Use of hydrophobized hydrotalcites as catalysts for ethoxylation

Details Use of hydrophobized hydrotalcites as catalysts for ethoxylation Use of hydrophobized hydrotalcites as catalysts for ethoxylation

1992-12-02

1994-03-08

Prescott, Arthur C.

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

Organic compounds

Fatty compounds having an acid moiety which contains the...

554148, 554154, 568618, 568626, 544401, 558260, 560160, 560179, 502341, B01J 2302, C07C 4103, C07C 4300, C07C 6922

Patent

active

052929108

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to the use of hydrophobicized hydrotalcites corresponding to general formula I: 44 carbon atoms or two anions of aliphatic monocarboxylic acids containing 2 to 34 carbon atoms and the conditions 1<x<5, y.gtoreq.2x+2 {y+2(m+n)}=2x+3, m+n.ltoreq.0.5 m.gtoreq.0, n>0, and 0<z<10 apply, as catalysts for the ethoxylation or propoxylation of compounds containing active H atoms and of fatty acid esters selected from the group consisting of esters of optionally hydroxy-substituted fatty acids containing 2 to 22 carbon atoms with monoalkanols containing 1 to 22 carbon atoms and of partial esters and full esters of optionally hydroxy-substituted fatty acids containing 2 to 22 carbon atoms with polyols containing 2 to 12 carbon atoms and 2 to 6 hydroxyl groups.


STATEMENT OF RELATED ART

Hydrotalcite is a natural mineral having the ideal formula Mg.sub.6 Al.sub.2 (OH).sub.16 CO.sub.3.4H.sub.2 O, the structure of which is derived from that of brucite (Mg(OH).sub.2). Brucite crystallizes in a layer structure with the metal ions in octahedral vacancies between two layers of close-packed hydroxyl ions, only every second layer of the octahedral vacancies being occupied. In hydrotalcite, some magnesium ions are replaced by aluminum ions so that the layer packet acquires a positive charge. This is equalized by the anions which are situated in the interlayers together with zeolitic water of crystallization. The layer structure is clear from the X-ray powder diagram (ASTM Card No. 14-191) which may be used for characterization.
Synthetically produced hydrotalcites are also known, cf. for example DE-C 1 592 126, DE-A 3 346 943, DE-A 3 306 822 and EP-A 0 207 811.
In natural and synthetic products, the Mg.sup.2+ :Al.sup.3+ ratio can vary between about 1 and 5. The OH.sup.- :CO.sub.3.sup.2- ratio can also so vary. Natural and synthetic hydrotalcites can be represented in approximate terms by general formula II: the composition of the hydrotalcites, particularly in their water content, lead to line shifts in the X-ray diffractogram.
Natural or synthetic hydrotalcites continuously give off water on heating or calcination. The elimination of water is complete at 200.degree. C. It can be shown by X-ray diffraction that the structure of the hydrotalcite is still intact. Any further increase in temperature leads to degradation of the structure with elimination of hydroxyl groups (as water) and carbon dioxide. Natural hydrotalcites and hydrotalcites synthesized by various methods, for example in accordance with the publications cited above, show generally similar behavior on calcination.
Calcined hydrotalcites have already been used with excellent results as ethoxylation and propoxylation catalysts, cf. DE-A 38 43 713. However, they are attended by the disadvantage that they have to be converted from the natural and synthetic hydrotalcites into a calcined form suitable for catalytic purposes by heating for several hours, for example at temperatures of 400.degree. to 600.degree. C.
Hydrophobicized hydrotalcites, in which the carbonate ions are completely or partly replaced by anions of acids, for example even fatty acids, have already been used as stabilizers for thermoplastic resins, cf. DE-C 30 19 632.


DESCRIPTION OF THE INVENTION



SUMMARY OF THE INVENTION

The present invention is based on the discovery that hydrophobicized hydrotalcites are suitable for the ethoxylation or propoxylation of compounds containing active H atoms and of fatty acid esters. This discovery is surprising insofar as untreated natural and synthetic hydrotalcites, i.e. those in non-calcined form, are not active as ethoxylation or propoxylation catalysts.
In the context of the invention, compounds containing active H atoms are, for example, fatty alcohols, fatty acids and amines, which form nonionic detergents on ethoxylation or propoxylation. A typical example of this is the reaction of fatty alcohols typically containing 10 to 18 carbon atoms with ethylene oxide and/or propylene oxide in the pres

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