Reductive Methylation of Homogeneous Primary β-Lauryl/myristyl 7/3 Polyethyleneoxy n = 3–18 Ethylamines under Phase-Transfer Catalysis Conditions

Homogeneous tertiary N,N-dimethyl-N-β-lauryl/myristyl 7/3 polyethyleneoxy n = 3–18 ethylamines, LM(EO)(n)AT, are niche intermediates in the synthesis of homogeneous N-alkyl (C(1)–C(18))-N,N-dimethyl-N-β-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 β-lauryl/myristyl 7/3 polyethyleneoxy n = 3–18 ethylamines, LM(EO)(n)AP, on the reaction time (10–90 min), the temperature (70 °C), the molar ratio formic aldehyde /LM(EO)(n)AP (1.1/1–2.5/1), the molar ratio HCOOH/LM(EO)(n)AP (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 CH(3) and C(18)H(37) 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)(n)AT will allow their personalization as reference structures for the study of the evolution of basic colloidal characteristics useful in forecasting technological applications. LM(EO)(n)AP 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)(n)OH, to acrylamide monomer) or by cyanoethylation of LM(EO)(n)OH under basic catalysis at 25–50 °C, in the presence of Fe(2+) cations as oligomerization/polymerization inhibitor, followed by partial acid hydrolysis of homogeneous β-alkyl (C(12)H(25)/C(14)H(29)) 7/3 polyethyleneoxy n = 3, 6, 9, 12, 18 propionitriles, LM(EO)(n)PN, to β-alkyl (C(12)H(25)/C(14)H(29)) 7/3 polyethyleneoxy n = 3, 6, 9, 12, 18 propionamides, LM(EO)(n)PD, which led to LM(EO)(n)AP by Hoffmann degradation. Homogeneous higher tertiary polyetheramines LM(EO)(n)AT were structurally characterized.