Multivariate Analysis in Selective Nitroacetophenone Conversion by Hydrogen Sulfide under Phase Transfer Catalysis

Response surface methodology (RSM) was employed to model and optimize an improved Zinin reduction of a nitroarene, <i>p</i>-nitroacetophenone (<i>p</i>-NAP), by hydrogen sulfide (H₂S) under biliquid phase transfer catalysis. A novel Zinin reagent, H₂S laden aqueous <i>N</i>-methyldiethanolamine (MDEA) solution, was prepared and used for this purpose. A quadratic regression model was tested with a multivariate experimental design based on the relationship between <i>p</i>-NAP conversion (response) and four independent variablestemperature, catalyst concentration, <i>p</i>-NAP–sulfide mole ratio, and MDEA concentration. The optimum values of the independent variables were found as temperature 339.45 K, catalyst concentration of 0.082 kmol/m³, <i>p</i>-NAP/sulfide mole ratio of 0.452, MDEA concentration of 2.20 kmol/m³, and maximum <i>p</i>-NAP conversion of 96.31% has been attained. The analysis of variance (ANOVA) has been used to evaluate the goodness of the fit of the model, and the desirability function has been used to find the value of the optimized parameters to maximize the <i>p</i>-NAP conversion

Dual Optimization in Phase Transfer Catalyzed Synthesis of Dibenzyl Sulfide using Response Surface Methodology

A new reaction protocol has been developed to prepare dibenzyl sulfide (DBS), a value-added organosulfur fine chemical, by utilizing toxic hydrogen sulfide (H₂S). H₂S absorbed in monoethanolamine (MEA) has been used as a sulfiding agent for benzyl chloride (BC) under liquid–liquid phase-transfer-catalyzed condition. Response surface methodology was used to model and optimize the process parameters for simultaneous dual-maximization of BC conversion and DBS selectivity. BC/sulfide mole ratio, MEA/sulfide mole ratio, temperature, and catalyst concentration were chosen as independent variables, and conversion of BC and selectivity of DBS were chosen as responses. A quadratic regression model was derived with satisfactory prediction. Dual optimization with desirability function predicts a maximum BC conversion of 100% and a maximum DBS selectivity of 95.2% under experimental conditions: temperature 353 K, catalyst concentration 0.14 kmol/m³, BC/sulfide mole ratio 2.83, MEA/sulfide mole ratio 3.7. The analysis of variance and regression with R² values of 0.9996 for BC conversion and 0.9833 for DBS selectivity confirm the good agreement of experimental results with predicted values and therefore, the models can be successfully used to predict the synthesis of DBS successfully