Efficient Microwave‐Assisted Synthesis of 9,9‐Bis[4‐(2‐hydroxyethoxy)phenyl]fluorene from 9‐Fluorenone and 2‐Phenoxyethanol

Abstract

9‐Fluorenone (1) smoothly reacts with phenoxyethanol (2) in the presence of Al³⁺‐montmorillonite catalyst and 3‐mercaptopropionic acid as a cocatalyst under microwave irradiation at 160°C for 10 min to give 9,9‐bis[4‐(2‐hydroxyethoxy)phenyl]fluorene (3) in 81% yield, which was much higher than the yield of 33% obtained by conventional heating using an oil bath. A similar acceleration effect of microwave irradiation was observed in other metal‐cation‐exchanged montmorillonite catalysts as well.

Keywords:

• fluorene
• microwave
• montmorillonite

Acknowledgment

This research was partially supported by the New Energy and Industrial Technology Development Organization (NEDO), Project of Development of Microspace and Nanospace Reaction Environment Technology for Functional Materials. We are grateful to Hiroko Kobashi for measurements of complex dielectric constants of alcoholic compounds and to Norifumi Kobayashi and Yoshiaki Ayuta (University of Tsukuba) for analyses of surface areas of Na⁺‐ and Al³⁺‐montmorillonites. A kind gift of Kunipia F by Kunimine Industries Co., Ltd., is also acknowledged.