108-24-7
Acetic anhydride
CAS: 108-24-7
Molecular Formula: C4 H6 O3
108-24-7 - Names and Identifiers
| Name | Acetic anhydride |
| Synonyms | Acetyl oxide Acetyl Anhydride Acetic anhydride ACETICACIDPHENYL-METHYLESTER Acetic Anhydride (Controlled Chemical) |
| CAS | 108-24-7 |
| EINECS | 203-564-8 |
| InChI | InChI=1/C4H6O3/c1-3(5)7-4(2)6/h1-2H3 |
108-24-7 - Physico-chemical Properties
| Molecular Formula | C4 H6 O3 |
| Molar Mass | 102.09 |
| Density | 1.087 |
| Melting Point | -73.1 °C |
| Boling Point | 140 °C |
| Flash Point | 130°F |
| Water Solubility | REACTS |
| Solubility | Miscible with ether, chloroform and benzene. |
| Vapor Presure | 10 mm Hg ( 36 °C) |
| Vapor Density | 3.5 (vs air) |
| Appearance | Liquid |
| Specific Gravity | 1.082 |
| Color | Colorless |
| Odor | Very strong; pungent; vinegar-like characteristic odor. |
| Exposure Limit | NIOSH REL: ceiling 5 ppm (20 mg/m3), IDLH 200 ppm; OSHA PEL: 5 ppm;ACGIH TLV: ceiling 5 ppm. |
| Merck | 14,56 |
| BRN | 385737 |
| PH | 3 (10g/l, H2O, 20°C) |
| Storage Condition | Store at RT. |
| Stability | Stability Flammable. Incompatible with strong oxidizing agents, water, strong bases, alcohols. |
| Sensitive | Moisture Sensitive |
| Explosive Limit | 2.0-10.2%(V) |
| Refractive Index | n20/D 1.390(lit.) |
| Physical and Chemical Properties | Properties of colorless volatile liquid, with a strong pungent odor and corrosive. |
| Use | Mainly used in the production of cellulose acetate, cellulose acetate paint, non-flammable film, but also used as strong acetic acid acyl agent, sulfonated and nitrated dehydrating agent |
108-24-7 - Risk and Safety
| Risk Codes | R11 - Highly Flammable R20/21/22 - Harmful by inhalation, in contact with skin and if swallowed. R37/38 - Irritating to respiratory system and skin. R41 - Risk of serious damage to eyes R34 - Causes burns R20/21 - Harmful by inhalation and in contact with skin. R10 - Flammable R20/22 - Harmful by inhalation and if swallowed. R19 - May form explosive peroxides R40 - Limited evidence of a carcinogenic effect |
| Safety Description | S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S39 - Wear eye / face protection. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S33 - Take precautionary measures against static discharges. S16 - Keep away from sources of ignition. |
| UN IDs | UN 2924 3/PG 2 |
| WGK Germany | 3 |
| RTECS | AK1925000 |
| FLUKA BRAND F CODES | 21 |
| TSCA | Yes |
| HS Code | 29152400 |
| Hazard Class | 8 |
| Packing Group | II |
| Toxicity | LD50 orally in rats: 1.78 g/kg (Smyth) |
108-24-7 - Upstream Downstream Industry
108-24-7 - Nature
Open Data Verified Data
A colorless transparent liquid with a strong sour taste, the vapor of which is a tear gas. It is miscible with chloroform, benzene and ether. Soluble in water. Mixed with water to produce acetic acid. Dissolved in ethanol, ethyl acetate. Flammable, its vapor and air can form an explosive mixture, in the case of open flame, high heat energy caused by combustion explosion. A chemical reaction may occur in contact with a strong oxidizing agent.
Last Update：2024-01-02 23:10:35
108-24-7 - Preparation Method
Open Data Verified Data
anhydrous sodium acetate reacts with acetyl chloride. In order to avoid boiling of the reactants, the reaction needs to be cooled with water, and the crude product is obtained after the reaction is completed. Sodium acetate was added to the obtained crude product and fractionated with a fractionating column to collect a fraction at 135 to 140 ° C. To obtain acetic anhydride.
Last Update：2022-01-01 09:25:43
108-24-7 - Use
Open Data Verified Data
alcohols, primary and secondary aromatic amines were examined. Used in organic synthesis, dyes, pharmaceutical industry and the manufacture of acetyl compounds.
Last Update：2022-01-01 09:25:43
108-24-7 - Safety
Open Data Verified Data
flammable, corrosive, irritating, can cause human burns. After inhalation of respiratory tract irritation, causing Cough, chest pain, Dyspnea. Staff should be protected. If the skin and eyes are touched, they should be immediately rinsed with plenty of flowing water. It is strictly prohibited to mix with oxidants, reductants, acids, alkalis, active metal powders, alcohols, edible chemicals, etc. Store in a cool, ventilated warehouse. Keep away from fire and heat source. Protection from direct sunlight.
Last Update：2022-01-01 09:25:43
108-24-7 - Reference Information
| LogP | -0.58 at 20℃ |
| NIST chemical information | Information provided by: webbook.nist.gov (external link) |
| EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
| introduction | acetic anhydride has strong acetylation and antioxidant capacity; strong hydrolyzability; it can react quickly with halogen; it can react with high carbon fatty acids to produce high carbonate anhydride and acetic acid, which is mainly because the boiling point of acetic acid is lower than other fatty acids. First, acetic acid is evaporated, and finally high carbon anhydride is prepared. Under heating, acetic anhydride can be decomposed into ketene and acetic acid. Corrosive and tear gas. Stimulate the skin and mucous membranes, can cause ulcers. |
| acetic anhydride concentrated sulfuric acid reaction | acetic anhydride concentrated sulfuric acid reaction can be used to check steroids, steroidal saponins, triterpenes and cardiac glycosides in traditional Chinese medicine ingredients. The method was to dissolve the sample in chloroform and add several drops of acetic anhydride-concentrated sulfuric acid (20:1) mixture. The reaction solution showed yellow → red → purple → green and other changes, and finally faded. The color change process of this reaction varies with the number and position of the double bonds in the molecule, and the unsaturated double bonds act quickly. This reaction can also be used to distinguish between triterpene saponins and steroidal saponins. The former produces red or purple, and the latter shows blue-green. |
| use | mainly used for the production of acetate fiber, acetate fiber paint, non-combustible film film, also used as strong acetate, sulfonation and nitrification dehydrating agent, etc. mainly used for the synthesis of cellulose acetate, drugs, acetylating agents, dyes and spices acetic anhydride is an important acetylation test,, can make alcohol, phenol, ammonia and amine form acetate and acetamide compounds respectively. In the presence of Lewis acid, acetic anhydride can also cause acetylation of aromatic hydrocarbons or olefins. In the presence of sodium acetate, acetic anhydride and benzaldehyde undergo condensation reaction to form cinnamic acid. Acetanhydride is used to make cellulose acetate, acetic acid plastic, non-combustible film film; in the pharmaceutical industry, it is used to make gimycin, furazol, dibazol, caffeine, aspirin, sulfa drugs, etc.; in the dye industry, it is mainly used to produce dispersed dark blue HCL, dispersed scarlet S-SWEL, dispersed yellow brown S-2REL, etc.; in the perfume industry, it is used to produce coumarin, borneol acetate, sunflower musk, cyan acetate, rosin acetate, Ethyl acetate, geranyl ester, etc; acetyl peroxide, made from acetic anhydride, is the initiator and bleach of the polymerization reaction. |
| Production method | There are several process routes: 1. Acetic acid lysis method (ketene method) uses acetone or acetic acid as raw material, and first thermally decomposes to generate intermediate ketene, and then The ketene-containing gas is quenched and cooled in two packed towers connected in series with a mixture of acetic acid and acetic anhydride (circulating liquid) for simultaneous chemical absorption to generate acetic anhydride: h2C = C = O + CH3COOH-(CH3CO)2O process is as follows: acetic acid is gasified in an evaporator, mixed with phosphoric acid catalyst at 20kPa under negative pressure, preheated to 600 ℃ by preheating resolver, decomposed into ethylene ketone containing water and acetic acid at 700-720 ℃. In order to avoid the formation of diketene (boiling point 127.4 ℃) with a boiling point similar to that of acetic anhydride, ammonia is introduced at the outlet of the preheating decomposition tube, and cooled to about 0 ℃ by a cooler to separate the effluent and the acetic acid at the end of the reaction. The reaction gas that removes acetic acid is sent to the absorption tower and reacts with acetic acid to form acetic anhydride. The control temperature of the first absorption tower is 30-40 ℃, the concentration of acetic anhydride is 85%, the control temperature of the second absorption tower is 20 ℃, and the concentration of acetic anhydride is 10-20%. In order to maintain the acetic acid concentration of the absorption tower, glacial acetic acid is regularly added to the second absorption tower, and the acetic acid of the second absorption tower is circulated to the first absorption tower for suction night. The crude acetic anhydride extracted from the circulating liquid of the first absorption tower is rectified by the define distillation tower to obtain acetic anhydride with a concentration of more than 95%. This method has many steps to produce, high energy consumption, and the total yield of acetic anhydride is only about 70%, which is a relatively old method. When pyrolyzed with acetone, the cracking temperature is 650-800 ℃, the residence time is 0.25-0.75s, a small amount of carbon disulfide is added to inhibit carbon formation, and the product is quenched with acetic acid. The generated ketene is then absorbed with acetic acid to form acetic anhydride. 2. The reaction of acetaldehyde oxidation court is as follows: 2CH3CHO + O2 --(CH3CO)2 + H2O uses acetaldehyde as raw material, cobalt acetate-copper acetate as catalyst, and carries out liquid phase catalytic oxidation with air or oxygen at 45-55 ℃,0.29-0.39MPa. Ethylene anhydride accounts for 40% of the product. If ethyl acetate is added as diluent, the finished acetic anhydride can improve the 50%, and the crude product is refined and separated. The technological process is as follows: raw acetaldehyde is added with diluent ethyl acetate and catalyst cobalt acetate and copper carbonate, then acetic acid and recycled water are added to form oxidation material, the oxidation material is continuously added to the bottom of the oxidation tower, oxygen is introduced from each section of the tower body, the reaction temperature is controlled between 40-60 ℃ and the pressure is maintained at 100-300kPa, continuous discharge, the aldehyde content in the discharged feed liquid should not exceed 2%, and the tail gas is introduced into the absorption tower for water absorption. In the de-esterification process, the water generated by the reaction is quickly distilled with the ethyl ester to prevent the resulting acetic anhydride from being hydrolyzed into acetic acid. Then the anhydride acid mixture is distilled in the decatalyst tower, the catalyst is left in the tower kettle, the residual anhydride acid in the tower is evaporated after the storage is concentrated, and the catalyst is released for treatment and reuse. The anhydride-acid mixture separates acetic anhydride from acetic acid in the anhydride-acid separation column. The separation tower is a stainless steel real material tower with a vacuum degree of 53.3-80kPa during operation time, acetic acid at the top of the tower and crude acetic anhydride at the bottom of the tower. After the crude acetic acid is evaporated to the low boiling material under reduced pressure in the stainless steel refining tower, the finished acetic anhydride is collected. This method is simple to operate and obtains by-product acetic acid. It is currently the main production method of acetic anhydride. Consumption quota of acetaldehyde oxidation method: acetaldehyde 1681kh/t, ethyl acetate 70kg/t, oxygen 571kg/t. 3. Carbonylation of methyl acetate uses methanol and acetic acid as raw materials, uses rhodium-based catalyst, and uses chromium compounds as cocatalysts to carbonylation to generate acetic anhydride. In industry, it is carried out in two steps: the first step is the esterification of methanol into methyl acetate; the second step is the carbonylation of acetate to generate acetic anhydride at a temperature of 175 ℃ and a pressure of 25MPa. The selectivity for generating acetic anhydride is 95%. The research and development of this process is regarded as an achievement of carbon-chemistry, which has attracted the attention of all countries. 4. Acetyl chloride method acetyl chloride is prepared by reacting with sodium acetate. |
| category | corroded articles |
| toxicity classification | poisoning |
| acute toxicity | oral administration-rat LD50: 1780 mg/kg; Inhalation-rat LC50: 4240 mg/m3/24 hours |
| stimulation data | skin-rabbit 450 mg/24 hours mild; Eye-rabbit 0.25 mg severe |
| explosive hazard characteristics | blastable when mixed with air |
| flammability hazard characteristics | flammable in case of open flame, high heat and oxidant; Heating decomposition releases stimulating smoke |
| storage and transportation characteristics | warehouse ventilation and low temperature drying; Store separately from strong acid, anhydride oil, oxidant and alkali. |
| fire extinguishing agent | foam, mist water, carbon dioxide. |
| occupational standard | TWA 20 mg/m3; STEL 40 mg/m3 |
| auto-ignition temperature | 629 °F |
| toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
| immediate life-threatening and health concentration | 200 ppm |
Last Update：2024-04-09 21:32:03
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