Oxyalkylation of alkanols with alkylene oxides

Details Oxyalkylation of alkanols with alkylene oxides Oxyalkylation of alkanols with alkylene oxides

2000-11-01

2001-10-16

Richter, Johann (Department: 1621)

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

Organic compounds

Oxygen containing

C568S618000

Reexamination Certificate

active

06303832

ABSTRACT:

The present invention relates to a process for the oxyalkylation of alkanols, the reaction being carried out using a heterogeneous basic catalyst, which is selected from basic aluminates; the compounds prepared therewith and their use as carrier oils for fuel detergent additives or as nonionic surfactants in detergents or cleaning agents.
The catalytic oxyalkylation of organic compounds by means of an alkylene oxide has long been known. Homogeneous or heterogeneous catalysts are in principle suitable. The reaction products are referred to as oxyalkylates or alkoxylates. Oxyalkylates of alkanols are used, for example, as carrier oils in fuel additive mixtures or as nonionic surfactants in detergents and cleaning agents.
For the synthesis of carrier oils, C
2
-C
20
-alkanols are usually used, preferably a C
13
-alcohol (tridecanol N). Preferably used alkylene oxides are propylene oxide and butylene oxide.
For the synthesis of nonionic surfactants, C
2
-C
22
-alkanols, preferably oxo alcohols, are usually used. Oxo alcohols are known to be predominantly monohydric alcohols obtainable by oxo synthesis, such as C
13
-C
15
-oxo alcohols or C
11
-oxo alcohols or mixtures thereof. A preferably used alkylene oxide is ethylene oxide.
After the oxyalkylation of the alkanol, it is necessary to remove the catalyst from the reaction product. This is particularly true for the reaction products used as carrier oils or nonionic surfactants, since the catalyst residues on the one hand can have a corrosive action and on the other hand can lead to undesired deposits and emissions during combustion in the engine space. In the case of heterogeneous catalysis, it is possible to remove the catalyst by filtration, for which purpose, however, correspondingly good filterability of the catalyst is required. In the case of homogeneous acid or base catalysis, corresponding neutralization is suitable. For example, after the use of base catalysis, the corresponding catalyst is removed from the reaction mixture by finish processes.
For example, hydrotalcite which has been rendered hydrophobic has been used for the heterogeneous catalysis of the oxylation of various organic compounds (cf. DE-A-38 43 713 or U.S. Pat. No. 4,962,237). However, the removal of said hydrotalcite by filtration is very unsatisfactory because presumably the pores of the deep filter used for this purpose become blocked and thus complicate the filtration process.
The removal of the preferably basic additive used for the homogeneous catalysis of the oxyalkylation, in particular potassium hydroxide, sodium hydroxide, alkaline earth metal oxides, alkali metal and/or alkaline earth metal carbonates and/or hydroxides, is preferably effected by neutralization with the aid of phosphoric acid with formation of the corresponding phosphate (cf. U.S. Pat. No. 4,306,943). In this process, the exact metering of the phosphoric acid is critical. Moreover, the phosphate formed must be disposed of in a landfill or incinerated.
Further processes for removing the catalyst are also known, for example adsorption on a carrier material, for example magnesium silicate, in which case the pyrophoric character of the material wet with alkoxylate is critical. In another known process, the catalyst is removed by using an ion exchanger.
It is an object of the present invention to provide an improved process for the oxyalkylation of alkanols.
We have found that this object is achieved, surprisingly, by using basic aluminates as heterogeneous catalysts for the oxyalkylation of alkanols. This makes it possible to avoid the disadvantages of the prior art processes in a surprisingly advantageous manner.
We have found, surprisingly, that basic aluminates catalyze the oxyalkylation of alkanols extremely selectively and moreover can be readily filtered off after the reaction, so that the expensive finish processes required to date need no longer be carried out. The basic aluminates furthermore have a basicity which is comparable with that of potassium hydroxide or sodium hydroxide. In addition, improved space-time yields are obtained.
We have also surprisingly found that, in comparison with the use of homogeneous catalysts, such as KOH, the use of basic aluminates as catalysts does not have an adverse effect on the performance characteristics of the reaction products when used as carrier oil or nonionic surfactant.
The present invention therefore relates firstly to a process for the oxyalkylation of alkanols, at least one alkanol being reacted with at least one alkylene oxide in a base-catalyzed reaction, wherein the reaction is carried out using a heterogeneous basic catalyst which is selected from basic aluminates.
The basic aluminates used according to the invention as a catalyst are, for example, alkali metal or alkaline earth metal aluminates, in particular sodium or potassium aluminate. However, other aluminates may also be used provided that they have sufficient basicity. Basic aluminates can be used in solid form, for example individually or in the form of mixtures of a plurality of aluminates as catalyst compositions.
Sodium aluminate is a substance having the following composition:
NaAlO
2
or Na
2
O.Al
2
O
3
which has a three-dimensional network structure (cf. Roempp Chemielexikon, 9th edition, vol. 1, under the keyword “Aluminate”, on page 131) and Hollemann/Wiberg, Lehrbuch der anorganischen Chemie, 81st-90th edition, page 647 et seq., Sauerstoffverbindungen des Aluminiums).
The novel process is not subject to any particular restrictions with regard to the alkanols and alkylene oxides which can be used.
Examples of alkanols which can be used are monohydric, dihydric, trihydric, tetrahydric and polyhydric alkanols, such as the compounds disclosed in DE-A-38 43 713, on page 3, lines 35-41 and lines 47-50, in U.S. Pat. No. 4,962,237, in column 2, lines 29-41, or in U.S. Pat. No. 4,306,943, in column 1, lines 50-58, which are hereby incorporated by reference.
If the novel process is used specifically for the preparation of carrier oils, for example, C
2
-C
20
-alkanols are used, preferably C
13
-alkanol (tridecanol N). If nonionic surfactants are specifically to be prepared, for example, C
2
-C
22
-alkanols, preferably C
13
-C
15
-oxo alcohols, C
15
-C
17
-oxo alcohols or C
9
-C
11
-oxo alcohols, e.g. C
10
-oxo alcohols and C
11
-oxo alcohols, are used.
Furthermore, the alkylene oxides to be reacted are not subject to any particular restrictions per se. For example, the compounds stated in U.S. Pat. No. 4,962,237, in column 3, lines 12-20, may be used. If carrier oils are to be synthesized, propylene oxide or butylene oxide is preferably used. In the case of the preparation of nonionic surfactants, ethylene oxide is preferably used.
The amounts of alkylene oxide used may be varied over a wide range and depend primarily on the desired property profile of the oxyalkylate and on the type of the respective alkylene oxide. The amounts are usually from 1 to 100 mol per mole of initiator (i.e. alcoholate). For example, from 1 to 20, preferably from 10 to 20, mol of propylene oxide, from 1 to 40, preferably from 18 to 30, mol of butylene oxide, and from 1 to 100, preferably from 3 to 80, mol of ethylene oxide, in each case per mole of initiator, may be used.
The novel process is preferably carried out by a procedure in which
a) the alkanol is first activated with a basic aluminate
and then
b) the activated alkanol is oxyalkylated with the alkylene oxide.
The alkanol is first mixed with the basic aluminate in an amount of from 0.1 to 1.0, preferably from 0.1 to 0.3, % by weight, based on the total weight of alkanol and alkylene oxide, and usually treated before the reaction under reduced pressure of from about 1 to 100, for example 20-40, mbar and, for example, at from 20 to 150° C., preferably from about 50 to 100° C. (for example on a rotary evaporator), for example for from about 1 to 2 hours, for the preparation of the alcoholate (initiator).
The alcoholate (initiator) formed is then reacted under pressure, for example in an autoclave, for example at from 1 to 10, usual

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