1494
J. Chem. Eng. Data 2001, 46, 1494-1496
Solubility of β-Carotene in Binary Solvents Formed by Some Hydrocarbons with Cyclohexanone and 1-Octanol Teresa Treszczanowicz,*,† Teresa Kasprzycka-Guttman,‡,§ and Andrzej J. Treszczanowicz† Applied Thermodynamics Department, The Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland; Department of Chemistry, Warsaw University, ul. Pasteura 1, 02-093 Warsaw, Poland; and Drug Institute, ul. Chełmska 30/34, 00-725 Warsaw, Poland
Experimental results are reported for the solubility of β-carotene in six binary mixed solvents formed by cyclohexanone with cyclohexane, hexane, and toluene and by 1-octanol with cyclohexane, hexane, and toluene at 293.15 K. A colorimeter was used for analysis of the β-carotene concentration. The β-carotene solubility in pure solvents increases in the order 1-octanol < hexane < cyclohexanone < cyclohexane < toluene. The solubility data as a function of binary solvent mass fractions were smoothed by a rational type equation.
Introduction This study deals with the solubility of β-carotene in mixed binary solvents formed by 1-octanol with hydrocarbons at 293.15 K and is a continuation of our earlier studies on the solubility of β-carotene in mixed solvents formed by 2-propanone and 2-butanone with hexane, cyclohexane, and toluene.1 Currently, only limited solubility data on solids of non-electrolytes in binary mixed solvents are known, but no data are known of any biologically active substances such as β-carotene. Experimental Section
Table 1. Physicochemical Properties of the Solvents Studied: M ) Molecular Mass, d ) Density at 293.15 K, nD ) Refractive Index at 298.15 K nD solvent
Ma/g‚mol-1
da/g‚cm-3
exptl
lit.a
cyclohexanone 1-octanol cyclohexane hexane toluene β-caroteneb
98.145 130.231 84.162 86.178 92.141 536.85
0.9452 0.82499 0.77855 0.65937 0.86693 1.00
1.4498 1.4273 1.4236 1.3722 1.4941
1.4500 1.4276 1.42354 1.37226 1.49413
a
Materials. β-Carotene (Sigma, 95 mol % purity) was used as received. The analysis of the β-carotene samples by liquid chromatography showed that the purity was >95% of the trans isomer. Organic solvents [hexane (99.95 mol %), standard, from Chemipan, Poland; toluene (99 mol %), analytical reagent grade, from the Płock Refinery Industry R&D Centre, and cyclohexane (99 mol %), standard, from Ubichem Ltd.] were distilled; cyclohexanone and 1-octanol, of analytical reagent grade (99 mol %) supplied by Fluka, were twice distilled. All reagents were stored over molecular sieves type 4A. Refractive indices are listed in Table 1 and agree well with the literature values.2 Binary solvent mixtures were prepared by mass; therefore, solvent compositions could be uncertain to 0.0001 mole fraction. The methods of sample equilibration and analysis were presented in an earlier paper.1 Results and Discussion Table 2 presents the results of the β-carotene solubility in the binary mixed solvents expressed in molar concentrations cβ/mol‚L-1, mole fractions xβ together with the mean standard deviation4 σn, and mixing function xM β . Experimental results of the β-carotene solubilities obtained primarily in mass fractions were recalculated to mole fractions using data in Table 1. The detailed procedure was * Author to whom correspondence should be addressed (e-mail
[email protected]). † Polish Academy of Sciences. ‡ Warsaw University. § Drug Institute.
Riddick et al.2
b
Lenfant and Thyrion.3
given in a preceding paper.1 The molar concentrations cβ given in Table 2 are calculated using data in Table 1 and the relationship
cβ )
103xβ id V0βxβ + (1 - xβ)V12
(1)
0 0 0 0 0 0 0 where Vid 12 ) V1x1 + V2x2 and x1, x2 ) 1 - x1 are mole fractions of components of the binary solvent mixture (without the solute, β-carotene) and V0β, V01, and V02 are molar volumes of the pure components. The β-carotene solubility in pure solvents (including ketones measured in a previous paper1) increases in the order 1-octanol < 2-propanone < hexane < 2-butanone < cyclohexanone
