Physicochemical properties of 1,4-butanediol

1,4-Butanediol 1,4-Butanediol: Alternative names: 1,4-dihydroxybutane; butylene glycol. English names: 1,4-Butanediol; 1,4-Dihydroxybutane; Tetramethylene glycol; 1,4-Butylene glycol. Molecular formula: C4H10O2. Molecular weight: 90.12. CAS number: 110-63-4. Properties: Colorless, viscous oily liquid. Flammable; freezing point 20.1°C, melting point 20.2°C, boiling point 228°C, 171°C (13.3 kPa), 120°C (1.33 kPa), 86°C (0.133 kPa); relative density 1.0171 (20/4°C); refractive index 1.4461. Flash point (open cup) 121°C. It is miscible with water, soluble in methanol, ethanol, and propanol, and slightly soluble in ether. It is hygroscopic and has a bitter taste. 　　Preparation method: 1. Acetylene method: First, 1,4-butynediol is synthesized by reacting acetylene and formaldehyde in the presence of a Cu-Bi catalyst at 98 kPa and 80–95°C. The latter is then hydrogenated under the catalysis of skeletal nickel at 1.372–2.06 MPa and 50–60°C to yield 1,4-butanedioic acid, followed by further catalytic hydrogenation using Ni-Cu-Mn/Al2O3 at 13.7–20.6 MPa and 120–140°C to produce 1,4-butanediol. After removing metal ions with ion exchange resin, distillation is used to purify the product to obtain pure material. 2. Succinic anhydride hydrogenation method 3. Butadiene method: 1,3-butadiene undergoes acetyloxylation with acetic acid and oxygen to produce 1,4-diacetoxy-2-butene, which is then converted through hydrogenation and hydrolysis. 4.1,4-Dichlorobutene method: 1,4-Dichlorobutene is an intermediate in the process of producing chloroprene from butadiene; using it as a starting material, 1,4-butanediol is obtained through hydrolysis and hydrogenation. 　　Uses: 1,4-butanediol has a wide range of uses. In the United States and Western Europe, more than half is used for the production of **furan; followed by the production of γ-butyrolactone and polybutylene terephthalate, which is an engineering plastic with rapid development ； 1,4-Butanediol is used as a chain extender and polyester precursor in the production of polyurethane elastomers and soft polyurethane foams ； Esters derived from 1,4-butanediol are excellent plasticizers for cellulose, polyvinyl chloride, polyacrylates, and polyesters. 1,4-Butanediol possesses good hygroscopic softening properties; it can be used as a softener for gelatin and as a water absorber, as well as a treatment agent for cellophane and other unprocessed papers. N-methylpyrrolidines, N-vinylpyrrolidines, and other pyrrolidine derivatives can also be prepared; they are used in the manufacture of vitamin B6, pesticides, herbicides, as well as solvents, plasticizers, lubricants, humectants, softeners, adhesives, and brighteners in the electroplating industry. 　　Toxicity: Toxic. When attached to diseased or injured skin or consumed, it initially exerts its **effect**, causing specific pathological changes in the liver and kidneys; subsequently, death occurs suddenly due to central nervous system paralysis (without a long incubation period). The oral LD50 in rats is 210–420 mg/kg. Production equipment should be sealed to prevent leaks, and operators must wear protective gear. Persons with skin injuries must not come into contact with this product. 　　Packaging and transportation: It is packaged in aluminum, stainless steel, galvanized iron drums or plastic tanks, or transported by tank trucks in accordance with the regulations for flammable and toxic substances. Due to its melting point of up to 20°C, a heating element should be installed in the tank truck.

Quality standard for 1,4-butanediol: Q/(HG)SJ773-1998. The physical properties of 1,4-butanediol are shown in Table 1. Chromatographic standard (colorimetric standard) GCS: Purity: 99.5%–99.9%; Moisture content: ≤0.05%. Table 1: Physical properties of 1,4-butanediol. Parameter | Specification. Appearance: Colorless transparent liquid. Flash point (open cup): 155°C; Viscosity (20°C): 91.6 mPa·s; Flash point (closed cup): 121°C; Viscosity (50°C): 23 mPa·s. Surface tension (20°C): 45.27 Mn/m; Density (20°C): 1.017 g/cm³; Specific heat capacity (20°C): 2.2 J/(g·K); Specific heat capacity (25°C): 1.015 g/cm³. Latent heat of fusion: 16.3 kJ/g; Freezing point (pure substance): 20.2°C; Heat of vaporization (203.5°C): 56.5 J/g; Heat of vaporization (with 0.5% moisture): 19°C. Ignition temperature: 354°C; Refractive index (20°C): 1.4460; Auto-ignition temperature: 402°C; Refractive index (25°C): 1.4446; Critical temperature: 354°C. Solubility: Slightly soluble in ether, miscible with water, soluble in ethanol, etc. Boiling point: 228–230°C. LD50: 2200 mg/kg (oral, in mice); 1800 mg/kg (oral, in rats). Heat of combustion: 601.6 kJ/mol. Products of combustion (decomposition): Carbon monoxide, carbon dioxide