Study On Synthesis Of 2-Methy1-3-hydroxyquinoline

With the increasing development of the synthesis and dye of chemical fibers and improvement of people's sense of environment protection, it has great economic and social value to develop quinophthalone dispersion dyestuffs, which is harmless and has high performance. 2-methyl-3-hydroxyquinoline(MQL) is a key intermediate for the synthesis of quinophthalone dispersion pigments, so it is very important to study its synthesis.In this paper, on the basis of much relating literature and many preparatory experiments, the synthesis route of MQL was designed as following: o-nhrotohiene (ONT) was brominated, and then hydrolyzed to prepare o-nitro benzaldehyde(ONBA), which was then reduced to get o-aminobenzaldehyde(OABA), at last, OABA cyclized with monochloroacetone to yield MQL. The results showed that the method, which using hydrogen bromide and hydrogen peroxide instead of bromine to brominate ONT, then hydrolyzed by concentrated sulfuric acid to prepare ONBA, not only avoided the direct use of caustic bromine, made the process manipulation easier, but also enhanced the efficiency of bromine, and the yield was 49.2%, much higher than the existing industrial methods'. The method that used ferrous sulfate and ammonia water to reduce ONBA was long used, the yield was 77.3%. The yield of the cyclic condensation between OABA and monochloroacetone was 76.7%.In this paper, the bromination reaction was studied in-depth, the impact of the ratios of raw materials, the period of introduction of the hydrogen peroxide and thetotal reaction period were analyzed. The result showed that the suitable mole ratios were n(HBr) : n(ONT) = 2.8 - 3.2 : 1. n(H2C>2) : n(ONT) = 3.0 - 3.5 : 1, the preferred time of hydrogen peroxide introduction was 6 - 8h, total reaction time was 14 - 18h.The impact of temperature and reaction time to the hydrolysis reaction were also studied, The result showed that the suitable reaction temperature was 90癈 ?110癈, and the suitable reaction time was closely related with temperature, when temperature was 100癈, the preferred reaction time was 8 - 15min.