Differential scanning calorimetric study on the Claisen rearrangement and thermal polymerisation of diallyl ether of bisphenols

摘要

The diallyl ethers of bisphenol A (APP), 4,4'-dihydroxy biphenyl (ABP) and bisphenol sulfone (ABS) were synthesised and the kinetics of their thermal rearrangement to the diallyl bisphenols were studied by DSC. The ethers manifested two distinct exotherms corresponding to the Claisen rearrangement of the ether and thermal polymerisation of the rearranged product. The kinetics of both reactions as estimated by the Kissinger and Ozawa methods showed that the rearrangement is disfavoured by the electron-withdrawing substituent and favoured by electron-releasing groups at the para position of the allyloxy group. The rate constants calculated from the activation parameters showed the structural dependency. Thus, the rearrangement was facilitated in the order ABP>APP>ABS. The polymerisation kinetics revealed that the polymerisability of the allyl phenols due to the presence of substituent groups on the phenyl ring that can stabilise the free radical formed by way of degnerative transfer at the allylic position. Thus, the polymerisation tendency increased in the order APP>ABP>ABS. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 17]