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Acetic anhydride production process

Acetic anhydride is a colorless volatile, with a strong irritating smell and corrosiveness liquid. Name of acetic anhydride, molecular formula C4H6O3, the flash point of 64.4 DEG c.. Density of 1.082 0g / cm3. Melting point - 74.13 DEG c.. The boiling point of 138.63 DEG c.. The refractive index nD 1.390. 20 degrees of viscosity of 0.91 mPa? S. Spontaneous ignition temperature of 388.9 DEG c.. Soluble in cold water, in water is decomposed into acetic acid, ethyl acetate and ethanol production. Soluble in chloroform, ether and benzene. Toxic, eye and mucosa has a strong irritating, mass concentration of 0.36 mg / m3 when the eye irritation; 0.18mg / m3, can change a person's brain electrical image, can cause tissue protein modification. The steam stimulation is stronger, extremely easy to burn the skin and eyes, such as frequent exposure can cause dermatitis and chronic conjunctivitis. On rat oral LD50 was 1780 mg / kg. When spilled and or adhesion to the skin, to immediately with water or 2% washing soda, systemic poisoning should be timely medical treatment. Air max allowable volume fraction 5 u L / L.

Acetic anhydride is the country to encourage the development of basic organic chemical raw materials, mainly used for the production of cellulose acetate, of which two cellulose acetate is used in the manufacture of cigarette filter tip and plastic, three cellulose acetate is the manufacturing of advanced film material, is widely used in medicine, pesticides, dyes, military, spices, metal finishing industries.Acetic anhydride is" precursor" products, acetic anhydride production, management must be in the public security organ for archival filing certification, enterprises sold every batch of goods to perform detailed registration, and to the public security organ for the record. According to the legal provisions, to undocumented units 200 kg acetic anhydride, will be sentenced to 3 years imprisonment.

Industrialization of acetic anhydride production process has three kinds: the oxidation of acetaldehyde, ethylene ketone and methyl acetate carbonylation.

Acetaldehyde oxidation technology source for the Canadian Sha Winigan chemical company. The production process is as follows: acetaldehyde and oxygen at 60 degrees C, 101 kPa or 70 degrees C, 600-700kPa under the conditions of the oxidation reaction, oxygen or air as the oxidant, using ethyl acetate as solvent, cobalt acetate as catalyst, acetic acid copper as promoter. Acetaldehyde and oxygen ( in excess of about 1%-2%) reaction is first generated peroxy acetic acid, acetic acid and acetaldehyde reaction of acetic anhydride and acetic acid. Under this condition, the conversion rate of acetaldehyde acetic anhydride and acetic acid production rate is 95%, the mass ratio of 56: 44. The total yield of 70%-75% acetic anhydride. By changing the processing conditions, can improve the yield of acetic anhydride. Reaction equation:

CH3CHO+O2 - CH3COOOH;