Step 1, using tert-butanol alkali metal salt as raw material, taking carbon dioxide as another reactant and solvent, reacting under carbon dioxide supercritical state to generate a mixture of mono-tert-butyl carbonate alkali metal salt dissolved in supercritical carbon dioxide;
Step 2, dissolving carbonyl chlorides in liquid carbon dioxide;
In step 3, the solution obtained in step 2 is added to the mixture generated in step 1 to react under the supercritical state of carbon dioxide to generate di-tert-butyl tricarbonate;
Step 4: Cool down the supercritical carbon dioxide in which di-tert-butyl tricarbonate is dissolved after the reaction in step 3 to liquefy the carbon dioxide, then transfer to the separation tank, slowly release the pressure and heat, and the di-tert-butyl tricarbonate decomposes to produce the product di-tert-butyl dicarbonate butyl ester.
The preparation method of di-tert-butyl dicarbonate consists of the following steps:
Put sodium tert-butoxide and n-hexane into the reaction kettle, raise the temperature to dissolve completely under the protection of N2 gas, then stir and cool to 5°C, after passing carbon dioxide into the reaction kettle to saturation, add a three-way catalyst to the reaction solution, Control the temperature in the reaction kettle within the range of -12°C, put solid phosgene into the reaction kettle in 10 batches every 0.5 hours, and react for 3 hours after the input is completed. After the reaction is completed, add water to wash, and steam at normal pressure alkane solvent to obtain crude di-tert-butyl dicarbonate, crystallize below 0°C, and after the crystallization is sufficient, centrifuge the mother liquor to obtain the required di-tert-butyl dicarbonate;
The weight ratio of described sodium tert-butoxide to n-hexane is 1: 6.8;
The weight ratio of described solid phosgene to sodium tert-butoxide is 0.5: 1.0;
The weight ratio of the amount of water added and sodium tert-butoxide is 2.2: 1.0;
The three-way catalyst is a mixture of solid acid, organic base, and interfacial catalyst;
Wherein: the solid acid catalyst is: after dissolving anhydrous aluminum trichloride in ethanol, then adding gac as carrier in it; the addition of described solid acid catalyst and the weight ratio of sodium tert-butoxide are 0.003: 1.0;
Wherein: the organic base is: diethylenetriamine, the weight ratio of its addition to sodium tert-butoxide is 0.003: 1.0;
Wherein: the interfacial catalyst is: tetrabutylammonium bromide, the weight ratio of its addition and 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 sodium metal to 400g xylene, heat to 130-140°C to obtain sodium sand, slowly add 95-96g tert-butanol dropwise at this temperature to obtain sodium tert-butoxide The solution was cooled to below 5°C and suction filtered to obtain sodium tert-butoxide, and the mother liquor was applied mechanically;
(2) Dissolve the prepared sodium tert-butoxide in petroleum ether, and pass through carbon dioxide at -5 to 10°C for 3 hours to react. After the reaction is completed, a monoester sodium salt solution is obtained;
(3) Add 2g of N,N-dimethylformamide, 1g of pyridine, and 1g of triethylamine to the monoester sodium salt solution, cool down to -5~0°C, slowly add 60g of diphosgene dropwise, dropwise within 1.5h Complete, warm up to room temperature (25°C), keep the temperature for 2 hours, after the reaction is completed, let it stand for suction filtration, wash the organic solution with water, dry it with anhydrous magnesium sulfate, evaporate the solvent under normal pressure, and obtain 65-70g of crude product, which is obtained after cooling and crystallization 57～60g of di-tert-butyl dicarbonate, the yield is 60～63%.
(1) Use N2 to empty the high-pressure reactor with a capacity of 2L, add 85g of tert-butanol, 650g of n-hexane, and 25g of sodium metal successively, heat to 110°C, and stir rapidly. At this time, the pressure in the kettle is about 0.2MPa, and fine-tune the vent valve Control the pressure in the kettle, react for 5-6 hours, and when there is no change in the pressure in the kettle for 15 minutes, the preparation of sodium tert-butoxide is completed;
(2) Cool down to -5-5°C, open the vent valve, and feed CO2 until CO2 is no longer absorbed. After the aeration, continue to stir for 20 minutes, keep the temperature constant, add 1g of pyridine, and dissolve triphosgene with 65g of n-hexane. Then drop it into the reaction kettle for about 3-4 hours, keep the temperature constant, keep it at -5-5°C for 1h, raise the temperature to 25-30°C and keep it for 2h, and remove the solvent at 80-90°C under normal pressure ( Does it refer to distillation operation), then add water to wash, the amount of water added is 300g, separate layers, take the organic phase, lower the temperature of the organic phase to 0-5°C, freeze and crystallize, centrifuge, and dry to obtain 105g of di-tert-butyl dicarbonate , the yield is 89%, and the product purity is 99.3%.
