Extraction of Sodium Picrate by 3m-Crown-m Ethers and Their Monobenzo Derivatives (m = 5, 6) into Benzene: Estimation of Their Equilibrium-Potential Differences at the Less-Polar Diluent/Water Interface by an Extraction Method

Table 2

Individual distribution constants of NaL⁺ and NaL⁺Pic⁻ into some diluents at 25°C.

(a)

L	()
	o = Bz	DCM	DCE	NB
15C5	2.6 (−1.5)	−1.14 (1.0)	−1.54 (0.3)	0.0, −0.3, 0.62 (1.7)
B15C5	2 (−1.1)	−0.34 (2.3)	−0.54 ()	2.2, 3.7, 2.1 (4.1)
18C6	2.4 (−1.6)	−0.44 (0.77)	0.47 (0.84)	−0.3, −1.4, 0.7 (1.1)
B18C6	0.3 (−2.7)	0.19 (2.62)	1.16 (2.47)	1.5, 2.0, 2.1, (3.7)
Without L	—	−5.73	−6.09, −4.38 [17]	−5.18, −5.95 [17]

(b)

L
	Bz	DCM	DCE	NB
15C5	0.94	2.87	2.47	3.82
B15C5	1.29 (1.42 [13])	3.01 (3.13 [13])	2.61 (2.73 [13])	3.75
18C6	−0.26	1.88	1.16	3.68
B18C6	0.48 (1.18 [13, 15])	2.47 (3.36 [13, 15])	2.06 (2.97 [13, 15])	3.71
Without L

Standard values calculated from the thermodynamic relation, . See footnote f in Table 1. Unpublished data by Kudo. Standard values calculated from (5). Values determined by ion-transfer polarographic measurements at the presence of 0.05 M (C₄H₉)₄N⁺B in the NB phase. See [18]. Values determined by the ion-transfer polarographic measurements at the presence of 0.05 M (C₄H₉)₄N⁺B in the NB phase. See [19]. Not determined. The values are a logarithmic individual distribution-constant of a single Na(I) ion into the DCM, DCE, or NB phase and are standardized at  V. See [20] and footnote h.