Kinetics of the Three Components Condensation of Triethoxymethane, Aniline and CH2-Acidic Compounds Forming Arylaminomethylene Compounds

Article abstract of DOI:10.1007/BF00899677

Condensation of triethoxymethane and aniline with dimedone gives 2-anilinomethylene dimedone as the main product.An 1H-NMR-spectroscopic investigation of the kinetics in chloroform-d1 and methanol-d4 shows different rate determining steps in these solvents.There are two predominant rate determining steps in a complicated multistep reaction sequence.The initial one involves condensation of aniline with triethoxymethane to form diphenyl formamidine via ethyl phenyl formimidate.The second step involves reaction of the intermediate diphenyl formamidine with dimedone.The rates are strongly dependent upon the nature of the solvent and the concentration of catalytic acid.In methanol the reaction of dimedone with the intermediate diphenyl formamidine is rate determining.For preparative purposes the isolation of the intermediate diphenyl formamidine and the subsequent use of less polar solvents offer an advantage, because the second step is found to be accelerated. - Keywords: Enaminones; Formimidate; Formamidine