Theoretical Study On Nucleophilic Addition-Condensation Reaction Of Thiosemicarbazide With Aldehyde And Ketone

Thiourea derivatives have been playing important roles in biology, medicine,daily life,industrial and agricultural production because of their special functional structure.They have potential applications in various branches of chemistry and some marginal subjects.However,less theoretical researches have been carried on the reaction between thiourea derivatives and other substances,while thermodynamic parameters of the reactions are still faultiness.Quantum chemical methods can be applied to investigate molecular thermodynamics,spectroscopy and reaction kinetics.Recently,intense researches of quantum chemistry have been focused on the electronic structure,spectroscopic properties and thermodynamic properties of the reactants and products through addition -condensation reaction of thiourea derivatives with aldehydes and ketones,which may play important roles in theoretical researches and practical applications.The major research contents are as follows:(1) For reactants and products in nucleophilic addition-condensation reaction of vanillin with thiosemicarbazide,their geometry configurations were optimized by means of quantum chemistry DFT/B3LYP/6-31G. From the Mulliken atomic net charge of main elements,as well as E_HOMO and E_LUMO data of vanillin,it can be assumed that the compound has a higher activity of nucleophilic addition reaction.The thermodynamic properties of reactants and products were obtained via vibrational analyses for all optimal geometries.The changes of enthalpy and Gibbs free energy,and standard equilibrium constants were calculated.Then,by calculating the energies of electron transitions at excited states of molecule,the UV-Vis data of excited states were obtained.(2)For reactants and products in nucleophilic addition-condensation reaction of thiosemicarbazide with salicylaldehyde,their geometry configurations were optimized by means of quantum chemistry DFT/B3LYP/6-31G.From the Mulliken atomic net charge of main elements,as well as E_HOMO and E_LUMO data of salicylaldehyde,it can be assumed that the compound has a higher activity of nucleophilic addition reaction.The thermodynamic properties of reactants and products were obtained via vibrational analyses for all optimal geometries.The changes of enthalpy changes and Gibbs free energy,and standard equilibrium constants were calculated.Then,by calculating the energies of electron transitions at excited states of molecule,the UV-Vis data of excited states were obtained.(3) For reactants and products in nucleophilic addition-condensation reaction of thiosemicarbazide with 4-chlorochalcone,their geometry configurations were optimized by means of quantum chemistry DFT/B3LYP/6-31G.From the Mulliken atomic net charge of main elements,as well as E_HOMO and E_LUMO data of 4-chlorochalcone,it can be assumed that the compound has a higher activity of nucleophilic addition reaction.The thermodynamic properties of reactants and products were obtained via vibrational analyses for all optimal geometries. The changes of enthalpy changes and Gibbs free energy,and standard equilibrium constants were calculated.Then,by calculating the energies of electron transitions at excited states of molecule,the UV-Vis data of excited states were obtained.