| 摘要 |
1,190,228. 5-chloro-2,3-pyridine-diol. J. R. GEIGY A.G. 30 Aug., 1967 [31 Aug., 1966], No. 39657/67. Heading C2C. Novel 5-chloro-2,3-pyridine-diol is prepared by reacting furfural at a temperature of about 0‹ in an aqueous medium with at least double the molar amount of chlorine or the equivalent amount of a substance or system which releases the said amount of chlorine under the conditions of the reaction, the pH being kept between 0 and 2 during the addition of the first half of the chlorine and between 0 and - 1 during the addition of the second half, reacting the so obtained mixture at a temperature of 30-60‹ C., and a pH of below 1, with at least an equimolar amount of sulphamic acid, and separating the product. |
