Synthesis Of 9-fluorenylmethanol And 9,9-bis(Hydroxymethyl) Fluorene From Fluorene Of Anthracene Residue

Anthracene residue is a kind of industrial organic solid waste.It is the remains after extracting anthracene and carbazole from I anthracene oil/crude anthracene from high-temperature coal tar.It is rich in high value-added components such as fluorene and phenanthrene,which are important chemical intermediates,and they are widely used in the fields of biology,medicine,materials and pesticides.Due to the similar physical properties of fluorene and phenanthrene,and the further enrichment of other components in the anthracene residue,it is difficult to achieve effective separation of them using conventional separation methods.In order to alleviate the pressure of solid waste stacking,a large amount of anthracene residue is used as a cheap fuel,which causes a serious waste of resources.The downstream products of fluorene,9-fluorenylmethanol and 9,9-bis（hydroxymethyl）fluorene are both of important chemical raw materials.This research adopts reaction–separation coupling technology to convert the fluorene of the anthracene residue into9-fluorenylmethanol and 9,9-bis（hydroxymethyl）fluorene,taking advantage of the difference in solubility with phenanthrene.The extraction and separation of phenanthrene from anthracene residue can be achieved during the reaction or after the reaction,and the high value-addeddownstreamproductsof9-fluorenylmethanoland9,9-bis（hydroxymethyl）fluorene can be co-produced.At present,the process of synthesizing9-fluorenylmethanol and 9,9-bis（hydroxymethyl）fluorene with fluorene as the raw material is complicated with low yield.Therefore,the highly efficient synthesis of them is the focus and the difficulty of this research.The research of this subject provides new ideas for the reduction and recycling of industrial organic solid wastes such as anthracene residues.The main content and results of the paper are as follows:（1）Synthesis of 9-fluorenylmethanol from fluorene by two-step methodThe acylation stage uses fluorene as the raw material,dimethyl sulfoxide（DMSO）as the solvent,sodium ethoxide–ethanol solution（Et ONa–Et OH）as the catalyst,and a one-stage temperature reaction is adopted.The experiment investigated the effects of the amount of ethyl formate and n-butyl formate as acylating reagents,reaction temperature and time on the synthesis of 9-formylfluorene.When n（fluorene）:n（Et ONa–Et OH）:n（ethyl formate）=1:1.8:1.4,the reaction lasts for 70 minutes at 50 ^oC,and all fluorene can be converted into 9-formylfluorene.When high-boiling n-butyl formate is used,it can increase the reaction temperature and shorten the acylation reaction time.When n（fluorene）:n（Et ONa–Et OH）:n（n-butyl formate）=1:1.8:1.6,fluorene can be completely converted at 70^oC for 40 min.When the temperature exceeds 75 ^oC,yellow-green viscous by-products will be formed.NaBH₄ was used as the reducing agent,the dosage of reducing agent and the influence of inorganic salt additives Na Cl,Zn Cl₂,Ca Cl₂,Ba Cl₂,Ca（NO₃）₂ and Ca CO₃ on the reduction process was investigated.The results show that When n（fluorene）:n（NaBH₄）=1:1.2,the reaction time is shortened from 6 h to 3 h.At the same time,the yield of 9-fluorenylmethanol increased from 49.87%to 92.26%.The effect of Na Cl additives is not obvious,Ba Cl₂/Ca Cl₂/Ca（NO₃）₂ has a significant promotion,and Ca CO₃ has no effect.Using the NaBH₄–inorganic salt composite system as the reducing agent,the addition of soluble inorganic salt further improves the reducing ability of NaBH₄ and the selectivity of the product.When n（fluorene）:n（NaBH₄）:n（Ca Cl₂）=1:1.2:1.5,9-formylfluorene can be completely reduced after 1.5 hours at 25 ^oC,and the selectivity of 9-fluorenylmethanol is close to 100%.（2）Synthesis of 9-fluorenylmethanol from fluorene by two-step method and its separation from phenanthreneThe model compounds and pretreated anthracene residue were used as raw materials for reaction.The mass balance results showed that the other components,phenanthrene,anthracene and carbazole,did not participate in the reaction of fluorene.After the formylation reaction is finished by adding water,most of the phenanthrene can be precipitated.Taking the model compounds of fluorene and phenanthrene as the raw material,the purity of phenanthrene is 96.90%,and the yield is 98.95%;the purity of 9-fluorenylmethanol is97.68%,and the highest yield is 91.58%.Taking anthracene residue as raw material,due to the accumulation of other components in the pretreatment process,the purity of the final phenanthrene and 9-fluorenylmethanol are 83.88%and 94.35%,and the yields are 64.46%and 89.49%,respectively.（3）Synthesis of 9-fluorenylmethanol from fluorene by one-step methodWith fluorene as raw materials,aqueous formaldehyde solution and paraformaldehyde as hydroxymethylation reagents,and reacts in a mixed solvent of DMSO–Et OH at 13 ^oC.When n（fluorene）:n（alkali）:n（CH₂O）=1:0.2:1.0,the experiment investigated the effect of basic catalysts K₂CO₃,Na₂CO₃,KHCO₃,Na HCO₃ and K₂CO₃/γ-Al₂O₃,reaction time and feeding sequence on the synthesis of 9-fluorenylmethanol.As the conversion of fluorene increased,the selectivity of 9-fluorenylmethanol decreased.When the conversion of fluorene is lower than 16.39%,the selectivity of 9-fluorenylmethanol is 100%.The reaction time increased as follows:K₂CO₃（15 min）<Na₂CO₃（60 min）<KHCO₃（90 min）<Na HCO₃（180min）.Using fractional crystallization,after finishing the reaction with water,the primary precipitate is mainly fluorene,and the secondary precipitate is mainly the target product9-fluorenylmethanol.The purity is higher than 94.00%for both.（4）Synthesis of 9,9-bis（hydroxymethyl）fluorene from fluorene by one-step methodUsing fluorene as raw material,the effects of solvent type,alkali type and dosage,formaldehyde dosage and reaction time were investigated.Using DMSO–Et OH as solvent,and paraformaldehyde as hydroxymethylation reagent,Et ONa–Et OH as the catalyst,when n（fluorene）:n（K₂CO₃）:n（CH₂O）=1:0.2:2.2.5 is adopted,the selectivity of9,9-bis（hydroxymethyl）fluorene was 74.80%for 3 min.The product was not detected with triethylamine（TEA）,and KOH was beneficial to the formation of 9-methylenefluorene,the selectivity is 80.12%.The conversion of fluorene is 100%,and the selectivity of9,9-bis（hydroxymethyl）fluorene is 84.24%,by using K₂CO₃ as catalyst,when n（fluorene）:n（K₂CO₃）:n（CH₂O）=1:0.2:2.2 is adopted at 13 ^oC for 90 min.（5）Fluorene is separated from phenanthrene by one-step hydroxymethylationThe model mixed compounds of fluorene and phenatharene were used as raw material,and reacted under the same conditions as the synthesis of 9-fluorenylmethanol and9,9-bis（hydroxymethyl）fluorene,respectively.When the target product is9-fluorenylmethanol,the separated products include the mixture containing phenanthrene and unreacted fluorene,and the 9-fluorenylmethanol with the purity and yield of 98.04%and13.03%,respectively.When 9,9-bis（hydroxymethyl）fluorene is the target product,we obtained 9,9-bis（hydroxymethyl）fluorene with the purity of 87.26%and the yield of 73.87%,and phenanthrene with the the purity and yield of 97.18%and 98.96%,respectively.