RU2126012C1 - Process for preparing water-soluble oligosaccharides - Google Patents

Abstract

FIELD: organic chemistry. SUBSTANCE: claimed process comprises treating chitin with sulfuric acid solution on heating and recovering the desired product. Chitin is added portionwise to reaction, chitin to sulfuric acid weight ratio being from 1:1-1.5. In order to recover the desired product, not more than 7.5 ml of acetone is used per 1 g of chitin. Amount of sulfuric acid and acetone is reduced by about 2 times. EFFECT: more efficient preparation process. 2 cl

Description

 The invention relates to the production of low molecular weight oligosaccharides from chitin, which can be used alone or as intermediates, alone or in a mixture with inorganic or organic compounds of different structures. Chitin oligosaccharides are used as biologically active substances in medicine, cosmetics, food industry, animal husbandry and crop production.

 A known method of producing water-soluble oligosaccharides (RF patent N 2057761, IPC C 08 B 37/08, 1996), which use sulfuric acid of 55-75% concentration in the amount of 2.7-10 ml per 1 g of chitin, the reaction mixture is treated water in an amount of 20-25 ml per 1 g of chitin and neutralized with calcium-containing compounds.

 The disadvantage of this method is the high consumption of acid and the difficulties of neutralization (the formation of bulk sediment, the appearance of a stable foam, etc.).

The prototype of the proposed method is a method of producing water-soluble oligosaccharides according to the USSR author's certificate N 1571047, IPC C 08 B 38/08, 1990. According to the prototype, 65% sulfuric acid in the amount of 2.7 - 10 ml per 1 g of chitin is used the treatment is carried out at 40-50 ^° C for 20-120 minutes, after which acetone is added to the reaction mixture in an amount of 5-7 volumes per 1 volume of acid, the precipitate is separated, dissolved in water, centrifuged, the solution is neutralized and dried. The disadvantage of this method is the high consumption of reagents.

 The essence of the invention lies in the fact that in the method of producing oligosaccharides, comprising treating chitin with a solution of sulfuric acid by heating and isolating the target product, chitin is introduced into the reaction mixture in parts, adding each subsequent part after diluting the previous one, with a weight ratio of chitin and sulfuric acid of 1: 1 -1.5. To isolate the target product, acetone is used in an amount of 7.5 ml per 1 g of chitin.

 As a result, the amount of consumed sulfuric acid and acetone is reduced by about half compared with the prototype.

 To implement the claimed method, chitin is introduced into the reaction in parts. The first part of chitin is mixed with 55 - 75% sulfuric acid, heated and after liquefying the reactive mixture, the second part of chitin is added, mixed and incubation is continued under the same conditions until the reaction is completed.

 The invention is illustrated by examples.

 Example 1

1 g of crab shell chitin is mixed with 3 ml of 65% sulfuric acid, stirred for 15 minutes at 40 ^° C. until a semi-liquid solution is added to which 1 g of chitin is added, the mixture is stirred at 40 ^° C. for another 1 hour 45 minutes, after whereupon 15 ml of acetone (5 volumes with respect to 1 volume of acid) are added, stirred, the supernatant is removed, and 40 ml of water (20 ml with respect to 1 g of chitin) is added to the precipitate, after stirring, the mixture is centrifuged, the supernatant is neutralized by the addition of CaCO ₃ . In the supernatant, the concentration of water-soluble chitin oligosaccharides is measured using the specific Elson-Morgan reaction for glucosamine and an amino sugar concentration of 1.3% is obtained.

From the data obtained, the consumption of the main reagents per 1 g of water-soluble oligosaccharides, measured as amino sugar, was: H ₂ SO ₄ - 5.8 g; acetone - 29 ml; chitin - 3.8 g.

 Example 2

4.5 ml of 65% sulfuric acid are added to 1.5 g of chitin of the shrimp shell, stirred for 15 minutes at 40 ^° C until a liquid solution is added, to which another 1.5 g of chitin is added, the mixture is stirred at 40 ^° C within 1 hour 45 minutes, after which 22.5 ml of acetone are added (5 volumes with respect to 1 volume of acid), stirred, the supernatant is removed, and 70 ml of water is added to the precipitate (23 ml with respect to 1 g of chitin), after stirring, the mixture is centrifuged, the precipitate (colloidal chitin) is dried and 1.53 g of insoluble material are obtained, and the supernatant is neutralized. by CaCO ₃ . In the supernatant, the concentration of water-soluble chitin oligosaccharides is measured using a specific Elson-Morgan reaction on glucosamine and an amino sugar concentration of 1.2% is obtained.

From the data obtained, the consumption of the main reagents per 1 g of water-soluble oligosaccharides, measured as amino sugar, was: H ₂ SO ₄ - 5.2 g; acetone - 31 ml; chitin - 3.5 g.

 Example 3

1.0 g of crab shell chitin is mixed with 3.0 ml of 65% sulfuric acid, stirred for 10 minutes at 45 ^° C. until a liquid solution is added to which another 1.0 g of chitin is added, and the mixture is stirred at 45 ^° C. for 1 hour, after which 70 ml of water are added, centrifuged, the precipitate (colloidal chitin) is dried and 0.95 g of insoluble material is obtained, and the supernatant is neutralized by adding 3.18 g of CaCO ₃ . In the supernatant, the concentration of water-soluble chitin oligosaccharides is measured using the specific Elson-Morgan reaction for glucosamine and an amino sugar concentration of 1.0% is obtained.

From the data obtained, the consumption of the main reagents per 1 g of water-soluble oligosaccharides, measured as amino sugar, was: H ₂ SO ₄ - 4.3 g; CaCO ₃ - 4.5 g; chitin - 2.9 g.

 For comparison, we give an example of the prototype method.

 Example 4 (by the method of the prototype).

2.1 g of crab shell chitin are mixed with 6.3 ml of 65% acid, incubated at 40 ^° C. for 90 minutes, 34.0 ml of acetone are added (5.4 volumes with respect to 1 volume of acid), mixed, the supernatant is removed, and the precipitate is added 50 ml of water (24 ml relative to 1 g of chitin), stirred, centrifuged, the precipitate (colloidal chitin) is dried and 1 g of insoluble material is obtained, and the supernatant is neutralized by the addition of CaCO ₃ , filtered, the solution is lyophilized to obtain 1.35 g of material containing 55% water-soluble chitin oligosaccharides, measured specifically them by Elson - Morgan.

From the data obtained, the consumption of the main reagents per 1 g of water-soluble oligosaccharides, measured as amino sugar, was: H ₂ SO ₄ - 8.5 g; acetone - 46 ml; chitin - 2.83 g.

The proposed method provides a significant reduction in reagent consumption, achieved by introducing chitin into the reaction mixture in parts at different times as it dissolves and liquefies the reaction mixture. The minimum amount of sulfuric acid and acetone consumed by the prototype method per 1 g of the starting chitin is 2.7 ml (for a 65% solution of H ₂ SO ₄ this is 2.7 g) of sulfuric acid and 14 ml of acetone. According to the proposed method, it is equal to 1.5 g of acid and 7.5 ml of acetone, respectively. When calculating the finished product, which is a mixture of water-soluble chitin oligosaccharides, it can account for 39 and 33% savings in acid and acetone, respectively.

Claims (2)

 1. A method of producing water-soluble oligosaccharides, including treating chitin with a solution of sulfuric acid by heating and isolating the target product, characterized in that chitin is introduced into the reaction mixture in parts, adding each subsequent part after diluting the previous one, with a mass ratio of chitin and sulfuric acid of 1: (1 - 1.5).  2. The method according to claim 1, characterized in that for the isolation of the target product, acetone is used in an amount of not more than 7.5 ml per 1 g of chitin.