Process for the preparation of polyether polyols

Details Process for the preparation of polyether polyols Process for the preparation of polyether polyols

2002-10-22

2003-09-23

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Aluminum containing

C556S001000, C556S021000, C556S174000, C556S182000, C568S006000, C568S618000, C568S620000, C526S266000, C526S273000, C502S152000

Reexamination Certificate

active

06624321

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a process for the preparation of polyether polyols by the reaction of alkylene oxides and compounds containing active hydrogens in the presence of specific Lewis acid metal compounds as catalysts, novel bis(perfluoroalkylsulfonic acid) compounds of elements from Group 13 of the Periodic Table of the Elements and a process for the preparation thereof, and the use thereof as catalysts for ring-opening polymerization of cyclic ethers.
Polyether polyols can be produced by a polyaddition reaction between alkylene oxides such as, for example, ethylene oxide, propylene oxide, butylene oxide, and compounds containing active hydrogen atoms, such as alcohols, amines, acid amides, phenols, and are used, inter alia, for the preparation of polyurethane plastics, surfactants and lubricants. Industrial polyaddition reactions between epoxides and starting compounds generally takes place by alkali catalysis. The alkali catalysts predominantly used are alkali hydroxides. Disadvantages of alkali hydroxide catalyzed polyether polyol preparation include the long reaction times (i.e., >5 hours) and the labor-intensive working-up of the product which is necessitated by neutralization of the alkaline polymer. See, for example, U.S. Pat. Nos. 4,129,718, 4,482,750 and 4,029,879, J.P. Patent Number 73026391, Encyclopedia of Polymer Science & Eng., Vol. 6, New York 1986, pages 273 to 307). A further problem is the base-catalyzed rearrangement of epoxides, for example propylene oxide, to allyl or propenyl alcohols, which takes place as a side-reaction and leads to monofunctional polyethers having a terminal double bond.
Acid catalysis, in particular with Lewis acids such as, for example, boron trifluoride, has also long been known, in addition to basic catalysis, for polyaddition reactions between alkylene oxides and starting compounds. Acid catalysis for the preparation of polyether polyols has the disadvantages that side reactions (for example formation of volatile low molecular weight cyclic ethers) are favored to an increased degree, hydroxyl groups are substituted by acid anions, and the relative molar mass distribution of the polyols is broader than that which typically occurs when compared to similar products prepared by base catalysis. Further disadvantages are the difficulty of separating (Lewis) acid catalysts and their sensitivity to hydrolysis, which necessitates the use of special materials (for example enamels) in the reaction apparatus used. Furthermore, the high catalytic reactivity of acid catalysts makes the reaction difficult to control.
U.S. Pat. No. 4,543,430 describes a process for the monoalkoxylation of hydroxylized compounds in the presence of trifluoromethane sulfonic acid salts. The alcohol-epoxy ratio must always be ≧2 in order to form only the monoaddition product.
A process for the preparation of polyethers by the reaction of diepoxides with dihydroxides in the presence of metal triflate salts is described in EP 493,916. The process requires deactivation of the catalyst.
In order to increase selectivity, EP-A 569,331 proposes a process for the preparation of additional products by the reaction of an alcohol with an epoxide compound, in which the catalysts comprises a complex metal compound of a metal from the main or subgroups of the Periodic Table of the Elements with sulfonate radicals of a perfluoro-containing, alkanesulfonic acid and at least one weakly bonded neutral, unidentate or multidentate ligand is used. A metal complex compound corresponding to the formula La(CH
3
CN)
x
(H
2
O)
y
(CF
3
SO
3
)
3
is particularly suitable for the latter process (see claim 12 of EP-A 569,331). Disadvantages of the latter metal complex catalysts with regard to the process for the preparation of polyether polyols include the difficulty of separating and recovering completely the complex system of metal perfluoroalkylsulfonate and ligands from the polyol reaction mixture, and the low catalytic activity of the latter metal complex compounds, such that large quantities of catalyst must be used for the process for the preparation of polyethers. Polyether preparation with the latter metal complex compounds would therefore be highly uneconomical.
U.S. Pat. Nos. 4,721,816 and 4,721,817 describe a process for the preparation of alkanol-alkoxylate products in the presence of catalysts which are obtained by the reaction of one or more aluminum compounds and a sulfur-containing or phosphorus-containing acid. This process is characterized in that corrosive acids are used which have the disadvantages described above. Furthermore, a two-component system, such as that described above, is very demanding as to precise dispensing of the two components. Comparative Examples show that the aluminum component alone has only very low catalytic activity.
It has surprisingly now been found that, without the simultaneous presence of ligands, accelerators or co-catalysts, specific metal compounds enable polyaddition reactions to take place between epoxides and starting compounds having active hydrogen atoms, with high selectivity and catalytic activity. These compounds in a catalytically active quantity show (even after hydrolysis) neutral to slightly acidic behavior. That is to say that these compounds have pH values of ≦7.0. Consequently, it is possible to dispense with a neutralization of the catalyst at the end of the reaction.
SUMMARY OF THE INVENTION
The present invention therefore provides a process for the preparation of polyether polyols from alkylene oxides and starting compounds which contain active hydrogen atoms. This process is carried out in the presence of metal compounds which correspond to the general formula (I):
(X)
n
M(E—R—E′
I
)
m
  (I)
wherein:
X: represents a halide, thiolate, sulfinate, sulfonate, sulfate, amide, or carboxylate;
M: represents a metal from Group 13 of the Periodic Table of the elements;
E: represents oxygen, sulfur, selenium, NR
1
or PR
1
;
 wherein:
R
1
: represents a hydrogen atom or a C
1
-C
20
hydrocarbon radical, preferably a C
1
-C
10
hydrocarbon radical, which may be alkyl or aryl;
R: represents a C
1
-C
30
hydrocarbon bridge which may be an alkylene, an arylene or an aralkylene bridge, and wherein R can form one or more rings with R
1
;
E′: represent a hydrogen atom, a C
1
-C
20
hydrocarbon radical, preferably a C
1
-C
10
hydrocarbon radical, which may be alkyl or aryl, OR
2
, NR
2
, R
3
, halogen, SR
2
or PR
2
R
3
, and wherein:
R
2
and R
3
: are the same or different, and each independently represents a hydrogen atom or a C
1
-C
10
hydrocarbon radical which may be alkyl, aryl or aralkyl, and wherein R
2
can form one or more rings with R
3
or R, and/or R
3
can form one or more rings with R or R
2
, and/or two or more ERE′ units can form one or more rings;
n: represents 1 or 2;
m: equals (3−n);
and
I: represents an integer from 1 to 10.
The process according to the invention is generally carried out at temperatures of from 40 to 200° C. and at total pressures of from 0 to 20 bar, and, optionally, in the presence of an inert organic solvent.
Examples of alkylene oxides which are used are C
1
-C
20
alkylene oxides, preferably ethylene oxide, propylene oxide, butylene oxide and mixtures thereof. The building of the polyether chains by alkoxylation may be carried out with only one monomeric epoxide, but may also take place in either random or block manner with two or three different monomeric epoxides. Further details are to be found in “Ullmanns Encyclopädie der industriellen Chemie”, English language edition. 1992, Vol. A21, pages 670 to 671.
Compounds containing active hydrogen atoms, including those compounds preferably having molecular weights of 18 to 400 and having 1 to 8 hydroxyl, thiol and/or amino groups are suitable as the starting compounds in accordance with the present invention. The following compounds may be named as examples: ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,4-butanediol, hexamethylene glycol, bisphenol

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