Chem. J. Chinese Universities ›› 2023, Vol. 44 ›› Issue (6): 20220701.doi: 10.7503/cjcu20220701

• Organic Chemistry • Previous Articles     Next Articles

Influencing Factors and Mechanism of Dehydration Product Formation During Hydroxylmethylation of Fluorene to 9-Fluorenylmethanol

LIU Junli1,2, YE Cuiping1,2(), GUO Meixin1, LI Wenying3   

  1. 1.College of Environmental Science and Engineering,Taiyuan University of Technology,Jinzhong 030600,China
    2.Shanxi?Zheda Institute of Advanced Materials and Chemical Engineering,Taiyuan 030000,China
    3.State Key;Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology,Taiyuan 030024,China
  • Received:2022-11-05 Online:2023-06-10 Published:2023-02-09
  • Contact: YE Cuiping E-mail:yecuiping@tyut.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21776192);the Research and Development Project of Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, China(2021SX-FR003)

Abstract:

During one-step synthesis process of 9-fluorenylmethanol with paraformaldehyde as hydroxymethylation reagent, 9-fluorenylmethanol is easy to undergo base-catalyzed β-elimination(E1cb) to yield dibenzofulvene, and the selectivity of 9-fluorenylmethanol decreased. To achieve the process of regulation and control, the factors affecting the dehydration of 9-fluorenylmethanol, such as temperature, the types of alkali and ethanol and paraformaldehyde were investigated. The mechanism of by-product formation in the process of hydroxymethylation of fluorene to form 9-fluorenylmethanol was speculated according to the experimental results, kinetic calculation and isotope tracing. The results showed that increasing the temperature and alkalinity, and adding formaldehyde promoted the dehydration reaction. Ethanol promotes dehydration reaction through hydrogen bonding, and a large amount of ethanol would lead to the internal protonation of fluorenyl anion and 9-fluorenylmethanol anion. The intermediate may have the behavior of intramolecular hydrogen transfer or intermolecular hydrogen capture from fluorene and 9-fluorenylmethanol, facilitating dehydration reactions.

Key words: Dehydration reaction, Isotope tracing, Intramolecular hydrogen transfer, Intermolecular hydrogen capture

CLC Number: 

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