Catalysis of Organic..

484 Reductive AlkylationTable 2. Regression coefficients for the rate of reductive alkylationParameter Coefficient Parameter CoefficientConstant 16.0 - -Pt -3.51 Pt*S 15.69S -41.19 Pt*pH -0.18pH 1.99 PH*S -2.88The data from Table 1 was fitted to a multiple regression model and theregression coefficients determined from the model are listed in Table 2. Thus therate of reaction at any given value of Pt-loading, S-loading, and pH, within theparameter space, can be determined from the regression equation shown below:Rate = 16.0 - 3.51*Pt - 41.19*S + 1.99*pH + 15.69*Pt*S - 0.18*Pt*pH - 2.88*S*pHRate0.0-5.05.0-10.010.0-15.15.0-20.302010012Pt3450.10.20.3S0.40.5Figure 2 Response surface for the rate of reaction for catalysts prepared at pH=6Since pH during catalyst preparation does not seem to affect the ratesignificantly, the response surfaces obtained at pH 2 to 6 were similar. Thus, thisvariable was held constant at pH=6 and the resultant response surface (reaction rate)is shown in Figure 2 with Pt and S loading as determined from the regressionequation. It is clear that one can obtain a highly active catalyst even at a low Ptloading by choosing the optimal S loading in the catalyst. Further studies need to beconducted to establish this optimal Pt/S loading.ConclusionsThe current work clearly establishes that the sulfided Pt catalyst is highlyeffective for the reductive alkylation of ADPA with MIBK. The most significantparameter that determines the reductive alkylation rate is the Pt/S ratio.