LAUSR

This article indicated a novel methodology of evaluation of steric effect of (hydroquinone (HQ), tertButyl hydroquinone (TBHQ) and 2, 5-ditert-butyl hydroquinone (DTBHQ)) by using a BriggsRauscher chemical oscillating system. The macro cyclic [NiL](ClO4)2 complex catalyst with 5,7,7,12,14,14-hexamethyl-1,4,8,1,1-tetraazacyclotetradeca-4,1,1-diene as ligand is used. The calculated experimental data confirmed the diverse perturbation effects of all three additives towards the active Briggs-Rauscher oscillator in their concentration ranges from 5.0 × 10 -7 M to 1.25 × 10 -5 M. Hydroquinone generate inhibition time (tin) higher than t-BHQ, whereas, no influence of 2,5-DBHQ were observed in Briggs-Rauscher system. Our claim for such differences in perturbation is due to the strong steric hindrance effect of these additives. The presence of bulky group (tertiary butyl) reduces the reactivity of the antioxidants by covering the active sides (OH-group) from the attack of HOO ●