Yield:6223-35-4 87.5%

Reaction Conditions:

with sulfuric acid;acetic anhydride at 20; for 2 h;Cooling with ice;

Steps:

14.1 (1)
Preparation of 3,8-dimethyl-5-isopropyl azulene-1-sodium sulphonate

(1)
Preparation of 3,8-dimethyl-5-isopropyl azulene-1-sodium sulphonate
Under ice bath, 25 ml pear-shaped flask was sequentially added with 4 mmol of guaiazulene, 2 ml of Ac₂O, and then added with a mixture of 1 ml of concentrated H₂SO₄ and 2 ml of Ac₂O through constant pressure dropping funnel (with a drying tube on the top).
After completion of dropwise addition, the mixture was stirred at room temperature for about 2 h and the reaction was tracked with TLC until the raw material disappears.
The mixture solution was poured into 4 ml of water, and then dropwise added with NaOH solution to adjust pH to 8-9.
Then the mixture solution was cooled to precipitate, leached, and washed with cold water and petroleum ether sequentially, dried, to obtain 1.05 g of blue solid. Yield: 87.5%. m.p. 106-107° C.

References:

Sichuan Guokang Pharmaceutical Co., Ltd;Zhang, Luyun;Yang, Fang;Shi, Wanqi;Zhang, Ping;Li, Ying;Yin, Shufan US2014/206741, 2014, A1 Location in patent:Paragraph 0108-0110

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