| 摘要 |
PURPOSE:To improve purity and yield of the titled compound useful as a raw material for medicines, agricultural chemicals, etc., without requiring a separation step, by reacting a vinylpyridine with sulfurous acid in the absence of an organic solvent, e.g. ethanol. CONSTITUTION:A vinylpyridine of formula I (R is H or alkyl) is reacted with sulfurous acid, preferably within 1:1.1-10 molar ratio range between the compound of formula I and the sulfurous acid at 10-100 deg.C, preferably 30-60 deg.C to give a compound of formula II. There are various methods for reacting the compound of formula I with the sulfurous acid, but for example excess sulfurous acid gas is dissolved in water to form dilute sulfurous acid, which is then reacted with the vinylpyridine or the vinylpyridine is added to water while blowing excess sulfurous acid gas thereinto at the same time. 2-Vinylpyridine, 5-ethyl-2-vinylpyridine, etc. may be used as the compound of formula I .
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