Preparation, GIAO NMR Calculations and Acidic Properties of Some Novel 4,5-dihydro-1H-1,2,4-triazol-5-one Derivatives with Their Antioxidant Activities

Abstract

Six novel 3-alkyl(aryl)-4-(p-nitrobenzoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (2a-f) were synthesized by the reactions of 3-alkyl(aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (1a-f) with p-nitrobenzoyl chloride and characterized by elemental analyses and IR, 1 H-NMR, 13 C-NMR and UV spectral data. The newly synthesized compounds 2 were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents such as acetone, isopropyl alcohol, tert-butyl alcohol and N,Ndimethylformamide, and the half-neutralization potential values and the corresponding pK a values were determined for all cases. Thus, the effects of solvents and molecular structure upon acidity were investigated. In addition, isotropic 1 H and 13 C nuclear magnetic shielding constants of compounds 2 were obtained by the gauge-including-atomic-orbital (GIAO) method at the B3LYP density functional level. The geometry of each compound has been optimized using the 6-311G basis set. Theoretical values were compared to the experimental data. Furthermore, these new compounds and five recently reported 3-alkyl-4-(2-furoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3a-c,e,f) were screened for their antioxidant activities.

Synthesis, Acidity and Antioxidant Properties of Some Novel 3,4-disubstituted-4,5-dihydro-1H-1,2,4-triazol-5-one Derivatives

“…1,2,4-Triazole and 4,5-dihydro-1 H -1,2,4-triazol-5-one derivatives are reported to possess a broad spectrum of biological activities such as antifungal, antimicrobial, hypoglycemic, antihypertensive, analgesic, antiparasitic, hypocholesteremic, antiviral, anti-inflammatory, antitumor, antioxidant and anti-HIV properties [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. In addition, several articles reporting the synthesis of some N -arylidenamino-4,5-dihydro-1 H -1,2,4-triazol-5-one derivatives have been published [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ].…”

“…In addition, several articles reporting the synthesis of some N -arylidenamino-4,5-dihydro-1 H -1,2,4-triazol-5-one derivatives have been published [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. The acylation of 4,5-dihydro-1 H -1,2,4-triazol-5-one derivatives has also been reported [ 3 , 5 , 9 , 10 , 11 , 12 , 17 ].…”

Contribution of minor compounds present in the peppermint (Mentha piperita) to the iron-catalyzed lipid oxidation of soybean oil-in-water emulsion

“…Although a-tocopherol at 20-60 lg/mL showed 58% inhibition of the Fe 2? -ferrozine complex formation (Gulcin et al, 2003), its radical scavenging activity is much higher (5 times) than that of iron-chelation (Yüksek et al, 2008), suggesting its possible fast degradation. a-Tocopherol showed higher radical and hydrogen peroxide scavenging activity than polyphenols derived from methanolic extract of Ichnocarpus frutescens in the lipid oxidation of rat brain homogenate (Kumarappan et al, 2012).…”

Experimental and theoretical investigations on the keto–enol tautomerism of 4-substituted 3-[1-methylpyrrol-2-yl)methyl]-4,5-dihydro-1H-1,2,4-triazol-5-one derivatives

“…pyrazolones [30], betaketonitriles [31], cyclohexanediones [32,33]. On the other hand, 1,2,4-triazol-5-one system, bearing different substituents, has been a subject of extensive experimental and computational studies which were aimed to determine structural and spectral properties of respective derivatives [34][35][36][37][38][39][40].…”