Molecular Formula | C6H11NO4X2 |
Molar Mass | 161.16 |
Density | 1.3744 (rough estimate) |
Melting Point | >300°C (dec.) |
Boling Point | 737.18°C (rough estimate) |
Flash Point | 627.8°C |
Water Solubility | insoluble |
Solubility | Soluble in concentrated hydrochloric acid, sulfuric acid, glacial acetic acid and 78-97% phosphoric acid, insoluble in water, dilute acid, alkali, alcohol and other organic solvents. |
Vapor Presure | 0mmHg at 25°C |
Appearance | White powder |
Color | White |
Merck | 14,2065 |
Storage Condition | Room Temp |
Stability | Stable. Incompatible with strong oxidizing agents. |
Refractive Index | 1.6000 (estimate) |
MDL | MFCD00466914 |
Physical and Chemical Properties | Appearance: White amorphous material, odorless, tasteless. Solubility: soluble in dimethyl acetamide or concentrated acid containing 8% lithium chloride; Insoluble in water, dilute acid, alkali, ethanol or other organic solvents. |
Use | Chitin is an important raw material for the preparation of chitosan and glucosamine series products. Chitin and its derivatives have important applications in medicine, chemical industry, health food and so on. For the preparation of soluble chitin and glucosamine, can be used for cosmetics and functional food additives, can be prepared photographic emulsion |
Risk Codes | R20/21/22 - Harmful by inhalation, in contact with skin and if swallowed. R36/37/38 - Irritating to eyes, respiratory system and skin. |
Safety Description | S24/25 - Avoid contact with skin and eyes. S36 - Wear suitable protective clothing. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. |
WGK Germany | 3 |
RTECS | FM6300000 |
FLUKA BRAND F CODES | 3 |
TSCA | Yes |
HS Code | 32139000 |
Reference Show more | 1. Li Yang, Liu Zhao, Hu Miao, et al. Study on Stability of Pickering Emulsion Prepared from Chitin Nanocrystals with Different Crystallinity [J]. Journal of Agricultural Machinery 2020 v.51(03):341-347. 2. Wei Lirong, Qin, Wang, Yan, Li Yongcheng. Breeding of Chitin Deacetylase-producing Strain and Study on Its Fermentation Characteristics [J]. Chinese Brewing 2018(7):61-66. 3. Lu Mengyuan, shi Jiaxian, Xia Xiang, et al. Analysis of Enzymatic Properties and Degradation Products of Chitinase Expressed by Escherichia coli on Different Substrates [J]. Food and Fermentation Industry, 2015, 041(003):26-32. 4. Sun Xubing, Wu Xuemei, Zhu Jianfa, et al. Adsorption Performance and Mechanism of Carboxyl Chitin on Pb(Ⅱ) [J]. China Environmental Science, 2018, v.38(08):220-230. 5. You Yaohui, Sun Xubing, Zheng Xiaogang, Xu Ling, Lin Lei, Cao Kun. Preparation and properties of carboxymethyl chitin retention aid [J]. Fine Chemicals, 2017,34(08):935-941. 6. Ji Lei, Liu Tianhong, Wang Ying, Tang Huanhuan, Li Xiao, Li Hongyan, Jiang Xiaodong, Sun Yuanqin, Yang Qing. Comparison of Preparation Methods and Properties of Chitosan [J]. Journal of Food Safety and Quality Inspection, 2021,12(03):951-959.[2] Liu Congyan, Li Ruiyun, Ma Chengyao, Liu Yuping, Qu Ding, Li Xiaoqi, Chen Yan. Biotransformation of icariin by β-glucosidase immobilized on chitosan crosslinked mesoporous silica [J]. Chinese herbal medicine, 2021,52(03):685-691.[3] Liu Yuan. Construction of Chitosan Functional Carrier and Study on Immobilization of Lysozyme and Protease [D]. Huazhong Agricultural University, 2020. 7. Wang Xiaosong, Ma Lei, Liu Zhiying, Li Tuo, Zhu Han, Liu Dongyang, Shen Qirong. Cloning, Expression and Enzymatic Characteristics of Chitinase Gene chi8 from Trichoderma guizhou NJAU4742 [J]. Journal of Nanjing agricultural university, 2021,44(01):111-118. 8. he, l., Ou-Yang, y., Li, n., Chen, y., Liu, s. q., & Huang, g. h. (2020). Regulation of chitinase in Spodoptera exigua (hübner) (Lepidoptera: noctuidae) during infection by Heliothis virescens ascovirus 3h (HvAV-3h). Frontiers in physiology, 11, 166.http 9. [IF = 9.381] Yang Zhang et al."Enzymatic single-step preparation and antioxidant activity of hetero-chitooligosaccharides using non-pretreated housefly larvae powder." Carbohyd Polym. 2017 Sep;172:113 10. [IF = 4.539] Beijing Sun et al."Surface-modified chitin by TEMPO-mediated oxidation and adsorption of Cd(II)." Colloid Surface A. 2018 Oct;555:103 11. [IF = 1.303] Lei He et al."Molecular characterization, activity analysis and transcriptional detection of chitinases encoded in the genome of Spodoptera exigua." J Asia-Pac Entomol. 2019 Jun;22:499 12. [IF = 9.381] Qiao Zhang et al."Establishment of successive co-fermentation by Bacillus subtilis and Acetobacter pasteurianus for extracting chitin from shrimp shells." Carbohyd Polym. 2021 Apr;258:117720 13. [IF = 7.514] Haipeng Su et al."Engineering a carbohydrate binding module to enhance chitinase catalytic efficiency on insoluble chitinous substrate." Food Chem. 2021 Sep;355:129462 14. [IF = 7.514] Jing Li et al."Biochemical characterization of two β-N-acetylglucosaminidases from Streptomyces violascens for efficient production of N-acetyl-d-glucosamine." Food Chem. 2021 Dec;364:130393 15. [IF = 3.367] He Lei et al."Regulation of Chitinase in Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) During Infection by Heliothis virescens ascovirus 3h (HvAV-3h)." Front Physiol. 2020 Mar;0:166 |
remove debris from shrimp and crab shells, clean them, dry them in the sun, and soak them in 5% hydrochloric acid to remove inorganic salts (calcium carbonate, calcium phosphate, etc.), then wash off residual acid with clear water. Then use 10% sodium hydroxide solution to remove impurities such as fat and protein.
Add dilute potassium permanganate solution bleaching decolorization, and then washed with water, and 1% of sodium bisulfite elution of residual potassium permanganate, after washing, drain, drying, can be prepared chitin.
thickeners, emulsifiers, stabilizers, adhesives, pharmaceutical excipients, medical sutures, etc. It can be used as a sustained release agent, a lubricant, and a coating agent as an auxiliary material. Microgranules, tablets, capsules, microfilms and the like of the corresponding drug can be prepared by direct compression, wet granulation or coating. Can be made of dialysis membrane, ultrafiltration membrane and reverse osmosis membrane and fiber and other cross-chain complex can be formed into molecular sieve. As a cross-linking agent with glutaraldehyde and the like, it can be immobilized with many enzymes or microbial cells, such as immobilized asparaginase. Can be used as artificial skin, artificial blood vessels, artificial kidney, etc. Glycans can inhibit gastric ulcer, lower cholesterol, blood lipids.
sealed storage.
update date: | 2022/11/12 10:05:38 |
EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
Overview | Chitin is a nitrogen-containing polysaccharide, also known as chitin, chitin, chitin, chitin, chitin, cutin, etc. It is the second most abundant biopolymer in nature and is widely distributed. It is an important component of the shells of many lower animals, especially arthropods such as shrimp, crabs, insects, etc. Shrimp shells contain about 15% ~ 30%, crab shells contain about 15% ~ 20%. It is also a component of the cell membrane of lower plant fungi, including lichens, green algae, yeast, jellyfish and squid. It is estimated that the annual biosynthesis exceeds 1 billion tons, which is a huge renewable resource. The appearance is white or yellowish transparent. It is a 2-acetylglucosamine polymer. Its chemical structure is similar to that of natural cellulose. In addition to hydroxyl groups, the molecule also contains acetylamino and amino functional groups, which can be used for structural modification. There are many groups, which have more functional properties than cellulose and its derivatives. They are insoluble in water, ethanol, ether, salts, dilute acids and bases; soluble in acetic acid, it reacts with concentrated caustic soda solution to form glassy colloidal soluble chitin (also known as polyamine glucose, chitosan, sugar solution chitin, chitosan, etc.), which can be used to: ① purify water and extract uranium from seawater Ion exchange resin; ②Filler and molecular sieve of gel chromatography column; ③Preparation of food packaging film or soluble in vivo surgical thread that can be degraded by organisms or enzymes; ④Water retention agent for cultivating plants or microorganisms; (5) Anti-shrink and anti-wrinkle treatment of textiles, fixation of direct dyes or vulcanized dyes. Chitin is insoluble in general acid and alkali, and its chemical properties are very stable, which is an important reason for restricting its long-term failure to develop. The chitosan after deacetylation is white to light yellow powder. Although it is also insoluble in water, alkali solution and organic solvent, it is soluble in dilute acid solution, including inorganic dilute acid (hydrochloric acid, nitric acid, etc.) And organic dilute acid (acetic acid, lactic acid, formic acid, ascorbic acid, malic acid, etc.). In the aqueous solution of multivalent organic acids such as citric acid and tartaric acid, it is dissolved when heated at a high temperature, and then it is gel-like after the temperature drops. Chitin is a β (1 → 4) polymer of 2-acetylamino -2-deoxy-D-glucose, a polysaccharide compound 2-amino -2-deoxy-D-glucose after acetyl group is removed by a polymer connected by β (1 → 4) glycosidic bonds, namely chitosan. Figure 2-7 shows the chemical structures of chitin, chitosan and cellulose, and the structures among the three are similar. Since the existing technology cannot completely remove the acetyl group of chitin and turn it into 100% chitosan, and it is difficult to completely separate the two, the existing chitosan products are usually a mixture of chitin and chitosan, but the chitosan content is required to be above 60%. However, chitosan as a functional food base requires chitosan content above 85%. |
chitin derivative | chitin derivative is a product obtained by chemical modification of chitosan (Chitosan), and chitosan is chitin (Chitin) obtained by deacetylation, its structural formula is as follows: The molecular structure of chitosan and chitosan derivatives The chitosan derivatives overcome that chitosan is only soluble in acid, easy to degrade, and easy to precipitate in organic solvents, the weakness of poor physical and chemical stability has greatly expanded the application field of chitin. Chitosan can obtain different derivatives through chemical modification, hydrolysis and formation of chitosan metal complexes with metals. The methods of chemical modification are: ① Acylation reaction: Chitin and Chitosan react with acid chloride or acid anhydride to introduce aliphatic or aromatic acyl groups with different molecular weights on the macromolecular chain, which can improve solubility. ② alkylation reaction: alkylation reaction can be carried out on the hydroxyl group of chitin (O-alkylation) or the amino group of chitosan (N-alkylation). N-alkylation is more likely to occur, and the solubility of the product depends on the length of the alkyl chain. ③ Carboxylation reaction: Carboxymethylated chitin is prepared by the reaction of basic chitin and chloroacetic acid. ④ esterification reaction: C6-hydroxyl of chitosan can undergo esterification reaction with oxygen-containing inorganic acid, such as reaction with concentrated sulfuric acid, sulfur trioxide and chlorosulfonic acid to prepare chitosan sulfate. ⑤ chitosan quaternary ammonium salt reaction: chitosan is chemically modified with glycidyl trimethyl ammonium chloride, and quaternary ammonium salt groups can be introduced into chitosan molecules to prepare chitosan quaternary ammonium salt. ⑥ silanization reaction: chitin can be completely trimethylsilanized to obtain derivatives with good solubility and reactivity, and the protective group is easily removed. Therefore, it can be modified and modified under controlled conditions. ⑦ hydrolysis reaction: chitin and chitosan can be completely degraded or not completely degraded, either acid or enzymatic. ⑧ chitosan metal polymer (such as chitosan copper polymer (CCC) and chitosan zinc complex (CZC)) obtained by chemical reaction between chitosan and metal salts is a new type of organic polymer, which is widely used for anticorrosion. |
production process | crustacean shells, such as shrimp shells and crab shells, are composed of two parts. The surface is a thin and transparent stratum corneum, the main component is calcium, and the inside is a thicker chitin layer. It is necessary to first dissolve calcium with acid, and then convert insoluble chitin into soluble chitin under the action of alkali. Process flow: washing raw materials → adding hydrochloric acid → soaking acid for decalcification → washing with dilute alkali → boiling alkali for degreasing and deproteinization → washing with acid → secondary acid for decalcification → washing with dilute alkali → secondary alkali for degreasing → water washing → water washing → chitin → adding concentrated alkali → alkali boiling for heat preservation and deacetylation → water washing → drying → packaging → soluble chitin. soak shrimp shells or crab shells with 5% hydrochloric acid for 1~2 days until no bubbles appear. After taking it out, rinse it with a lot of water until it is neutral. At this time, inorganic salts such as calcium carbonate in the carapace are removed and are soft. Soak the soft carapace with 8-10% caustic soda solution again for 1-2 days, heat and boil for 1-2 hours, take it out and wash it with a lot of water until neutral to remove stratum corneum and fat. Soak the soft carapace with 0.2% potassium permanganate solution for 1 hour, and remove the organic pigment on the carapace by oxidation. After taking out and rinsing with clear water, immerse in 1% sodium bisulfite solution for 10 minutes, then add a small amount of hydrochloric acid to make the solution acidic, and continue soaking for 20 minutes to remove manganese dioxide attached to the carapace. At this time, the carapace should be white to obtain insoluble chitin. To prepare soluble chitin, take out insoluble chitin and rinse it with clear water to neutral, immerse it in 40% caustic soda, heat to 40-60 ℃, soak for about 24 hours, turn it every 1 hour at the beginning, and then gradually extend it for 5-6 hours. Take it out after the specified time, rinse it with clear water to neutral, and dry it to be the finished product. A small amount of finished product is immersed in 1% acetic acid solution. If it can be dissolved in a short time, it is qualified. If it is insoluble, the reaction is incomplete, and the alkali leaching time can be appropriately extended to remedy it. Sealed with polyethylene plastic bags and packed in wooden cases or cartons. During storage and transportation, it is not allowed to be co-stored and mixed with toxic substances. |
process flow chart of preparing chitin from shrimp and crab shells | chitin is the main component in carapace and is widely distributed in nature. Shrimp and crab shells are the main raw materials for extracting chitin. The content of chitin varies with the type of shell. The content in shrimp shell is about 14% ~ 25% and that in crab shell is about 10% ~ 25%. Chitin is a polyacetyl glucosamine, which belongs to nitrogen-containing polysaccharides. It is insoluble in water, organic solvents, acid and alkali solutions. Only after concentrated alkali treatment or other methods to remove the acetyl group in its molecule, it can be dissolved in dilute acid, called soluble chitin. chitin has the characteristics of alkali resistance, sun resistance, heat resistance, corrosion resistance, no weathering, no deliquescence, moth-proof, etc., and has firm adhesion to textiles, leather, etc., making it scratch, anti-crepe, anti-shrink, wear resistance, strong color fixation ability, etc., so soluble chitin has a wide range of uses. Chitin production process flow chart |
application field | chitin and products made of chitin have a wide range of uses due to their unique physical and chemical properties, such as moisture resistance, sun resistance, mildew resistance and corrosion resistance. Used in textile, printing and dyeing industry as fixing agent, fabric shrink-proof finishing agent, etc. The pharmaceutical industry manufactures anticancer drugs chlorourethromycin, artificial skin, surgical lines, and cholesterol-lowering alcohol drugs. Water treatment agents, flocculants and health food additives for environmental protection, beverage and food industries. Paper making, wood-based panels and other industries are used as adhesives. A new generation of biodegradable film for food packaging agricultural mulch. In agriculture, it is used in fertilizers, pesticide sustained-release agents, compound materials, seed dipping agents, and scientific research for enzyme fixation and interception, separation membrane artificial kidney, etc. For the development and application of chitin, Japan and the United States are the largest producers and the largest consumer market in the world. Chitin and its derivatives are widely used in cosmetics industry, such as shampoo, hair conditioner, bath lotion, hair gel, mousse, perfume, evening dew, aqua cosmetics, cream, lipstick and other series of products, with the following excellent performance and efficacy: (a) safe and non-toxic. (B) good film-forming property, air permeability and biocompatibility. It forms a film on the surface of the skin. Because the film is a three-dimensional network structure, various moisturizing factors and physiological functional substances can be embedded in it, and it has a continuous slow release effect. (c) good skin adhesion. (d) good stability: pH1 ~ 14 stable. Cold, thermal stability is good, good compatibility. (e) good skin conditioning, biodegradable, and meet environmental protection requirements. |
toxicity | natural product, non-toxic. LD50 77.5 g/kg (mouse, oral). The Ames test was negative. |
Anti-corrosion effect of chitin | Chitin itself is very stable and soluble in weak acids, such as acetic acid, lactic acid, citric acid, bran acid, etc. are often used in industrial processes to dissolve chitin, and its solubility is proportional to the acid concentration. Taking acetic acid as an example, 10g/L chitin needs to be dissolved in 1% acetic acid. Once dissolved, it can be further diluted with water. The degree of deacetylation of chitin also affects its ability to form a film. For those with higher deacetylation degree, it is easier to form a film after the aqueous solution is dried. It is used to form a film on the surface of meat and meat products, that is, it has anti-corrosion effect. Anti-mildew and preservation: Ham containing chitin is the most important example of Nippon Maru Ham. The addition of chitin in the production process is about 200mg/kg, which can inhibit the growth of bad molds. Chitin-containing pickles: Japan's Asahi Chemical, Asama Chemical and its downstream manufacturers all use chitin as a preservative to provide pickles to reduce the use of salt. Its process requires chitin with low viscosity and high deacetylation. Its process is such as soaking sashimi to keep fresh: 98% DAC chitin solution and 1% acetic acid solution, soaking for 3 hours with a final concentration of 50-200 mg/kg, which can reduce the number of raw bacteria and increase the service life of commodities by 24-36 hours. However, there are also process instructions. If it is also operated by soaking, the concentration of chitin should be increased as much as possible so that the dosage after soaking can have sufficient anti-bacteria and moisturizing ability. However, the viscosity also increases when the concentration is too high, so the viscosity must be reduced in a special way, but the effect of condensation and film formation is not lost. |
usage limit | GB 2760-1996(g/kg): beer 0.4; Vinegar 1.0; Mayonnaise, sesame paste, peanut butter, hydrogenated vegetable oil, ice cream, vegetable fat powder 2.0; Lactic acid bacteria beverage 2.5; Jam 5.0. |
use | pharmaceutical excipients, medical sutures, etc. Among them, it can be used as a sustained-release agent, lubricant, and coating agent as an auxiliary material. The microparticles, tablets, capsules, microfilm agents and the like of the corresponding drugs can be prepared by direct tabletting, wet granulation or coating. It can be made into dialysis membrane, ultrafiltration membrane and reverse osmosis membrane; and the cross-chain complex with fiber can be made into molecular sieve. With glutaraldehyde as cross-linking agent, it can be immobilized with many enzymes or microbial cells, such as immobilized asparaginase. Can be used for artificial skin, artificial blood vessels, artificial kidneys, etc. Chitosan can inhibit gastric ulcer, reduce cholesterol and blood lipid. chitin is widely used, for example:(1) chromatographic carrier (2) environmental protection: chitin and its derivatives have good chelation ability on various metals, especially some harmful metals that can cause serious environmental pollution, such as mercury, cadmium, copper, nickel, chromium, etc., so it is very promising in water purification and sewage treatment. (3) Purification of radioactive pollution: Many radioactive pollution causes derivatives of radioactive transitional elements, which can be removed by chitosan. (4) Comprehensive utilization of ore: It is an effective collector for zirconium, niobium, rubidium, etc. (5) Glass fiber finishing agent (6) Application in the dye industry: Chitin can be made into polymer-type dyes. (7) Additives for the paper industry (8) Finishing agents for other fabrics (9) Photographic industrial materials: The currently rapidly developing international photographic method (Polaroid) without liquid fixing and development is the use of chitin with wear resistance and photosensitive ability. (10) medical and surgical supplies: chitin hydrolysate a glucosamine salt for the treatment of enteritis, colon ulcer and pneumonia. D-glucosamine or N-acetylglucosamine is used as a chemotherapeutic agent for some tumors, and the effect is very good. Chitin has a certain effect of assisting bacteriolysis. It can also be used as blood anticoagulant, wound healing agent, etc. Use chitin to make surgical sutures, artificial skin and wound dressings, artificial blood and hemostatic sponges, contact glasses, and drug carriers. The use effect is good. Other uses include fillers for adhesives, cigarette paper, leather finishing agents, flocculants, etc. In addition, it has attracted extensive attention for enzyme immobilization, seasoning, beverage and daily chemical products. chitin is an important raw material for preparing chitosan and glucosamine series products. Chitin and its derivatives have important applications in medicine, chemical industry, health food and other fields, and have broad application prospects. It is used to make soluble chitin and glucosamine, can be used as an additive for cosmetics and functional foods, and can prepare photographic emulsion, etc. as adsorption clarifying agent and thickener. China stipulates that it can be used for jam, with a maximum usage of 5.0 g/kg; The maximum usage in lactic acid bacteria beverage is 2/5 g/kg; The maximum usage in hydrogenated vegetable oil, mayonnaise, peanut butter, sesame paste, ice cream and vegetable fat powder is 2.0 g/kg; The maximum usage in vinegar is 1.0 g/kg; The maximum usage in beer is 0/4 g/kg. Thickener, stabilizer, tannin remover. Mainly used for fruit juice, fruit wine, etc. to prevent discoloration and astringency. It can also be used as a binder, glazing agent, filler, film forming agent and emulsifier. isolated from shrimp shell chitin for chitinase analysis. It is a polysaccharide composed of N-acetyl-D- glucomasine, and can also be used in the manufacture of glucosamine and chitosan. The quality requires purification before it can be used as a substrate for chitinase. An important raw material for the preparation of chitosan and glucosamine series products; chitin extracted from shrimp shells, suitable for chitin enzyme analysis; used for the fixation of α-amylase; through the immobilization of inulin enzyme to produce fructose; In the bacterial production of N,N′-diacetylchitodisaccharides, the preparation of keratin glue is a polysaccharide found in various organisms, especially crustacean shells. |
Production method | After removing calcium carbonate from the shells of crustaceans such as shrimps and crabs in an acidic aqueous solution, use hot weak lye to remove protein. The carapace can also be crushed and the protein can be boiled with 2% dilute alkali solution for about 1.5h and separated, then 5% ~ 10% hydrochloric acid can be added to the insoluble substance to change calcium carbonate into calcium chloride and dissolve and remove, then centrifuged, washed with water and dried. chitin naturally exists in the shells of crustaceans. crab shells contain 15% ~ 20% and shrimp shells contain 15% ~ 30%. Shrimp and crab shells can be used as raw materials to extract chitin. Remove the meat from shrimp and crab shells, soak them in 4% ~ 6% hydrochloric acid for 3~4 days after washing, dissolve inorganic salts and remove them; After washing, soak in 10% o sodium hydroxide for 1~2 hours, wash off protein, bleach and oxidize with 1% KMnO4 to remove impurities after washing; After washing, elute the residual potassium permanganate with 1% sodium bisulfite solution, finally, it is thoroughly washed and dried to obtain the finished chitin. The chitin used in industry is taken from the carapace of crustaceans (freshwater and seafood shrimp, crabs, etc.). Some by-products of the brewing industry are also raw materials for chitin. For example, the use of Aspergillus niger fermentation to produce citric acid residues, as well as the use of Brucella, Brackella and Opora fermentation broth can provide a certain amount of deacetylated chitin. Chitin extraction: remove the meat of shrimp and crab shells and clean them. Soak in 4-6% hydrochloric acid to dissolve and soften inorganic salts in the shell. Wash with water and remove protein with 10% sodium hydroxide solution. After washing with water again, bleach and oxidation with 1% KMnO4 to remove impurities. After the third water washing, the residual MnO4 is eluted with 1% NaHSO3, and then fully washed with water and dried to obtain pure chitin. Raw material consumption (kg/t) shrimp and crab shell 1200035% industrial 13000 hydrochloric acid caustic soda (95% solid) 1500 potassium permanganate 135 sodium bisulfite 340 method 1. using shrimp and crab shell as raw materials to make shrimp and crab shells, clean, dry and pulverize, react with excess 2mol/L hydrochloric acid solution (1:10) for 4-5h, filter, and then treat with 2mol/L hydrochloric acid at about 0 ℃ for 12-20h, filter and wash to neutral. Shrimp and crab shells [2mol/L HCl]→[0 ℃, 12-20h] filter out solids and use excess 50-100g/L(5%-10%) sodium hydroxide or potassium hydroxide solution (1:8) for alkaline treatment for 3-4h, and the temperature is controlled at 90-95 ℃. Acid and alkali treatment can be repeated 1-2 times to remove calcium carbonate, phosphate, protein and pigment. Solid [NaOH]→[3-4h, 90-95 ℃] filter out solid [HCl]→ solid [NaOH]→ solid is washed with appropriate amount of absolute ethanol and ether, and dried under reduced pressure to obtain white solid chitin. Industrial production can be washed with water instead of organic solvent. The yield of shrimp shell is 20% and crab shell is about 15%. Solid [anhydrous ethanol, ether] → chitin is added with 400-450g/L(40%-45%) sodium hydroxide solution (1:15-20) from the finished chitin product, reacted at a temperature of about 110 ℃ for 1h, filtered, and washed with water to neutral. According to the requirements of different deacetylation degrees, repeat the treatment for 1-2 times, and dry under reduced pressure to obtain the deacetylation degree of 60%-99%. During the deacetylation process, due to solvation, part of the glycosidic bonds are hydrolyzed, resulting in a decrease in relative molecular weight. In order to avoid the destruction of macromolecules, chitosan can be obtained by adding 10g/L (1%) sodium borohydride (NaBH4) solution or introducing inert gas, such as placing chitin in 400g/L(40%) sodium hydroxide solution and reacting at 110 ℃ for 2.5-3h. Chitin Finished Product [NaOH]→[110 ℃, 1h, pH7] Chitin Method 2. The preparation method using snail shell as raw material Wash, dry and crush the snail shell, and sift through 80 mesh to obtain snail shell powder for later use. Take 400g of snail powder, add 10 times of 1mol/L hydrochloric acid of the raw material, stir for 24 hours at room temperature, filter, wash the residue to neutral, dry, and repeat the above operation twice to obtain desalted snail powder (71.5g). Take desalted snail shell powder, add 8 times the volume of 2.5mol/L sodium hydroxide solution, stir for 24 hours, filter and dry to obtain chitin (59.8g). The yield is about 15%. Chitin is dissolved in 50% sodium hydroxide solution, kept at 130-140 ℃ for 2 hours, filtered, washed with water until neutral, and further deacetylated to obtain chitosan. Methods The pupal skin of silkworm moth after eclosion was taken 3. the preparation method using pupal skin as raw material, dried at 60 ℃, and impregnated with equal volume of petroleum ether. Add 3 times the volume of 3% hydrochloric acid to defatted pupa skin and decalcification at room temperature for 12 hours. Add 30g/L(3%) sodium hydroxide solution to decalcified pupa skin, boil for 3-5h, and then remove protein to obtain gray chitin. Add 420g/L (42%) sodium hydroxide solution (add a small amount of NaBH4) to chitin, boil, filter every 2 hours, wash with water, replace with new lye once, continue to deacetyl until 8 hours, filter, wash with water to neutral, and dry naturally to obtain white chitosan. The yield is 10%-13%, the degree of deacetylation can reach 91%, the intrinsic viscosity is 790-890 ml/g, and the relative molecular mass is 0.81 × 106-1.34 × 106. The preparation of chitosan with low molecular weight can be prepared by hydrogen peroxide degradation method, controlling different concentrations and reaction time of hydrogen peroxide, and chitosan with relative molecular weight ranging from 4.31 × 104-1.32 × 104 can be prepared. The operation is simple, the time is less, and no special reagents and equipment are needed. |
category | toxic substances |
toxicity classification | poisoning |
acute toxicity | intravenous-rat LD50: 50 mg/kg |
flammability hazard characteristics | thermal decomposition discharges toxic nitrogen oxide smoke |
storage and transportation characteristics | warehouse low temperature ventilation and drying |
fire extinguishing agent | water, carbon dioxide, foam, dry powder |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |