Synthesis, spectral and thermal study of (2E, 6E) 2,6-bis(4-hydroxy benzylidene)-4-R-cyclohexanone

ABSTRACT

(2E,6E) 2,6-Bis(4-hydroxybenzalidene)-4-R-cyclohexanone (BHBC, R = H and MBHBC, R = CH₃) was synthesized by condensing cyclohexanone/4-methylcyclohexanone with 4-hydroxy benzaldehyde using mixture of boric acid and hydrochloric acid as a catalyst at 60-70 ºC for 1 h. The structures of BHBC and MBHBC are supported by FTIR, ¹HNMR, ¹³CNMR and MS techniques. DSC endothermic transition at 282.48 ºC (BHBC) and two endothermic transitions at 214.66 and 224.83 ºC and assigned as melting transitions. The compositions of the two isomers of MBHBC were determined from their corresponding peak areas and observed compositions are 81.5% and 18.5%, respectively for Isomer-I and Isomer-II. BHBC and MBHBC are thermally stable up to 305 ºC and 285 ºC, respectively and followed three step degradation kinetics. Both the compounds followed apparently first order degradation kinetics and were completely degraded into low molecular mass hydrocarbons.