Nano-TiO₂: An Efficient and Reusable Heterogeneous Catalyst for Ring Opening of Epoxides Under Solvent-Free Conditions

Abstract

Nano-TiO₂ is an effective heterogeneous catalyst for the ring opening of epoxides with aromatic amines to afford β-amino alcohols in good to excellent yields at room temperature under solvent-free conditions. It was found that the catalyst is recyclable, and the activity of the catalyst was not weakened markedly even after several reaction cycles. In addition, the catalytic activity of TiO₂ strongly depends on particle size or surface area.

GRAPHICAL ABSTRACT

Keywords:

• β-Amino alcohol
• epoxide
• heterogeneous catalyst
• nano-TiO₂
• solvent-free

ACKNOWLEDGMENTS

The work was supported in part by grants from NSFZJ (Y4080177, Y4090248, R4090137), NSFC for Distinguished Young Scholars (51025207), and ZJED Innovative Team for S. Huang.

Notes

^a Isolated yield.

^b The ratio of isomer 3a/4a is close to 94/6, which was determined by ¹H NMR.

^c Loading catalyst 5 mol%.

^d Loading catalyst 15 mol%.

^e TiO₂ was modified by hexadecyltrimethoxysilane.

^a Epoxides (2 mmol) were treated with aromatic amines (2 mmol) in the presence of 5–10 nm TiO₂ (10 mol %) at room temperature under solvent-free condition for 3 h.

^b Isolated yield.

^c The ratio of isomer 3/4 was determined by ¹H NMR or calculated after isolation.

^a Cyclohexene oxide (2 mmol) were treated with aniline (2 mmol) in the presence of metal oxides (10 mol%) at room temperature under solvent-free condition for 3 h.

^b Isolated yield.