Application of Hydroxymethylation of Fluorene by One-step Method to 9-Fluorenylmethanol in Extraction and Separation of Phenanthrene from Anthracene Residue

Abstract

It is difficult to separate fluorene and phenanthene by conventional separation method owing to their similar properties. The reaction-separation coupling technique was adopted to solve the problem, in which fluorene is first converted into 9-fluorenylmethanol. The factors affecting the yield and selectivity of 9-fluorenylmethanol by one-step synthesis with potassium carbonate as catalyst were investigated for the separation of phenanthrene from anthracene residue further. The results showed that with DMSO+10% ethanol as solvent, n(fluorene)∶n(formaldehyde)∶n(potassium carbonate)=1∶1∶0.2, and reaction at 13 ℃ for 15 min, the yield of 9-fluorenemethanol is about 25% and the selectivity is higher than 84%. Ethanol can inhibit the formation of 9-fluorenyl anion, and the inorganic salt affects the mass transfer and slows down the dehydration reaction. Using the mixture of fluorene and phenanthrene with mass ratio of 1∶4 as raw material, the yield and purity of phenanthrene reaches 97.6% and 93.2% after five reaction-separation cycles, respectively; the total yield of 9-fluorenylmethanol is 66.5%, and the average purity is 95.0%.

Keywords

• reaction-separation coupling technique
• 9-fluorenylmethanol
• carbonate
• ethanol
• inorganic salt