Phenyl packings

Scalia and Games developed a packed column SFC method for the analysis of free bile acids cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), lithocholic acid (LCA), and ursodeoxycholic acid (UDCA) [32]. The baseline separation of all five bile acids was achieved on a packed phenyl column with a methanol-modified carbon dioxide in less than 4 min. The elution order showed a normal-phase mechanism because the solutes eluted in the order of increasing polarity following the number of hydroxyl groups on the steroid nucleus. The method was also applied to the assay of UDCA and CDCA in capsule and tablet formulations. The method was found to be linear in the range 1.5-7.5 ng/ml (r > 0.99, n = 6). The average recoveries (n= 10) for UDCA and CDCA were 100.2% with a RSD of 1.7% and 101.5% with a RSD of 2.2%, respectively. The reproducibility of the method was less than 1.5% (n = 10) for both UDCA and CDCA. 

Miscellaneous steroids were separated on a packed phenyl column (Spherisorb, 10 cm x 4.6 mm ID) using UV detection at 254 nm and a... 

The molecular structure of decabenzylferrocene also helped to explain the rather low solubility of this compound in toluene or benzene, in sharp contrast with the previously found excellent solubility properties of other decabenzylmetallocenes and the pentabenzyl-Cp thallium and indium complexes in these solvents. The steric crowding of the benzyl groups in the ferrocene and their limited mobility leave little space for the solvent arene molecules to interact and subsequently to dissolve the molecule. This is quite similar to the situation encountered in the pentaphenylcyclopenta-dienyl derivatives with their closely packed phenyl rings (see Fig. 3). 

C. H. de Villeneuve, J. Pinson, M. C. Bernard, and P. Allongue, Electrochemical formation of close-packed phenyl layers on Si(lll), J. Phys. Chem. BlOl, 2415, 1997. 

Henry de Villeneuve C, Pinson J, Bernard MC, Allongue P (1997) Electrochemical formation of close-packed phenyl layers on Si(l 11). J Phys Chem B 101 2415-2420... 

The principle of headspace sampling is introduced in this experiment using a mixture of methanol, chloroform, 1,2-dichloroethane, 1,1,1-trichloroethane, benzene, toluene, and p-xylene. Directions are given for evaluating the distribution coefficient for the partitioning of a volatile species between the liquid and vapor phase and for its quantitative analysis in the liquid phase. Both packed (OV-101) and capillary (5% phenyl silicone) columns were used. The GG is equipped with a flame ionization detector. 

Phenyl trimethylsilylmethyl sulfide 196.4, b 48 /0.04mm, 113-115 /12mm, 158.5 /52mm, d" " 0.9671, Hq 1.5380. If the sample is suspect then add H2O, wash with 10% aqueous NaOH, H2O again, dry (anhydrous CaCl2) and fractionally distil through a 2ft column packed with glass helices. [J Am Chem Soc 76 3713 1954.]... 

Equation (16) was tested against some data obtained for (R) 4-phenyl-2-oxazolidinone using a range of mixtures of ethanol, acetonitrile and -hexane as the mobile phase. The column chosen was similar to that previously used for the separation of the 4-phenyl-2-oxazolidinone which was 25 cm long, 4.6 mm I.D. packed with 5 mm silica particles bonded with the stationary phase Vancomycin. The results obtained are shown in Table 1 and this is the data used in subsequent computer calculations. 

Preparation of cholesta-5,7-diene-ia,3/3-diol a solution of 500 mg of the 1,4-cyclized adduct of cholesta-5,7-dien-3/3-ol-ia,2a-epoxideand 4-phenyl-1,2,4-triazoline-3,5-dione in 40 ml of tetrahydrofuran is added dropwise under agitation to a solution of 600 mg of lithium aluminum hydride in 30 ml of THF. Then, the reaction mixture liquid Is gently refluxed and boiled for 1 hour and cooled, and a saturated aqueous solution of sodium sulfate is added to the reaction mixture to decompose excessive lithium aluminum hydride. The organic solvent layer is separated and dried, and the solvent Is distilled. The residue Is purified by chromatography using a column packed with silica gel. Fractions eluted with ether-hexane (7 3 v/v) are collected, and recrystallization from the methanol gives 400 mg of cholesta-5,7-diene-la, 3/3-diol. 

Chloro-1 -methyl-5-phenyl-s-trizolo[4,3-a]quinoline A stirred mixture of 6triethyl-orthoacetate (0.925 g,0.0057 mol) and xylene (100 ml) was refluxed, under nitrogen, for 2 hours 40 minutes. During this period the ethanol formed in the reaction was removed by distillation through a short,glass helix-packed column. The mixture was concentrated to dryness In vacuo and the residue was crystallized from methanol-ethyl acetate to give 1.28 g of 7-chloro-1-methyl-5-phenyl-s-triazolo[4,3-a]-quinoline (83.9% yield). The analytical sample was crystallized from methylene chloride methanol and had a melting point 252.5°-253.5°C. 

Fig. 7 a, b. Possible models of packing, for trans-planar chains of s-PS, for the limiting ordered modifications a) hexagonal (a") the relative heights of the centers of the phenyl rings are indicated in c/6 units [28] b) orthorhombic (P") the relative heights of the centers of the phenyl rings are indicated in c/4 units [7, 29]... 

Fig. 19a,b. Crystal structure of bis[4-butoxycarbonyl)-phenyl]terephthalate (B-A) and bis[4-valeroyloxy)-phenyl]terephthalate (V-A). a crystal packing in B-A viewed along a b crystal packing in V-A viewed along b. (Reprinted from [106])... 

In 1997, Sridhar et al. [117] investigated the crystal structure of the mesogenic 4-isothio-cyanato phenyl 4-pentylbicyclo[2,2,2]octane-1-carboxyl-ate. The crystal structure of this compound shows a layered packing along the fl-axis and imbrication along the other two axes. 

Vani and Vijayan [121] investigated the crystal structure of 7M-p-methoxy-benzylidene-p-phenyl-azoaniline (MBPAA). The two crystaUographically independent molecules are oriented antiparallel to each other. The packing of the molecules shows a herringbone arrangement. 

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