Application of fluorene two-step synthesis of 9-fluorenylmethanol in extraction and separation of phenanthrene from anthracene residue

Anthracene residue is a typical industrial organic solid waste,which is mainly rich in phenanthrene and fluorene.As important chemical intermediates,phenathrene and fluorene are widely used in photoelectric materials,medicine,pesticides and other fields.Due to their similar properties,it is difficult to achieve effective extraction by conventional separation methods.The reaction-separation coupling technology was adopted,according to the solubility difference of phenanthrene and the intermediate product,9-formylfluorene of fluorene converting to 9-fluorenylmethanol by two-step method,the extraction of phenanthrene and the co-production of 9-fluorenylmethanol with high value-added were realized.The two-step method for the synthesis of 9-fluorenylmethanol with fluorene as raw material was adopted under alkali catalysis.Firstly the fluorene was acylated into 9-formylfluorene,and then reduced to 9-fluorenylmethanol.The effects of the type of acylation reagent,reducor,and auxiliary,and other factors such as reactant ratio,temperature and time on the conversion of fluorene were investigated.Results show that fluorene can be efficiently converted into 9-formylfluorene in di-methyl sulfoxide (DMSO),with 20% ethanolic sodium ethoxide as catalyst,and with ethyl formate as the acylation reagent under 50oC.Adding inorganic salt auxiliaries,barium chloride or calcium chloride,before sodium borohydride,the reduction selectivity of 9-fluorenylmethanol can be improved by inhibiting the formation of by-products,the selectivity and recovery yield of 9-fluorenylmethanol is up to 100% and 98.14%,respectively.Other components,phenanthrene,anthracene and carbazole do not participate in the reaction of fluorene,and phenanthrene can be separated during the reaction.With the mixture of fluorene and phenanthrene as the raw material,the purity of the obtained phenanthrene is 96.90%,and the yield is 98.95%.The purity and the recovery yield of 9-fluorenylmethanol can reach up to 97.68% and 91.58%,respectively.However,when anthracene residue as the raw material,the purity of phenanthrene and 9-fluorenylmethanol decline to 83.88% and 94.35%,due to the other components of anthracene residue enriched during the pretreatment process,and the recovery yield was 64.46% and 89.49%,respectively.