A new series of novel pyrazoline compounds were synthesized by addition of thiosemicarbazide to the 2,6-dibenzylidenecyclohexanone (Chalcone) and its para substituted derivatives. This study was conducted for four purposes. Firstly, a series of five membered ring pyrazoline compounds were synthesized and the structure of all new products obtained are supported by spectral data (1H-NMR, 13CNMR, IR and UV-Vis.), and the effect of substituents were studied. Secondly, the reaction kinetics of the new synthesized compounds were studied to investigate the reaction mechanism pathway and order of the reaction; it was found that, the reaction undergoes via Claisen route of mechanism with first-order reaction. Thirdly, the thermodynamics of the reaction were studied, the rate of the reaction, Arrhenius parameters (A), and thermodynamic parameters for activation includes (free energies (Ea), entropies (ΔS#), and Gibbs free energy (ΔG#) were estimated. Finally, the compensation effect was also studied, and found the same pathway for all of the synthesized pyrazoline compounds.

The dissociation constant is a quantitative measure of the strength of an acid in solution. This study examines dissociation constant for the series substituted acids like Ortho-alkoxy-4-formylbenzoic acid. The use of (2-methoxy ethanol) as a solvent contributed to the study expected to form free ions or solvent separated ion pair which has been studied with the use conductometric method at different temperatures ranged from 293.15 to 318.15K. The study aims at figuring out dissociation constant, equivalent conductance at infinity dilution, and Walden product by minimization technique using Fuoss-Hsia for both (Modified and Complete) equations. It has been found in the results that the calculated values based on statistical sum square (different between practical and theoretical values) is equivalent conductance at infinity dilution and dissociation constant. It has also been observed that increase the temperature leads to the increase of the molar conductance at infinity dilution, and the increase in association. Moreover, the substituted alkoxy group also affected dissociation of compounds. In this study, the thermodynamic parameters (Ho, Go and So) have also been evaluated and discussed. Finally, the effect of substituent groups on rate of dissociation was studied and explained with agreement to the principles of mesomeric(M) and Inductive effect(I) of substituent groups on dissociation constant.

The audio electrical conductances of aqueous solutions of magnesium, manganese II, barium, and copper succinates have been measured at various temperatures in the range of 298.15 K to 313.15 K, using an audio frequency conductance bridge. The evaluation of conductance data was carried out by minimisation technique using the theoretical equations of the complete and modified forms of Pitts (P) and Fuoss-Hsia (F-H), each a three-parameter equation, association constant (KA), molar conductance (Λm), and distance parameter (a). Quantitative results showed that these salts do not behave as “strong” electrolytes, and that their dissociations are far from complete. The abnormally low conductances of these electrolytes are not due to the presence of electrically neutral molecules but to the ion-pair formation. The Walden product values, as well as the standard thermodynamics functions (ΔH∘,ΔG∘,ΔS∘) for the association reaction at the four temperatures studied, have been evaluated.

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Abstract-Kinetics of the addition of thiourea to 2,6-dibenzylidenecyclohexanone and its derivatives have been studied. The reaction is found as a pseudo-first order process which includes a nucleophilic attack by thiourea at the carbonyl group of the ketone system to produce the heterocyclic pyrimidine thione "thiopyrimidine" (Claisen route mechanism). The effect of the substituents at the para position of the 2,6-dibenzylidenecyclohexanone and its derivatives on the rate of reaction, at different temperatures, is studied. Arrhenius parameters, entropies, enthalpies and free energies of activations are estimated. A suitable mechanism, which is correspondent with the results and with Claisen routes mechanism, is suggested for this reaction. IndexTerms-2,6-dibenzylidenecyclohexanone and its derivatives, mechanism route, kinetics study, thiourea, thiopyrimidine.