32results about How to "Reduce the number of crystallization" patented technology

The invention provides a synthesis process of acipimox, which comprises: 1) in an aqueous solution, under the action of a catalyst, reacting 5-methylpyrazine-2-carboxylic acid with hydrogen peroxide; Step 1) Add an auxiliary agent to the solution obtained, wherein the auxiliary agent is selected from one of sulfite, bisulfite, oxalic acid and oxalate; 3) Add to the solution obtained in step 2) Activated carbon, filter; and 4) The solution obtained in step 3) is cooled to crystallize and dried to obtain the finished product of acipimox. The synthesis process of the invention can effectively reduce the number of crystallization times, avoid recrystallization operation, improve yield and reduce production cost.

The invention relates to a method for strengthening purification and separation of artemisinin by a chitosan functional membrane. An extractant is added to an extract containing artemisinin and wax oil to obtain an extraction solution, the chitosan functional membrane or a modified chitosan functional membrane is added to the extraction solution, and separation and purification are performed to obtain artemisinin. The chitosan functional film or the modified chitosan functional film can adsorb the wax oil in the extraction solution, and the wax oil is easily separated from artemisinin after being adsorbed, so that high-purity artemisinin is obtained. At the same time, the chitosan functional film or the modified chitosan functional film has simple preparation method, and abundant and non-toxic and harmless raw materials. The method can also reduce a number of crystallization times and a crystallization time required in a process of obtaining an artemisinin product, and is an efficientpurification and separation method.

The invention discloses a method for purifying sucralose-6-ethyl ester. The method comprises: a secondary boiling step: taking a boiled and negative-pressure-treated mother liquor of sucralose-6-ethyl ester; ‑Adding a predetermined proportion of water to the ethyl ester mother liquor, fully stirring and heating it for boiling, stirring and boiling for a preset time, and then solid-liquid separation to obtain a secondary boiling mother liquor in which sucralose‑6‑ethyl ester is dissolved; phase-separated extraction step : the secondary boiled mother liquor is left to stand for phase separation, the upper phase after the phase separation is taken, and the alkane extractant is used for extraction at a preset temperature to remove the residual white oil in the upper phase; recrystallization and purification step: extracting the obtained The lower layer effluent obtained is evaporated to obtain a solid, and the solid is purified by recrystallization to obtain sucralose-6-ethyl ester; recovery and circulation step: the upper layer effluent after extraction is separated, and the alkane extractant is recovered and recycled to the phase-separating extraction step use. The method is simple, efficient, and low in cost, can effectively remove trace amounts of white oil, and improve the purity of sucralose-6-ethyl ester.

The invention discloses a method for preparing high-purity stigmasterol from phytosterol oleate. The method comprises the following steps of taking phytosterol oleate as a raw material, and performingsubzero fractionation, saponification, solid-liquid separation and two times of crystallization and purification to obtain a stigmasterol product with purity equal to 95% or more. Compared with the prior art, in the method, the phytosterol oleate is taken as the raw material to prepare the high-purity stigmasterol, the method has fewer crystal number of times and is simple in operation steps, thesolvent used for crystallization and purification can be recycled, making full use of resources is realized, and the production cost is lowered.