A Schiff-Base Modified Pt Nano-Catalyst for Highly Efficient Synthesis of Aromatic Azo Compounds

Yanyan Teng,Haomeng Li,Huilong Wang,Xiao Chen,Yuqing Shao,Qinggang Liu,Min Wang,Xinkui Wang,Changhai Liang

doi:10.3390/catal9040339

Yanyan Teng, Haomeng Li + Show 7 more

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https://doi.org/10.3390/catal9040339

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Abstract

A Schiff-base modified Pt nano-catalyst was prepared via one-pot aldimine condensation and then impregnation-reduction of a platinum precursor, in which the Pt nanoparticles (NPs) with an average size of 2.3 nm were highly dispersed on the support. The as-prepared catalyst exhibited excellent activity and selectivity in the hydrogenation coupling synthesis of aromatic azo compounds from nitroaromatic under mild conditions. The strong metal–support interaction derived from the coordination of nitrogen sites on Schiff-base to Pt NPs enables stabilizing the Pt NPs and achieving the catalytic recyclability. The scheme can also tolerate various functional groups and offer an efficient method for the green synthesis of aromatic azo compounds.

Highlights

Aromatic azo compounds (Aazo) are important raw materials, which are widely used in the fields of pigments [1,2,3], radical reaction initiators [4,5,6], food additives [7,8], electronic devices [9,10,11,12], and drugs [13,14,15,16]
For the Pt0.5 /SiO2 -Shiff catalyst, additional the fresh Pt0.5/SiO2-Shiff catalyst (Figure 1c), indicating Pt NPs with small particles are highly bands at 2869 and 2927 cm−1 can be assigned to the symmetric and asymmetric vibrations of the dispersed on the support
The unsubstituted when i-propanol is used as a solvent and the reaction temperature is raised to up to 86.1% when i-propanol is used as a solvent and the reaction temperature is raised to 90 °C

Summary

Introduction

Aromatic azo compounds (Aazo) are important raw materials, which are widely used in the fields of pigments [1,2,3], radical reaction initiators [4,5,6], food additives [7,8], electronic devices [9,10,11,12], and drugs [13,14,15,16]. Other methods, including the oxidation of anilines by transition metals, the reduction of nitroaromatics by stoichiometric amounts of metals, and the rearrangement of aromatic azoxy compounds, have been developed for the synthesis of Aazo [20,21,22,23,24,25]. These conventional procedures generally require harsh reaction conditions or a long reaction time.

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