TiO₂ nanotubes catalyzed the synthesis of azo-linked xanthenes under ultrasonic conditions

ABSTRACT

A series of new azo-linked xanthene derivatives was synthesized via the eco-friendly multi-component condensation of azo-linked salicylaldehyde derivatives and dimedone under ultrasound irradiation as green energy source in the presence of TiO₂ nanotubes (TNTs) as suitable heterogeneous catalyst. TNTs have moderate surface areas (S_BET = 238 m².g⁻¹) and high physiochemical stability ( > 250°C). The yield of 74–87% was achieved within 10 min at room temperature. The current method has advantages such as the simple experimental procedure, green conditions, utilization of reusable TiO₂ nanotubes catalyst, and good to excellent yield of products.

KEYWORDS:

• Azo-linked xanthene
• TiO₂ nanotube
• recyclable catalyst
• eco-friendly method
• multi-component condensation

Funding

We are grateful to Research House of Professor Reza, Education of Guilan for the partial support of this work.