CA2053900A1 - Calcined hydrotalcites as catalysts for ethoxylating or propoxylating fatty acid esters - Google Patents

Abstract

Use of calcined hydrotalcites as catalysts for the ethoxylation or propoxylation of fatty acid esters Abstract of the disclosure Calcined hydrotalcites, as catalysts for the ethoxylation or propoxylation of fatty acids having 8 to 22 carbon atoms with monoalkanols having 1 to 22 carbon atoms or polyols having 2 to 6 hydroxyl groups and 2 to 15 carbon atoms, give the desired products in high yields and with a narrow range of the homolog distribution of the ethoxylation or propoxylation products.

Description

' Henkel KommanditgeSellschaft auf AXtien , D 8579 2~39~0 P 1329g/89 M/YH/UM ~#40) 27 April 1989 Use of calcined hydrotalcites a~ catalysts for the e~hoxylation or propoxylation of fatty a~id esters.
The invention relate to the use of calcined hydrotalcites a~ catalysts for the ethoxylation or propoxylation of fatty acid ester~ selected from the group formed by e~ters of op~ionally hydroxy-substituted fatty acid~ having 8 to 22 carbon atom~3 with monoalkanols having 1 to 22 carbon atom~l and by parti~l esters and full e~ters of optionally hydroxy-sub~ituted fatty acids i having 8 to 22 carbon atom~ with polyols having 2 to 12 carbon atoms and 2 to 6 hydroxyl groups.
Hydrotalcite i8 a natural mineral hav1ng the . ideal for~ula ~g6Alz(OH)l6Co3 . 4H2O

the structure oP which i-~ derived from that of brucite ~g(OH)2). ~rucite crystallize~ in a layer structur~ with ~: the metal ions in octahedral vacancie~ between two layers : of closely packed hydroxyl ion~, only every second layer of the oc~ahedral vacancies being occupi~d. In hydro . talcite, soms magnesium ion ar~ replaced by aluminum ions, which gives the layer package a positive charge.
Thi3 i~ compen~ated by the anions present in the inter-mediate layers together wi~h zeolitic water of crystalli-æation. The layer structure is clearly vieible in the X-ray powder diagram (ASTM card No. 14-191), which can be used for characterization.
Synthetically prepared hydrotalcites are also known and are described, for examp.le, in 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 MgZ~:Al3~
ratio can vary be~ween about 1 and 5. The OH-sCO3Z ratio ; can alsu vary~ Natural and synthetic hydrotalcites can be ;`

:, . . ..

- ~ - 2~39 ~
described approximately by thQ general formula I

Mg~l(OH)y(CO3)~ n H20 (I) where the condition~ 1 c < 5, y > z, (y + 0-5z) =
2x + 3 and 0 ~ n ~ 10 apply. Difference3 in the comp~
osition of the hydrotalcite~, in particular with respect to the water content, resul~ in line shifts in the X-ray diffraction diagram.
Natural or synthetic hydrotalcites con~inuously release wa~er on heating or calcination. The dehydration is complete at 200C, when it can ba shown, by X-ray dif~raction, tha~ the structure of tha hydrotalcite ha bee~ retained. A further increase in tempexa~ure result~
in degradation of the structure with e1imination of hydroxyl group~ (as water) and of carbon dioxide. Natural hydrotalcite~ and thoYe prepared synthetically by various processe~, for example in accordance with the above publica~ion~, exh~bit a generally ~imilar behavior on calcination.
Calcined hydrotalcites have already been employed ~0 for various purposes, for example a~ ab~orbents and in reaction~ of alkylene oxides with alkyl acetates to prepare mono-/ di- and triethylene glycol ethyl e~h~r acetates, cf. JP-A 56t36,431, cited in C.A. 95[11)97 099m For polyalkoxylates, a n~rrow range of the degree of polyalkoxylation i~ of particular imporkance, cf.
JAOCS, Vol. 63, 691-695 (1986), and HAPPI, 52-54 (1986).
It ha~ now been found that calcined hydrotalcites can be u~ed according to the invention as catalysts to po1ya1k~xylate fatty acid ester~ of the type mentioned in the introduction in high yields and in short reaction times ~o give reaction produc~ having a narrower poly-alkoxylation range or homolog di~tribu~ion than can be obtained when the sodium methoxide usually employed as cataly~t is u~ed.
For the purposes of the invention, all catalys~cs which can be obtained by calcina~ion from the natural .

~3~
, and/or synthetic hydrotalcites mentioned in the introduc-tion are suitable; hydrotalcite~ which, before calcina_ tion, hav~ the general formula I

Mg~l(OH)~(CO3)z n H2~

with the abovementioned conditions for x, y, z and n are pxeferred; value~ for x of from 1.8 to 3 are partLcularly preferred.
The calcined hydrotalcite~ employed according to the invention have the advantage that they can easily be incorporated into the alkoxylation reaction mixture and can be separated off again by simple measures due to their insolubility in the reaction mixture. Hsw~er, they may also remain in the reaction mixture if their pre~ence ~; doe~ not i~terfere with the furth~r u~e of the reaction product~.
Example~ of fatty acid esterq of the type men-- tioned in the introduction which ean b~ alkoxylated, ~ according to the invention, using calcined hydrotalcites : are listed below, the fatty acid component of the fatty acid esters being listed fir~t and the alcohol componen~
thereof then being listed separately.
Fatty acid~:
Fatty acid~ having 8 to 22 carbon atoms of ;; natural or synthetic origin, in par~icular straight-chain, saturated or unsaturated fatty acids, including technical-grado mix~ures thereof~ as can be obtained by lipolysis from animal andJor vegetable fats and oils, for example from coconut oil, pal~ kernel oil, p~lm oil, soya oil, sunflower oil, rapeseed oil, cotto~eed oil, fish oil, beef tallow and lard; specific examples are caprylic acid, capric acid, lauric acid, lauroleic ac.id, my:ristic acid, myri~tolaic acid, palmitic acid~ palmitoleic acid, oleic acid, elaidic acid, arachidic acid, gadoleic acid, behenic acid~ brassidic acid and erucic acid; furthermore methyl-branched, saturated and un~aturated atty acid~
having 10 to 22 carbon atoms, which are produced as by-product~ in the dimerization of the corr~sponding unsa-' . : ' " : ' ' '` ' ' ' ' ' ~" ` ' ~`, ' ~: ~ , ,.: ' , ::

' ~ . ' :
.. ..

- 4 ~ 3 ~ Q O
turated fatty acid~.
Hydroxyfatty acids:
Natural or synthetlc hydroxyfa~ty acid~, in particular having 16 to 22 carbon atom~, for example ricinoleic acid or 12 hydroxy~taaric acid.
Alkanols:
Saturated or un~aturated monoalkanols, in par-ticular products of hydrogenation of the abovementioned straight-chain, saturated or unsaturated fatty acids or derivatives thereof, such as methyl estsx~ or glyceride~
aliphatic or cyclic alkanol~ having 1 to 6 carbon atom~, for example methanol, ethanel, propanol, butanol, hexanol and cyclohexanol; including the Guerbet alcohol~ derived from the abovementioned monoalkanols.
Polyols:
~ thylene glycol, 1,2 propylene glycol, 1,2-buty-lene glycol, neopentyl glycol, glycerol, diglycerol, triglycerol, tetraglycerol, ~rimethylolpropane, cli-tri-methylolpropane, pentaerythri~ol, di-pentaerythritol, and sugar alcohol~, in particular sorbitan.
A~ stated in the introduction, the e3ters of the above fatty acids with the abovementioned polyol~ may also be in the form of partial ester~ or partial ester-containing technical~grad~ ester mixtures, in particular in the form of glycerida~.
The struc~ure of the ethoxylated or propoxylated fatty acld e3ter~ obtained according to the invention cannot alwayY be de~ermined unambiguou~ly. Fatty acid monoalkanol esters and fa~ty acid polyol full ester~
react - with a high probability of an insertion oi the ethyleneoxy and/or propyleneoxy unit~ into the ester bond - to give e sentially hydroxyl group-fre~ end products.
The structura of the hydroxyl group-containig products which result from the reacti.on of polyol partial esters of fatty acids with ethylene oxide and/or propylene oxide i~ unknown for the time being; hexe, reac~ions a~ the free OH group~ are also conceivable, in particular in the case of free pximary OH group~.
The deri~aeives to be prepared accordin~ to the - 5 - 2~3~
- invention u~ing calcined hydrotalcite are commorcial products, 80 more detailed description is ~uperf1uou~.
Typical repre~entative~ of the~e derivative~ are, for example, products of the adduction of 41 moles of S ethylene oxide with castor oil, product~ of the adduction of 25 mole~ of ethylene oxide with hardened ca~tor oil, products of the adduction of 7 parts by weight of athylene oxide with 10 parts by weight of a palmitic acid~stearic acid monoglyceride/diglyceride mixture containing 40 to 45% by weight of monoglyceride, and products of the adduction of 20 mole3 of ethylene oxide wi~h sorbitan monostearate.
According to a further advantageou~ embodiment of the invention, the calcined hydrotalcite~ are added to the reaction mixtures in an amount of frem 0.1 to 2~ by weight, relative to the end product of the ethoxyla~ion or propoxylation.
The calcined hydrotalcites to be employed according to the invention can be obtained from natural or ~ynthetic hydrotalcites by heating for ~everal hour~
at temperatures of greater than lOO~C; calcina~ion temperatures of from 400 to 600C are par~icularly preferred.
The inven~ion is illustrated in greater detail below with reference to preferred illu~tra~ive examples and a compari~on example.

Example 1.

Ca~tor oil + 1.4 mol of ethy1ene oxide.
A commercial synthetic hydrotalcite wa~ calcined for 4 hours at 500C.
In order to react a commerci~l ca~tor vil with 1.4 mol of ethylene oxide, the cas~or oil was introduced into a pressure reactor, and 0.5~ by weight, relative to the expected end product, of the praviously obtained calcined hydrotalcite was added. Tho reactor was flushed with nitrogen and evacuated for 30 minute~ at a temparature of 100C. The temperature wa~ subsequently , .
.

~ .

~3~
increa~ed to 165 - 175C, and the de~ired amount of ethylena oxide wa~ injected at a prsssure of from 3 to 5 bar. When the reaction wa~ complete9 a post-reAction time of 30 minute~ wa~ allowed (total reaction time:
3 hour~). After ~he su~pended catalyst had been filtered off, the reaction mixture de ired, having a saponi-fication numbar of 155 (theor.: 13S), was obtainad.
Example 2.
Methyl laurate ~ 2 mol of ethylene oxide.
Under the conditions indicated in Example 1, a comm~rcial methyl laurate and 2 mol of ethylene oxide gavo, aft~r a reaction time of 0.75 hour, the desired product having a saponification number of 1~5 (theor.: 185.7).
Example 3.
Rapeseed oil + 3 mol of ethylene oxide.
Under the conditions indicated in Example 1, a commercial rape~eed oil gave the abovemen~ioned ethoxy-lation product having a saponification number of 150 (~heor.: 130). The ~otal reac~ion time wa~ 2.5 hour~.
Compari30n example.
Example 2 wa~ repeated, but the calcined hydrotalcite employed therein wa~ replaced by sodium methyoxide a~ the catalyst. The compo~ition of the ethoxylation produc~ obtained wa~ determined by gas chroma~ography ~in area percen~), and compared wi~h that of the produc~ from Example 2; the re~ults are summarized in the table below. The term "E0 degree" indicates the number of ethylene oxide molecules adducted with methyl laurate, a degree of ethoxylation of 0 denoting unreacted starting material.
The table show~ tha~ the amount of unreacted starting material in the product of the comparison example is higher by a factor of 2 and the amount of desired end product is more than 3 time~ lower than in tho produc~ of Example 2.

.. . ., -- 7 --2 ~
T~bl~

Homolog di~tributiorl in the ethoxylation of methyl laurate 5EO degree Example 2 Compari~on exampla ( area percent ) 0 31.3 60.0 1~.1 11.2 2 lJ~.1 4.2 3 12.2 3.3 4 9.6 3.0 5.8 4.2 6 ~.3 ~.8 7 3.2 2.6 8 2.4 2.3 9 1.8 ~-~
1.4 1.7 11 0.9 1.2 12 0.6 0.9 :, .: ~

Claims (7)

Henkel Kommanditgosellschaft auf Aktien M/YH/UM

Patent claims

1. The use of a calcined hydrotalcite as catalyst for the exhoxy1ation or propoxy1alion of fatty acid esters selected from the group formed by esters of optionally hydroxy-substituted fatty acids having 8 to 22 carbon atoms with monoa1kano1s having 1 to 22 carbon atoms, and by partial esters and full esters of option-ally hydroxy-substituted fatty acid having 8 to 22 carbon atoms with polyols having 2 to 12 carbon atoms and 2 to 6 hydroxyl groups.

2. The use as claimed in claim 1, wherein saturated or unsaturated fatty acid C1-C4-alkyl esters are ethoxy-lated or propoxylated.

3. The use as claimed in claim 1 or 2, wherein glycerides of optionally monohydroxy-substituted, saturated or unsaturated fatty acids are ethoxylated or propoxylated.

4. The use as claimed in at least one of claims 1 to 3, wherein the hydrotalcite, before ca1cination, has a composition of the formula I

MgxA1(OH)y(CO3)z: . n H2O (I) in which the conditions 1 < x < 5, y > z, (y + 0.5 z) =
2x + 3 and 0 < n < 10 apply.

5. The use as claimed in at 1east one of claims 1 to 4, wherein, for the hydrota1cite of the general formula I
MgxAl(OH)y(CO3)x . n H2O

x is a number from 1.8 to 3, and y, z and n are as defined above.

6. The use as claimed in at least one of claims 1 to 5, wherein the hydrotalcite had been calcined at a temperature between 400 and 600°C.

7. The use as claimed in at least one of claims 1 to 6, wherein the calcined hydrotalcite is employed in an amount of from 0.1 to 2% by weight, relative to the end product of the ethoxylation or propoxylation.