Catalysis of Organic..

Arunajatesan, Cruz, Möbus and Chen 48154. Optimization of Reductive AlkylationCatalysts by Experimental DesignAbstractVenu Arunajatesan, Marisa Cruz, Konrad Möbus and Baoshu ChenDegussa Corporation, 5150 Gilbertsville Hwy, Calvert City, KY 42029Venu.arunajatesan@degussa.comReductive alkylation is an efficient method to synthesize secondary amines fromprimary amines. The aim of this study is to optimize sulfur-promoted platinumcatalysts for the reductive alkylation of p-aminodiphenylamine (ADPA) with methylisobutyl ketone (MIBK) to improve the productivity of N-(1,3-dimethylbutyl)-Nphenyl-p-phenylenediamine(6-PPD). In this study, we focus on Pt loading, theamount of sulfur, and the pH as the variables. The reaction was conducted in theliquid phase under kinetically limited conditions in a continuously stirred tankreactor at a constant hydrogen pressure. Use of the two-factorial design minimizedthe number of experiments needed to arrive at the optimal solution. The activity andselectivity of the reaction was followed using the hydrogen-uptake andchromatographic analysis of products. The most optimal catalyst was identified tobe 1%Pt-0.1%S/C prepared at a pH of 6.IntroductionThe synthesis of an N-alkylarylamine by the reductive alkylation of an aromaticprimary amine with a ketone is used in the preparation of antioxidants for polymersand rubber. The alkylation of an amine with a ketone is typically carried out in theliquid phase using heterogeneous catalysts such as Pd, Pt, Rh, or Ru supported oncarbon (1,2). The reaction of ADPA with MIBK yields an imine, which then ishydrogenated over a Pt or sulfur promoted-Pt catalyst to yield 6-PPD.CH 3H 3 CCH 3H 3 CCH 3H 3 CH 2NH NH 2 OCH 3NH NPtS/CNH NCH 3 HHCH 3ADPA MIBK Imine 6-PPDOptimization of a process or catalyst by experimental design such as twofactorialdesign can lead to significant reduction in time required to achieve the goal.In their excellent work, Mylroie et al. (3) reduced the time required for theoptimization of the reductive alkylation process conditions by a factor of 10. Here,we turn our attention to the optimization of the catalyst rather than the process.