Synthesis, characterization and quantum chemical calculations of substituted 1,2,4-triazole derivatives

This thesis are planned in two main stages experimental and theoretical studies. Stage 1: Synthesis and characterization of structures to be studied in the thesis In this step, N-phenyl-2- (thiophene-2-carbonyl) hydrazine-1-carbothioamide and N-ethyl-2- (thiophene-2-carbonyl) hydrazine-1-carbothioamide were obtained by the reaction of thiophene-2-carbohydrazide with phenyl isothiocyanate and ethyl isothiocyanate respectively in the presence of ethyl alcohol. The obtained N-phenyl-2-(thiophene-2-carbonyl) hydrazine-1-carbothioamide and N-ethyl-2- (thiophene-2-carbonyl) hydrazine-1-carbothioamide was added base (KOH) to give the ring closure reaction. result of the ring closure reaction is obtained the 4-phenyl-5- (2-thiophene) -2,4-dihydro-3H-1,2,4-triazole-3-thione and 4-ethyl-5-(2-thiophene)-2,4-dihydro-3H-1,2,4-triazole-3-thione. The 4-phenyl-5- (2-thiophene) -2,4-dihydro-3H-1,2,4-triazole-3-thione compound obtained in the second step was converted to compound 1- (3-methyl-3-mesityl) -cyclobutyl-2 - {[5- (thiophen-2-yl) -4-phenyl-4H- 1,2,4-triazol-3- yl] sulfanyl}-ethanone by reaction with 2-chloro-1- (3-methyl-3-mesityl-cyclobutyl) -ethanone in dry acetone containing potassium carbonate. Also 4-ethyl-5-(2-thiophene)-2,4-dihydro-3H-1,2,4-triazole-3-thione which was prepared in a second step is reacted with four different coumarin compounds to obtain compounds containing coumarin, 3,4,5-trisubstituted 3,4,5-trisubstituted 1,2,4-triazole sulfonyl compounds. Organic compounds prepared by us have been experimentally characterized by spectroscopic methods such as FT-IR, 1H-NMR, and 13C-NMR after beıng purified by appropriate purification methods. Stage 2: Theoretical characterization of the substances to be synthesized in the thesis: In addition to the characterization studies of the experimentally obtained compounds, theoretical calculations were made at the cc-PVDZ basis set level by using the Gaussian 09W and GaussView 5.1 packages of molecules and the Density Functional Theory (DFT) method. As a result of the studies, it was seen that experimental and calculated values were in good agreement. The molecular electrostatic potential (MEP), charge distribution on the atoms, and thermodynamic parameters for all compounds were evaluated. Different parameters were calculated for all compounds using B3LYP/cc-Pvdz, those parameters are including energy of the highest occupied molecular orbital (EHOMO), energy of the lowest unoccupied molecular orbital (ELUMO), energy bandgap ( ΔE = ELUMO - EHOMO), dipole moment (μ), hardness (ɳ), softness (σ), electronegativity (χ), electrophilicity index (ω), nucleophilicity (ε) index and The fraction of transferred electrons (ΔN) which is related to transfer electron between the inhibitor and metal surface.