【作者】 陈盛；

【导师】 徐振元； 杜晓华；

【作者基本信息】 浙江工业大学 ， 应用化学， 2007， 硕士

【摘要】 5-氨基-2-氯-4-氟苯硫基乙酸甲酯1是一个重要的中间体，主要应用于氟噻乙草酯等超高效、广谱、低毒除草剂的合成。本文确定了以3，4-二氯硝基苯8为起始原料，经亲核取代、还原、氧化、席曼反应、硝化、水解、亲核取代等7步反应的合成路线，总收率达到53％。8与多硫化钠溶液在60～70℃发生亲核取代反应，然后在回流状态下被还原，经双氧水氧化得到中间体双(4-氨基-2-氯苯基)二硫化物7，产品纯度99.6％，收率为94.3％。和文献相比，7在不经过重结晶的情况下得到了更好的纯度同时缩短了反应时间，操作简单。7经席曼反应得到双(2-氯-4-氟苯基)二硫化物6，其中重氮化反应收率在95％以上，再在浓盐酸体系中发生氯氧化反应，合成2-氯-4-氟苯磺酰氯5，经减压蒸馏提纯，产品纯度95.3％，两步总收率为69.8％。5在无水硫酸钠存在下与混酸于40℃发生硝化反应得到2-氯-4-氟-5-硝基苯磺酰氯4。本方法反应时间短，浓硫酸消耗量少，产品纯度98.5％，收率97.8％。4与红磷、碘、乙酸组成的混合体系发生还原酰化发应，得到S-乙酰基-5-乙酰胺基-2-氯-4-氟苯硫酚3，纯度94.2％，收率92.9％。3与10％盐酸在回流状态下发生水解反应，反应2h，得到5-氨基-2-氯-4-氟苯硫酚2，纯度为94.7％，收率达到98.7％。2与氯乙酸甲酯在二氯乙烷为溶剂、三乙胺为缚酸剂，室温下发生亲核取代发应，得到1，产品纯度为92.1％，收率达到91.9％。本文研究了原料配比、反应温度、反应时间、反应溶剂、缚酸剂等因素的影响，得到了较优的实验结果，并且于2006年完成氟噻乙草酯中试研究。本方法具有操作简单、对环境友好、产品质量优等优点，是一条适宜工业化生产的工艺路线。更多还原

【Abstract】 Methyl 2-[(5-amino-2-chloro-4-fluorophenyl)thio] acetate 1 is thekey intermediate in the synthesis of fluthiacet-methyl, which is asuper-effective, wide-spectral and safe herbicide. In this paper, a newmethod of preparing this intermediate was studied:3,4-dichloro-nitrobenzene 8 as the start material, via nucleophilicsubstitution, reduction, oxidation, Schiemann reaction, oxychlorination,nitration, hydrolyzation, and nucleophilic substitution to synthesis theproduct, in 53% total yield.Bis(4-amino-2-chlorophenyl) disulfide 7 was prepared by reacting 8with the solution of sodium sulfide and sulfur and then hydroperoxide.Yield: 94.3%, purity: 99.6%.Bis(2-chloro-4-fluorophenyl) disulfide 6 was prepared by a typicalSchiemann reaction, including the diazonium tetrafluoroboric of 7prepared by diazotization with the yield of 95%, then turned into 2-chloro-4-fluorobenzenesulfonyl chloride 5 by oxychlorination withchlorine gas in conc. hydrochloric acid at 50～60℃. The total yield:69.8%, purity: 95.3%.2-Chloro-4-fluoro-5-nitrobenzenesulfonyl chloride 4 was preparedin 97.8% yield in 98% purity by nitration of 5 with 95% fuming nitricacid in conc. sulfuric acid in the existence of anhydrous sodium sulphateat 40℃for 1 hour.S-5-Acetamido-2-chloro-4-fluorophenyl ethanethioate 3 was preparedby reduction of 4 with red phosphorus and iodine in the acetic acid at thetemperature of 115～117℃for 28 hours. Yield: 92.9%, purity: 94.2%.5-Amino-2-chloro-4-fluorobenzenethiol 2 was prepared byhydrolyzation of 3 with 10% hydrochloric acid at the temperature of101℃for 2 hours. Yield: 98.7%, purity: 94.7%.Methyl 2-[(5-amino-2-chloro-4-fluorophenyl)thio] acetate 1 wasprepared by nucleophilic substitution of 2 with methyl 2-chloroacetateat the room temperature in the condition of dry dichloroethane as solventand triethylamine for 1 hour. Yield: 91.9%, purity: 92.1%.In conclusion, the process has advantages in simple operation, goodyield, high purity and little waste, which are industrially valuable.更多还原