Name: Terephthalic Acid
Chinese alias: purified terephthalic acid; PTA 1, 4- phthalic acid; Terephthalic acid, terephthalic acid; Terephthalic acid; Pure terephthalic acid; Phthalic acid; Terephthalic acid; P-dibenzoic acid
English name: p- phthalic acid
Molecular formula C8H6O4；; HOOCC6H4COOH
Molecular weight: 166. 13
Chinese Academy of Sciences login number: 100-2 1-0
InChI = 1/c8h6o 4/C9-7( 10)5- 1-2-6(4-3-5)8( 1 1) 12/H 1-4H，(H，9， 10)(H， 1 1， 12
terephthalic acid
Binary aromatic carboxylic acid formed by connecting two opposite carbon atoms on benzene ring with two carboxyl groups respectively.
product performance
This product is white crystal or powder with low toxicity and flammability. If it is mixed with air, it will burn or even explode in case of fire within a certain limit.
Autoignition point 680℃
Ignition point: 384~42 1℃
The sublimation heat is 98.4kJ/mol.
The heat of combustion is 3225.9kJ/mol.
Flash point >; 1 10℃
The density is1.55g/cm3.
Soluble in alkali solution, slightly soluble in hot ethanol, insoluble in most organic solvents such as water, ether, glacial acetic acid, ethyl acetate, dichloromethane, toluene and chloroform, but soluble in DMF, DEF and DMSO.
Terephthalic acid can be esterified; Under strong conditions, halogenation, nitration and sulfonation will also occur.
Environmental effect
health hazard
Invasion route: inhalation, ingestion and percutaneous absorption.
Health hazard: It can irritate eyes, skin, mucous membrane and upper respiratory tract, and no occupational poisoning has been reported.
Toxicological data and environmental behavior
Toxicity: low toxicity.
Acute toxicity: LD50 1670mg/kg (abdominal cavity of mice); Rats 3200mg/kg (oral); 3550 mg/kg (taken orally by mice)
Hazard characteristics: In case of high heat, open flame or contact with oxidant, there is a danger of burning.
Combustion (decomposition) products: carbon monoxide and carbon dioxide.
environmental standard
The maximum allowable concentration of harmful substances in the air of workshops in the former Soviet Union was 0. 1mg/m3.
In the former Soviet Union (1975), the maximum allowable concentration of harmful substances in water was 0.1mg/l/l.
Emergency treatment
Emergency treatment of leakage
Cut off the fire. Wear a gas mask and gloves. Collect it and transport it to an open place for burning. Such as a large number of leaks, collected and recycled or discarded after harmless treatment.
protective measure
Respiratory system protection: Wear a gas mask when the concentration in the air is high.
Eye protection: You can use a safety mask.
Protective clothing: wear work clothes.
Hand protection: Wear chemical resistant gloves when necessary.
Others: Take a shower and change clothes after work. Pay attention to personal hygiene.
Emergency treatment
Skin contact: Take off contaminated clothes and rinse with running water.
Eye contact: immediately open the upper and lower eyelids and rinse with flowing water 15 minutes. See a doctor.
Inhalation: Leave the site and go to a place with fresh air. See a doctor.
Intake: If taken by mistake, rinse mouth, give milk or egg white and cure.
Fire extinguishing methods: misty water, foam, carbon dioxide, dry powder and sand.
Specialized skills
PTA production process can be divided into two parts: oxidation unit and hydrofining unit. Using acetic acid as solvent, raw material p-xylene is oxidized into crude terephthalic acid by air under the action of catalyst, and then crystallized, filtered and dried in turn to obtain crude products; Crude terephthalic acid is hydrogenated to remove impurities, then crystallized, centrifugally separated and dried to obtain PTA products.
A method for purifying crude terephthalic acid includes the following steps: drying crude terephthalic acid, ball milling, sieving to make the particle size reach 1-5 microns, soaking in water at 60-100 DEG C, stirring, clarifying, skimming, and finally centrifugal separation at the temperature of 80-65438+. Crude terephthalic acid (TPA) is the precipitate of alkali decrement wastewater after acid precipitation, and the dry weight content of impurities is 15%- 18%.
The main patent manufacturers of PTA process are BP-Amoco, DuPont -ICI and Mitsui Petrochemical Company. After years of development, the above three companies are quite different in technology, each with its own characteristics and the same level. Before the project, the total production capacity of PTA plant using BP-Amoco process in the world reached 7176,000 tons/year, DuPont -ICI process was 3.495 million tons/year, and Mitsui oil coating process was125,000 tons/year ... 4-C6H4( COOH )2. Colorless crystals. Sublimation occurs above 300℃. Very slightly soluble in water, soluble in dimethyl sulfoxide, dimethylformamide and hexamethylphosphoryl triamine. Because of its low solubility and high melting point, it is difficult to extract purity.
Terephthalic acid is prepared industrially by oxidizing p-xylene with nitric acid or by air oxidation under the catalysis of cobalt salt. Terephthalic acid can also be produced by rearrangement of potassium benzoate or potassium phthalate in the presence of cadmium or zinc catalyst and carbon dioxide.
Uses: Terephthalic acid and its dimethyl ester are mainly used for polycondensation with ethylene glycol to form polyester, and the synthetic fiber made from it is called polyester. Polyester can also be made into film or injection molding, which is widely used in electronics and automobile manufacturing. Terephthalic acid can also be used to make herbicides and adhesives.
PTA is one of the important organic raw materials. Its main use is to produce polyester fiber (polyester), polyester film and polyester bottles, which are widely used in chemical fiber, light industry, electronics, construction and other aspects of the national economy and are closely related to people's living standards.
The application of PTA is relatively concentrated. More than 90% of PTA in the world is used to produce polyethylene terephthalate (PET), and the rest is used as raw materials for polypropylene terephthalate (PTT), polybutylene terephthalate (PBT) and other products.