Chitin, also known as chitin and chitin, is a polysaccharide extracted from the shells of marine crustaceans, with the chemical formula (CeightHthirteenOfiveN)n。Chitin is light beige to white, soluble inConcentrated hydrochloric acid、phosphoric acid、sulphuric acidandacetic acid, insoluble in alkali and other organic solvents, and insoluble in water.Deacetylated derivatives of chitinChitosan(chitosan) is insoluble in water, but soluble in some dilute acids.
Chitin has a wide range of applications, and can be used in industries such as cloth, clothing, dyes, paper and water treatment.It can be used as insecticide and plant antiviral agent in agriculture.Fish feed is used in fishery.Cosmetic cosmetics, hair protection, moisturizing agents, etc.Medical supplies can be used as contact lenses, artificial skin, sutures, artificial dialysis membranes and artificial blood vessels.
Chinese name
chitin [2]
Foreign name
Chitin[2]
Alias
chitin[2]、chitin[2]
chemical formula
(CeightHthirteenNOfive)n
molecular weight
(203.19)n
CAS login number
1398-61-4[2]
EINECS login number
215-744-3
Water solubility
Insoluble in water
Density
1.75 g/cm³
Appearance
Quasi white amorphous substance, odorless and tasteless
It was discovered by the French scholar Braconno in 1811.
It was extracted from crustacean shells by Odier in 1823.
Physical and chemical properties
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General name: chitin, chitin, chitin
English name: Chitin
Chemical name: β - (1,4) - 2-acetylamino-2-deoxy-D-glucose
Molecular formula: (CeightHthirteenNOfive)n
Character: white amorphous substance, odorless and tasteless.
Solubility: soluble in 8%lithium chlorideOfDimethylacetamideOr concentrated acid;Insoluble in water, dilute acid, alkali, ethanol or other organic solvents.
In nature, chitin is widely found in the shells of lower plant fungi, shrimp, crabs, insects and other crustaceans, and the cell walls of fungi.
The chemical structure of chitin andPlant fibreElements are very similar.All six carbon sugarPOLYMERThe molecular weight is more than 1 million.The basic unit of cellulose isglucoseIt is a polymer composed of 300~2500 glucose residues connected by β - 1,4 glycoside chain.The basic unit of chitin isAcetylglucosamineIt is a polymer formed by connecting 1000~3000 acetylglucosamine residues through 1,4 glycoside chains.
Molecular weight: chitin is a high molecular weight substance with a molecular weight of more than 1 million.The higher the molecular weight is, the stronger the adsorption capacity is, which is suitable for industrial and environmental protection applications.Low molecular weight is easily absorbed by human body.Chitosan with a molecular weight of about 7000 contains about 30 glucosamine residues.
Deacetylation purity: Chitin is deacetylated into chitosan.Chitin cannot be used by the body because it is insoluble in acid, alkali and water.Deacetylation can increase its solubility, so it can be absorbed by the body.Chitosan is called when more than 55% of N-acetyl group is removed.
distribution
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(1) Arthropods are mainly crustaceans, such as shrimp and crab, with chitin content up to 58%~85%;Next are Insecta (such as locusts, butterflies, mosquitoes, flies, silkworms, etc.), Polypoda (such as Malus, centipede, etc.), Arachnida (such as spiders, scorpions, ticks, mites, etc., with chitin content of 4%~22%).
(2) Molluscs mainly include Bineuropoda (such as chitons), Gastropoda (such as abalones and snails), Digopoda (such as hornshells), Lambranchia (such as pitons), Cephalopoda (such as cuttlefish and nautilus), etc. The chitin content reaches 3%~26%.
(3) Annelida includes Procyclida (such as hornworm), Trichopoda (such as sand worm and earthworm) and Leech (such as locust). Some of them contain very little chitin, while others contain as much as 20%~38%;
(4) Protozoa, called protozoa for short, are single celled animals, includingFlagellates(e.g. trypanosoma), sarcopoda (e.g. amoeba)Sporidae(such as plasmodium), ciliates (such as paramecium), etc., which contain less chitin.
(5) The coelenterates include hydrozoa (mesohydra, simple polyp, etc.), medusae (such as sea moon jellyfish, jellyfish, chardonnay jellyfish, etc.), corallidae, etc. They generally contain very little chitin, but some can also reach 3%~30%.
(6) Algae are mainly green algae, containing a small amount of chitin.
(7) Fungi include ascomycetes, basidiomycetes, algal fungi, etc. The content of chitin varies from trace to 45%. Only a few fungi, such as Olm ycetes and Triohamycetes, do not contain chitin.
(8) Chitin exists in the hard parts of joints, hooves and feet of other animals, as well as the joints between muscles and bones of animals.In addition, oligomeric chitin or chitosan is also found in plants. One case isPlant cell wallWhen attacked by pathogensPolysaccharideDegraded to havebiological activityChitosan is one of the oligosaccharides. A typical example is that after a tree trunk is injured, chitosan is found at the wound healing site;The other is the lipooligosaccharides produced by rhizobia, which are also chitosan tetrasaccharides, chitosan pentasaccharides and chitosan hexasaccharides.
application
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Industry
Chitin is used for many different purposes in industry.Chitin is used for water and wastewater purification asfood additivesIt can play a thickening role in and drugs to stabilize the state of food and drugs.Chitin can also be used as dye, fabricAdhesive。Industrial separation film andion exchange resinIt can be made into chitin.Chitin is also used for the size and strength of processed paper.
medicine
The product of chitin, as a tough and strong material, can be used as surgical thread.In addition, chitin has some unusual characteristics, such as accelerating human wound healing, and even becoming a separate wound healing agent.There are many applications in biomedical materials, which have the advantages of good biocompatibility, no biological toxicity, low price, easy modification, good mechanical strength, etc.
clothing
At room temperature, every 100g of chitin powder can absorb 200-225g of 40wt% sodium hydroxide solution, in which about 100g of water is absorbed.The adsorption value of chitin is related to the concentration of alkali solution and adsorption temperature.At zero temperature, for 20-30wt% sodium hydroxide solution, about 800g can be adsorbed per 100g chitin powder, including about 600 for water.Chitin has natural antibacterial effect, and the broad-spectrum antibacterial rate is very high. More than 90% of common bacteria cannot survive on chitin fiber;Therefore, the fabrics made of chitin fiber and colored cotton or pure cotton are particularly suitable for infant clothing and high-end underwear for men and women.[1]
