Synthesis of some oxime ether compounds, experimental and theoretical investigation of their structural, spectroscopic and physicochemical properties

In this study, three oxime ether compounds, 1-phenyl-ethanone-O-propyl-oxime, 1- (4-bromo-phenyl)-ethanone-O -propyl-oxime and 1-naphthalen-2-yl-ethanone O-propyl-oxime have been synthesized from reacting of acetophenone, bromoacetophenone and 2-acetonaphthalene molecules with hydroxylamine hydrochloride and chloropropane. Structures of synthesized molecules have been revealable by IR and NMR spectroscopy techniques. The most important evidence the synthesis of molecules is the loss of carbonyl stretching vibration observed in ketone molecules around 1700 cm-1 in the oxime ether compounds and the formation of imine (C=N) band in the 1660-1600 cm-1 range. Furthermore, the oxime hydrogens observed in the NMR spectra confirm the formation of molecules observed in the NMR spectra of oxime ether compounds. Molecules synthesized and proposed molecular structures have been modeled by using Gaussian 09 package program and Density Functional Theory (DFT)/B3LYP method. The basis set screening has been performed by selecting 4- [2-5 (-ethyl-pyridine-2-propyl) ethoxy] benzaldehyde oxime molecule from literature which is suitable for the structure of the three molecules we synthesized and are available experimental bond lengths. The optimizations have been performed starting the smallest basis set 3-21G and then respectively 6-31G, 6-31G(d,p), 6-31G++(d,p), 6-311G, 6-311G(d,p), 6-311G++(d,p) and 6-311G++(2d,p) basis sets. The selected bond lengths are tabled, the basis set giving the closest results to the experimental values has been determined as 6-311++G(d,p). This basis set has been used in all subsequent theoretical studies. The most stable molecular structures were determined from conformation analysis of three molecules and drawn energy diagrams. The molecular properties such as bond length, bond angle and dihedral angles have been determined the spectroscopic properties such as IR, NMR and UV-Vis. have been examined as theoretically and compared with the experimental values. Some physicochemical properties of molecules, atomic charges, HOMO-LUMO molecule orbitals and their energies, chemical parameters such as chemical potential, softness, chemical hardness and electrophilic index, potential energy graphs and thermodynamic properties, enthalpy, heat capacity and entropy values were investigated as theoretically. All results observed experimentally and calculated theoretically are compatible with the literature and have been presented to the literature. The results are thought to be useful for researchers working on such molecules.