Solvent Effects On 4-Acetylpyridine And 2-Acetylthiazole

Experimental and theoretical research of solvent effect can not only provide data support for the inquiry on the chemical reaction mechanism,reaction activity and spectrum properties of organic compounds,but also make realistic significance for the filter of reaction solvent and the optimization of reaction conditions.The infrared spectra of 4-AP and 2-AT in 17 pure organic solvents were undertaken to determine,and the relationship between the carbonyl stretching vibration frequencies and the empirical parameters of solvent polarity for the corresponding solvents were analyzed in order to discuss the interaction mechanism.The experiment results showed that in non-alcohol solvents,the best correlation between carbonyl stretching vibration frequencies of drifted 4-AP?or 2-AT?and parameters was the G,the next was the S.The correlation between the?_?C=O?and the AN or E_t?30?were poor.The parameters of LESR made a good correlation with?_?C=O?.The LESR can offer accurate physically meaningful explanation of solvent-solute intermolecular interaction.According to setting the molar fractions of cyclohexane in binary solvent from 1.0 to 0.0,and the second solvent were polar solvent,like CCl₄,CHCl₃,CH₂Cl₂ and three kinds of alcohol.The intermolecular interaction between 4-AP?or 2-AT?and solvent had been discussed.The results showed the carbonyl stretching vibration frequencies of solutes were shifted to lower wave numbers,and the absorption band in CHCl₃ or CH₂Cl₂ solvent were widen,indicating that there may be different kinds of interaction between the carbonyl group in 4-AP?or 2-AT?molecule and CHCl₃ or CH₂Cl₂ solvents molecule.And a new absorption band in alcohol solvents were observed,reflecting that there was a specific interaction between the carbonyl group and alcohol solvents molecule to produce new carbonyl group species,which may be an associated species by the hydrogen bonding.The geometries of 4-AP-Ethanol and 2-AT-Ethanol were fully optimized by DFT/RB3LYP/6-311++G?d,p?method combined CPCM solvent model.It can be found that there was a strong hydrogen bonding between 4-AP?or 2-AT?and ethanol.And the hydrogen bonding changed the structure,energy,?_?C=O?of 4-AP and 2-AT.The condensation reaction between 4-AP?or 2-AT?and aniline was monitored by FT-IR experiments.The changes of infrared absorption peaks of solutes during the reactions in different solvents were observed to investigate the solvent effects on the reaction rate and conversion degree.The results showed that the fastest speed and the highest conversion degree of reaction were obtained in cyclohexane,the next was in methylbenzene.However,it was difficult to react in ehanol for the reason that the intermolecular intereaction between ethanol and aniline was stronger than the strength of the hydrogen bonding between ethanol and the carbonyl of 4-AP?or 2-AT?.Compared with the condensation reaction between 4-AP and aniline,the reaction rate of the condensation reaction between 2-AT and aniline was faster,and the conversion of 2-AT was higher.It was mainly attributed to the stronger effect of solvent on carbonyl group of 2-AT which made the property of double-bond weaker.In conclution,the solvent effect has a significant influence on reactions and the study on solvent-solute interaction can be used to provide the scientific basis for selecting solvent of reactions.