Synthesis of 4-(4-ethyl-phenyl)-3-(4-methyl-phenyl)-1,2,4-oxadiazol-5(4H)-one and 4-(4-ethyl-phenyl)-3-(4-methyl-phenyl)-1,2,4-oxadiazole-5(4H)-thione and solvent effects on their infrared spectra in organic solvents.

In the present study novel 4-(4-ethyl-phenyl)-3-(4-methyl-phenyl)-1,2,4-oxadiazol-5(4H)-one (compound (4)) and 4-(4-ethyl-phenyl)-3-(4-methyl-phenyl)-1,2,4-oxadiazole-5(4H)-thione (compound (5)) were synthesized. These oxadiazole ring derivatives were characterized by IR, 1H NMR, 13C NMR and HRMS analyses. The solvent effects on CO, CN and CS stretching vibrational frequencies (ν(CO), ν(CN) and ν(CS)) of synthesized compounds were investigated experimentally using attenuated total reflection (ATR) infrared spectroscopy and compared with the theoretical results assigned using the potential energy distribution (PED) contributions. Furthermore, the ν(CO), ν(CN) and ν(CS) of compound (4) and compound (5) were correlated with empirical solvent parameters such as the solvent acceptor numbers, the Swain equation, the Kirkwood-Bauer-Magat equation, and the linear solvation energy relationships. Apart from the linear effects investigated in similar studies, solvent-induced vibrational shifts were investigated using the quadratic equation. The prediction capabilities of empirical solvent parameters were statistically compared. It was found that the linear solvation energy relationships show better correlation than the other empirical solvent parameters. Additionally, the quadratic equation provided more accurate predictions for the vibrational frequency locations than the Swain and the linear solvation energy relationships equations.

Substituent effect study on experimental ¹³C NMR chemical shifts of (3-(substituted phenyl)-cis-4,5-dihydroisoxazole-4,5-diyl)bis(methylene)diacetate derivatives.

Eleven novel (3-(substituted phenyl)-cis-4,5-dihydroisoxazole-4,5-diyl)bis(methylene) diacetate derivatives were synthesized in the present study. These dihydroisoxazole derivatives were characterized by IR, (1)H NMR, (13)C NMR and elemental analyses. Their (13)C NMR spectra were measured in Deuterochloroform (CDCl3). The correlation analysis for the substituent-induced chemical shift (SCS) with Hammett substituent constant (σ), inductive substituent constant (σI), different of resonance substituent constants (σR, σR(o)) and Swain-Lupton substituent parameters (F, R) were performed using SSP (single substituent parameter), and DSP (dual substituent parameter) methods, as well as single and multiple regression analysis. From the result of regression analysis, the effect of substituent on the (13)C NMR chemical shifts was explained.

Experimental and theoretical investigations of 4-chloro-N-(2-methoxyphenyl)benzamidoxime.

4-Chloro-N-(2-methoxyphenyl) benzamidoxime (CMB) has been synthesized and characterized by X-ray diffraction, (1)H NMR, (13)C NMR, FT-IR and FT-Raman spectra. The X-ray study showed that CMB has a Z configuration, due to the strong intramolecular N-H···O hydrogen bond and centrosymmetric dimer form due to intermolecular O-H···N' and O-H···O' hydrogen bonds. The 2-methoxyphenyl and 4-chlorophenyl rings are twisted from the mean plane of the hydroxyamidine group by 33.09 (1) and 44.89 (1)°, respectively. The optimized molecular structure and vibrational frequencies have been calculated with DFT (B3LYP) method by using a 6-311G(d,p) basis set. The (1)H and (13)C NMR chemical shifts were calculated by the gauge-including atomic orbital (GIAO) method with the B3LYP/6-311G (d,p) level. A comparison between experimental and calculated theoretical results indicate that the density functional B3LYP method provided satisfactory results for predicting IR, Raman, (1)H NMR and (13)C NMR spectra properties.