520-45-6
Dehydroacetic acid
CAS: 520-45-6;16807-48-0
Molecular Formula: C8H8O4
520-45-6 - Names and Identifiers
520-45-6 - Physico-chemical Properties
| Molecular Formula | C8H8O4 |
| Molar Mass | 168.15 |
| Density | 1.1816 (rough estimate) |
| Melting Point | 111-113 °C (lit.) |
| Boling Point | 270 °C (lit.) |
| Flash Point | 157°C |
| Water Solubility | 500mg/L at 25℃ |
| Solubility | Insoluble in water, soluble in alkaline water, easily soluble in acetone, ether, benzene and hot ethanol, sublimated by heat. |
| Vapor Presure | 0.001 hPa (20 °C) |
| Appearance | Colorless crystal or light yellow powder |
| Color | Light yellow or cream |
| Merck | 14,2865 |
| BRN | 6129 |
| pKa | 5.53±0.40(Predicted) |
| PH | 4 (2g/l, H2O, 20℃) |
| Storage Condition | Store below +30°C. |
| Stability | Stable. Incompatible with oxidizing agents, bases, reducing agents. |
| Refractive Index | 1.4611 (estimate) |
| MDL | MFCD00066709 |
| Physical and Chemical Properties | DHA is widely found in many deep-sea fish oils, but also in marine algae and some terrestrial plants. DHA is an omega -3 unsaturated fatty acid, which is essential for nutrition. mp44. Light, oxygen, heat is very unstable, easy oxidation, cracking, usually should add antioxidants. Lecithin, dextrose, cyclodextrin or inert gas may be added to improve the stability of the preparation. |
| Use | Used as a preservative, synthetic intermediate of chloropirinol |
520-45-6 - Risk and Safety
| Hazard Symbols | Xn - Harmful |
| Risk Codes | 22 - Harmful if swallowed |
| Safety Description | S22 - Do not breathe dust. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. |
| WGK Germany | 1 |
| RTECS | UP8050000 |
| TSCA | Yes |
| HS Code | 29322980 |
| Toxicity | LD50 orally in rats: 1000 mg/kg (Spencer) |
520-45-6 - Upstream Downstream Industry
| Raw Materials | Toluene Sodium hydroxide diketene Hydrochloric acid |
| Downstream Products | Sodium dehydroacetate clopidol |
520-45-6 - Reference
| Reference Show more | 1. [IF=5.505] Qu Chengbin et al."Dihydroartemisinin Exerts Anti-Tumor Activity by Inducing Mitochondrion and Endoplasmic Reticulum Apoptosis and Autophagic Cell Death in Human Glioblastoma Cells."Front Cell Neurosci. 2017 Sep;0:310 |
520-45-6 - Nature
Open Data Verified Data
colorless flake or needle-like crystal or white crystalline powder, odorless, slightly sour. It is stable to heat and has hygroscopicity, and can volatilize with water vapor.
Last Update：2024-01-02 23:10:35
520-45-6 - Preparation Method
Open Data Verified Data
from diketene in a certain temperature and catalyst under the action of polymerization, refined.
Last Update：2022-01-01 10:09:59
520-45-6 - Introduction
Odorless, tasteless. Soluble in water, soluble in alkaline water, easily soluble in acetone, ether, benzene and hot ethanol, sublimated by heat. It is stable to light and heat. No hygroscopicity, heating can volatilize with water vapor. Solubility (W/W,25 ℃); Acetone 22%, benzene 18%, methanol 5%, carbon tetrachloride 3%, ethanol 3%, water <0.1%.
Last Update：2022-10-16 17:25:49
520-45-6 - Use
Open Data Verified Data
Dehydroacetic acid is a broad-spectrum food preservative, which can resist the growth of mold, yeast and bacteria. The antibacterial effect is not affected by pH value, but the preservative effect is the best under neutral conditions. China's provisions can be used for preserved bean curd, Pickles, the maximum use of 0.3g/kg.
Last Update：2022-01-01 10:09:59
520-45-6 - Reference Information
| LogP | 0.78 at 20℃ |
| NIST chemical information | Information provided by: webbook.nist.gov (external link) |
| EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
| Uses | Dehydroacetic acid is used as an intermediate in organic synthesis; Paste of resin emulsions such as vinyl acetate emulsion and acrylic acid vinyl emulsion, also used in paste of polyvinyl alcohol, carboxymethyl cellulose, starch, bone glue and other mixtures; Recently, it is more widely used in adhesive, mosquito coil, feed, shampoo, toothpaste and other fields; because this product has an inhibitory effect on mold, yeast, and Gram bacillus, it is used as an antifungal and preservative for medicine, cosmetics and food. my country's GB2760-1996 regulations can be used for fermented bean curd, assorted pickles, and raw orange juice. DHA can promote the growth of brain cells, improve brain function, improve the brain, prevent Alzheimer's disease, and promote the development of the retina in infants. However, in the application of prevention and treatment of cardiovascular diseases, side effects such as gastrointestinal discomfort, pulmonary embolism, skin reaction and agranulocytosis may occur Deoxyacetic acid is a broad-spectrum feed preservative that can inhibit the growth of mold, yeast and bacteria. Bacteriostasis is basically not affected by PH, but the antiseptic effect is the best under neutral conditions. It is also used as a food preservative. It can be used for preservative of fermented bean curd, pickles and original orange sauce according to domestic regulations, with a maximum use of 0.3 g/kg. as a preservative, chlorpyridoxine synthesis intermediate dehydroacetic acid is a broad-spectrum food preservative, can inhibit the growth of mold, yeast and bacteria. Bacteriostasis is basically not affected by Ph value, but the antiseptic effect is the best under neutral conditions. According to domestic regulations, the maximum amount of antiseptic for fermented bean curd, pickles and original orange sauce is 0.3 g/kg. Preservative; Anti-mold agent. Dehydroacetic acid is an organic synthesis intermediate, toughening agent, and a broad-spectrum food preservative. Since it was discovered that it has antibacterial properties in 1940, it has received attention from many countries and has been allowed to be used for food preservation. As a food additive, dehydroacetic acid is allowed to be used in cheese, butter, margarine, cool drinks, fermented milk and lactic acid bacteria drinks, bean paste, stuffing, etc. As a food additive, sodium dehydroacetate is generally used. The product is also used for daily cosmetics, fiber products, medicines (such as the treatment of ringworm), and the preservation of dental materials. |
| production method | commonly used methods are ethyl acetoacetate dealcoholization condensation method and diethylene condensation method. The double ethylene ketone synthesis process has the advantages of low cost and high yield. Under alkaline conditions (such as in the presence of sodium ethoxide, sodium phenol, sodium hydroxide, sodium acetate, pyridine, triethylamine) or under the catalysis of aluminum bromide, it is condensed by diketone. Dehydroacetic acid can be obtained by ethyl acetoacetate condensation and other methods, but the most feasible production method in industry is diethylene ketone dimerization. The solvent benzene (or toluene) and the catalyst triethylenediamine are sequentially added to the reaction kettle, and heated until the benzene is refluxed (about 75~80 ℃); then under continuous stirring, the diketene is slowly added, and the temperature is strictly controlled About 80 ℃, after the flow is added, the reaction continues to react for 30min, the reaction liquid is naturally cooled and the solid is precipitated, and the crude product is obtained by filtration. The crude product is dissolved by heating (80 ℃) with dilute sodium carbonate solution (Ph value 8~9), decolorized with activated carbon, the obtained clear liquid is neutralized with 1:1 hydrochloric acid under stirring to Ph value 3~4, the precipitates are collected, and the finished product is obtained by drying at 70~90 ℃. According to literature reports, the amount of catalyst is 0.3%, the reaction temperature is 40 ℃, the reaction time is 75min, and the yield is 88.2%. If polymerization inhibitor is added in the reaction process, the yield can be increased to 94.1% and the purity can be 99.8%. Dehydroacetic acid can be obtained by ethyl acetoacetate condensation and other methods, but the most feasible production method in industry is diethylene ketone dimerization. The solvent benzene (or toluene) and the catalyst triethylenediamine are sequentially added to the reaction kettle, and heated until the benzene is refluxed (about 75-80 ℃), and then under continuous stirring, the diketene is slowly added, and the temperature is strictly controlled About 80 ℃, after the flow is added, the reaction continues to react for 30min, the reaction liquid is naturally cooled and the solid is precipitated, and the crude product is obtained by filtration. The crude product is dissolved by heating (80 ℃) with dilute sodium carbonate solution (PH8-9), decolorizing with activated carbon, and the obtained liquid is neutralized with 1:1 hydrochloric acid under stirring until PH3-4, the precipitates are collected, and the finished product is obtained by drying at 70-90 ℃. According to literature reports, the amount of catalyst is 0.3%, the reaction temperature is 40 ℃, the reaction time is 75min, and the yield is 88.2%. If polymerization inhibitor is added in the reaction process, the yield can be increased to 94.1% and the purity can be 99.8%. Method 1. Preparation of crude fish oil using fish liver or crushed fish as raw materials Take fresh fish liver that has removed the gallbladder and washed and chopped, put it into a pot, add water, pass steam to 80 ℃, flow out the oil, filter, cool the filtrate to 0 ℃, precipitate solid fat, and filter under pressure to obtain the filtrate, which is crude fish oil. Fish oil [water] →[80 ℃] oil quality [filtration] → crude fish oil or crushed fish as raw material, minted and mixed with starch at 7-10 ℃, added hexane for extraction for 15min, filtered to obtain filtrate. After washing the filtrate with sodium chloride solution, add anhydrous sodium sulfate to dehydrate, recover hexane, and obtain crude fish oil. Crushed fish [starch, hexane] →[7-10 ℃,15min] filtrate [NaCl]→ [anhydrous sodium sulfate] preparation of crude fish oil refined fish oil crude fish oil, saponification with sodium hydroxide ethanol solution, filtration, acid acidification of filtrate, extraction with water-insoluble organic solvent, washing of extract with water, removal of organic layer, clear liquid of light red or reddish brown in water layer, and no solid precipitation at 10 ℃ for 30min, refined fish oil. Crude fish oil [alkaline ethanol solution] → filtrate [organic solvent] →[HCl] extract [water washing] → refined fish oil pre-concentration alcoholization of refined fish oil, and urea inclusion crystallization method is used to remove the fatty acids with lower saturation in fish oil to produce fish oil fatty acid ethyl ester. Refined fish oil [ethanol, urea inclusion crystallization] → Preparation of fish oil fatty acid ethyl ester DHA Put fish oil fatty acid ethyl ester into an extraction tank, open the steel cylinder, after CO2 is condensed, pressurized to a set pressure by a high-pressure metering pump, and then preheated to working temperature, then enter the extraction tank. The SC-CO2 carries fish oil fatty acid ethyl ester into the rectification column, and the components come out from the top of the column successively according to the solubility, and enter the separator to receive after decompression. Experimental conditions: extraction pressure is 11-15MPa, extraction temperature is 35 ℃; Distillation pressure is 11-15MPa, distillation temperature is 40-85 ℃. EPA-rich fraction of 12-13.5MPa and DHA-rich fraction of 14-15MPa were collected and determined by gas chromatograph, and EPA -10 DHA was purified to 90%. EPA-rich fraction and DHA-rich fraction were extracted at 11.5-13MPa and 13.5-15MPa respectively, EPA was purified to 67% and DHA was purified to more than 90%. Fish oil fatty acid ethyl ester [supercritical CO2 extraction] → [separation] DHA method 2. extraction of herring leftovers fish oil, ground herring leftovers, add half times the amount of water, adjust pH8.5-9.0, keep the temperature for 45min, add 5% salt, stir to dissolve, continue to keep the temperature for 15min, filter, press the filter residue, merge the filtrate and press liquid, centrifuge while hot to prepare herring oil. The total content of EPA and DHA in herring oil was 8.9%. Herring leftovers [H2O, 5% NaCl]→[pH8.5-9][filtration, centrifugation] → preparation of herring oil polyunsaturated fatty acids (PUFA) herring oil is taken, sodium hydroxide ethanol (95%) solution is added, nitrogen-filled reflux saponification is carried out, saponified liquid is cooled to 15-20 ℃, a large amount of fatty acid sodium salt is precipitated, squeezed and filtered, the filtrate is cooled to -20 ℃, and then pressure filtration is carried out. Add equal volume of water to the filtrate, adjust the pH3-4, centrifuge for 10min, and prepare PUFA-I. Dissolve the PUFA-I in sodium hydroxide ethanol solution, cool at -20 ℃, press filter, add a small amount of water to the filtrate, cool at -10 ℃, and filter to remove cholesterol crystals. Add a small amount of water to the filtrate, cool at -20 ℃, centrifuge for 5min, pour out the upper layer of liquid, acidify the lower layer of jelly (PUFA sodium salt) and centrifuge for 10min to prepare PUFA-II. The total content of EPA and DHA in the PUFA-II was 64.8%. Herring oil [NaOH ethanol] → [nitrogen] saponification solution [cooling] filtrate [pH3-4]→ [centrifugation] PUFA-I[NaOH ethanol] → PUFA-II method 3. using arachidonic acid as raw material and arachidonic acid as raw material, After desaturation, EPA is obtained. EPA grew by C2 chain to obtain docosapentaenoic acid. Docosapentaenoic acid is desaturated to obtain DHA. Arachidonic acid [desaturation] → EPAEPA[C2 chain growth] → docosapentaenoic acid [desaturation] → DHA method 4. supercritical multi-fluid precision distillation technology currently commonly used at home and abroad High vacuum distillation method, molecular distillation method, silver nitrate complexation method, simple supercritical CO2 extraction and industrial chromatography preparation process, all have many drawbacks and deficiencies, and are not suitable for the industrial development of high purity EPA and DHA. The supercritical multi-fluid precision distillation technology is used to directly separate high-purity EPA and DHA, which is operated at room temperature. The product is not easy to oxidize and degrade. The middle fraction can be recycled and rectified repeatedly. It has good separation performance and is easy to realize large-scale industrial production. Methods Light alkaline hydrolysis was 5. to extract fish oil. This process uses light lye to decompose fish liver protein tissue and destroy the binding relationship between protein and liver oil, thus separating fish oil more fully. This method of liver oil is of good quality and low price. Fish oil plants in our country mostly use this method to produce fish oil. Methods The potassium method is 6. to extract fish oil. The light alkali used in the traditional light alkaline hydrolysis method is a dilute solution of sodium hydroxide and the salt is a sodium chloride solution. The process is very mature. However, the content of sodium salt in the waste liquid produced in the extraction process is high and cannot be further utilized, forming new waste. According to the extraction principle of the light alkali hydrolysis process, Yang Guane et al. used potassium hydroxide and potassium nitrate instead of sodium hydroxide and sodium chloride in the light alkali hydrolysis process. The extraction rate and quality of fish oil remained stable; the waste residue after extraction of fish oil, The waste liquid contains a lot of amino acids and proteins, which can be used as raw materials for high-efficiency green fertilizers, and no new waste is generated. The extraction method is as follows: after homogenizing a certain amount of fish liver in a homogenizer, add three flasks, add half to one and a half times the amount of water, stir the water bath to raise the temperature to 45-50 ℃, add 40% potassium hydroxide aqueous solution twice, adjust the pH8-9, continue stirring to raise the temperature to 80-90 ℃, keep the temperature for 30min, add 4% potassium nitrate of fish liver, continue stirring, salting out for 15min, centrifuging while hot, isolated crude fish oil. Fish liver [water] →[45-50 ℃][4% KOH]→[pH8-9][80-90 ℃]→[30min][4% KNO3]→[15min][centrifugation] → determination method of crude fish oil products: peroxide value-sodium thiosulfate drip method; Acid value-alkali titration method; Iodine value-sodium thiosulfate titration method; Saponification value-hydrochloric acid drip method; DHA, EPA content determination-gas chromatography. Results (n = 3): The extraction rate of fish oil was 24.4%. Acid value is 2.58; Iodine value is 309; Saponification value is 178.7; Peroxide value is 0.070%;DHA content is 19.60%. |
| category | pesticide |
| toxicity classification | poisoning |
| acute toxicity | oral-rat LD50: 500 mg/kg; Oral-mouse LD50: 1330 mg/kg |
| storage and transportation characteristics | warehouse ventilation and low temperature drying; separate from food raw materials storage and transportation |
| fire extinguishing agent | dry powder, foam, sand |
| spontaneous combustion temperature | 336°C |
| toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
Last Update：2024-04-09 02:00:09
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