Synthesis And Optimization Of 1,5-naphthalene Diisocyanate And It's Raw

1,5-naphthalene diisocyanate referred to as NDI whose raw materal 1,5-naphthalene diamine referred to as NDA.NDI is a raw material for the synthesis of polyurethane elastomers,and the NDA is not only the NDI's raw material,but plays an important role in the pesticide industry and dyestuff industry.Accessed to research literature to understand the various synthetic methods of these two products,and compared the pros and cons,than we make determination that the 1,5-naphthalene diol and ammonia as raw material,after the Bucherer reaction synthesis NDA,and than used NDA and phosgene for the synthesis of NDI.We mainly used the visible ultraviolet spectrum scanner and the infrared spectrometer for qualitative analysis of NDI and NDA.As a secondary qualitative analysis according to the determination of the melting point to two different methods,compare the sample and standard sample,and infer the possible by-products.HPLC was used to establish the quantitative analysis conditions,so providing an easy method for the calculation of yield and other NDI and NDA.We found out the synthetic route of NDA through a lot of exploration experiments and initially identified the experimental conditions,and then analyzed the a variety of factors affecting synthesis of NDA,including the amount of catalyst,reaction temperature,reaction time and ammonia ratio,we also considered the possibility of further reaction in the reaction liquid after added in ammonia.The experiment also found that the amount of ammonia is related to the pressure which has some influence on the reaction.Through the optimization of the process we obtain the optimum operating conditions as that,when 9 parts of 1,5-naphthalene diamine,we needed 2.100 parts of NaHSO3 and 45 parts of ammonia,the reaction temperature was 155? and the reaction time was 7h.Through lots of exploration experiments we found out the route of synthesis NDI,and understand the key factors impacting synthetic from these preliminary experiments,it is including the choice and amount of solvent,the content and amount of phosgene,the amount of moisture content and role of activated carbon and so on.Phosgene is the most important factor in the synthesis of NDI,more free chlorine contained in phosgene,thus a lot of side effects occurred,so hindering the synthesis of NDI.The reaction needing an excessive phosgene,when the amount of phosgene is insufficient,thereaction is extremely complex and there are many side effects.We got the optimum operating conditions from the optimization of various factors as that when 30 parts of NDA,we needed 800 parts of chlorobenzene,which 400 parts was used to dissolve NDA and 400 parts was used to absorb phosgene,the amount of phosgene was about 113 parts,and activated carbon dosage was 3 parts.In this thesis,we done a systematic study of the synthesis of 1,5-naphthalene diisocyanate and its raw materials,and provides a reliable reference for the production process to optimize the various factors.