DE3500938A1 - STABILIZATION OF PALM CORE OIL AND PALM CORE FATTY ACID ALKYL ESTERS FOR THEIR PROCESSING TO COLOR-NEUTRAL REACTION PRODUCTS - Google Patents

Description

Düsseldorf, 11.1.19 85 HENKELKGaA

_Λ ZR-FE / patents

Henkelstrasse 67 · 0 HF / Ge

Dr. Gla / Pr

Patent application D 7234

"Stabilization of palm kernel oil and palm kernel fatty acid alkyl esters for processing them into neutral colors Follow-up response peaks "

Coconut oil and palm kernel oil are important natural raw materials for the production of oleochemicals today Follow-up products on an industrial scale. The chemical processing of this natural raw material is important usually the conversion of the resulting triglyceride> to the corresponding fatty acid esters with lower mono-

functional alcohols, especially the corresponding * "■ methyl esters. The methyl ester or the

Fatty acid ethyl ester mixture by direct transesterification of the triglyceride with methanol or via the Triglyceride cleavage to fatty acid and glycerine and subsequent esterification of the fatty acids or fatty acid mixtures to the alkyl esters are obtained.

When comparing the quality - determined in particular by the storage behavior, the oxidation stability and on Stabilization possibilities and especially with regard to the influence on the color values of subsequent reaction products from these stored input materials - shows that coconut oil or the reaction products obtained from coconut oil behave much better than palm kernel oil and its reaction products. Is coconut oil

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much more stable to oxidation than palm kernel oil. The same applies to the methyl esters produced therefrom or methyl ester mixtures. The slightly increased iodine levels can only be partly the reason for this c of palm kernel oil can be used in comparison to the iodine numbers of coconut oil. Both contain fat raw materials natural antioxidants, mainly in the form of o £ tocotrienol. Coconut oil contains more than 30 ppm significantly more antioxidant than palm kernel oil, compare H. Behringer et al. in fats, soaps, paints 78 (1976) pp. 228-231.

While coconut oil and coconut fatty acid methyl ester are normally stable against autoxidation for months at room temperature, this is not the case for palm kernel oil and palm kernel fatty acid methyl ester. The applicant was able to demonstrate that palm kernel oil and palm kernel fatty acid methyl ester absorb oxygen much more quickly than coconut oil and coconut fatty acid methyl ester. Corresponding studies show that palm kernel oil itself has 10 to 25 times more oxygen uptake than coconut oil. In the more stringent aging test, in which the oxygen uptake of natural fats and oils and of fat and oil derivatives is measured in a Warburg manometer device as a measure of the oxidation behavior, the induction time of palm kernel oils, after which strong oxygen uptake occurs, is around 80 ^° C 10 to 20 hours, while in comparative studies with coconut oil after measuring times of 50 or 90 hours, none

O ₀ oxygen uptake can be determined.

These differences in quality between palm kernel oil and its derivatives on the one hand as well as coconut oil and its derivatives on the other hand results in that the respective starting materials ₃ c and / or their reaction sequence during storage, transport and / or the work-up are damaged different and accordingly apply significant quality differences .

Henkel KGaA

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The invention is based on the task of eliminating the undesirable instability of the palin seed oil or that obtained therefrom Eliminate reaction products. The obvious thought, the deficit of palm kernel oil in natural However, balancing antioxidants by adding known antioxidants led to that surprising finding that with this conception not readily satisfactory secondary reaction products can be obtained.

Important measures for the usefulness of a fat raw material on a natural basis are color values that at Soap solution - obtained by alkaline saponification of the corresponding fatty acid methyl ester or fatty acid methyl ester mixed - or obtained from fatty acid diethanolamides by amidating cleavage of the fatty acid methyl ester starting materials - be measured. These color numbers are decisive parameters for the usefulness of both those originally used Oils as well as the methyl esters made from them.

The object of the invention in the narrower sense is accordingly the stabilization of palm kernel oil and especially of alkyl esters of palm kernel fatty acids - in particular Palm kernel fatty acid methyl ester - against harmful influences during storage with access to air, that in the subsequent reaction of the stored oleochemical starting materials reaction products such color neutrality can be obtained that no undesirable color deterioration is accepted Need to become. The term "color neutrality" means here and in the following description of the invention 35

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a color stability within the framework of the individual reaction stages that is known and accepted in practice Color stability of coconut oil of normal quality and its derived products roughly corresponds to. The invention wants to do so the palm kernel oil in practical handling and processing - but above all those available from palm kernel oil Palm kernel fatty acid alkyl esters - make the corresponding materials based on coconut oil comparable.

The ones carried out to solve this problem Investigations have surprisingly shown that the choice of two very specific oxidation stabilizers, which are known per se ensures the desired success. The use of other oxidation stabilizers, which are to be regarded as equivalent due to general chemical knowledge does not lead to the result the previously defined color neutrality in the subsequent reaction products, in particular from palm kernel fatty acid methyl ester.

The invention accordingly relates to the use of di-3,5-tert-butyl-4-hydroxytoluene and / or Tocopherols as stabilizers in palm kernel oil and palm kernel fatty acid alkyl esters for their processing color-neutral reaction products.

Di-3,5-tert-butyl-4-hydroxytoluene - hereinafter referred to as BHT denotes - and tocopherols can be used in a mixture, but in particular also each individually, to form the invention Purpose to be used. It has been shown that even by adding very small amounts of BHT, but also

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by adding small amounts of tocopherol, palm kernel fatty acid methyl ester Stabilized in this way at room temperature for a long time, for example up to 2 months It can be ensured that alkanolamides or soaps produced therefrom have the desired good color values. Closer Information on the desired color values is contained in the example section.

If tocopherols are used as stabilizers within the meaning of the invention, then in particular (X-, ρ-, / W ^ - and. ^ - tocopherol as well as C ^ _-, P ~> / T ~ ^un ^ f / ~~ tocotrienols are used Consider, especially their mixtures, as they occur as accompanying substances in vegetable oils.

In particular, mixtures rich in ^ -Tocopherol come here from soybean oil damper condensate and the ^ C-tocopherol obtained from it through exhaustive methylation - the im the rest is also synthetically accessible - for use.

Palm kernel oils that arise with considerable differences in quality or during transport or storage are damaged differently, can be caused by the addition according to the invention of small amounts of BHT and / or Stabilize tocopherol to form standardized raw materials. It is more important that the corresponding stabilization results also obtained on the corresponding palm kernel fatty acid alkyl esters of various origins can be. It is advisable to use the stabilizing additives used in accordance with the invention directly after the production of the fatty acid methyl ester or fatty acid methyl ester mixture to add - or an insufficient fatty acid alkyl ester mixture is initially preferred to purify multiple distillation and to stabilize the distillate immediately.

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Are instead of the stabilizers used according to the invention If other known antioxidants are used, then, surprisingly, the required color neutrality is achieved not contained in the reaction products of the palm kernel fatty acid methyl ester. For example, shows the use of 2-tert-butylhydroquinone or the use of butylated hydroxyanisole and the concomitant use of propyl gallate does not achieve the stabilizing effect sought according to the invention. Both with the tert-butyl hydroquinone derivative As with propyl gallate, high color index values are obtained in the saponification products and in the diethanolitides. The use of the butylated hydroxyanisol leads to higher amounts added, for example to amounts of over 500 ppm initially only leads to undesirably high saponification color numbers, however, after prolonged storage, undesirably high diethanolamide color numbers are also obtained.

The stabilizers used according to the invention are usually in amounts below 500 ppm and in particular already effective in amounts below 300 ppm - based on the stabilized feedstock. BHT can already be used in Quantities from 10 to 100 ppm and in particular in the range from about 20 to 50 ppm give entirely satisfactory results deliver in the sense of the task according to the invention. Tocopherols that are naturally present can also be added to the tocopherols in the Satisfactory color stabilization in the range below 100 ppm, in particular in the range from at least 20 to 100 ppm for subsequent reaction products. When stored in metal containers, for example in steel tanks it can be advantageous to add complexing agents for metal ions to the material to be stabilized, for example Citric acid, ascorbic acid or ascorbic acid fatty alcohol esters, in particular ascorbic acid palmitate.

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The palm kernel fat to be stabilized according to the invention; Acid alkyl esters are obtained by known processes either by splitting the palm kernel oil into fat and subsequent esterification of the fatty acid mixture obtained with the corresponding lower alcohol or by direct transesterification of the palm kernel oil with the corresponding alcohol. The alcohol component of the palm kernel fatty acid alkyl ester preferably consists of methanol. As a rule, it is desirable that the palm kernel fatty acid alkyl esters intended for further chemical processing contain only fatty acids with 12 to 18 carbon atoms as acid components. From this point of view, the so-called first run fatty acids with 6 to 10 carbon atoms are normally separated from the mixtures of free fatty acids by fractional distillation in the case of direct esterification. If the palm kernel fatty acid alkyl esters are obtained by transesterification, the undesired esters of the Cg-C, _2- fatty acids after the

Transesterification removed from the ester mixture by distillation. In principle, this procedure can of course fr'-also to apply such ester mixtures by direct Esterification - without prior fractionation of the fatty acids - made from palm kernel fatty acid mixtures became. The invention accordingly relates in a particular embodiment to palm kernel fatty acid methyl ester mixtures, in particular the C. ^ ig fatty acid range, produced by esterification of palm kernel fatty acids, especially those with 12 to 18 carbons Atoms of substances with methanol or by transesterification of pork kernel oil with methanol and, if desired, isolation of the

C ₁₀ , Q fatty acid ester cut containing added Jl ^ --Χ ο

pi-3,5-tert-butyl-4-hydroxytoluene and / or added Tocopherol in quantities below 500 ppm, for the production of 35 color-neutral reaction products.

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Examples

In the following examples, the following key figures are used as a measure of the stability of the palm kernel fatty acid ester used: peroxide number (POZ), carbonyl number (COZ), saponification color number (VFZ) and diethanolamide color number (DEAFZ). These key figures were determined as follows:

Peroxide number (POZ)

The POZ was determined using the Wheeler method - see DGF standard methods C-VI 6a (84), Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart (1950-1984) -. A sample of the ester in a mixture of chloroform and glacial acetic acid is reacted with potassium iodide in the cold and the iodine formed by the peroxide present is titrimetrically determined with sodium thiosulphate using starch solution as an indicator. The POZ is calculated in mVal O ₂ / kg according to the formula

a. N 1000

POZ =

Here mean:

a = consumption of sodium thiosulphate standard solution (ml) N = normality of sodium thiosulphate standard solution K = weight of the sample (g)

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Carbonyl number (COZ)

The COZ was also determined using a DGF standard method See loc. cit. C-V 18 (58). Included a sample of the ester with a 0.5 N aqueous alcoholic hydroxylamine chlorohydrate solution is used for a longer period of time heated to reflux. Then it is in the cooled down Mixture using the released hydrogen chloride with 0.5 N alcoholic sodium hydroxide solution titrated with a pyridine / bromophenol blue indicator. The COZ is calculated using the formula

a «14

COZ =

a '= consumption of 0.5N sodium hydroxide solution (ml) E = weight of the sample (g)

Saponification color numbers (VFZ)

₂ c To determine the VFZ, 10 g of fatty acid ester are added

100 ml of methanolic 1 N potassium hydroxide solution is heated to reflux for 1 hour. On the cooled sample

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the VFZ are measured using a 5 1/4 cuvette in the Lovibond tintometer measured. For esters of good quality are supposed to the values red <£ 1.0 and yellow 4.5 are complied with.

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Diethanolamide color numbers (DEAFZ)

To determine the DEAFZ, equivalent amounts of fatty acid esters and diethanolamine in the presence of 1 percent by weight, based on the total amount, sodium methylate at 85 ° C in the course of 5 hours Brought reaction. The 'released methanol is thereby continuously distilled off. On the cooled reaction pro-

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The DEAFZ is able to use a 5 1/4 cuvette in the Lovibond tintometer measured. The color of the diethanolamide for red <^. 1.5 and yellow ^ .15 (a color number according to Gardner of ^ 3 accordingly) as satisfactory to call).

Examples 1 and 2

Palm kernel oil was split ^{with water at 220 ° C. in an autoclave.} After the glycerol had been washed out, the Cg- _1Q fatty acids were largely distilled off from the fatty acid mixture obtained, so that a mixture consisting _{essentially of C, n} , _{O fatty acids}

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stayed behind.

The C _{10 Ί palm} kernel fatty acid mixture obtained was reacted in an autoclave with methanol in a weight ratio of 1: 1 at 220 ° C. under autogenous pressure over the course of 2 hours. Methanol and water of reaction were distilled off from the resulting mixture. Reaction twice with excess methanol and distillation gave a C ₁₂ _._ palm kernel fatty acid methyl ester mixture which had the following numbers: acid number 0.3; Saponification number approx. 238; Iodine number 18.

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POZ, COZ, VFZ and DEAFZ were determined on the freshly distilled ester. Samples of the ester were found at 10 ppm 3,5-di-tert-butyl-4-hydroxytoluene (BHT; commercial product) or 50 ppm oC tocopherol (DL; 99%; commercial product) added as a stabilizer. These samples and a stabilizer-free sample (approx. 500 ml each) were in 500 ml wide neck bottles with loosened screw cap stored at approx. 20 C in the dark for 6 weeks. Then the above-mentioned key figures were determined again.

In the case of example 2, a C.-, _ft- palm kernel fatty acid methyl ester prepared by the method indicated above was stabilized again with 10 ppm BHT.

The results found are given in Table I below.

Patent application

723 4

35009? 8

Henkel KGaA ZR-FE / patents

W PQ

H σι rH CN CO H σ » co CO Q) ο O rH O O rH O Tuesday in O O U O O in Q Red " CO Q) VO rH approx O H CO O rH Tuesday co ■ H in Ü rH CO _H O O O O O O Εκ O I, ^> co " O O V VO co co H in CN CN O CN cT H O H rH H CN rH Ο) O* O O O O O O X! VO H CO CN in r. (Woe rH CN O CN O O I.
U Q) I ^L ag O VO VD O VD VO W. I. approx I. e I. I. H
Q) Gi G ₁ P ₁ • Η Gi G ₁ O O O approx rH in rH iH CN COZ \ ροζ I •H Q) M. 0 + J (d ■ H H •H id ■ Ρ
CO •H Q) m

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Example 3
C, ~ .Q-Palm kernel fatty acid methyl ester, which is longer than 6

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Weeks had been stored and POZ 40 and COZ showed 0.6, was distilled twice, with a total of 3.7 Percent by weight of residue was incurred. The distillate had the key figures: acid number 0.3; Saponification number 241; Iodine number 14.

POZ, COZ, VFZ and DEAFZ were measured on the freshly distilled ester. Samples of the ester were given with 10 resp. 50 ppm 3,5-di-tert-butyl-4-hydroxytoluene (BHT; commercial product), 50 ppm cC-tocopherol (99%; commercial product) and 50 ppm tocophenol mixture from soybean oil (with approx. 50 percent by weight ^^ - tocopherol as the main ingredient; Commercial product) as substances to be used according to the invention and 50 ppm of 2-tert.-buty! Hydroquinone (TBHQ; Han- gel product) and 50 ppm 2-tert-butylhydroxyanisole BHA; Commercial product) added as comparison substances. These Samples and a stabilizer-free sample (approx. 500 ml each) were placed in 500 ml wide-necked bottles with a loosened The screw cap was stored at approx. 20 ° C in the dark for 4 weeks. After that, the above metrics were determined again. The results found are shown in Table II below.

30 35

Patent application D 723 4

- vs -

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c Red I. en) ο O CN CN CN in : 0 O O C. ) σι co CN CN CNJ CN iti CA (U ο O O O O • m O O oil (Where CNJ O C ^ co co O [^ * co +1 H H H cn CNJ H H I.
Your 4- co CN (N CO O co CN OO M. Q) -i- ο O d VF2 Di OJ VO co
i-J iH rH r- ( π) CN r-H W. (U O O O in O O a CO 00 VO VO co " 00 * O O m O O CO CN CO co (N CN EH O O O O O O O co CO CO O VO CA CO 4Y id (N CN CN ■ "· H (Q I. «Φ • Η ιΗ "H" 'ψ ">} · • Η - (ζ H O CC H 0) 0 r] Oi (U O r; O O) I. I. O O α fs £ - | O CQ rf W. I. O Cm m V ^ m B, ε ε ε B. ε CU O* Of O) O, CU Ph Oh 0 < CU O O O O O O ■ Η in in in in in

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TABLE II

stabilizer camp
Time
(Weeks) POZ COZ VFZ Red DEAFZ Red -, _ 3.0 0.3 yellow 1.2 yellow 1.7 - 4th 43.0 0.8 6.0 3.0 9.0 4.4 10 ppm BHT '4 2.7 0.3 18.0 1.2 18.0 2.2 50 ppm BHT 4th 2.3 0.2 6.0 1.2 17.0 2.2 50 ppm oC tocopherol 4th 2.0 0.3 6.0 1.3 17.0 2.2 50 ppm tocopherol 4th 1.6 0.3 7.0 1.0 13.0 2.5 made from soybean oil 4.5 13.0 50 ppm THBQ 4th 1.9 0.2 2.2 9.0 50 ppm BHA 4th 1.8 0.2 8.0 1.8 27.0 4.0 8.0 18.0

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The test results found are shown graphically in FIG. It can be seen from this that an addition of 50 ppm BHT was sufficient to give the palm kernel fatty acid methyl ester the same stability that a has comparable coconut fatty acid methyl ester.

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Claims (4)

Claims / 1) 1 Use of di-3,5-tert-butyl-4-hydroxytoluene and / or tocopherols as stabilizers in palm kernel oil and palm kernel fatty acid alkyl esters for their Processing to color-neutral reaction products. 2) embodiment according to claim 1, characterized in that that the stabilizers are di-3,5-tert-butyl-4-hydroxytoluene and / or tocopherols in amounts below 500 ppm, preferably in amounts below 300 ppm and especially in amounts ranging from about 10 to 100 ppm are present. 3) embodiment according to claims 1 and 2, characterized in " characterized in that the product V to be stabilized is palrakernfatty acid alkyl esters which are obtained by transesterification of palm kernel oil with lower alcohols, in particular with methanol. 4) Palm kernel fatty acid methyl ester mixture, in particular of the "" 1? -I Q fatty acid range, produced by esterifying palm kernel fatty acids, in particular those with 12 to 18 carbon atoms, with methanol or by transesterifying palm kernel oil with methanol and, if desired, isolating the C ₁ ~ _Λ Q- Fatty acid ester cut, I line ¹ * JO containing added di-3,5-ter.-butyl-4-hydroxytoluene and / or added tocopherol in amounts below 500 ppm, for the production of color-neutral reaction products.