The project work focuses on the organic reaction monitoring by DPPH on the synthesised eight compounds of two series having variable electronegative atoms X=O/S/NH which have been screened for CNS depression study by synergistic activity by standard drug. This project is a comparison between the SAR study with antioxidant potentiality by DPPH by using logP values with IC50 values with lambda max in UV.The logP value of 4-carboxamido phenyl thio urea (-0.31) is lesser than 2-carboxy phenyl thiourea (1.53), so the same property arises during potentiality of lmax in UV. The logP value of 4-carboxy phenyl thiourea (0.84) is greater than 2-carboxamido phenyl urea (0.47), so antioxidant potentiality of IC50 value for 2-carboxamido phenyl urea is -661.18 ppm which is more effective than 4-carboxy phenyl thiourea which is 43.79 ppm.