Study of Local Anesthetics. Part* 168 Critical Micelle Concentration of Alkyloxy Homoloqs of Local Anesthetic Heptacainium Chloride Determined by Ion Sensitive Electrode

The critical micelle concentrations (c.m.c.) of alkyloxy homologs of local anesthetic N-[2-(2-alkyloxyphenylcarbamolyoxy)-ethyl]-piperidinium chloride (CnA) with n=3, 5, 7, 8, 10 and 12 carbons in alkyloxy substituent determined by surfactant ion sensitive electrode (ISE) depend exponentially on n: lnc.m.c.=0.70+0.49n and lnc.m.c.=0.57+0.62n at t=25 °C and pH≈4.5 in water and 0.1 mol.l-1 NaCl solution, respectively, where the free energy of transfer of the alkyloxymethylene group from the aqueous phase into the micelle hydrophobic interior is ΔG0=(-0.49±0.008)RT in water and ΔG0=(-The critical micelle concentrations (c.m.c.) of alkyloxy homologs of local anesthetic N-[2-(2-alkyloxyphenylcarbamolyoxy)-ethyl]-piperidinium chloride (CnA) with n=3, 5, 7, 8, 10 and 12 carbons in alkyloxy substituent determined by surfactant ion sensitive electrode (ISE) depend exponentially on n: lnc.m.c.=0.70+0.49n and lnc.m.c.=0.57+0.62n at t=25 °C and pH≈4.5 in water and 0.1 mol.l^-1 NaCl solution, respectively, where the free energy of transfer of the alkyloxymethylene group from the aqueous phase into the micelle hydrophobic interior is ΔG⁰=(-0.49±0.008)RT in water and ΔG⁰=(-0.62±0.06)RT in the 0.1 mol.l^-1 NaCl solution. The enthalpic and entropic contributions to the standard Gibbs energy of micellization of heptacainium chloride (heptyloxy homologs of C_nA) in 0.1 mol.l^-1 NaCl solution were calculated according to the phase separation model in the temperature range of 25-45 °C.0.62±0.06)RT in the 0.1 mol.l-1 NaCl solution. The enthalpic and entropic contributions to the standard Gibbs energy of micellization of heptacainium chloride (heptyloxy homologs of CnA) in 0.1 mol.l-1 NaCl solution were calculated according to the phase separation model in the temperature range of 25-45 °C.