Table 3.

Physicochemical properties of alditols at 25°C.

Alditol	Molecular weight	Maxium van der Waals radius (Å)(a)	Partial molar volume  (cm3  mol−1)(b)	Permeability  (m  s−1)(c)	“Water activity” constant K (d)
Glycerol	92.1	2.8	70.84	1.49 ± 0.40 × 10−10	1.16
Erythritol	122.1	3.1–3.2	86.83	4.92 ± 0.27 × 10−10	1.34
Xylitol	152.1	3.2–3.3	102.12	9.9 ± 3.4 × 10−11	1.66
D-Arabitol	152.1	3.2			1.41
L-Arabitol	152.1	3.2			1.21
Ribitol	152.1	3.2	100.6		1.49
D-Glucitol	182.2	3.4	118.8		1.65
D-Mannitol	182.2	3.4	119.22	7.6 ± 4.8 × 10−11	0.906

^(a)The values for glycerol, erythritol, xylitol and D-mannitol are from Kiyosawa [93]. Other values represent estimates of the present author.

^(b)At infinite dilution at 25°C [94]. Values for ribitol and sorbitol are from Back et al. [95].

^(c)Using the giant alga Chara cell membrane [96].

^(d)The values of K are those of a correlating constant from the equation a _w = x ₁ exp(−K x ₂ ²), where x ₁ and x ₂ are molar fractions of water and solute, respectively, and a _w is water activity [97].