Ex. 10-13) suggest that DBU and DBN will provide benefits at higher ratios of aluminum atoms to DBU or DBN. Me-TBD provides a large increase in yield even when present at the 1:1 mole ratio. Examples 10-13 again demonstrate the sensitivity of aluminum to TBD ratio. Excellent results are seen at the 1:1 and 2:1 ratios, but only small yields and low product molecular weights are obtained at the 1:2 and 4:1 ratios.

EXAMPLES 14-20 AND COMPARATIVE SAMPLE C

[0108] Polymerizations are performed in the same general manner as in the previous examples, using various cyclic amidines as indicated in Table 3. The aluminum compound is diisobutyl aluminum hydride (DIBAL). The mole ratio of DIBAL to the cyclic amidine is as indicated in Table 3, as are the amount of DIBAL and the results. The mole ratio of DIBAL to the cyclic amidine is also the mole ratio of aluminum atoms to cyclic amidine in each case.

TABLE-US-00003 TABLE 3 PO Polymerizations with DIBAL Al:cyclic Al ppm Al Cyclic amidine Yield, %1° Sample compound compound amidine ratio.sup.1 g OH PDI M.sub.n Comp. C* DIBAL 2000 None N/A 1.19 31 1.06 1392 Ex. 14 DIBAL 2350 DBN 1:1 1.91 5 1.03 2214 Ex. 15 DIBAL 2350 Me-TBD 1:1 2.02 5 1.03 2332 Ex. 16 DIBAL 2350 DBU 1:1 2.66 5 1.02 3016 Ex. 17 DIBAL 2100 TBD 1:2 1.60 5 1.08 1860 Ex. 18 DIBAL 2100 TBD 1:1 2.85 5 1.07 3431 Ex. 19 DIBAL 2100 TBD 2:1 2.52 7 1.08 2894 Ex. 20 DIBAL 2100 TBD 4:1 1.78 10 1.08 2011 *Comparative. .sup.1Mole ratio, aluminum compound to cyclic amidine.

[0109] All of the cyclic amidines provide increases in yield and product molecular weight when used with DIBAL. The data with TBD indicates that DIBAL:cyclic amidine combinations are less sensitive to DIBAL:cyclic amidine ratio than are some other aluminum compounds, although best results are still seen at the 1:1 and 2:1 ratios.

EXAMPLES 21-24 AND COMPARATIVE SAMPLES D-F

[0110] Polymerizations are performed in the same general manner as in the previous examples, using various aluminum compounds as indicated in Table 4, in combination with TBD. The aluminum compounds are di(isobutyl)aluminum chloride (iBu.sub.2AlCl),

##STR00006##

The mole ratio of aluminum compound to the cyclic amidine is as indicated in Table 4, as are the amount of aluminum compound and the results. The mole ratio of aluminum compound to the cyclic amidine is also the mole ratio of aluminum atoms to cyclic amidine in each case.

TABLE-US-00004 TABLE 4 PO Polymerizations Using Various Al Compounds and TBD Al:cyclic Al ppm Al Cyclic amidine Yield, %1° Sample compound Compound amidine ratio.sup.1 g OH PDI M.sub.n Comp. D* (iBu).sub.2AlCl 2950 None N/A 1.68 16  1.05 1846 Ex. 21 (iBu).sub.2AlCl 2950 TBD 1:1 2.75 4 1.03 3281 Comp. E* Al(BHT).sub.2Me 2000 None N/A 0.83 ND 1.04 1045 Ex. 22 Al(BHT).sub.2Me 2000 TBD 1:1 1.27 6 1.03 1568 Ex. 23 Al(OiPrPh).sub.2Me 6600 TBD 1:1 2.00 ND 1.03 2361 Comp. F* Al(OtriPh).sub.2Me 8850 None N/A 1.41 ND 1.06 1592 Ex. 24 Al(OtriPh).sub.2Me 8850 TBD 1:1 2.75 ND 1.03 3352 *Comparative. ND—not done. .sup.1Mole ratio, aluminum compound to cyclic amidine.

[0111] In each case, the addition of TBD leads to a large increase in yield and product molecular weight.

EXAMPLES 25-32 AND COMPARATIVE SAMPLE G

[0112] Polymerizations are performed in the same general manner as in the previous examples, using tetraethyldialuminoxane (TEDA) in combination with various cyclic amidines as indicated in Table 5. The mole ratio of TEDA to the cyclic amidine is as indicated in Table 5, as are the amount of TEDA and the results. Because TEDA contains two aluminum atoms, the mole ratio of aluminum atoms to cyclic amidine in each case is double the mole ratio of TEDA to the cyclic amidine reported in Table 5.

TABLE-US-00005 TABLE 5 PO Polymerizations Using TEDA Al:cyclic Al ppm Al Cyclic amidine Yield, %1° Sample compound compound amidine ratio.sup.1 g OH PDI M.sub.n Comp. G* TEDA 3100 None N/A 1.47 36  1.06 1657 Ex. 25 TEDA 1550 DBN 1:1 3.04 5 1.03 3361 Ex. 26 TEDA 1550 Me-TBD 1:1 0.80 4 1.03  971 Ex. 27 TEDA 1550 DBU 1:1 2.79 5 1.03 3206 Ex. 28 TEDA 1550 TBD 1:8 0.84 ND ND ND Ex. 29 TEDA 1550 TBD 1:4 2.06 ND 1.03 2556 Ex. 30 TEDA 1550 TBD 1:2 2.91 5 1.03 3579 Ex. 31 TEDA 1550 TBD 1:1 2.79 6 1.03 3357 Ex. 32 TEDA 1550 TBD 2:1 2.45 9 1.04 2831 *Comparative. ND—not done. .sup.1Mole ratio, aluminum compound to cyclic amidine.

[0113] The combination of TEDA with DBN, DBU and TBD provides a large increase in yield and molecular weight, compared to the case of TEDA by itself. Me-TBD does not lead to such increases at the 1:1 ratio evaluated, but is expected to provide yield and molecular weight increases at different ratios of TEDA to Me-TBD. At very low TEDA-TBD ratios, as in Example 28, the TBD has little effect on yield or molecular weight, but otherwise the TEDA/TBD combination exhibits a large positive effect over a range of TEDA:TBD ratios.

EXAMPLES 33-42

[0114] Various combinations of aluminum compound and cyclic amidine are evaluated in propoxylations of small molecule starters. The starters are glycerin, sorbitol, ortho-toluene diamine (oTDA), and bis(3-aminopropyl) methyl amine (BAPMA). The cyclic amidine is TBD in all cases. The mole ratio of aluminum compound to TBD is 1:1 in all cases; the mole ratio of aluminum atoms to cyclic amidine is also 1:1. Polymerizations are performed in the same general manner as in the previous examples. The aluminum compound is as indicated in Table 6, as are the results of the polymerizations.

TABLE-US-00006 TABLE 6 PO Polymerizations from Small Molecules Using TBD Starter Al ppm Al molecular Yield, Sample compound compound Starter weight g PDI M.sub.n Ex. 33 Et.sub.2AlCl 2000 glycerin 92 1.73 1.06 304 Ex. 34 EtAlCl.sub.2 2000 glycerin 92 1.75 1.07 302 Ex. 35 Al(BHT).sub.2Me 8000 glycerin 92 1.74 1.06 308 Ex. 36 Et.sub.2AlCl 2000 sorbitol 182 1.37 1.05 462 Ex. 37 EtAlCl.sub.2 2000 sorbitol 182 1.28 1.05 462 Ex. 38 Al(BHT).sub.2Me 8000 sorbitol 182 1.48 1.05 439 Ex. 39 Et.sub.2AlCl 2000 oTDA 122 2.47 1.01 377 Ex. 40 EtAlCl.sub.2 2000 oTDA 122 2.57 1.01 374 Ex. 41 Et.sub.2AlCl 2000 BAPMA 142 2.19 1.07 337 Ex. 42 EtAlCl.sub.2 2000 BAPMA 142 2.19 1.06 330

[0115] As demonstrated by the data in Table 4, the combination of various aluminum compounds with TBD results in the effective propoxylation of various low molecular weight hydroxyl-containing and amine-containing starters. As before, polydispersity remains low.

EXAMPLES 43-45 AND COMPARATIVE SAMPLES H-J

[0116] Various combinations of aluminum compound and TBD are evaluated in ethoxylations of the 700 molecular weight triol starter described in previous examples. The ethoxylations are performed with and without TBD. The mole ratio of aluminum compound to TBD is 1:1 in all cases in which TBD is present; the mole ratio of aluminum atoms to cyclic amidine is also 1:1 in those cases. Polymerizations are performed in the same general manner as in the previous examples. The aluminum compound is as indicated in Table 7, as are the results of the polymerizations.

TABLE-US-00007 TABLE 7 EO Polymerizations Using TBD ppm Cyclic Yield, %1° Sample Catalyst catalyst amidine g OH PDI M.sub.n Comp. Et.sub.2AlCl 2000 None 1.11 60  1.11 1293 H* Ex. 43 Et.sub.2AlCl 2000 TBD 2.69 4 1.07 3641 Comp. EtAlCl.sub.2 2000 None 1.03 ND 1.07 1400 I* Ex. 44 EtAlCl.sub.2 2000 TBD 2.59 5 1.07 3508 Comp. Al(BHT).sub.2Me 8000 None 1.02 35  1.07 1360 J* Ex. 45 Al(BHT).sub.2Me 8000 TBD 2.37 ND 1.06 3253 *Comparative. ND is not determined.

[0117] The data in Table 7 shows that ethylene oxide is successfully polymerized onto a 700 molecular weight triol starter using an aluminum catalyst/cyclic amidine system.

Comparative Samples K-Q

[0118] PO polymerizations are performed in the same general manner as in the previous examples, using AlCl.sub.3 or tris(diisopropoxylaluminum) phosphate (TDIPAP) as the aluminum compound in combination with TBD. The mole ratio of aluminum compound to TBD is as indicated in Table 8, as are the amount of aluminum compound and the results.

TABLE-US-00008 TABLE 8 PO polymerizations Using AlCl.sub.3 or Tri(diisopropylaluminum) phosphate Al Al ppm Al compound:TBD Sample compound compound ratio.sup.1 Yield, g Comp. K* AlCl.sub.3 2000 N/A 0.79 Comp. L* AlCl.sub.3 2000 2:1 0.75 Comp. M* AlCl.sub.3 2000 1:1 0.76 Comp. N* AlCl.sub.3 2000 1:2 0.74 Comp. O* TDIPAP 2950 N/A 1.02 Comp. P* TDIPAP 2950 1:1 1.05 Comp. Q* TDIPAP 2950 1:3 0.86 *Comparative. .sup.1Mole ratio, aluminum compound to TBD.

[0119] Low yields are obtained in each case despite the presence of TBD, which is shown above to provide enhanced polymerization rates when used in conjunction with other aluminum catalysts.

EXAMPLES 46-57 AND COMPARATIVE SAMPLES R AND S

[0120] Larger-scale propoxylations of the 700 molecular weight triol starter are performed in a semi-batch reactor using various aluminum compounds and TBD as the cyclic amidine. The cyclic amidine is omitted in Comp. Sample R. The aluminum compound:cyclic amidine molar ratio in each of Examples 46-53 and 55-57 is 1:1; this ratio is 2:1 for Example 54.

[0121] The amount of PO fed, the run time and yield are indicated in Table 9, together with the % primary hydroxyl groups, polydispersity and M. of the product. Less PO is fed in Comparative Samples R and S and in Example 47 due to slow rates of polymerization.

TABLE-US-00009 TABLE 9 PO partial Al ppm Al Cyclic pressure PO fed Run Time Yield %1 Sample compound Compound amidine (psi) (mL) (hr) (g) OH PDI M.sub.n R* TEDA 1555 None 30 34 19.6 56 ND 1.04 1356 46 TEDA 1555 TBD 30 164 11.3 157 ND 1.03 3633 47 Al(BHT).sub.2Me 8000 TBD 8 98 62.2 109 ND 1.04 2477 48 Al(BHT).sub.2Me 8000 TBD 20 164 13.5 165 6 ND ND 50 Al(BHT).sub.2Me 8000 TBD 30 164 12.8 161 ND 1.04 3647 51 Et.sub.2AlCl 2000 TBD 20 164 19.5 163 5 1.03 3612 52 EtAlCl.sub.2 2000 TBD 20 164 24.5 158 ND 1.04 3512 53 AlMe.sub.3 1200 TBD 30 164 15.2 157 ND 1.03 3544 54 AlMe.sub.3 1200 TBD** 30 164 11.5 158 ND 1.03 3594 S* AlEt.sub.3 1900 None 30 100 22.4 106 22  1.12 2035 55 AlEt.sub.3 1900 TBD 30 164 26.6 153 7 1.03 3463 56 AlEt.sub.3 1900 DBU 30 164 12.8 161 4 1.03 3707 57 AlEt.sub.3 1900 MTBD 30 164 8.4 160 4 1.03 3749 *Comparative. **Aluminum catalyst:TBD mole ratio is 2:1 in this example; the mole ratio of Al compound to cyclic amidine is 1:1 for all other examples.

[0122] Large increases in yield and molecular weight are again seen in these semi-batch polymerizations when the cyclic amidine is present. Polydispersity and the proportion of primary hydroxyl groups each are quite low. The results with AlMe.sub.3 and AlEt.sub.3 are particularly surprising in that low proportions of primary hydroxyl groups are obtained. Trialkyl aluminum catalysts by themselves are known to be poorly stereospecific, promoting both the head-to-tail and head-to-head polymerizations of propylene oxide. This phenomenon is illustrated by Comparative Sample S, in which 22% of the hydroxyl groups are primary. Including the cyclic amidine not only increases yield and molecular weight but also promotes greater stereospecificity, yielding a product having a low proportion of primary hydroxyl groups.