【摘要】 本文探讨了等人提出的制备硝基乙酸乙酯的方法的一些优缺点,提出了改进的方法,并得到了很好的结果,产率自60％左右提高到90％以上,而且产物的纯度也大大提高。更多还原

【Abstract】 Ethyl nitroacetate is frequently prepared by Rodionov’s method[2],by which ethyl α-oximinoaeetoacetate is oxidized in aqueous solution with dichromate-sulfuric acid mixture;a yield of 60.7% has been claimed.We found as other workers did that,though ethyl nitroacetate could thus be prepared,the yields fluctuated considerably[5,6].The reason lies probably in the fact that ethyl α-oximinoacetoacetate is not completely soluble in the aqueous reaction mixture under the specified experimental conditions,and thus side reactions can not be avoided,e.g.further oxidation of ethyl nitroacetate.It was considered that addition of an inert solvent during the oxidation might be helpful,and we found that benzene works so well that a 90% yield of ethyl nitroacetate of reliable purity can be invariably secured.The improved procedure consists as follows: Ethyl α-oximinoacetoacetate (35g) in benzene (120 c.c.) and a solution of Na2Cr2O72H2O (59 g) in water (35 c.c.) are placed in a flask.1:1 sulfuric acid (made from 58.1 g cone.H2SO4) is added dropwise with stirring,and the temperature of the reaction mixture is kept at 4-7°.The yield of ethyl nitroacetate is 27.4 g (90.2%),b.p.78-79°/2 mm,nD25 1.4232.It was noticed that the color of the aqueous layer in the whole course of oxidation is dark brown rather than the usual dark green color of trivalent chromium salt;we are attempted to suggest that the chromate ion in the oxidation process is reduced to tetravalent state which is dark brown in color[7].更多还原