Tetrahydrophthalic anhydrides as addition curing polyimide end caps: Thermal isomerization of methylendianiline 3,6-diphenyltetrahydrophthalic bisimides

The thermal isomerization of methylendianiline 3,6- diphenyltetrahydrophthalic bisimides was analyzed. The solution NMR spectra were obtained on a Bruker DMX-600 spectometer in CDCl ₃ with TMS as the internal standard. The pure product was obtained via column chromatography eluting with a 1:1 ethyl acetate/n-hexane solution. It was suggested that since the coupling constants between the bridgehead H-1,2 and the olefinic H-4,5 were expected to be small, the H-1,2 can be analyzed.