Differential scanning calorimetric study on the Claisen rearrangement and thermal polymerisation of diallyl ether of bisphenols C.P. Reghunadhan Nair * , K. Krishnan, K.N. Ninan Propellant and Special Chemicals Group, Vikram Sarabhai Space Centre, Trivandrum-695 022, India Received 13 January 2000; received in revised form 21 March 2000; accepted 21 March 2000 Abstract The diallyl ethers of bisphenol A (APP), 4,4 0 -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 decreased due to the presence of substituent groups on the phenyl ring that can stabilise the free radical formed by way of degenerative transfer at the allylic position. Thus, the polymerisation tendency increased in the order APP>ABP>ABS. # 2000 Elsevier Science B.V. All rights reserved. Keywords: Diallyl bisphenols; Claisen rearrangement; Thermal polymerisation; DSC kinetics 1. Introduction Diallyl bisphenols are important precursors for many thermoset polymer formulations. They are known to react with maleimides, particularly bisma- leimides to form tough network polymers with good mechanical properties and thermo mechanical pro®le [1,15]. In some cases, the phenolic groups are trans- formed to other reactive groups such as cyanates, serving as network interlinkers in cyanate ester-bis- maleimide linked interpenetrating polymers [2]. Com- mercial polymer formulations such as Matrimide contain diallyl bisphenol A as an important compo- nent in blends with bismaleimides [3]. Maleimide reacts with allyl phenols through an Alder-ene reac- tion also known as Wagner-Jauregg reaction [4,5]. The o,o 0 -diallyl phenols are formed by the thermal, Claisen rearrangement of the corresponding bisallyloxy ethers. The rearrangement is done at carefully con- trolled temperature conditions to achieve full conver- sion without risking the polymerisation of the rearranged product. An understanding of the kinetics of the rearrangement would lead to a better control of the conditions for achieving high yield and purity. The Claisen rearrangement of allyl ethers have been stu- died very early [6,7]. The reaction has been reported to conform to ®rst order kinetics and is generally unca- Thermochimica Acta 359 (2000) 61±67 * Corresponding author. Tel.: 91-471-56-4775; fax: 91-471-46-1795. 0040-6031/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII:S0040-6031(00)00504-9