4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) is a hydrogen ion buffer which has a good buffering capacity in the pH range of 6.8~8.2 and can control a constant pH for a long time. How to synthesize HEPES with high purity?
The researchers invented a high-purity HEPES preparation method, which not only has high purity, but also has low purification cost, simple process, easy operation and no pollution. Specifically, the following steps are included:
(1) Preparation of HEPES salt: the vinyl sulfonate is formulated into a certain concentration of aqueous solution, and then N-hydroxyethylpiperazine is added for addition reaction to obtain 4-hydroxyethylpiperazineethanesulfonate. The molar ratio of vinyl sulfonate to N-hydroxyethylpiperazine is 1.00~1.15:1; the most preferred reaction temperature is 60~110°C, and the reaction time is 2~6 hours.
(2) Acidification: The purpose of acidification is to convert HEPES salt obtained by reacting N-hydroxyethylpiperazine with sodium, potassium or ammonium vinylsulfonate to HEPES. The acidulant used is a strong acid having a pKa of less than 4.5, including sulfuric acid, hydrochloric acid, formic acid and oxalic acid, preferably sulfuric acid and oxalic acid. The acidifier and 4-hydroxyethylpiperazineethanesulfonate are used in a molar ratio of 0.9 to 1.2:1, preferably 0.95~1.05:1, a suitable acidification temperature is 0~40°C, an acidification reaction time is 1~2 hours.
(3) Crystallization and desalting: The acidified liquid is cooled, and the salt of the acidifying agent is precipitated by crystallization, and then removed by filtration. A suitable crystallization temperature is -20~10°C, preferably -10~5°C, and the crystallization time is 0.5~1 h.
(4) Sulfate removal: sulfate ions can be effectively removed by soluble barium salt or calcium salts. Suitable soluble barium salt or calcium salts include barium chloride, barium formate, barium acetate, barium hydroxide, calcium chloride, calcium formate, calcium acetate, calcium hydroxide. Preferred precipitants are barium chloride, barium acetate or hydrogen. Yttrium oxide.
(5) Washing purification: The primary purification product may contain trace amounts of HEPES-Na, HEPES-K or HEPES-NH4, vinyl sulfonate, or N-hydroxyethylpiperazine. It can be removed by using the difference in solubility with HEPES in small molecule alcohols. The pure product of HEPES can reach 99.9%.
The 4-hydroxyethylpiperazineethanesulfonic acid obtained by the invention has high purity, simple operation process, low purification cost, simple process, easy operation and no pollution.
References
Cui Hongyou, Wang Jiangang, Zhu Liwei. Preparation method of high-purity 4-hydroxyethylpiperazineethanesulfonic acid, 2015.7, CN104803949A
86-15062454963
sales@yacoo.com.cn
