1.Alkyl vs. alkoxy chains on ionic liquid cations.
Henderson WA1, Young VG Jr, Fox DM, De Long HC, Trulove PC. Chem Commun (Camb). 2006 Sep 21;(35):3708-10. Epub 2006 Aug 3.
The crystal structures and thermal behavior of the 1-(2-methoxyethyl)-2,3-dimethylimidazolium chloride and hexa-fluorophosphate salts are compared with the analogous 1-butyl-2,3-dimethylimidazolium salts to examine the influence of the ether oxygen on salt thermal properties for a typical constituent cation used in the preparation of ionic liquids.
2.3,3'-Di-n-propyl-1,1'-(1,3-phenyl-ene-dimethyl-ene)di(1H-imidazol-3-ium) bis-(hexa-fluorophosphate).
Haque RA, Nasri SF, Rosli MM, Fun HK. Acta Crystallogr Sect E Struct Rep Online. 2012 Jul 1;68(Pt 7):o2153. doi: 10.1107/S1600536812026955. Epub 2012 Jun 20.
In the title compound, C(20)H(28)N(4) (2+)·2PF(6) (-), the dihedral angles between the benzene ring and the imidazole rings are 70.18 (11) and 69.83 (11)°, while the imidazole rings form a dihedral angle of 40.52 (12)°. In the crystal, weak C-H⋯F inter-actions link the mol-ecules into a two-dimensional network parallel to (001). A π-π inter-action with a centroid-centroid distance of 3.601 (1) Å is also observed in the crystal structure.
3.Separation and pre-concentration of glucocorticoids in water samples by ionic liquid supported vortex-assisted synergic microextraction and HPLC determination.
Qin H1, Li B, Liu MS, Yang YL. J Sep Sci. 2013 Apr;36(8):1463-9. doi: 10.1002/jssc.201200989. Epub 2013 Mar 22.
We have developed a synergic microextraction procedure based on ionic liquid for the pre-concentration and determination of glucocorticoids in water samples. Using nonionic surfactant Triton X-100 (TX-100) as synergic reagent, 1-butyl-3-methylimidazolium hexa-fluorophosphate accomplished extraction rapidly without heating in water bath. One key property of ionic liquids that highlights their potential is their wide liquid temperature range. The improved extraction was named as ionic liquid supported vortex-assisted synergic microextraction. Compared with the traditional liquid-liquid extraction and cloud point extraction, ionic liquid supported vortex-assisted synergic microextraction was accomplished in 8 min with considerably high recovery. The proposed method greatly improved the sensitivity of HPLC for the determination of glucocorticoids. The results obtained indicated a good linearity with the correlation coefficient of 0.997 over the range of 0.
4.Applications of BOP reagent in solid phase synthesis. Advantages of BOP reagent for difficult couplings exemplified by a synthesis of [Ala 15]-GRF(1-29)-NH2.
Fournier A1, Wang CT, Felix AM. Int J Pept Protein Res. 1988 Jan;31(1):86-97.
The BOP reagent [benzotriazol-l-yl-oxy-tris-(dimethylamino)phosphonium hexa-fluorophosphate] introduced by Castro et al. [Tetrahedron Lett. (1975) 14, 1219-1222] is ideally suited for solid phase peptide synthesis. The rate of coupling using BOP compared favorably to DCC and other methods of activation including the symmetrical anhydride and DCC/HOBt procedures. BOP couplings using the solid phase procedure proceeded more rapidly and to a greater degree of completion for peptide bond formations that were previously determined to be very slow using the conventional DCC method. Stepwise solid phase peptide synthesis using BOP was successfully utilized for the preparation of the (22-29) and (13-29) fragments of [Ala15]-GRF(1-29)-NH2. Single couplings with 3 equiv. BOP and Boc-amino acids and 5.3 equiv. of diisopropylethylamine in DMF were used for each cycle. The yields of the fragments were superior and the purities comparable using the BOP procedure (single couplings) to those observed using multiple couplings via the DCC coupling method.
