DE1468014B - Process for the preparation of hydroxyalkyl ethers of galactomannans - Google Patents

Description

35

The invention relates to a process for the preparation of hydroxyalkyl ethers from natural occurring galactomannans, such as guar and locust bean gum (carubine).

Hydroxyalkyl ethers of these galactomannans, namely the hydroxyethyl and hydroxypropyl ethers known for a long time. So far, the galactomannans mentioned have been used in excess for their production dilute aqueous sodium hydroxide solution dissolved or dispersed and with ethylene oxide or propylene oxide offset. The reaction mixture was left to stand at room temperature for a longer period of time until the total alkylene oxide was implemented. It was then neutralized and the highly viscous material obtained Solution evaporated to dryness. The resulting cake was ground. It is also known Manufacture hydroxyethyl guar by reacting the disodium compound of guar with ethylene chlorohydrin.

In both processes, the hydroxyalkyl ethers formed are highly contaminated, especially through Sodium salts. Their removal makes the galactomannan hydroxyalkyl ethers because of the good water solubility considerable difficulties.

A process has now been found for the preparation of hydroxyalkyl ethers of galactomannans by reacting the galactomannans with lower alkylene oxides in the presence of alkaline agents which does not have the disadvantages described. The method of the invention is characterized in that the galactomannans in about 1.5 to 10 times the weight of a water-miscible organic solvent containing _{about 10 to 50 ° / 0} , in particular 20 to 30 ° / _{0, which is among the} Reaction conditions with the alkylene oxide practically does not react, suspended and at 30 to 80 ° C in the presence of 0.5 to 20 ° / ₀ (based on galactomannan) of an amine and / or a quaternary ammonium base as a catalyst with the alkylene oxide and then the resulting Hydroxyalkyl ethers of the galactomannans isolated by filtration or centrifugation.

Naturally occurring galactomannans are suitable as starting material for the process according to the invention, such as B. guar or carob gum, which is obtained by grinding the endosperm of the seeds of the guar bean or the carob tree be won. You can use both raw products and purified flours.

Water-miscible organic solvents are used to disperse the galactomannans Question which under the chosen reaction conditions is practically impossible or only to a small extent react with the lower alkylene oxides. Secondary alcohols such as isopropanol and secondary alcohols are suitable Butanol, secondary amyl alcohols, further tertiary alcohols, such as tert. Butanol and amyl alcohol, furthermore Ketones such as acetone, methyl ethyl ketone, diethyl ketone. Others that are miscible with water are also suitable Solvents such as dioxane and dimethylformamide. It is also possible to use mixtures of the aforementioned Solvent to use. In view of the subsequent cleaning, one is preferred to do so Use solvents that have a relatively low boiling point and are therefore easy to evaporate are.

The use of primary alcohols such as methanol, ethanol and n-propanol for dispersing or slurrying the galactomannans is also possible per se. However, since the primary hydroxyl groups react much faster than the secondary and tertiary of the alcohols mentioned above, the yields, based on the alkylene oxide used, drop considerably in these cases. i

The water content of the organic solvents used for dispersing should be about 10 to 50 ° / ₀ , but in particular 20 to 30 ° / ₀ , based on the solvent mixture. It is directed primarily to the properties of the solvent by _# and is essential for the quality of the resulting hydroxyalkyl ethers of galactomannans. If too little water is used or if one works in an anhydrous medium, no clearly soluble galactomannan ethers are obtained. If, on the other hand, too much water is added, the hydroxyalkylgalactomannans formed swell to a great extent, especially at high degrees of conversion, and thus make working up considerably more difficult.

The solvents mentioned are used in an amount sufficient to stir or stir the preparation. pumpable dispersions is sufficient. Generally therefor is a weight ratio of solvent to galactomannan of about 1.5: 1 to 3: 1 sufficient. Of course, you can also do a larger one Work dilution, approximately in a ratio of 10: 1; however, one becomes for economic reasons choose the dilution ratio as low as possible.

3 4

The alkylene oxide is added to these suspensions. The reaction according to the invention can be added in gaseous or liquid form. In some cases, it is usually advantageous, open or closed stirred vessels, to carry out the alkylene oxides in a solvent. It can be introduced into the reaction vessel in batches or in a cone solution. be carried out continuously. In the latter case __ As alkylene oxides, for example, question 5 can be used, for example, to pass the reaction mixture through ethylene oxide, propylene oxide, glycide, butene oxide, Bu-temperature-controlled tubes,
tadiene monoxide. At a temperature of about 50 to 6O ⁰ C is

The amount of the alkoxylating agent used, the reaction time about 2 to 4 hours. At higher

if the temperature fluctuates with the desired degree of substitution, the reaction proceeds accordingly

of the conversion product. For making io faster.

ethers that are clearly soluble in cold water are used. from 0.5 to 1, preferably 0.6 to 0.8 parts of alkylene since the resulting hydroxyalkyl ethers of galactooxide to 1 part of anhydrous galactomannan, nannans are insoluble in the reaction medium and so. usually occur in finely divided form. One separates

Suitable catalysts for the process according to the invention, therefore, in a suitable manner by filtering, centrifuging, are primary, secondary and tertiary fuging and pressing off the solvent. With amines and / or quaternary ammonium bases. A large number of aliphatic groups, which can also be interrupted by part of the catalyst and the heteroatoms ent during the reaction, can also be removed from the separated solvents, as well as cyclic by-products,
contain aliphatic or aromatic groups. In general, it is necessary that the resulting It is also possible that the amino group is constituent crude product by washing out with part of the solution of a heterocyclic ring system. To be cleaned as a catalytic converter. For example, the following are suitable for batch analyzers: Working preferred embodiment, methylamine, dimethylamine, trimethylamine, tetra- the crude product is stirred in a sufficient amount of methylammonium hydroxide, ethylamine, diethylamine, 25 solvents also used in the reaction or triethylamine, tetraethylammonium hydroxide, Isopropylamine, preferably a slightly less watery mixture, pylamine, diisopropylamine, butylamine, dibutylamine, neutralized, filtered or centrifuged and tributylamine, tetrabutylammonium hydroxide, iso-washes with a little solvent. Of course, butylamine, diisobutylamine, the isomeric hexylamine, the crude product can also be washed out with a heptyl-, octyl-, nonyl-, decyl- and dodecylamine 30 solvent until it reaches a neutral reaction, as well as being formed by exhaustive methylation are the ammonium bases. Furthermore, but mostly larger than in the case of the above-described aniline, dimethylaniline, cyclohexylamine, piperidine, benen purification processes are mentioned, which include the neutralization of N-methylpiperidine, N-dimethylpiperidineammonibasic constituents. The purified umhydroxyd, pyridine, alkylpyridines, dicyclohexyl- 35 hydroxyalkyl ethers of the galactomannans can be dried anamine, pyrrolidine, benzylamine and dimethylbenzyl- closing.

amine. As representatives of amines, which further The hydroxyalkyl which can be prepared according to the invention

Functional groups contained in the molecule are covered by natural galactomannans in ether

for example called: ethanol lamb, diethanolamine, very pure form. The ash content, determined as Triethanolamine, propanolamine, dipropanolamine, tri-sulfated ash, is usually below 1% · You are in water

propanolamine. It is also possible to make such amines easily soluble.

to use which has more than one amino group. The products which can be prepared according to the invention can be contained in the molecule, such as. B. Ethylenediamine, use in most cases where propylenediamine, diethylenetriamine, etc. Of the permanent hydrocolloids are desired. The above-mentioned amines or quaternary 45 can be used, for example, as water-soluble ammonium bases, about 0.5 to 20% are required, binders, as thickeners for textiles, in particular 3 to 10%, based on the galacto or other printing inks and as sedimentation, mannan. The required additional amount depends on filtration and flotation aids,
in general according to the basicity and the molecular weight of the catalyst. The speed of the etherification, inter alia, the reaction speed field viscometer at 20 revolutions per minute is dependent on the height of the 5 ° in each case in a 2% aqueous solution with Brook additive. In general, spindle 7 is used to measure
by increasing the amount of amine or the. . . .
quaternary ammonium base the reaction rate example
age increased. It should be noted, however, that the 55 57 g of commercially available pure guar flour (Feuchtiger-mentioned catalysts even with alkylene oxydene content 12.3%) were able to react in a solution of. So if you use a lot of them, 5 g of dimethylaniline in 100 g of 70% isopropanol, a corresponding amount of alkylene oxide is dispersed in with vigorous stirring. The secondary reactions obtained are lost and are therefore no longer available for the dispersion in a stirred autoclave with 30 g of etherification reaction. 60 propylene oxide added and with constant stirring

The inventive process is heated for 3 hours at 6O ⁰ C in temperature range.

Temperatures from about 30 to 80 ° C, in particular 50 to After the reaction mixture has cooled down

6O ⁰ C carried out. Below 30 ⁰ C, the reaction of the resulting Hydroxypropyläther is filtered off. The

tion rate for the practical implementation of the crude product was in 100 g of 90% isopropanol already too low. At higher temperatures, about 65 stirred up and neutralized with acetic acid. To

above 8O ⁰ C, running side reactions in reinforced Filter, was charged with 50 g of isopropanol

Measures from which discoloration of the reaction was washed and the thus purified product in the

Product. Vacuum drying cabinet dried at 70 ° C.

5 6

68 g of a pale yellowish powder were mixed with 30 g of ethylene oxide and kept under constant pressure

obtained, which is heated in water to a clear solution of stirring 3 ¹ Z ₂ hours at 6O ⁰ C.

solved. The viscosity of 2 ° / _o solution was After cooling, the reaction mixture was

1100 cP. The ash content (sulphate ash) of the dry-filtered. The hydroxyethyl ether was in 100 g

Neten product was 0.7 ° / _0th 5 to 90 ° / _o isopropanol "stirred with acetic acid

. . against phenolphthalein "neutralized, filtered and with

Examples _50g i _SO p _ropano i washed. Subsequently was

57 g commercial pure guar flour (moist - dried in a vacuum drying oven at 70 ° C,

keitsgehalt 12.3 ° / ₀₎ were dissolved in a solution of 3 g were 67 g of a slightly yellowish powder

Of triethylamine in 100 g of 80 ° / ₀ acetone by kräf- io (sulfate ash content 0.9 ° / ₀₎ obtained, which in water

dispersed term stirring. The resulting ^ dispersion dissolved clearly. A 2 ° / ₀ solution had a viscosity

was in an autoclave with 30 g of ethylene oxide of 1150 cP.

added and with constant stirring for 3 hours to _n ■ ·, _A

60 ° C heated. ^H

After cooling, the reaction mixture was 15 55 g locust bean gum (water content of 10.1 ° / ₀₎

the hydroxyethyl ether formed was filtered off, with 100 g of monoethanolamine in a solution of 5 g

Of 90%, then 80 stirred twice with 50 g of pure acetone in 150 g ° / ₀ isopropanol. the

Washed and obtained in the vacuum drying cabinet at 70 ⁰ C dispersion was in an autoclave with

dried. . 40 g of ethylene oxide are added and 3 hours at 60 ° C

72 g of a pale yellowish powder 20 were stirred.

obtained, the 2 ° / ₀ aqueous solution was clear. After cooling, the formed hydroxy

It had a viscosity of 1000 cP. The sulfate ethyl ether is filtered off. For cleaning he was in

ash content of the dry product was 0.5% x 100 g of 90 ° / _o isopropanol stirred and after

. -ίο filtering off with 50 g of pure isopropanol

Example _{i 25 washing} Then the product cleaned in this way was

57 g commercial pure guar flour (moist product dried in a vacuum drying cabinet at 70 ° C,

content 12.3 ° / ₀ ) were in a mixture of 73 g of an almost colorless powder (sulfate

80 g isopropanol and 25 g of a 2O ° / o aqueous ash content obtained 1.1 ° / _0), the 2 ° / ₀ aqueous

Solution of tetraethylammonium hydroxide disper solution was clear. It had a viscosity of

greed. This dispersion was in an autoclave 30 9500 cP.

Claims (4)

Patent claims: 1. A process for the preparation of hydroxyalkyl ethers of galactomannans by reacting galactomannans with lower alkylene oxides in the presence of alkaline agents, characterized in that the galactomannans in about 1.5 to 10 times the amount by weight of about 10 to 50 ° / "of water containing, with Water-miscible organic solvent, which under the reaction conditions practically does not react with the alkylene oxide, suspended and at 30 to 80 ⁰ C in the presence of 0.5 to 20 ° / ₀ (based on the galactomannan) of an amine and / or a quaternary ammonium base as The catalyst is reacted with the alkylene oxide and the resulting hydroxyalkyl ethers of the galactomannans are then isolated by filtration or centrifugation. 2. The method according to claim 1, characterized in that the method at a Weight ratio of suspending agent to galactomannan of 1.5: 1 to 3: 1 performs. 3. The method according to claim 1 or 2, characterized in that 3 to 10 ° / ₀ amine or quaternary ammonium bases are used as a catalyst, based on galactomannan. 4. The method according to claim 1 to 3, characterized in that the reaction is carried out at temperatures between 50 and 60 ° C.