The microwave spectrum of 2-methylthiophene was recorded in a frequency range from 2 to 26.5 GHz using a molecular-jet Fourier transform microwave spectrometer with a Fabry–Pérot type resonator chamber and coaxial arrangement of the resonator and the molecular beam. Measuring and assigning spectra of the ³⁴S and ¹³C isotopologues allowed the determination of the semiexperimental equilibrium structure ($r_{\mathrm{e}}^{\mathrm{SE}}$). Comparing the structure to that of thiophene revealed a decrease in the ∠(S−C2−C3) angle from 111.595(6)° to 111.37(1)° by addition of the methyl group to the C(2) position, as well as an increase in the S−C2 bond length from 1.7102(1) Å to 1.7219(2) Å. A–E splittings from internal rotation of the methyl group were observed, and the V₃ potential in the vibrational ground state was determined to be 197.7324(18) cm⁻¹. The V₃ value and the rotational constants A, B, C were calculated with a large number of different methods and basis sets for benchmarking purposes by comparing them to the fitted parameters. The V₃ value was also compared to those of other thiophene and furan derivatives to gain a better understanding of the steric and electrostatic effects in these classes of compounds.

The present paper focuses on a hybrid system combining electrochemical oxidation (EO) and activated carbon (AC) adsorption in a concept known as three-dimensional (3D) electrocatalytic technology for the treatment of oxytetracycline from aqueous solution; the conventional one-factor-at-a-time variation approach (AC dosage, OTC concentration, and current density) was used for determining the effects of operating parameters on the 3D electrochemical process and optimized via fuzzy logic modeling. The process’s superior performance was assessed based on comparative studies of the degradation efficiency of the 3D electrochemical process with AC adsorption and conventional 2D electrochemical process. The study showed that the AC particle electrode enhanced the performance of the 3D system by up to 21% in terms of OTC degradation efficiency compared to both adsorption and the conventional two-dimensional (2D) electrochemical system. When 2D and 3D processes were compared in required energy and electricity budgets, 3D electrode process with 0.75 g/L activated carbon requires 27.60 kWh/m³ and it perceived 2 times lower than 2D process; accordingly, the electricity budget is €5.38 and €2.81 for electrooxidation and 3D electrode process, respectively. The obtained results suggest that under the electric field, polarized AC worked as both adsorbent and a catalyst in the 3D electrochemical system, enhancing subsequently the decomposition of electro-generated H₂O₂ to more hydroxyl radicals (·OH) and promote the capacity of OTC mineralization.

The microwave spectra of benzothiazole were measured in the frequency range 2–26.5 GHz using a pulsed molecular jet Fourier transform microwave spectrometer. Hyperfine splittings arising from the quadrupole coupling of the ¹⁴N nucleus were fully resolved and analyzed simultaneously with the rotational frequencies. In total, 194 and 92 hyperfine components of the main species and the ³⁴S isotopologue, respectively, were measured and fitted to measurement accuracy using a semi-rigid rotor model supplemented by a Hamiltonian accounting for the ¹⁴N nuclear quadrupole coupling effect. Highly accurate rotational constants, centrifugal distortion constants, and ¹⁴N nuclear quadrupole coupling constants were deduced. A large number of method and basis set combinations were used to optimize the molecular geometry of benzothiazole, and the calculated rotational constants were compared with the experimentally determined constants in the course of a benchmarking effort. The similar value of the χ_cc quadrupole coupling constant when compared to other thiazole derivatives indicates only very small changes of the electronic environment at the nitrogen nucleus in these compounds. The small negative inertial defect of −0.056 uŲ hints that low-frequency out-of-plane vibrations are present in benzothiazole, similar to the observation for some other planar aromatic molecules.

The regioselectivity of the reaction between phenyldiazen-1-ium-1-ylidene p-tolyl methanide and ethyl 4-benzoyl-4H-benzo [1,4]oxazine-2-carboxylate were studied by means of the DFT/B3LYP method coupled by the 6-31g(d) basis and MP2 in connection with 6-31G(d) and 6-31G+(d,p) basis set. The mechanism of this regioselectif reaction has performed by transition state optimization, evaluation of the potential energy surface, calculation of IRC and reactivity indices. Location and verification of minima and transition structures have been realized by using the Berny's algorithm. The process of formation of the two regioisomers is achieved through concerted and asynchronous mechanism. The results are in good agreement with the experimental data.

Quantum chemical calculations were performed on amitrole used as herbicide in agriculture to investigate its interaction with humic substances which are the main components of soil organic matter. They contain carboxylic, phenolic, amine and quinonic groups as well as specific structural configurations. Global and local reactivity have been studied to predict reactive centers and to determine the favorable site for interaction with surface. The results suggest us that hydrogen bonds are formed between this compound and the amino acids of soil organic matter. The effect of water as solvent is considered since adsorption of pesticide commonly occurs in aqueous environment.