Protonation alkylanilines

If the anodic oxidation of N-alkylanilines is performed in the presence of nucleophiles like enol ethers, nucleophilic substitution in the of-position to nitrogen by the enol ether can be observed in low yields. The electrophilic intermediate is the N-aryl iminium ion or the N-aryl imine after loss of two electrons and one or two protons. These intermediates add to the enol ether to give acetals (up to 26%) as addition products, or the first addition step is followed by an electrophilic aromatic substitution to form tetrahydroqui-nolines (13-39%) [47]. It should be noted at this point that better results for the nucleophilic a-substitution to nitrogen can be obtained with N,N-dialkylanilines (see next subsection). Optimum results, however, are obtained with N-acylated compounds via the intermediate N-acyl iminium ions (see Ref. 8). 

Relatively little is known about the protonation pattern of C-alkyl derivatives. Earlier reports87 pointed out that a number of meta-alkylanilines (m-anisidine and m-toludine) are preferentially ring protonated in the gas phase at equilibrium. 

Water soluble poly(N-alkylaniline)s were prepared with alkyl (Cj-Cig) substituents 20). Chen and coworkers reacted the base form of HCl-PANi with 1,3-propane sultone (27) vMch gave the sodium salt of poly(ani]ine propane sulfonate) which was passed through a protonated cation exchange resin resulting in water soluble poly(aniline propane sulfonic add). 

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