Views: 296 Author: Vickey Publish Time: 2023-08-21 Origin: Site
1,6-Hexanediol, also known as Hexamethylene glycol, 1,6-Dihydroxyhexane, 1,6-Hexylene Glycol, 1,6-HDO is a white waxy solid at room temperature, the state is shown below. When the temperature is higher than the melting point (42 ℃) above the colourless transparent liquid, boiling point 250 ℃, soluble in water, methanol, butanol, butyl acetate, slightly soluble in hot ether insoluble in benzene. It is an important chemical raw material, one of the important raw materials for many kinds of organic synthesis.
Chemical properties and stability: must be kept away from oxidising agents, reducing agents, acid chlorides, acid anhydrides, chloroformates. Store in sealed containers in a cool, dry place.
1. Commonly prepared by catalytic reduction of diethyl adipate or dimethyl adipate in the presence of sodium metal, ethanol or in the presence of lead-chromium oxides, or by catalytic reduction of 2,4diyne-1,6-diol. As shown in the figure below, the reaction catalyst was chosen to be copper chromite, the hydrogen flux pressure was 3.79-20.68 MPa and the reaction temperature was 255°C, which was able to obtain the target product in 85%-90% yield .
2. For laboratory preparation of small quantities, lithium aluminium hydride may be chosen as the reducing agent for the reaction. In a dry reaction flask fitted with a stirrer, a dropping funnel, and a reflux condenser (with a calcium chloride drying tube at the top), add the lithium aluminium hydride and the ether dried with sodium metal and stir for ten minutes. A solution of freshly distilled diethyl adipate (2) dissolved in anhydrous ether was slowly added dropwise, with the rate of acceleration of the drop being controlled to keep the reaction solution refluxing. The reaction system gradually became viscous, and an appropriate amount of anhydrous ether was added in several portions each to facilitate stirring. Continue to stir the reaction for ten minutes after addition. Slowly add water dropwise, or add ethyl acetate to decompose the remaining lithium aluminium hydride. It is filtered, dried over anhydrous magnesium sulphate, and the ether is removed by spinning to give an anhydrous viscous mass which solidifies on cooling as pure 1,6-hexanediol (1). The filter cake is dissolved in 20 per cent sulphuric acid, the ether is extracted several times, or continuously with ether, and after evaporation of the ether the product is collected and combined with (1) in 91 per cent yield. At present, researchers are more inclined to investigate the use of catalysts with mild conditions to catalyse the reaction to proceed.
Mainly used in the production of polyurethane, unsaturated polyester, plasticisers, hardeners of gelling agents, lubricating oils, such as heat stabilisation qualitative improver. Also used in pesticides pyrethroids, organic peroxides, cyclic musk, polyethylene plastic crosslinking agent and the production of polyether rubber, etc., but also can be applied to the treatment of vascular diseases, specific applications are as follows:
1) Polyurethane field
1,6-hexanediol can be applied to polyester resins to modify polyurethane elastomers. The modified resin has excellent mechanical strength, water resistance, heat resistance and oxidation resistance, which is widely used in synthetic rubber, elastic fibre and synthetic leather.
2) Polyester
Because 1,6-hexanediol unsaturated polyester carbon chain is more difficult to hydrolyse than other short-chain alcohols unsaturated polyester, and better flexibility, so it can improve the alkali resistance of the resin, improve its adhesion with glass fibre. As for saturated polyesters, polyesters made from 1,6-hexanediol and 4,4-dicarboxylic acid-diphenylsulfonic acid have high tensile strength and high elasticity. It has excellent solvent resistance and swelling resistance, and is particularly suitable for photographic film substrates. The polyester of 1,6-hexanediol and terephthalic acid is suitable for the treatment of polyester fibre.
3) Synthetic resin additives
Compared with plasticizers of low molecular weight, plasticizers using 1,6-hexanediol have excellent performance in terms of volatility resistance, resistance to oil spraying and frosting, migration resistance, and low-temperature resistance, and can be widely used in plastics, rubbers, epoxy resins, and other materials.
4）Others
Also used as a solvent, organic synthesis intermediates. It can also be used as active monomer for producing light-curing coatings, formulating printing inks, dye coupling agent and so on.
Currently 1,6-hexanediol is produced internationally by BASF, Bayer in Germany, UBE in Japan, and Nanming in China, with a total production of about 70,000 to 80,000 tonnes per year, and the production capacity is close to the maximum output. The demand for this product in the Asian market is also very high. Up to now, the domestic market demand for this product, has been from 3,000 tonnes/year in 2001, up to 20,000/year now, plus the current demand in the international market, the annual need for the shortage of about 40,000-50,000 tonnes. As a major fine chemical material, it has more and more extensive applications in the fields of polyurethane, polyester, coil coating, light curing agent, etc., and is regarded as the new cornerstone of organic synthesis.
