DE1003201B - Process for the production of polyhydric alcohols by catalytic reduction of carbohydrates - Google Patents

Description

GERMAN

The invention relates to a process for the production of polyhydric alcohols by catalytic reduction of carbohydrates that contain small amounts of impurities that undergo catalytic reduction affect. Carbohydrates that can be converted into polyvalent alcohols are, for. B. Strength and Starch hydrolysis products, such as soluble (thin-boiling) starch, dextrin, glucose syrup, starch sugar (glucose) and other mono-, di- and polysaccharides, such as fructose, galactode, arabinose, maltose, lactose, sucrose, Raffinose or inulin. If di- or polysaccharides or mixtures thereof are used as starting materials, then these are first hydrolyzed to monosaccharides, which are then reduced to polyhydric alcohols can, the hydrolysis and the hydrogenation preferably taking place at the same time. The reaction products can polyhydric alcohols with the same number of carbon atoms as the monosaccharides, e.g. B. Sorbitol, or polyhydric alcohols with a lower number of carbon atoms, e.g. B. glycerine or propylene glycol, be.

The catalytic reduction of aqueous solutions or suspensions of carbohydrates to polyhydric alcohols is known. However, it has been shown that in many cases the reduction is not as desired Wise and that this is probably due to impurities in the raw materials used is.

Various proposals have been made to avoid the adverse effects of contaminants on the to reduce catalytic reduction. Methods are known according to those contained in the starting material Chlorine ions are removed beforehand, e.g. B. by precipitation with metal salts or by treatment with Anion exchangers. If necessary, the colloidal impurities can first be precipitated. It has also been proposed that the catalytic reduction with the addition of a small amount of a salt a weak base, such as B. ammonium, magnesium, heavy metals and the like.

According to the invention, starting materials containing small amounts of impurities which adversely affect the catalytic reduction to polyhydric alcohols can easily and completely be converted into polyhydric alcohols if these starting materials are in aqueous solution or dispersion with a small amount of hydrogen peroxide before the catalytic reduction or a derivative thereof. The derivatives of hydrogen peroxide to be used according to the invention can be both inorganic and organic per compounds, e.g. B. sodium peroxide, barium peroxide, percarbonates, persulfates, perborates, perphosphates, sulfomonoperic acid (H ₂ SO ₅ ), peracetic acid, perbenzoic process for the production of polyvalent

Alcohols by catalytic reduction

of carbohydrates

Applicant:
Naamloze Vennootschap WA Scholten's

Chemical factories,
Groningen (Netherlands)

Representative: Dr.-Ing. A. v. Kreisler

and Dr.-Ing. K. Schönwald, patent attorneys,

Cologne 1, Deichmannhaus

Claimed priority:
V. St. v. America November 3, 1952

Cornells Martinus Hendrik Kool, Dr. Jan Lolkema

and Geert Moes, Hoogezand (Netherlands)

have been named as inventors

acid, benzoyl peroxide, alkyl peroxides, ozone and ozonides.

Since hydrogen peroxide and its derivatives are active oxidizing agents, all of them are activated by the Group - O - O - are marked, is the cheapest The influence of these substances is likely to be attributed to an oxidation of the impurities in the carbohydrate, whereby they are destroyed and / or converted into other compounds that do not have a delaying effect on the have catalytic reduction of the carbohydrate to a polyhydric alcohol.

Although the nature of these impurities has not been determined with certainty, it is not unlikely that that sulfur-containing compounds, such as sulfur dioxide, sulfites, bisulfites or protein-like substances, as a result of the manufacturing process used in the starting material, e.g. B. starch or hydrolysis products of strength, may be the main cause of the difficulty experienced.

A useful and extremely sensitive method for detecting traces of sulfur dioxide and / or Sulphites in carbohydrates, such as starch and starch hydrolysis products, is that which Rothenfusser in Journal for investigation of food, 58 (1929), pp. 98 to 109, is described. According to this method the sulfur dioxide that is present in the product to be analyzed as such or in the form of a sulfite

609 837,471

3 4

is, distilled and in an alcoholic hydrogen-permeable oxides, such as chromium, aluminum, tungsten oxides,

Oxide-containing benzidine solution collected. The sulfur can be added.

Dioxide is oxidized to sulfuric acid, which it is advantageous to use catalysts

forms insoluble benzidine sulfate. are practically alkali-free, as in the Dutch

This method is extremely sensitive and can be described in patent specification 65,118.

with her 0.5 to 1 mg of sulphurous acid still slightly after- If a starting material is used, the whole

point. or largely consists of polysaccharides, which also

It has been shown that the reduction to sorbitol must be hydrolyzed from next to monosaccharides,

Starch and starch hydrolysis products that contain sulfur, it is advantageous to add an acidifying substance,

In the form of sulfur dioxide and / or sulphites, ₁₀ which reacts neutrally at normal temperature, but at

runs smoothly and completely, if these carbohydrates of the temperature of the hydrolytic hydrogenation in

previously in aqueous suspension or solution with the presence of water forms acidic substances, such as

such amount of the oxidizing agent, e.g. B. hydrogen- this is described in Dutch patent specification 60 860

peroxide, to be treated that are written when using.

200 g of the treated throat hydrate according to the Rothen- ₁₅ If the method according to the invention is based on the her-

Fusser's method still has a negative reaction with the formation of lower polyhydric alcohols, such as glycerine,

Sulfur dioxide is obtained. Propylene glycol or mixtures thereof, by destructive

The amount of oxidant with which the carbohydrate, hydrogenation of carbohydrates, should be applied

z. B. starch or a starch hydrolysis product, before which the hydrogenation temperature is above 200 °, preferably 250

Hydrogenation must be treated for it to be rapid and _ao to 300 °. However, the invention is particularly useful for

can be completely converted into sorbitol, amounts to in the production of sorbitol and isomeric hexites, which in

generally only a few tenths to a few percent of the lower temperatures are significant. For

Weight of the carbohydrate. The reduction of monosaccharides, especially of

If glucose can be treated with such quantities of oxidizing agents, the temperature should generally not exceed it

achieve the 0.001% up to about 5%, calculated on the 35 160 °, while for hydrolytic hydrogenation

Carbohydrate. of polysaccharides, such as starch and dextrin, temperature

As an oxidizing agent, hydrogen temperatures of up to 200 ° will preferably be better. The reduction of GIu-

peroxide used. In most cases the kose starts at around 100 ° and proceeds quickly and without any problems

wanted effect with less than 1% of this oxidation- essential caramel formation at temperatures of 120

means, calculated on the weight of the carbohydrate, ₃₀ to 160 °. The most favorable temperature for the reduction

be achieved. In general, the amount of starch and high polymer hydrolysis products required will vary from

Amount of hydrogen peroxide from 0.001 to about 1%. Strength to sorbitol is about 180 to 200 ° (cf. the lower

The treatment of the carbohydrate with the Oxyland patent specification 60 685). For the reduction too

dation agent can be used at room temperature or in the sorbitol of starting materials, which are made from mixtures of

higher temperature, e.g. B. at 100 °. ₃₅ kose and polymers consist of glucose, such as glucose

In consideration of a possible attack by the hydrogen syrup and starch sugar, it is therefore preferable to

Approximate catalyst, it is appropriate, a possible way so that the material does not initially at a 160 °

To decompose excess of oxidizing agents or to exceed the temperature is hydrogenated until the GIu-

remove before the carbohydrate of the reduction undercool is largely reduced, and then the hydrogenation

is thrown. If the carbohydrate to be reduced _{40 is} continued at a temperature above 180 °, the

must be subjected to hydrolysis, such as. B. im is not so high that a split of

Case of starch and high polymer starch hydrolysis carbon-carbon bonds occur until the

products, the oxidizing treatment and the glucose polymers are reduced to sorbitol. The hydraulic

If desired, hydrolysis of the polysaccharide is also generally carried out at high pressure, e.g. B. 20 to be done in good time. 45 200 at.

Suitable starting materials for the present The obtained by the process according to the invention Processes are all carbohydrates that result from hydrogenation results from the processes described below or by hydrogenolysis (combined hydrolysis and seek out. These attempts were converted into polyhydric alcohols in an AutoHydration) are carried out from stainless steel with a can. However, the invention is particularly suitable for the 50 high-speed stirrers (about 500 rotations per position of sorbitol or a mixture of isomeric hexites) and with an electric heating device made of starch and starch hydrolysis products from important. tion. Under starch hydrolysis products, GIu- τ,. . ,, kosy, highly polymeric hydrolysis products of starch, such as ice cream

soluble starch and dextrin, and mixtures of glucose 55 The nickel catalyst used in this example

and polymers of glucose such as these obtained by reaction in the following manner:

_{495 g of crystallized nickel sulfate (NiSO 4} 7H ₂ O) were obtained from starch with acids and / or enzymes. Examples of such mixtures are GIu- dissolved in 15 l of water. There were 400 g of purified Kieselkosesirup, maltose syrup and starch sugar, the gur added from Ge, it g at 40 ° with stirring, 6680 of a blend of glucose, maltose and dextrin, gegebenen- 60 5 ° / _o aqueous ammonium bicarbonate solution allowed to flow in, if in addition to small Amounts of unreacted starch, and the stirring for about 1 ¹ ₂ hours with the same exist. Temperature continued. The reaction mixture was The reduction is left to stand for some time with hydrogen or hydrogen, the clear liquid containing gases containing decane is passed through in the presence of a catalyst, the precipitate is boiled with 15 l of water, and the mass is removed. As such, nickel, copper, cobalt, 65 are usually centrifuged and the solid oxides of these metals or mixtures of two or more compounds separated in this way are washed with hot water until the filtrate does not use any of these metals or oxides. They are mostly contained in sulfate more. The mass was then applied in a finely divided state at 110 °, preferably dried and reduced in a stream of hydrogen at 525 °, on a carrier, e.g. B. Kieselguhr. To activate the kata- The starting material was a starch sugar with a lysator, certain difficult- 70 moisture content of 14.5% and a dextrose-

equivalent of 82% calculated on the dry matter. ^{0.3 cm 3 of} a 30% strength hydrogen peroxide solution were added to a solution of 100 g of this starch sugar in 100 g of water and the mixture was heated to the boil for 15 minutes. The impurities were oxidized while at the same time the excess of hydrogen peroxide was decomposed. The solution was then cooled to room temperature and made up with water to the original volume. To this solution was added 10 g of the above catalyst and adjusted the p _H of the solution with phosphoric acid to 3.5. The mixture thus obtained was introduced into an autoclave, which was then connected to a hydrogen cylinder so that the hydrogen pressure became 100 atm. The mixture was ^{heated to 140 ° 1 x} / _a hour, which was sufficient to reduce most of the glucose present. Thereafter, the temperature was increased in about 1 hour from 140 to 200 ° and the mixture held for 1 ¹ U hours at this temperature, in order to reduce existing in the starting material polysaccharides. The autoclave was then cooled down to room temperature again. After the excess hydrogen had been let off, the autoclave was opened and the solution was freed from the catalyst by filtration. The filtered solution contained 0.1% glucose, 0.1% dextrin and 99.0% sorbitol, calculated on the dry matter.

This experiment was repeated in the same way with the same starting material, but without the oxidizing one Treatment. It was found that in this case the solution finally obtained contained 12.7% glucose; the dextrin and sorbitol content could not be precisely determined due to this high glucose content.

Analysis showed that the starting material used for these experiments was 0.02% sulphurous Acid contained - determined by iodometric titration with a 0.02 n-iodine solution - while after After the oxidizing treatment in this way no more sulphurous acid could be found. Of the Rothenfusser's experiment gave a completely negative result with 200 g of the treated carbohydrate.

Example 2

The catalyst used in this example was prepared in the following manner.

3 kg of crystallized nickel sulfate were dissolved in 90 l of water and the solution was mixed with 2.5 kg of kieselguhr. This mixture was at a temperature of 40 ° with stirring in the course of 15 minutes 15.5 1 5% sodium hydroxide solution was added and stirring was continued for a further 30 minutes. The crowd was nitrided through a large Büchner funnel; the residue was taken up again in water at 80 ° filtered and washed with water. These treatments were repeated until the filtrate only traces of sulfate contained. The catalyst thus obtained was dried at 100 ° in a vacuum oven and ground. The ground catalyst was reduced in a stream of hydrogen for 3 hours at 525 °.

A solution of 100 g of starch sugar with a water content of 14.5% and a dextrose equivalent of 90.7%, calculated on the dry matter, in 95 cm ^{3 of} water was mixed with 5 cm ^{3 of} a 3% strength hydrogen peroxide solution. The mixture was boiled for 10 minutes and then cooled back to room temperature, whereupon the weight of the solution was brought back to 200 g by adding water. To the solution thus treated were added 10 g of the above-described catalyst and 1.4 g of crystallized nickel sulfate.

This mixture was heated to a temperature of 140 ° to 150 ° in an autoclave for 1 hour with a supply of hydrogen under a pressure of 125 atm. In order to convert the glucose polymers into sorbitol, the temperature of the mixture was then increased in the course of 1 hour to about 200 ° and the mass 1 V was kept at this temperature for _{2 hours.} After cooling to room temperature, the liquid was filtered and analyzed. The reaction product turned out to be a practically pure sorbitol solution containing only traces of glucose and dextrin.

When the above-described experiment was repeated without the oxidizing treatment with hydrogen peroxide, an end product was obtained which contained 8.7% glucose, 3.4% dextrin and only 73% sorbitol.

In a gravimetric determination of the sulfur dioxide in the starch sugar, a content of 0.037% found. After the oxidizing treatment with hydrogen peroxide in the manner described above

In addition, Rothenfusser's experiment with 300 g of the treated sugar gave a completely negative result.

Example 3

A mixture of 125 g of potato starch and 125 cm ^{3 of} water was heated to 140 ° for 45 minutes with 0.8 g of sulfuric acid in a stainless steel autoclave equipped with a stirrer. After cooling to room temperature, the p _H of the solution thus obtained was adjusted with nickel to 4.2, followed by 12.5 g of the nickel catalyst prepared according to Example 2 were added.

The mixture was in the autoclave under a hydrogen pressure of about 100 at 1 hour to 140 bis 160 ° heated. In order to convert the glucose polymers into sorbitol, the temperature of the mixture was then increased increased in the course of 1 hour to about 200 ° and held at this value for 1 hour.

The reaction mixture was then cooled to room temperature and filtered. The solution had a caramel odor and reduced Fehling's solution in the cold. The percent reducing sugar was 13.1%, expressed as glucose on dry matter. Because of this high content of reducing sugars it was possible the sorbitol content of the solution cannot be determined.

The experiment was repeated, but with the difference that the mixture of 125 g of potato starch and 125 cm ^{3 of} water was heated with 0.8 g of sulfuric acid and 1 cm ^{3 of} 30% strength hydrogen peroxide before hydrogenolysis. In this case a product was obtained which consisted of 98% sorbitol, 0.7% glucose and 0.2% dextrin.

The potato starch used in these experiments contained traces of bisulphite and sulphite, which were caused by the manufacturing process of the potato flour. In Rothenfusser's experiment, 10 g of the potato starch resulted a positive reaction to sulphurous acid. After the oxidizing treatment, the reaction was turned negative.

Example 4

125 g of potato starch with a moisture content of 19% and a protein content of 0.3% were ^{suspended in 125 cm 3 of} water. To this suspension were added g of prepared in Example 1 was adjusted Nickelgurkatalysators 12.5 whereupon the p _H of the mixture with phosphoric acid to 3.5.

The starch was then heated by heating the mixture in an autoclave for 90 minutes under a Hydrogen pressure converted from 120 at to 200 ° in sorbitol. After cooling down to room temperature it was

the contents of the autoclave are filtered and then analyzed. The reaction product contained 6.3 ° / ₀ glucose, 4.6 ° / ₀ dextrin and about 78 ° / ₀ polyhydric alcohol, calculated as sorbitol, in the dry state.

The experiment was repeated, but prior to the hydrogenolysis, the suspension of 125 g potato starch in 125 cm ⁸ cm of water after addition of 1 ^s 30% hydrogen peroxide was stirred at a p _H = 7 6 hours at room temperature. The thus-treated starch suspension was added 12.5 g of catalyst was adjusted and then the p _H of the mixture with phosphoric acid to 3.5. The starch was then subjected to hydrogenolysis to sorbitol in the manner described above. In this experiment a reaction product was obtained which contained 97% sorbitol and only 0.3% glucose and 0.25% dextrin.

The starting material in this example was a secondary potato starch with a protein content of 0.3%. First quality potato starch, as used in the previous example, generally contains less than 0.08% protein.

Example 5

100 g of glucose syrup with a water content of 18.5% and a dextrose equivalent of 49.6%, calculated on the dry matter, were ^{diluted with 100 cm 3 of} water, whereupon 1 cm ^{3 of} a 3% strength hydrogen peroxide solution was added. The solution was heated to boiling for 10 minutes, cooled to room temperature and made up with water until the total weight was 200 g.

The thus treated glucose syrup solution was mixed with 10 g of the nickel catalyst prepared in Example 1 was added, was adjusted and then the p _H of the mixture with phosphoric acid to 3.5. The mixture was heated in the autoclave at 140 to 150 ° for ₂ hours under a hydrogen pressure of 100 at IV. In order to convert the glucose polymers into sorbitol, the temperature of the liquid was then increased over the course of 1 hour to about 200 ° and held at this value for 75 minutes. After cooling to room temperature, the solution was filtered to remove the catalyst and then analyzed. The solution contained 0.15% glucose, 0.18% dextrin and 98.9% sorbitol, calculated on the dry matter.

When a solution of 100 g of glucose syrup in 100 cm ^{3 of} water was hydrogenated without prior treatment with hydrogen peroxide, but otherwise under the same conditions, an end product was obtained which contained 4.1% glucose, 0.7% dextrin and only 84.1% Sorbitol, calculated on dry matter.

g of the glucose syrup used according to this example resulted in a Rothenfusser experiment positive reaction to sulphurous acid. With the iodometric Titration was carried out with a 0.02 n-iodine solution a sulfur dioxide content of 0.003%, calculated on the Glucose syrup, found. After treatment with hydrogen peroxide, the Rothenfusser experiment showed ίο still a negative result with 500 g of the treated syrup.

Claims (5)

Patent claims: 1. Process for the production of polyhydric alcohols by catalytic reduction of carbohydrates, especially starch and / or hydrolysis products of starch, which contain small amounts of impurities that impair the catalytic reduction, characterized in that the carbohydrate, ao before it is converted into polyhydric alcohol by catalytic reduction, in aqueous Solution or dispersion with a small amount of hydrogen peroxide or a derivative thereof is treated. 2. The method according to claim 1, characterized in that that the amount of hydrogen peroxide or its derivatives from 0.001 to 5%, preferably from 0.001 to 1% based on the weight of the carbohydrate. 3. The method according to claim 1 and 2, characterized in that the pretreatment with hydrogen peroxide or its derivatives in the production of sorbitol from starch and / or starch hydrolysis products is applied. 4. The method according to claim 1 to 3, characterized in that the starting products are carbohydrates Find use with sulfur compounds, especially with sulfurous acid or whose salts are contaminated. 5. The method according to claim 4, characterized in that the amount of hydrogen peroxide or its derivatives is chosen so that after the oxidizing treatment at least 200 g of des treated carbohydrates according to the Rothenfusser method result in a negative reaction. Considered publications:
U.S. Patents Nos. 2,282,603, 2,306,688,
581 235. 837/471 2 57