Aromatic nitriles, effective trimerizing catalysts

The key to the success of this process is a combination of specific catalysts and optimum reaction conditions. Effective catalysts for trimerization of aromatic nitriles are listed in Table I (4 ). Optimum reaction conditions for processing the aromatic nitrile-modified imide precursors depend on the chemical structure and characteristic property of the individual precursor of concern. In general, yield of the polymeric products increases with the increase of reaction temperature, pressure, time, and concentration of catalyst within the range of practical experimental limits (5 ). 

Table I. EFFECTIVE CATALYSTS FOR TRIMERIZING AROMATIC NITRILES CATALYST FORMULA...

Aromatic nitriles may be trimerized at moderate temperature and pressure with p-toluenesulfonic acid as catalyst. Studies were conducted to establish the effect of the reaction temperature, pressure, time, and catalyst concentration on yield of the trimerized product. Trimerization studies were also conducted to establish the effect of substituting electron donating or withdrawing groups on benzonitrile. Preliminary results of using the catalytic trimerization approach to prepare s-triazine cross-linked polyimide/graphite fiber composites are presented. 

The aromatic nitrile and catalyst selected for this study were benzonitrile and PTSA, respectively. Studies were conducted to establish the effect of reaction conditions on yield of trimerized product. Figure 1 shows the... 

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