| 摘要 |
PURPOSE:To obtain the titled compound industrially and easily in high yield and purity, by reacting a diketene continuously with free hydroxylamine, and treating the resultant reaction mixture containing acetoacetohydroxamic acid rapidly with an acid. CONSTITUTION:A diketene of formula I or a solution thereof in methanol, etc. and hydroxylamine of formula VI or a solution thereof in methanol or water, etc. are continuously fed respectively to a mixing reactor and reacted at -15- 25 deg.C for 10-20sec, and the resultant reaction mixture containing acetoacetohydroxamic acid of formula IV is rapidly treated, dehydrated and cyclized with an acid, e.g. hydrochloric acid, sulfuric acid, etc. at 60-80 deg.C for several minutes -1hr to give the aimed compound of formula V capable of exhibiting improved effect particularly as a soil blight controlling agent. Alternatively, the above- mentioned reaction process can be carried out by mixing the mixture solution of the diketene with an acid addition salt of the hydroxylamine respectively with a base solution continuously, and reacting the resultant free hydroxylamine in the reaction system with the diketene.
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