Study of CMC and Thermodynamic Properties on Formation Micelle of 1-Phenyl-3-methyl-4-benzoyl-pyrazolane-5 Salts in the Organic Solvent +Sec-octyl Alcohol Systems at 298.15 K Using a Microcalorimetric Method

Abstract

The power-time curves of the micelles formation process for quasi-surfactant (1-phenyl-3-methyl-4-benzoyl-pyrazolane-5 lithium, 1-phenyl-3-methyl-4-benzoyl-pyrazolane-5 sodium, 1-phenyl-3-methyl-4-benzoyl-pyrazolane-5 potassium) and organic solvent (octane, decane, dodectane, tetradecane, and hexadecane) with sec-octyl alcohol systems were determined using titration microcalorimetry. From the data and the area of the power-time curves, the critical micelle concentration (CMC), aggregation numbers (n), and thermodynamic functions (Δr, Δr, Δr) are obtained. The relationships between the carbon numbers of alkane with the CMC and the thermodynamic properties are discussed. It could be concluded that the values of CMC and ΔrGdecreased with the increment of the carbon number of alkane. The values of n, Δ_r and Δ_r increased with the increment of carbon number of alkane. For Δ_r and Δ_r , the relative order was demonstrated as PMBP Li > PMBP Na > PMBP K; for CMC, n, and Δr, the relative order was demonstrated as PMBP K >PMBP Na >PMBP Li at the same carbon number of alkane.

Keywords:

• 1-phenyl-3-methyl-4-benzoyl-pyrazolane-5 sodium (PMBP Na)
• 1-phenyl-3-methyl-4-benzoyl-pyrazolane-5 potassium (PMBP K)
• 1-phenyl-3-methyl-4-benzoyl-pyrazolane-5 lithium (PMBP Li)
• Alkane
• critical micelle concentration (CMC)
• microcalorimetric method
• sec-octyl alcohol
• thermodynamic properties (ΔrH_m ^θ, ΔrG_m ^θ, ΔrS_m ^θ)

Notes

n = 7.39, K = 2.496 × 10²³.