Quantum mechanistic insights on aryl propargyl ether Claisen rearrangement.

The mechanism of aryl propargyl ether Claisen rearrangement in gas and solvent phase was investigated using DFT methods. Solvent phase calculations are carried out using N,N-diethylaniline as a solvent in the PCM model. The most favorable pathways involve a [3,3]-sigmatropic reaction followed by proton transfer in the first two steps and then deprotonation or [1,5]-sigmatropic reaction.

Compatibility enhancement of polyimide-silica hybrid sol-gel materials without incorporation of silane-coupling agent.

A facile route has been developed to enhance compatibility between organic polyimide matrix and dispersed phase of inorganic silica particles without addition of conventional silane-coupling agent. The as-prepared hybrid sol-gel materials having reduced size of SiO2 particle dispersed in polyimide matrix were successfully synthesized through pre-catalyzed sol-gel route using an organic diamine base. The PI-silica hybrid materials through conventional polyamic acid-catalyzed sol-gel route with/without silane-coupling agent were also prepared for comparative control studies.