Study On The Synthesizes Of 9,9'-Spirobifluorene Bromide Derivatives

9, 9'-Spirobifluorene, one of the most typical spiro-compounds, was first synthesized in1930. Its properities and the corresponding derivatives were investigated continously. Themolecules with a Spirobifluorene backbone have gained wide application in various areas,such as molecular electronics and light-emitting materials prodution, enantioselectivemolecular recognition, etc. As the 9, 9'- spirobifluorene bromide derivatives(2-bromo-9, 9'-spirofluorene, 2, 2'-dibromo-9, 9'-spirofluorene, 2, 7-dibromo-9, 9'-spirofluorene and 2, 2', 7, 7'-tetrabromo-9, 9'-spirofluorene) were the key intermediates inpreparation of the compounds with a 9, 9'-Spirobifluorene structure, how to manufacturethem in high purity and low price was very valuable.In this paper, the 9, 9'spirofluorene bromide derivatives, namely2-bromo-9, 9'-spirofluorene, 2, 7-dibromo-9, 9'-spirofluorene and2, 2', 7, 7'-tetrabromo-9, 9'-spirofluorene and their key intermediates(2-bromo-9-fluorenoneand 2, 7-dibromo-9-fluorenone), were synthesized. The fluorene and fluorenone, which werecommercially available, were selected as raw reaction materials. The oxidative bromination offluorene and 9, 9'-spirofluorene with the system H₂O₂/NaBr/H₂SO₄ was first introduced in thepreparation of 2-bromofluorene, 2, 7-dibromofluorene and2, 2', 7, 7'-tetrabromo-9, 9'-spirofluorene. The main content includ: (1) 9, 9'-spirofluorene wasprepared through the addition of 9-fluorenone to 2-biphenylmagnesium bromide to yield9-(2'-biphenyl)-9-fluorenol followed by dehydration cyclization, and2, 2', 7, 7'-tetrabromo-9, 9'-spirofluorene was synthesized by oxybromination of9, 9'-spirofluorene; (2) 2-bromo-9-fluorenone and 2, 7-dibromo-9-fluorenone were obtained ina two-step reaction from oxditive bromination of fluorene followed by the treatment ofK₂Cr₂O₇ in formation of fluorenone, then were used as the material in the preparation of2obromo-9, 9'-spirofluorene and 2, 7-dibromo-9, 9'-spirofluorene.It was found that 2, 2', 7, 7'-tetrabromo-9, 9'-spirofluorene was prepared byoxybromination of 9, 9'ospirofluorene with the H₂O₂/NaBr/H₂SO₄ system in high selectivity. The effects of ratios of reactants, reaction time, reaction temperature, and different solventson the oxybromination reaction were investigated thoroughly. The optimal reactive conditionswere obtained on the basis of above investigation, conversion of crude was 100%, selectivityof TBSBF could reach 95.1%.It was found that 2, 7-dibromofluorene was synthesized by oxybromination of fluorenewith the H₂O₂/NaBr/H₂SO₄ system in high selectivity. The effects of ratios of reactants,reaction time, reaction temperature, and different solvents on the oxybromination reactionwere investigated, and the optimal reactive conditions were obtained, conversion of crude was100%, selectivity of 2, 7-dibromofluorene could reach 99%. It was also founded that2-bromofluorene could be obtained by oxybromination of fluorene in a specifically ratios ofreactants, and other reaction conditions were examined, the optimal reactive conditions wereobtained, conversion of crude was 82.0%, selectivity of 2-dibromofluorene could reach94.3%.