The Development Of Continuous Process And T Pilot Plant On The Diazotization Of 2-fluoroaniline

The reaction what diazonium salt is synthesized by aromatic amine and nitrite is called diazotization reaction.The diazonium salt occupies an extremely important position in organic synthesis,pharmaceutical,photographic materials,dyestuff industry and modification of carbon materials.Batch reactor is presently used in diazotization reaction in industrial production.Because of traditional kettle type process requires a lower reaction temperature,its feed rate is slow,and backmixing phenomena exists in the reaction still,there are some problems in traditional kettle type process,such as long reaction time,low yield and high energy-consuming.Comparing with reaction still,tubular reactor has a series of advantages,such as small size,short reaction time,continuous production,and high yield.So it can solve the problems about traditional kettle type process.In this thesis,the object of study is diazotization of 2-fluoroaniline and tubular continuous pilot plant used in the production of o-difluorobenzene is designed and built.The main contents include:(1)Laboratory equipment such as differential scanning calorimetry,reaction calorimeter was used to study the thermal hazards of diazotization of 2-fluoroaniline.Data obtained from the experiment,such as reaction heat and adiabatic temperature rise,provides data reference for subsequent research.(2)Tubular continuous process of diazotization is developed by the traditional kettle type process.The process is started with 2-fluoroaniline treated with hydrochloric acid to give2-fluoro aniline hydrochloride.Then reaction with sodium nitrite,after react with fluoboric acid generate 2-fluoroaniline diazonium difluoborate.Diazonium tetrafluoroborate was precipitated from reaction liquid According to the process,the small experimental apparatus was built and small experiments were carried out.On the basis of the above experiments,a better process is developed by changing the material ratio and reaction order.In the flowing state,first three kinds of raw materials(the mixed solution of 2-fluoroaniline and fluoboric acid,hydrochloric acid,sodium nitrite solution)were mixed by peristaltic pump in the mixer.Second the mixture is reacted by tubular reactor.The process is optimized through the study of the reaction parameters such as the dosage of the fluoboric acid,hydrochloric acid and sodium nitrite.The total yield could reach to 90.0% by optimal experiment.(3)On the basis of the small experiment,combined with the relevant standard requirements and design manual,the author completed the design,installation,trial tests of this pilot plant.