Research On The Sythesis Process Of Fluorene Derivatives

Fluorene derivatives are important fine chemical intermediates, which can be widely applied in the fields of pharmaceuticals, dyes, plastics, among them, fluorenone can be used as raw materials in epoxy resin, polyether and polycarbonate, etc, 2,7- bromide fluorene can be used in preparation of organic electroluminescent materials, 2,7- dibromo fluorenone can be used as additive in photoconductive and photoluminescence materials. In this paper, the crude fluorene was purified at first, then with fluorene as raw material, fluorenone was synthetized by using method of liquid phase catalytic oxidation, fluorene and bromine occurred electrophilic substitution reaction in preparation of 2,7- dibromo fluorene, with 2,7- dibromo fluorene as rawmaterial, 2,7- dibromo fluorenone was synthetized by using method of liquid phase catalytic oxidation, at last, the qualitative analysis of synthetic products were determined by NMR, IR, UV, melting point. The main contents are as follows:Study on the purification process of crude fluorene. There was certain purity requirement of raw fluorene for synthesis of fluorene derivatives, in view of high price for purity fluorene, This paper selected 70.15% purity of cheap crude fluorene as raw material, which was divided into two steps of purification. First, 92.37% purity and 59.9% yield crystallization fluorene could be obtained by recrystallization, then 96.91% purity and 91.3% yield fluorene could be obtained by solvent washing.Study on the synthesis process of fluorenone. Some factors such as reaction temperature, reaction time, catalyst, cocatalyst, solvent and air flow were discussed with single factor experiment. The optimum condition for the synthesis of fluorenone was obtained as follows: the best reaction temperature at 60℃ for 3h, the mass ratio of fluorene and solvent=1:2, the mass ratio of fluorene: catalyst: cocatalyst=1:0.05:0.02, air flow at 5m L·(g fluorene·min)-1, the maximum yield of fluorenone attained 97.1%, then 99% purity fluorenone could be obtained by purification. From viewpoint of quantum chemistry, the synthesis mechanism of fluorenone was deduced through the search for transition state.Study on the synthesis process of 2,7- dibromo fluorene. The optimization of process conditions was sent out to synthesize 2,7-dibromo fluorene with fluorine and bromine as raw material, hydrogen peroxide as the bromide ion oxidant, glacial acetic acid as the reaction solvent. The research found that bromine need to be dropwise added and protected from light, n(fluorene): n(bromine): n(hydrogen peroxide)=1: 1.13:1.62, the mass ratio of fluorene and glacial acetic acid =1:8.79, the reaction temperature at 30℃ for 3h. glacial acetic acid was added in batches, the yield of target product reached 89.3%, then 97.61% purity 2,7- dibromo fluorene could be obtained by purification. Under this condition, the bromine atom utilization rate was high, the reaction condition was mild and safe.Study on the synthesis process of 2,7- dibromo fluorenone. Effects of reaction temperature, reaction time, catalyst, etc, were investigated with single factor experiment. The results suggest that the optimum condition for the synthesis of 2,7- dibromo fluorenone was obtained as follows: the best reaction temperature at 75℃ for 4h, the mass ratio of 2,7- dibromo fluorene and solvent =1:5, the mass ratio of 2,7- dibromo fluorene: catalyst: cocatalyst=1:0.05:0.02, air flow at 7m L·(g 2,7- dibromo fluorene·min)-1, the maximum yield of 2,7- dibromo fluorenone was up to 94.9%, then 97.25% purity 2,7- dibromo fluorenone could be obtained by purification. This process greatly reduced the synthesis cycle of 2,7- dibromo fluorenone.