Thermodynamics of liquid mixtures containing n-alkanes and strongly polar components: VE and C P E of mixtures with either pyridine or piperidine

Thermodynamic study of heptane+secondary, tertiary and cyclic amines mixtures. Part IV. Excess and solvation enthalpies at 298.15K

“…These differences increase by about 0.005 kJ mol −1 if the data are reported to the same temperature by using the C E p value in Ref. [10]. The average disagreement amounts to 40 J mol −1 ; we consider this acceptable, in view of the difficulties of the measurements due to volatility and chemical reactivity of the amines.…”

“…i Taken from Ref. [10]. j Coefficients of G E /RT = x1x2 (g1 + g2(x1 − x2)), preliminary results from Ref.…”

Excess molar heat capacities and excess molar volumes of (ann-alkylalkanoate + 2,2,4-trimethylpentane, or 2,2,4,4,6,8,8-heptamethylnonane) atT= 298.15 K

“…A comprehensive discussion based on the quasi-chemical lattice theory (56) has been presented by Cobos. (59) Recently, Wilhelm et al (4,11,55,(60)(61)(62) suggested that the dimensionless quantity y 2 = {µ 2 1 N A /(4π ε 0 V m k B T )} 2 may serve as a rough indicator for the magnitude of the non-random (cooperative) contribution in any given series. Here, µ 1 is the permanent electric dipole moment of the polar component, N A is Avogadro's constant, ε 0 is the dielectric permittivity of vacuum, and V m is the molar volume.…”

“…Most interestingly, for some of the mixtures involving either an n-alkane, or cyclohexane, C E p,m as a function of mole fraction x is W-shaped similar to what is observed with mixtures of alkanes with other polar substances like cyclic ethers, (6) or alkanones, (7) or α,ω-dichloroalkanes, (8)(9)(10) or pyridine. (11) In the pure, dense liquid state, a strong case for correlation of molecular orientation between longer n-alkane molecules has been made by Bothorel et al (12,13) With increasing branching this correlation gradually disappears, and highly-branched alkanes such as 2,2,4-trimethylpentane, or 2,2,4,4,6,8,8-heptamethylnonane are essentially devoid of order. This communication is intended to expand our systematic studies by reporting excess molar volumes and excess molar heat capacities at constant pressure at the temperature T = 298.15 K and at atmospheric pressure of eight liquid mixtures consisting of an n-alkylalkanoate {n-butylmethanoate, HCOO(CH 2 ) 3 CH 3 , or ethylethanoate, CH 3 …”

Thermodynamics of organic mixtures containing amines. VIII. Systems with quinoline

“…The negative V E values for these mixtures have been considered to reveal structural effects, as free volume effects [15], which are more important in systems containing shorter alkanes (V E (hexane) = À1.28 cm 3 Á mol À1 ; V E (tetradecane) = À0.079 cm 3 Á mol À1 [15]). Pyridine systems behave similarly [68][69][70], although V E is s-shaped for the hexane solution (0.004 cm 3 mol À1 [70]) and large and positive for the tetradecane mixture (1.016 cm 3 Á mol À1 [68]). …”