Polymer-supported nitrite

The clean and efficient production of azo dyes is a classical chemistry problem. The manufacture of this industrially important family of compounds is traditionally associated with the additional formation of large quantities of hazardous and colored waste. A method for the construction of both phenolic and amino azodyes has been reported using a polymer-supported nitrite reagent to effect diazoti-zation of aromatic amines (Scheme 2.53) [80]. Waste minimization and operational simplicity, along with improved separation technologies, are key advantages of polymer-supported reagents in this area. 

Several batches of each type of aminopolystyrene functionalized with nitroform-alddiyde P-naphthylhydrazone were prepared and charactmzed by infrared and ultraviolet spectroscopy. In a typical experiment aminopolystyrene was diazmized with an excess of sodium nitrite in hydrochloric acid and then coiq>lcd with nitroform-aldehyde P-naphthylhydrazone to give a polymer-supported diarylnitroformazan (Figure 5) following the reaction pathway described earlier for synthesis of unsymmetrical... 

Kenawy 64) immobilized ammonium and phosphonium peripheral functionalized dendritic branches on a montmorillonite supported chloromethylstyrene/methyl methacrylate copolymer (74-75). These polymer/montmorillonite-supported dendrimers were used as phase transfer catalysts (PTC) for the nucleophilic substitution reaction between -butyl bromide and thiocyanate, cyanide, and nitrite anions in a toluene or a benzene/water system. These PT catalysts could be recycled by filtration of the functionalized montmorillonite from the reaction mixture. Generally,... 

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