By The Synthesis Of Benzaldehyde Between Fluorobenzaldehyde

m-Fluorobenzaldehyde was an important organic synthesis intermediate, and can be widely applied in fine chemicals synthesis, such as medicine, pesticides, plastics additives. This paper mainly introduced the process of synthesizing m-fluorobenzaldehyde by nitration and fluorodinitration of benzaldehyde.The first step we used indirect nitration. m-Nitrobenzaldehyde was prepared by condensation (benzaldehyde with isopropylamine, ammonia, methylamine, ethylenediamine to synthesize intermediate schiff base), nitration and hydrolysis. Factors influencing condensation and nitration were studied. Condensation results of some substrates and benzaldehyde were compared. The condensation result ammonia was the cheapest and adapt to industrialization. Under the optimal condensation conditions: n(benzaldehyde): n(ammonia) =1:2.4, reaction temperature: 40℃, reaction time: 2 h, yield of intermediate can be 99.8%. Under the optimal nitration conditions: n(Schiff base): n(sulphuric acid): n(nitric acid)=1:16:8, nitration temperature was 10-15℃,nitration time was 2 h , and 2 h in hydrolysis, yield of crude m-Nitrobenzaldehyde was 86.6%. The crude product was then purified by recrystallization with petroleum ether-toluene mixture (volume ration 1.5:1), and purity reached 99.8%.The second step we used fluorodinitration to synthesize m- fluorobenzaldehyde. Through the analyzing the experiments about single effect factors on fluorodenitration. we found that fluorodenitration can be afected by solvent, catalyst, reaction time, fluridizer and so on. Through comparison, we choosed the optimize reaction conditions on the fluorodenitration and the results were shown that these conditions were very good. We introduced one simple method of synthesizing quaternary ammonium fluoride and compared its reaction character as a fluridizer. We used Gas Chromatography to detect the process of fluorodenitration and analyzed various systems. We also analyzed fluorodenitration from the mechanism.Finally, we also studied the process of synthesizing m-fluorobenzaldehyde by Balz-Schiemann. First, stannous chloride, sodium polysulfide, ferrous sulfate reduce m-nitrobenzaldehyde for m-amidobenzaldehyde, then synthesize m- fluorobenzaldehyde by Balz-Schiemann. We compared these reduction methods, studied affection factors of Balz-Schiemann. and compared the yield with fluorodinitration.