SYNTHESIS OF [(TRIALKOXYSILYL)PROPYL]IMIDES

Imidization reactions between anhydrides and (alkoxysilyl)propylamines containing alkoxysilane groups result in hydrolysis and condensation of the,alkoxysilane groups and formation of SiOSi bonds. As a result, the direct reaction of various anhydrides with (gamma-aminopropyl)tria lkoxysilanes did not afford [(trialkoxysilyl)propyl]imides but instead resulted in insoluble crosslinked materials. A successful two-step sy nthesis of [(trialkoxysilyl)propyl] imides is reported. In the first s tep, an intermediate imide was prepared by reaction of an anhydride wi th 2-aminopyridine. Following removal of the water of imidization, add ition of an (gamma-aminopropyl)trialkoxysilane resulted in a transimid ization equilibrium which favored displacement of 2-aminopyridine and formation of a [(trialkoxysilyl)propyl]imide in high yield. Synthesis of a moisture-curable polyimide containing alkoxysilane endcaps is bri efly described.