Synthesis and Thermal Curing Parameters of a Novel Phenylquinoxaline Containing Both Terminal Ethynyl and Pendant Phenylethynyl Groups

摘要

The synthesis of 3,3'-bis(4-(3-ethynylphenoxy)phenyl)-7,7'-bis(phenyl-ethynyl)-2,2'- diphenyl-6,6'-biquinoxaline (I) was accomplished by reaction of 2,2'-bis(phenylethynyl)-5,5'-diaminobenzidine (II) and 4-(3-ethynylphenoxy) benzil. Thermal analysis of I indicated a softening temperature of 107 C, followed by an exotherm above 150 C corresponding to independent crosslinking reaction of the terminal acetylene groups and intramolecular cycloaddition (IMC) reaction of the 2,2'-bis(phenylethynyl)biphenyl moieties. In the course of the synthetic work, substantial improvements were made in the synthesis of II. The sample of I was cured at 200 C and the maximum partially cured transition temperature attained was 280 C. A sample of 3,3'-bis(4-(3-ethynyl-phenoxy)phenyl)-2,2'-diphenyl-6,6'-biquinoxaline was similarly tested as a model without IMC capability, and its corresponding value was 250 C. The difference in these two values is briefly discussed. (Author)