Study On Synthesis Of Oxadiazon Intermediate Aromatic Hydrazide And MVR Process Design For Sn Recovery

1-trimethylacetyl-2-(2,4-dichloro-5-isopropoxyphenyl)-hydrazine is an important intermediate for the synthesis of oxadiazon.With the increasing market demand of oxadiazon,its synthesis has been paid more and more attention.Therefore,the synthesis of 1-trimethylacetyl-2-(2,4-dichloro-5-isopropoxyphenyl)-hydrazine has a very broad market prospect.Firstly,on the basis of existing research,the synthesis route with 2,4-dichloro-5-isopropoxynitrobenzene as raw material was selected and optimized.In the synthesis of 2,4-dichloro-5-isopropoxy nitrobenzene to 2,4-dichloro-5-isopropoxyaniline,the reductant,catalyst,reaction time and reaction temperature were systematically analyzed.Hydrazine hydrate-FeO(OH)system was selected as the reductant and catalyst.The optimum reaction conditions were as follow: 2,4-dichloro-5-isopropoxy nitrobenzene: Hydrazine hydrate: FeO(OH)=1:1.8:0.15(mole ratio),reaction temperature: 80?,reaction time: 6h,and the yield of product 2,4-dichloro-5-isopropoxyaniline was about 94%.In the synthesis of 2,4-dichloro-5-i sopropoxyaniline to 2,4-dichloro-5-isopropoxyphenylhydrazine,the diazotization process,reduction process and alkalization process were optimized.In the diazotization reaction,the reaction temperature was chosen to be-5-5?,and the amount of acid was 6 equivalent.Also,stannous chloride-hydrochloric acid reduction system was used in the reduction reaction.The optimum conditions for alkalization were alkali ratio:3,alkali concentration :12%,and the yield of 2,4-dichloro-5-i sopropoxyphenylhydrazine was about 95%.In the synthesis of oxadiazon intermediate 1-trimethylacetyl-2-(2,4-dichloro-5-isopropoxyphenyl)from 2,4-dichloro-5-i sopropoxyphenylhydrazine,triethylamine was selected as the acid binding agent,and pivaloyl chloride was selected as the acylating agent.The optimum reaction conditions were as follow: the amount of triethylamine was 2 equivalent and the amount of pivaloyl chloride was 1.1 equivalent,and the yield was about 95%.From the whole synthesis process,the total yield can reach about 72%.Secondly,the MVR evaporation process for stannic chloride wastewater from the synthesis of 2,4-dichloro-5-isopropoxyphenylhydrazine was designed to effectively recover raw Sn,save cost and realize the resource utilization of waste liquid.