反应详情

5.15 g of 2-methyl-4-(6-carboxyhexyl)-thiazole-5-carboxylic acid (IX, R1 = CH3) and 5.4 g of p-toluenesulphonic acid monohydrate were dissolved in 200 ml of methanol. The reaction mixture was stirred for 2 hours at room temperature, then poured onto 500 ml of water. After saturating the aqueous solution with ammonium sulphate it was extracted with 3 × 200 ml of ethyl acetate, the ethyl acetate extract was washed with water, dried over sodium sulphate and evaporated in vacuo. Recrystallization of the obtained crude product from a mixture of diethyl ether and n-hexane afforded 4.3 g of 2-methyl-4-(6-carbomethoxyhexyl)-thiazole-5-carboxylic acid (X, R1 = CH3). M.p.: 106°-107° C. IR spectrum (KBr): ν OH (carboxylic acid) 3200-2200, ν C=O 1735, 1695, ν C-O 1235 cm-1.

1. concentrationAfter saturating the aqueous solution with ammonium sulphate it
2. extractionwas extracted with 3 × 200 ml of ethyl acetate
3. extractionthe ethyl acetate extract
4. washwas washed with water
5. dry with materialdried over sodium sulphate
6. customevaporated in vacuo
7. customRecrystallization of the
8. customobtained crude product