Study On Green Synthesis And Water Treatment Of Aromatic Heterocyclic Drugs

Green chemistry is currently the main direction of international chemical research,an inevitable trend of the development of the chemical industry,and the only way for human survival and social sustainable development.2-Nitrobenzyl bromide is an important intermediate in the biocide pyraclostrobin synthesis process.Currently,it has the problems of low yield and poor selectivity in industrial production.On the other hand,a large amount of high-concentration organic wastewater is generated during the pyraclostrobin production process,which seriously threatens human health and the ecological environment.In view of the low yield and poor selectivity of 2-nitrobenzyl,this paper uses2-nitrotoluene as raw material and Azobisisobutyronitrile as initiator to synthesis2-Nitrobenzyl bromide by HBr/H₂O₂ Oxidative Bromination which is low bromine source toxicity and environmental friendly.The effects of the ratio of raw materials,initiators and light,reaction temperature,reaction time,phase transfer catalyst,and solvent on conversion and selectivity were investigated.Under optimal reaction conditions,the yield of2-nitrobenzyl bromide can reach about 67%.This article selects simple and effective iron carbon microelectrolysis and Fenton oxidation techniques to pretreat high-concentration organic wastewater from a certain reaction during the synthesis of pyraclostrobin.In the iron carbon microelectrolysis experiment,the effects of Fe/C mass ratio,addition of iron powder,pH value and reaction time on the treatment effect of wastewater were studied,and the COD removal rate of the wastewater reached more than 56%.In the Fenton oxidation experiment,the effects of the molar ratio of H₂O₂ to Fe²⁺,the dosage of H₂O₂ and Fe²⁺,pH value and reaction time on the treatment of wastewater were studied,and the COD removal rate of the wastewater reached about 52%.The effect of the sequence of the two technologies on the wastewater treatment effect was studied and the result shows that the iron carbon microelectrolysis-Fenton oxidation combination process not only has a better treatment effect but also has a lower cost.The optimum operating conditions of the combined process were investigated,and the COD removal rate of the wastewater reached 68%or more.Although the final removal rate of wastewater COD can reach 76%by supplementing FeSO₄·7H₂O,a large amount of iron mud is generated during flocculation and precipitation,which makes post-treatment difficult.The kinetics of the iron carbon microelectrolysis and Fenton oxidation treatment of pyraclostrobin wastewater were studied respectively.The reaction kinetics equation of iron carbon microelectrolysis treatment of pyraclostrobin wastewater was obtained as:The Fenton oxidation kinetic equation of pyraclostrobin wastewater is:...