A calixarene antioxidant C-undecylcalix[4]resorcinarene for endothermic hydrocarbon fuels

Abstract

The antioxidation performance of small molecule antioxidants in high temperature environments is often limited due to insufficient thermal stability. Thus, macromolecular calixarene compounds were developed as thermal stable antioxidants to overcome the shortcomings of conventional small molecular hindered phenol antioxidants. In this work, C-undecylcalix[4]resorcinarene (C11C[4]R), with hydrocarbon soluble alkyl chain and hindered phenol structure, was used as antioxidants for endothermic hydrocarbon fuels. Thermogravimetric analysis shows C11C[4]R has better thermal stability than 2,6-di-tert-butyl-4-methylphenol (BHT), the commercial small molecular antioxidant, which made it suitable for intensively thermal-stressed conditions. Further tests shows that the radical scavenging activity of C11C[4]R is significantly better than BHT with a larger capacity and higher capture rate. C11C[4]R also presents a satisfactory antioxidation inhibition improvement in view of the oxidative stability of the model fuels in accelerated oxidation experiments. In addition, computational works were also conducted, by which the results suggest an improved H atom donation ability also contributes to the excellent antioxidation performance of C11C[4]R.