Step 1, using alkali metal salt of tert-butoxide as a raw material, and using carbon dioxide as another reactant and solvent, reacting in a supercritical state of carbon dioxide to generate a mixture of alkali metal salt of mono-tert-butyl carbonate dissolved in supercritical carbon dioxide;
Step 2, dissolving phosgene in liquid carbon dioxide;
Step 3, adding the solution obtained in step 2 to the mixture generated by the reaction in step 1 and reacting in a supercritical state of carbon dioxide to generate di-tert-butyl tricarbonate;
Step 4, cooling the supercritical carbon dioxide dissolved with di-tert-butyl tricarbonate after the reaction in step 3 is completed to liquefy the carbon dioxide, then transfer to the separation kettle, slowly release the pressure and heat, and the di-tert-butyl tricarbonate is decomposed to generate the product di-tert-butyl dicarbonate. Butyl ester.
The preparation method of di-tert-butyl dicarbonate is made up of the following steps:
Put sodium tert-butoxide and n-hexane into the reaction kettle, heat up to complete dissolution under N2 gas protection, then stir and cool to 5 ° C, feed carbon dioxide into the reaction kettle to saturation, add a ternary catalyst to the reaction solution, Control the temperature in the reaction kettle to be in the range of -12°C, put solid phosgene into the reaction kettle in 10 batches every 0.5 hours, and then react for 3 hours after the input is completed. alkane solvent to obtain crude di-tert-butyl dicarbonate, crystallize at below 0°C, after sufficient crystallization, centrifuge the mother liquor to obtain the desired di-tert-butyl dicarbonate;
The weight ratio of described sodium tert-butoxide and n-hexane is 1: 6.8;
The weight ratio of described solid phosgene and sodium tert-butoxide is 0.5: 1.0;
The weight ratio of the amount of added water and sodium tert-butoxide is 2.2: 1.0;
Described three-way catalyst is a mixture of solid acid, organic base, and interface catalyst;
Wherein: the solid acid catalyst is: after dissolving anhydrous aluminum trichloride in ethanol, add activated carbon to it as a carrier; the weight ratio of the added amount of the solid acid catalyst and sodium tert-butoxide is 0.003: 1.0;
Wherein: the organic base is: diethylenetriamine, and the weight ratio of its add-on to sodium tert-butoxide is 0.003: 1.0;
Wherein: the interface catalyst is: tetrabutylammonium bromide, and the weight ratio of its addition to tert-butanol is 0.003:1.0.
In the above scheme, the obtained Di-Tert-Butyl Dicarbonate product is 265kg, the content is 99.5%, and the yield is 85.0%.
The preparation method of Di-Tert-Butyl Dicarbonate comprises the following steps:
(1) Synthesis of sodium tert-butoxide: add 20g of sodium metal to 400g of xylene, heat to 130～140° C. to obtain sodium sand, and slowly drip 95～96g of tert-butoxide at this temperature to obtain sodium tert-butoxide The solution was cooled to below 5 °C and suction filtration was carried out to obtain sodium tert-butoxide, and the mother liquor was applied mechanically;
(2) dissolving the prepared sodium tert-butoxide in petroleum ether, introducing carbon dioxide at -5～10°C to react for 3h, after the reaction is completed, a monoester sodium salt solution is obtained;
(3) Add 2g N,N-dimethylformamide, 1g pyridine, 1g triethylamine to the monoester sodium salt solution, cool down to -5～0℃, slowly add 60g diphosgene dropwise within 1.5h After completion, the temperature was raised to room temperature (25°C), and the reaction was kept for 2 hours. After the reaction was completed, it was left to stand for suction filtration, the organic solution was washed with water, dried with anhydrous magnesium sulfate, and the solvent was evaporated under normal pressure to obtain 65-70 g of crude product, which was obtained after cooling and crystallization. 57-60 g of Di-Tert-Butyl Dicarbonate in a yield of 60-63%.
(1) Use N2 to empty the autoclave with a capacity of 2L, successively add 85g of tert-butanol, 650g of n-hexane, and 25g of sodium metal, heat to 110°C, stir rapidly, the pressure in the kettle is about 0.2MPa at this time, fine-tune the vent valve The pressure in the kettle is controlled, the reaction is carried out for 5 to 6 hours, and the preparation of sodium tert-butoxide is completed when there is no change in the pressure in the kettle for 15 minutes;
(2) Cool down to -5～5℃, open the open valve, pass CO2 until CO2 is no longer absorbed, continue stirring for 20min after ventilation, keep the temperature unchanged, add 1g pyridine, dissolve triphosgene with 65g n-hexane, Then dropwise into the reaction kettle, the dropwise addition time is about 3～4h, keep the temperature unchanged, keep the temperature at -5～5℃ for 1h, heat up to 25～30℃ and keep the temperature for 2h, and remove the solvent at 80～90℃ under normal pressure ( Whether it refers to distillation operation), then add water for washing, the amount of water added is 300g, layering, taking the organic phase, cooling the organic phase to 0 ~ 5 ℃, freezing and crystallization, centrifugal separation, and drying to obtain Di-Tert-Butyl Dicarbonate105g, The yield was 89%, and the product purity was 99.3%.
