RESUMEN
Homogeneous tertiary N,N-dimethyl-N-ß-lauryl/myristyl 7/3 polyethyleneoxy n = 3-18 ethylamines, LM(EO)nAT, are niche intermediates in the synthesis of homogeneous N-alkyl (C1-C18)-N,N-dimethyl-N-ß-lauryl/myristyl 7/3 polyethyleneoxy n = 3-18 ethylammonium chlorides (unitary degree of oligomerization of ethylene oxide in the polyoxyethylene chain). This paper synthetically presents the dependence of the reductive methylation yields of homogeneous primary ß-lauryl/myristyl 7/3 polyethyleneoxy n = 3-18 ethylamines, LM(EO)nAP, on the reaction time (10-90 min), the temperature (70 °C), the molar ratio formic aldehyde /LM(EO)nAP (1.1/1-2.5/1), the molar ratio HCOOH/LM(EO)nAP (5/1), the degree of oligomerization of ethylene oxide in the homogeneous polyoxyethylene chain in the 3,6,9,12,18 series, and the structure of the phase-transfer catalysts. The steric effects of hydrophobic groups CH3 and C18H37 grafted onto the ammonium function, and the micellar phenomena in the vicinity of their critical micellar concentration, directly proportional to the homogeneous degree of oligomerization, were highlighted. In all cases, a steady increase in reductive methylation yields was observed, with even quantitative values obtained. The high purity of the homologous series LM(EO)nAT will allow their personalization as reference structures for the study of the evolution of basic colloidal characteristics useful in forecasting technological applications. LM(EO)nAP were obtained either by direct amidoethylation (nucleophilic addition under basic catalysis of homogeneous lauryl/myristyl 7/3 polyethoxylated n = 3, 6, 9, 12, 18 alcohols, LM(EO)nOH, to acrylamide monomer) or by cyanoethylation of LM(EO)nOH under basic catalysis at 25-50 °C, in the presence of Fe2+ cations as oligomerization/polymerization inhibitor, followed by partial acid hydrolysis of homogeneous ß-alkyl (C12H25/C14H29) 7/3 polyethyleneoxy n = 3, 6, 9, 12, 18 propionitriles, LM(EO)nPN, to ß-alkyl (C12H25/C14H29) 7/3 polyethyleneoxy n = 3, 6, 9, 12, 18 propionamides, LM(EO)nPD, which led to LM(EO)nAP by Hoffmann degradation. Homogeneous higher tertiary polyetheramines LM(EO)nAT were structurally characterized.
RESUMEN
Resumen La tiramina y la N-benciltiramina reaccionan con formaldehído para formar azaciclofanos por medio de condensaciones tipo Mannich aromáticas y reaccionan con aldehídos no enolizables para formar las respectivas bases de Schiff. En este artículo se presenta la síntesis inesperada de N-bencil-N-formiltiramina y N-bencil-N-metiltiramina por medio de reacciones de transamidación y de transamidación-reducción de N-benciltiramina con N,N-dimetilformamida. Para explicar el curso de la reacción se propuso un mecanismo que involucra la formilación de N-benciltiramina y posterior reducción de Leuckart-Wallach inducida por ácido fórmico generado in situ.
Abstract Tyramine and N-benzyltyramine react with formaldehyde to form azacyclophanes by means of aromatic Mannich reactions and react with non-enolizable aldehydes to form the respective Schiff bases. In this paper we present the unexpected synthesis of N-formyl-N-benzyltyramine and N-methyl-N-benzyltyramine by means of transamidation and transamidation-reduction of N-benzyltyramine with N,N-dimethylformamide. A reaction mechanism involving formylation of N-benzyltiramine followed by a Leuckart-Wallach reduction is proposed for rationalising such transformation.
Resumo A tiramina e a N-benziltiramina reagem com formaldeído para formar azaciclofanos por meio de reações de Mannich aromáticas e reagem com aldeídos não-enolizáveis para formar as respectivas bases de Schiff. Neste trabalho apresenta-se a síntese inesperada de N-formil-N-benziltiramina e N-metil-N-benziltiramina por meio de transamidação e transamidação-redução de N-benziltiramina promovida pela N,N-dimetilformamida. Propõe-se um mecanismo de reação que envolve a formilação de N-benziltiramina seguida por uma redução de Leuckart-Wallach induzida pelo ácido fórmico gerado in situ.
