Solvent cyclohexane-acetone-triethylamine

Method. The derivatives are formed by shaking the sample (dissolved in acetone) for 1 h at 45 °C with a 3-5 molar excess of recrystallized DNS-C1. The reaction is buffered at pH 10.8.0.25 ml of 1N sodium hydroxide is then added in order to hydrolyze the unchanged DNS-C1. The derivatives are extracted with 3 ml of ethyl acetate after addition of 1 ml of a saturated aqueous solution of sodium chloride to the reaction mixture. The organic phase is used for TLC on activated layers of silica gel G. The cannabinoids yield mono-DNS derivatives with the exception of cannabidiol which forms a bis-DNS derivative. The following solvent systems are satisfactory for separation of cannabinoids on silica gel A, benzene-acetone (9 1) B, cyclohexane-ethyl acetate (5 1) C, cyclohexane-acetone-diethylamine (20 4 1) and D, cyclohexane-acetone-triethylamine (20 4 1). The R f values of nine cannabinoids in the above solvent systems are given in Table 4.25. 

Figure 8. Separation of DANSYL-ll-OH- 9-THC and A8-THC by one-dimensional TLC. Developing solvents (I) cyclohexane/ethyl acetate (95 5) (II) cyclohexane /acetone/triethylamine (70 25 5). The striped spots indicate breakdown products of DANS-Cl. The extreme right side of I and left side of II are blank...

TLC was carried out on various types of plates silica gel, silanized silica gel, cellulose and alumina, as well as in several different solvent systems benzene, chloroform, cyclohexane, benzene/acetone (90 10), cyclohexane/ethyl acetate (95 5), cyclo-hexane/acetone/triethylamine (70 25 5), hexane/benzene (60 40) and hexane/ether (80 20). Spots were either visualized by ultraviolet or developed by pulverization of a 1% blue B salt aqueous solution. 

Another attempt to relate the results from the use of a solvatochromic probe (Phenol Blue (66)) to the inherent properties of solvent mixtures was made by Phillips and Brennecke122. They obtained the interaction energies (required for the application of the non-random two-liquid (NRTL) approach) of 66 with each of the solvent components from its solubility in the neat solvent. The mixtures studied contained cyclohexane as one component and acetone, triethylamine, ethyl butyrate, cyclohexanone, toluene and acetophenone as the other. Then the local compositions deduced from the solvatochromism of 66 were compared with those calculated by the NRTL equation and reasonable agreement was found. 

Solvents A acetone. ACN acetonitrile, AcOH glacial acetic acid. Am aqueous ammonia (0.88%). B benzene. Bu l-butanol. Cc carbon tetrachloride, Ch chloroform, Cy cyclohexane. Dh dichloromethane, DEA diethylamine, DO dioxane. E diethyl ether, Et ethanol. Etac ethyl acetate. F formamide. H heptane. He hexane. Ibu isobutanol, lo isoocatne, IP isopropanol. Me methanol. MEK methyl ethyl ketone, Metac methyl acetate. P petroleum ether, Pr n-propanol. Py pyridine, T toluene, TEA triethylamine, THF tetrahydrofurane, W water. X xylene. 

Solvation of Pb(CH3)4 in solution increases along the series of solvents cyclohexane < 1,2-dimethoxyethane dioxane = hexamethylphosphoric acid triamide < pyridine < tetrahydrothiophene < triethylamine < tetrahydrofuran < triethylphosphane < N,N,N, N -tetramethylethylenediamine = acetone < dimethylformamide < dimethyl sulfoxide as derived from the increase of the NMR coupling constants J( H, Pb). Coordination of only one solvent molecule and trigonal bipyramidal geometry of the complexes was supposed [8]. For studies of the dispersion interaction of Pb(CH3)4 and various solvents, see [9, 28]. For a correlation of the ionization potential and the solvation energy of Pb(CH3)4 and other tetraorganometal compounds in acetonitrile, see [36]. 

FIGURE 3 2 Solvent extraction efficiencies (EF) as functions of dielectric constants (D), solubility parameters (6), and polarity parameters (P and E -). Solvents studied silicon tetrachloride, carbon disulfide, n pentane. Freon 113, cyclopentane, n-hexane, carbon tetradiloride, diethylether, cyclohexane, isooctane, benzene (reference, EF 100), toluene, trichloroethylene, diethylamine, chloroform, triethylamine, methylene, chloride, tetra-hydrofuran, l,4 dioxane, pyridine, 2 propanol, acetone, ethanol, methanol, dimethyl sulfoxide, and water. Reprinted with permission from Grosjean. ... 

Figure 18. Correlations between the solubility of cmchonidme and the reported empirical polarity (A) and dielectric constants (B) of 48 solvents [66]. Those solvents are indicated by the numbers in the figures 1 cyclohexane 2 n-pentane 3 n-hexane 4 triethylamine 5 carbon tetrachloride 6 carbon disulfide 7 toluene 8 benzene 9 ethyl ether 10 trichloroethylene 11 1,4-dioxane 12 chlorobenzene 13 tetrahydrofuran 14 ethyl acetate 15 chloroform 16 cyclohexanone 17 dichloromethane 18 ethyl formate 19 nitrobenzene 20 acetone 21 N,N-drmethyl formamide 22 dimethyl sulfoxide 23 acetonitrile 24 propylene carbonate 25 dioxane (90 wt%)-water 26 2-butanol 27 2-propanol 28 acetone (90 wt%)-water 29 1-butanol 30 dioxane (70 wt%)-water 31 ethyl lactate 32 acetic acid 33 ethanol 34 acetone (70 wt%)-water 35 dioxane (50 wt%)-water 36 N-methylformamide 37 acetone (50 wt%)-water 38 ethanol (50 wt%)-water 39 methanol 40 ethanol (40 wt%-water) 41 formamide 42 dioxane (30 wt%)-water 43 ethanol (30 wt%)-water 44 acetone (30 wt%)-water 45 methanol (50 wt%)-water 46 ethanol (20 wt%)-water 47 ethanol (10 wt%)-water 48 water. [Reproduced by permission of the American Chemical Society from Ma, Z. Zaera, F. J. Phys. Chem. B 2005, 109, 406-414.]...

It is to be noted that excellent agreement is found between tt and results and the earlier tt values for the following 21 solvents n-hexane, cyclohexane, triethylamine, isopropanol, dioxane, -propanol, ethanol, tetrahydro-furan, ethyl acetate, methyl acetate, ethyl formate, ethanol, methyl orthoformate, 2-butanone, acetone, acetic anhydride, nitromethane, dimethylacetamide, dimethylformamide, sulfolane, and dimethyl sulfoxide. The aromatic and polychlorinated aliphatic solvents give lower rr i and ir 2 results than the uv-based tt values (as expected in the light of the fact that these are really (ir + d5) terms all nmr shifts so far studied have involved negative d values in Equation 95). 

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