1 2 hexanediol synthesis

What is the synthesis method of 12 hexadiol
The synthesis methods of 12-hexadiol mainly involve direct synthesis and indirect synthesis. ‌ direct synthesis methods include hydrogenation reduction, ‌ hydrazine hydrate reduction and decarbonylation. ‌ hydrogenation reduction process is to produce 12-hexadiol by reacting hexadial with aluminum-magnesium alloy or hydrogen in the presence of a catalyst (‌, such as platinum, ‌ palladium, etc.) ‌. ‌ hydrazine hydrate reduction method is the reaction of adipic aldehyde with hydrazine hydrate to obtain 12-hexadiol. ‌ decarbonylation uses highly reductive benzothiadione sodium as catalyst ‌ to decarbonize hexadial to obtain 12-hexadiol. ‌ indirect synthesis method hexanol is first prepared, ‌ hexanol is oxidized to 12-hexanediol. ‌ The specific methods include epoxidation, ‌ solvent and hydroxylation. ‌ epoxide is obtained by oxidizing hexane with monoammonium persulfate over hexane, ‌ reacting with sodium hydroxide to obtain hexanol, ‌ finally reacting hexanol with hydrogen peroxide to produce 12-hexanediol. ‌ solvent method firstly oxidizes hexane to hexanone in the presence of potassium hydroxide, ‌ then reacts with ammonia in the presence of charcoal to obtain hexanol, ‌ finally reacts hexanol with hydrogen peroxide to produce 12-hexanediol. ‌ The hydroxylation process is to react hexane and hydrogen peroxide in the presence of cobalt sulfate to obtain 1, 6-adipic acid, ‌ the adipic acid is reduced by heating in the presence of sodium hydroxide to hexanol, ‌ finally the reaction of hexanol and hydrogen peroxide to produce 12-hexanediol. ‌

Other methods
1 Diacetone alcohol is obtained by condensation of acetone and then hydrogenated in liquid phase.
2 Refining method 2-methyl-2, 4-pentanediol is dissolved with 1% sodium hydroxide, 140 is heated for 1h, and vacuum distillation is carried out below 140.
3 A new type of copper ester hydrogenation catalytic system, a fixed bed continuous hydrogenation process with high space speed, low pressure and low hydrogen ester ratio, formed the esterification hydrogenation of adipate to produce hexadiol. The process has low energy consumption and no pollution, and the esterification rate can reach 98%. HDO is an environmentally friendly chemical raw material, which can be mixed with organic chemicals in any proportion without corrosion, and can be derived into a series of new fine chemicals, which is known as the new cornerstone of organic synthesis. Dimethyl adipate was prepared by esterification of adipate with solid strong acid resin instead of inorganic acid. After the reaction, the catalyst was quickly separated by filtration. In addition, the copper catalyst which can be used for catalytic hydrogenation of dimethyl adipate and dimethyl glutarate to produce dihydric alcohol can control the optimal reaction activity temperature in the fixed bed from 200 to 220, the reaction pressure can be reduced to the lowest 5MPa, the liquid space velocity is 0.3/h to 0.5/h, and the hydrogen ester molar ratio is 130 to 150. The yield was stable above 97%. The above indexes are better than the existing reports, especially the reaction pressure and hydrogen-ester molar ratio are significantly reduced, which can greatly reduce the investment and operating costs of the production plant, and reduce the difficulty of operation.
Each of these methods has its advantages and disadvantages. ‌ which method to choose depends on factors such as production needs, ‌ cost and required reaction conditions. ‌