MATHEMATICAL MODEL FOR THE OPTIMIZATION OF THE REACTION BETWEEN 2,3-BIS(m-TOLYL)QUINOLIZINIUM BROMIDE AND PIPERIDINE USING A FACTORIAL DESIGN

A number of nucleophiles have been successfully identified and quantified using the Krhnke reactionwith 2,3,-diphenyl derivatives of quinolizinium salts.Optimization of the reaction conditions by meansof a mathematical model involving analysis of the response surface has led to a better understanding ofthe factors exerting an influence on the above reaction.The parameters chosen were temperature,reaction time,base concentration,water concentration andnucleophile concentration.The reaction was developed in polar aprotic solvents(acetone,acetonitrile).To facilitate the nucleophilic attack,the presence of an organic base(triethylamine)was necessary,although concentrations in excess of 0.15M did not alter the development of the reaction.Sincepharmaceutical solutions are often aqueous,the influence of water on the reaction was studied.Lowwater volumes have no significant influence on the opening of the quinolizinium ring by the nucleophilicreagent.However,when the water proportion exceeded that of the organic solvent,the fluorescenceintensity was lower than expected.Development of the fluorescent reaction product was first detected5 min after the reaction started.The fluorescence intensity reached its optimum value after 138 min.

MATHEMATICAL MODEL FOR THE OPTIMIZATION OF THE REACTION BETWEEN 2,3-BIS(m-TOLYL)QUINOLIZINIUM BROMIDE AND PIPERIDINE USING A FACTORIAL DESIGN

A number of nucleophiles have been successfully identified and quantified using the Krhnke reaction with 2,3,-diphenyl derivatives of quinolizinium salts.Optimization of the reaction conditions by means of a mathematical model involving analysis of the response surface has led to a better understanding of the factors exerting an influence on the above reaction. The parameters chosen were temperature,reaction time,base concentration,water concentration and nucleophile concentration.The reaction was developed in polar aprotic solvents(acetone,acetonitrile). To facilitate the nucleophilic attack,the presence of an organic base(triethylamine)was necessary, although concentrations in excess of 0.15M did not alter the development of the reaction.Since pharmaceutical solutions are often aqueous,the influence of water on the reaction was studied.Low water volumes have no significant influence on the opening of the quinolizinium ring by the nucleophilic reagent.However,when the water proportion exceeded that of the organic solvent,the fluorescence intensity was lower than expected.Development of the fluorescent reaction product was first detected 5 min after the reaction started.The fluorescence intensity reached its optimum value after 138 min.