NO140266B - PROCEDURE FOR ISOMERIZATION OF SATURATED HYDROCARBONS OVER A PLATINUM AND / OR PALLADIUM CATALYM ON A CARRYED ACIDITY CARRIER MATERIAL - Google Patents

Description

Process for the purification of sugar esters.

It is known to purify sugar monoesters and sugar diesters of saturated and unsaturated organic acids by removing the organic solvent from a first prepared reaction mixture containing such esters, then adding water to the residue and setting the pH value of the aqueous mixture to a value below pH 7, and then separates the relevant sugar ester from the mixture. Here, it is appropriate to work below 20° C, especially at temperatures between 0 and 5° C. The most favorable pH value is stated to be between pH 3 and pH 4.

It has now been found that the purification of sugar monoesters, sugar diesters and sugar triesters of saturated and unsaturated higher fatty acids can be carried out significantly more favorably when, after the separation of the organic solvent from the reaction mixture first prepared, which contains such sugar esters, and after the addition of water heats this sugar ester-water mixture with vigorous stirring, so that the sugar ester melts, and transfers the mixture, which contains some dissolved sugar ester, to a homogeneous emulsion, after which as much acid and as much acid is added to this heated, homogeneous emulsion /or salt that the sugar ester precipitates and can easily be separated, e.g. by filtering. The pH value must therefore lie between 4 and 7, and especially between 6 and 7. The sugar esters are then separated from the reaction mixture in a known manner. In detail, the procedure is as follows: The production of sugar monoesters, sugar diesters or sugar triesters takes place in a known manner by transesterification of fatty acid esters with sugar using a transesterification catalyst and a suitable solvent, preferably in dimethylformamide (DMF) or dimethylacetamide. After the transesterification reaction, the solvent is distilled off in vacuum at the lowest possible temperature, and the residue, which besides the sugar ester also contains up to 2 percent of the solvent, is mixed with water. Now the aqueous mixture is heated with vigorous stirring, so that the formed sugar esters are brought to melting, and the aqueous mixture, which contains some dissolved sugar ester, is transferred to a homogeneous emulsion.

In order to obtain a homogeneous emulsion, the sugar ester produced after the solvent has been distilled off and possibly also pre-purified is mixed with approximately 3-20 times the amount of water, and the mixture is heated to a temperature between 30 and 60° C. In some cases, it can also be worked at somewhat higher temperatures. Temperatures above 90° C should be avoided if possible, as the sugar esters can then be attacked. During the process, vigorous stirring is appropriate. It can be advantageous in some cases to lower the melting temperature of the sugar ester by adding smaller quantities of contaminated substances. For this purpose, smaller amounts of saturated and/or unsaturated fatty acid esters of lower aliphatic alcohols, including polyhydric alcohols (polyols), can be used. However, it is also possible to use such non-species substances which can easily be removed during the later processing of the sugar ester.

After a homogeneous emulsion has been produced which can also be filtered through a cloth; is it appropriate to stir again for a short time, e.g. for 10 min., and then add enough acid and/or salt solution to this warm, homogeneous emulsion, that the sugar ester falls out and is easily separable, e.g. by means of filtering. The precipitated product can be treated in the same way - one or more times, but often already after. it. for the first time, a degree of purity is achieved which satisfies the requirements for many applications. The separation of the sugar ester from the aqueous sugar ester-water mixture then takes place in a known manner either from the hot mixture after cooling the mixture to room temperature or lower temperatures, e.g. by filtration or centrifugation.

The acids that can, in principle, be used include all acids, provided that, in the concentration used, these are indifferent in relation to the sugar esters. For example, sulfuric acid, phosphoric acid or the halogen hydrogen acids can be mentioned here. and especially then hydrochloric acid. It is usually sufficient to add so much acid to the hot, aqueous emulsion of the sugar ester that the acid concentration is approximately 10-4 to 10-3 mol/ltr. The use of a higher acid concentration is possible if the sugar ester is not thereby changed and. the thereby conditioned high amount, of introduced and of the sugar ester. absorptively held acid ions. does not appear disruptive, resp. in a later cleaning igj.en shall. is removed. Organic acids can also be used, but must. for weaker acids, correspondingly larger quantities are used.

Quite special, good, suitable, they seem to me. acids to be like. by. later processing and especially, during drying. off, sugar esters again. easy. thigh. themselves. remove. These are above all light, volatile acids, such as sulfuric acid, acetic acid and especially carbonic acid, individually, or also, in a mixture with each other.

By; use of, carbonic acid;- this is introduced in the var:me:, homogeneous: emulsion, and the introduction is then continued. long until" a. clear;, filterable. mixture is obtained. The introduction; can also take place.- under: pressure; Then: the. mixture is still stirred: for a short; time;, and; then, the sugar ester is separated in. known. manner.'.

Likewise, can- it to the precipitation- of sugar-

the esters from the hot, aqueous emulsion, salts or their aqueous solutions are used. Salts that are suitable for this purpose are, in general, those salts which are indifferent to the sugar esters, and whose subsequent presence in: the purified sugar esters does not act "disturbingly" or even is desirable. In particular, such salts are also suitable which in aqueous solution have an acidic reaction -sion, such as primary phosphates, however

also neutrally reacting salts such as table salt is usable. The salt concentration

then amounts to approx. 0.25-2.5 mol/ltr; The salt concentration must then. is chosen, then. high that. the emulsion separates, and the sugar esters can easily

avfilterer.es. Too high a salt concentration

should be avoided, because the sugar esters then too

after cleaning, absorbent retains correspondingly higher amounts of salt.

Mixtures of different acids or mixtures of acids with salts or mixtures of salts can also be used.

By. well. filters.are.only mixtures, the separation can. of the sugar ester already takes place, from the hot, sugar ester-water mixture. In some cases, it is. the. an advantage to cool the mixture to. a temperature between 10 and 30° G or even lower, before the sugar ester. be divorced. The separation. of the sugar ester. can take place by filtration, or centrifugation. or simple removal. of the aqueous layer.

The thus produced yet. moist sugar esters are dried: then or, also, if desired,, extracted with. an organic solvent, such as a lower alcohol which. is not. miscible or, only limited miscibility, with water, e.g., butanol, and: after drying the solution, the sugar ester is obtained. by, distilling off the solvent.

Used- for precipitation of the- hot, aqueous- emulsion" of the sugar ester not volatile acids or salts, or: mixtures of salts and acids;, so: contains- the sugar ester after, the purification, still; smaller amounts of these1 substances. These can be removed by repeated cleaning using volatile acids. One can, however, remove-these: substance is-by-that one. emulsify purified sugar esters first in water that is heated, and dialyze this mixture directly, or after neutralizing it; excess acid wood; aidi of lye, such; as. described in Norwegian patent no. 100-627'.

By: sugar esters, which are purified by the method according to the invention, are generally understood esters of aliphatic carboxylic acids with 6-30 carbon atoms with mono-, di- or oligosaccharides, or their derivatives. The sugar residue of these sugar esters can be a monosaccharide such as glucose, fructose, galactose, arabinose, xylose or a derivative of this sugar; where the reducing group is linked glucosidically as, e.g. methylglucoside, glycoseuride, isopropylidene glycose, N-ethanolglycosylamine, N-ethanolgalactosylamine. Of the disaccharides, especially cane sugar. are mentioned. As an oligo-saccharide, raffinose should be mentioned. The sugar esters to be purified according to the invention can be mono-, di- or tri-esters, i.e. that one or more of the hydroxyl groups of the sugar molecule may be esterified. Of the carboxylic acids that serve for esterification, the higher saturated or unsaturated fatty acids in particular have gained importance. For example, stearic acid, palmitic acid, oleic acid, linoleic acid and linolenic acid can be mentioned here.

The sugar esters that can be purified well in the simple way according to the invention are, for example, cane sugar monostearate, cane sugar distearate, cane sugar monopalmitate, cane sugar dipalmitate, cane sugar oleate, glucose ureidostearate, N-ethanol glucosylami stearate, monoacetone glucose stearate, cc-methylglucosidoleate, glucose stearate, a-methyl- galactosidostearate and galactosidostearate as also sugar esters, which are produced from the sugar and edible oils or fats and the like, and thus form mixtures of the most diverse sugar esters.

These compounds are only mentioned here as possible examples, without thereby limiting the invention to these examples.

The cleaning process is explained in more detail with the help of examples 1-17. In comparison to this, examples 18-20 are listed, which show that with the known working method only a significantly poorer cleaning is achieved. In all examples, the investigation of dimethylformamide (DMF) was carried out in a known manner, with the dimethylformamide being saponified. dimethylamine, and the dimethylamine was determined after distillation by reaction with coal sulfur substance such as copper and copper acetate dimethyl dithiocarbamate.

Example 1.

25 g of sugar monostearate, which also contained approx. 1 percent dimethylformamide was mixed with 500 ml of water, and the mixture was heated with vigorous stirring at 50° C., forming a homogeneous emulsion. Then became

the still warm emulsion mixed with 50 ml of n/10 HC1. This separated the emulsion

themselves. After cooling, the precipitated sugar monostearate was sucked off and dried. It still contained only a little dimethylformamide.

The still moist product was then mixed with 150 ml of water and subjected to dialysis at a temperature of 45 to 50° C. After a dialysis time of 40 hours, dimethylformamide and chloride could no longer be detected in the sugar monostearate.

Example 2.

54 g of sugar monostearate, which also contains approx. 1 percent dimethylformamide was mixed with 1.5 1 water, and the mixture was heated at 50° C. with vigorous stirring, forming a homogeneous emulsion. Then this still warm emulsion was mixed with 200 ml of n/10 HCl. The precipitated sugar stearate was sucked off after cooling, and the still moist product was again mixed with 1.5 1 of water and heated at 50° C. until a homogeneous emulsion had formed. Then, by adding 200 ml of n/10 HCl, the sugar ester was precipitated from the hot emulsion. The precipitated sugar monostearate was filtered off and dried. Yield: 43.8 g. No more dimethylformamide could be detected here.

Example 3.

50 g of sugar monopalmitate, which from the preparation still contained approx. 1 percent dimethylformamide was mixed with 1.5 1 water and the mixture was heated at 50° C. with vigorous stirring, forming a homogeneous emulsion. Then the still warm emulsion was mixed with 200 ml of n/10 HCl. The precipitated sugar palmitate was sucked off after cooling, and the still moist product was again mixed with 1.5 1 of water and heated at 50° C until a homogeneous emulsion had formed. The sugar ester was then precipitated from the hot emulsion by the addition of 200 ml of n/10 HCl. The precipitated sugar monopalmitate was filtered off and dried. Yield: 40.1 g. The product contained only very small traces of dimethylformamide.

Example 4.

50 g of sugar dipalmitate, which from the time of manufacture still contained approx. 1 percent dimethylformamide was mixed with 1.5 1 water and the mixture was heated at 50° C. with vigorous stirring, forming a homogeneous emulsion. Then the still warm emulsion was mixed with 200 ml of n/10

HC1. The precipitated sugar palmitate was sucked off after cooling, and the still moist product again mixed with 1.5 1 of water and heated at 50° C until a homogeneous emulsion had formed. The sugar ester was then precipitated from the hot emulsion by the addition of 200 ml of n/10 HCl. The precipitated sugar dipalmitate was filtered off and dried. Yield 45 g. The product now contains only very few traces of dimethylformamide.

Example 5.

25 g of sugar monostearate, which from the time of manufacture still contained approx. 1 percent dimethylformamide was mixed with 500 ml of water and the mixture was heated with vigorous stirring at 50° C., forming a homogeneous emulsion. Then the hot emulsion was mixed with 100 ml of n/10

acetic acid and the precipitated sugar monostearate were sucked off after cooling in an icebox. The still moist sugar monostearate was again mixed with 500 ml of water at 50° C, and the mixture, with vigorous stirring, heated at 50° C, forming a homogeneous emulsion, in the same way as above, the sugar ester was precipitated from the hot emulsion with 100 ml n/10 acetic acid. The precipitated product was sucked off after cooling in an icebox. It still contained only traces of dimethylformamide. The sugar monostearate was then emulsified in 150 ml of water at a temperature of 50° C., and dialyzed against distilled water at a temperature of 45-50° C. for a period of 40 hours. After dialysis, acetic acid and dimethylformamide could not be detected in the product.

Example 6.

10 g of sugar distearate, which from the time of manufacture still contained approx. 1 percent dimethylformamide was mixed with 500 ml of water, and the mixture was heated with stirring at 50° C. until a homogeneous emulsion had formed. It was then mixed with 50 ml of n/10 acetic acid, the emulsion separating and the sugar distearate falling out. After cooling, the sugar distearate was separated and dried. Dimethylformamide could no longer be detected in the product. Yield: 8.5 g.

Example 7.

10 g of sugar dipalmitate, which still contains 1 percent dimethylformamide from the preparation, was mixed with 500 ml of water, and the mixture was heated with stirring at 50° C. until a homogeneous emulsion had formed. It is then mixed with 50 ml n/10 acetic acid, the emulsion separating and the sugar dipalmitate falling out. After cooling, the sugar dipalmitate was filtered off and dried. Dimethylformamide could no longer be detected in the product. Yield: 8.2 g.

Example 8.

147 g of α-methylglucosidoleate, which from the preparation still contains approx. 0.5% of dimethylformamide was suspended in 7 1 of water, and the mixture was heated with vigorous stirring at 50° C. Then 30 ml of 10% hydrochloric acid was added, and the precipitated α-methylglucosidoleate separated after cooling by filtration through a large folding filter. The still moist product was again suspended in 6 1 of water, the mixture was heated with stirring at 50° C and again precipitated with the addition of 10 ml of 10% hydrochloric acid. After cooling, the sugar ester was separated and dried. 139.5 g of α-methylglucosidoleate was formed, in which no more dimethylformamide could be detected, which, however, still contained 0.123 percent chloride which can be removed by dialysis.

Example 9.

60 g of a sugar ester, which was prepared from cane sugar and edible oil by transesterification, and which from the preparation still contained 2 percent dimethylformamide, was suspended in 2.5 1 of water and the mixture was stirred for a long time at 50° C. until it had formed a homogeneous emulsion. The hot mixture was then mixed with 12 ml of 10% hydrochloric acid, stirred again for 10

minutes, and then cooled by adding approx. 300 g of ice. Most of the aqueous solution was removed and the sugar ester which had separated as an oil was extracted into 150 ml of butanol. After neutralization of the mixture, the butanol solution was separated in a separatory funnel from the still present aqueous solution. After drying over sodium sulphate, the butanol was distilled off in vacuum. This resulted in 32.5 g of cane sugar edible oil ester in the form of a succinic yellow oil, where

practically no more dimethylformamide could be detected. However, the product contains approx. 0.28 percent chloride, which can be removed by dialysis.

Example 10.

A quantity of sugar ester, which was produced by transesterification of 171 g of cane sugar with 140 g of palm kernel fatty acid methyl ester, and which, from the preparation, also contains approx. 2 percent dimethylformamide was suspended in water, and the mixture was stirred at 50° C. until a homogeneous emulsion had formed. The hot mixture was then mixed with 9 ml of 10% hydrochloric acid, stirred again for approx. 10 min., and the precipitated sugar ester filtered off after cooling. The filtered off sugar ester was then again suspended in 1 1 of water, and the mixture was stirred for a long time at 50° C. until a homogeneous emulsion had formed. The hot mixture was then mixed with 9 ml of 10% hydrochloric acid, and stirred for approx. 10 minutes and then filtered off after cooling. The filtered off sugar ester was extracted in 750 ml of butanol and the butanol solution separated in a separatory funnel from the still present aqueous solution. After drying over sodium sulfate, the butanol was distilled off in a vacuum at 60-90° C. This resulted in 166.5 g of cane sugar palm kernel fatty acid ester in the form of a succinic yellow oil, which still contained approx. 100 ppm dimethylformamide. By repeated precipitation of the sugar ester in a similar manner as above, the dimethylformamide can be removed completely.

Example 11.

100 g of sugar monostearate, which from production still contained approx. 1 percent dimethylformamide was mixed with 500 ml of water, and the mixture was heated at 50° C. with stirring, forming a homogeneous emulsion. The hot emulsion is then mixed with 100 ml of concentrated sodium chloride solution, and stirred for a short time. The precipitated sugar monostearate was filtered off after cooling. The still moist sugar monostearate was again, as indicated above, treated with 500 ml of water at 50°C, and the still warm emulsion was mixed with 100 ml of concentrated sodium chloride solution. The process was repeated several times, and after each time the amount of dimethylformamide still present was determined. The resulting values are listed in the following table:

Example 12.

25 g of sugar monostearate, which from the time of manufacture still contained approx. 1 percent dimethylformamide was mixed with 500 ml of water, and the mixture was heated with vigorous stirring at 50° C., forming a homogeneous emulsion. The emulsion was then fed with carbon dioxide until the sugar ester was filterable. After cooling the mixture, the precipitated sugar monostearate was filtered off and dried. Yield: 18.4 g: By repeating the process several times, the following values were found for the content of dimethylformamide:

Example 13.

10 g of sugar distearate, which from production still contains approx. 1 percent dimethylformamide was mixed with 500 ml of water, and the mixture was heated with vigorous stirring at 50° C., forming a homogeneous emulsion. Carbon dioxide was then added to the hot emulsion until the precipitate formed was filterable. After cooling, the precipitated sugar distearate was separated in a centrifuge. The product thus formed contained only a little dimethylformamide. Yield 8.6 g.

Example 14.

8.5 g of sugar dipalmitate, which from production still contains approx. 1 percent dimethylformamide was mixed with 500 ml of water, and the mixture was heated with vigorous stirring at 50° C., forming a homogeneous emulsion. Carbon dioxide was then added to the hot emulsion until the precipitate that had formed was filterable. After cooling, the sugar dipalmitate was separated in a centrifuge. The still moist product was treated several times at the same time

manner. The. could: then not be demonstrated; more dimethylformamide in the product. Yield: 7.8 g.

Example 15.

10 g; sugar distearate, which from

the position still contains approx. 1 percent dimethylformamide was: mixed with 500 ml of water,

and the mixture was heated under

stirring at 50° C. until it had formed; one. homogeneous: emulsion. The hot mixture was then mixed with 100-ml concentrated, sodium chloride solution, idet. the sugar distearate fell. out.. Post-separation: of the sugar distearate, this was sucked off,, and the ennui moist product was re-blended

with 500 mL of water. The mixture, as above, was heated, with stirring, at 50°

C, until: it had formed, itself. one, homogeneous

emulsion. Then, a sugar distea-

the rate fell out. by adding, of 100 mL con-

concentrated sodium bicarbonate solution.. Sugar di-

After cooling, the stearate was sucked off and dried. The product contained only traces of dimethylformamide.

Example 16.

50 g of sugar monostearate, which from

the position still contains approx. 1 percent dimethylformamide was brought into emulsion with 250 ml of 60° C. warm water. To the warm,

homogeneous emulsion was: it then set so. very, of a saturated aqueous solution of. primarily sodium phosphate,. that- the forward-

come, a, clear, filterable mixture. This was cooled and filtered. The sugar monostearate thus formed still contained ios-

fashions and approx. 80 ppm. dimethylformamide. By- further.' felling; and dialysis- could it

can be obtained. a completely clean product.

Example 1. 7.

10 g of N-ethanolglycosylamine stearate,

which from production still contains approx.

30.' ppm. dimethylformamide, was emulsified in 60<!> ml approx. 50<?> C hot water: under stirring

ring: The: hot;, homogeneous emulsjpn was added carbon dioxide! until the mixture is filterable: It was then cooled to room temperature and filtered. The residue was taken up, in 50 ml boiling; butanol, and the butanol solution was separated, from; the aqueous solution: in a separatory funnel. Then,

became; the butanol distilled off in vacuum at.

60f—80P C It appeared. 8.8>g, N-ethanolgly-

cosylamine stearate. if dimethylformamide-

content was below 0.1 ppm.

Example 18.

50 g of sugar monostearate, which from

the position still contains approx. 1 percent dimethylformamide. was mixed with 250 ml of water,

and. the mixture was heated with vigorous stirring at: 50° C., forming a homogeneous; emulsion Then it was stirred. until' the temperature had fallen to 20° G; The mixture was then mixed with 10 ml of 10% acetic acid. and- filtered after- 10 min-. The thus-produced sugar kermonostearate still had a dimethyl-formamide content: of approx. 0.8: percent It. had thus only been removed a little dimethylformamide-. by this way of working;

Example 19:

50 g sugar monostearate, which from

the position still contains approx. 1 percent dimethylformamide was suspended in 250 ml of water at room temperature and; the mixture then; mixed with 10 ml: 10% acetic acid: It was again stirred for 10 min., and then filtered off: the sugar monostearate. I- that so-

is led; resulting sugar monostearate: the dimethylformamide content was maximally reduced. with- 0;1. pst

Example 20.

1000 g of sugar monostearate, which from the preparation still contains 1 percent di;-, methylformamide was mixed with 25 1 of water,

log carbon dioxide was added to the mixture

gen. The precipitated sugar monostearate was filtered off and treated in the same way 3 times. After drying, 682 g of sugar monostearate was then obtained. despite 4 times

ger's treatment still contained 100 ppm dimethylformamide.

Claims (1)

Process for purifying sugar keresters of mono-, di- or oligo-saccharides with aliphatic carboxylic acids with 6-30 carbon atoms by removing it by ; the production used organic up-; solvent and mixing the residue with water, after which the sugar ester is precipitated by the addition of salts and/or acids in such an amount that the pH value is lower than 17, preferably 6-7. or by addition of salts with a concentration of preferably 0.25 - 2.5 mol/l and separated in a manner known per se, characterized by the sugar ester being heated to temperatures of 30-60° C before precipitation, so that Residuum mixed with water brought to melting is transferred in a homogeneous emulsion with its aqueous solution.