Search Results

1 - 10 of 130 items :

  • "chirality" x
Clear All

References 1. Kjonaas RA, Williams PE, Counce DA, Crawley LR. Synthesis of Ibuprofen in the Introductory Organic Laboratory. J Chem Educ. 2011;88:825-828. 2. Schurig V. The Importance of Chirality in Nature and Methods of the Separation of Enantiomers by Chiral Chromatography. Arab J Chem. 2008;1:111-122. 3. El-Fatatry HM, Mabrouk MM, Hammad SF, El-Malla SF. A Validated Enantioselective HPLC Method for Determination of Ibuprofen Enantiomers in Bulk and Tablet Dosage Form. J AOAC Int, 2016;99:604-611. 4. Loudiki A, Boumya W, Hammani H, Nasrellah H, El Bouabi Y

;14(22):3533-3536. 20. Bojarski J, Aboun-Enein HY, Ghanem A - What’s new in chromatographic enantioseparations. Curr Anal Chem. 2005;1:59-97. 21. Singh AK, Pedro LG, Gomes FP, et al. - Development and validation of sensitive methods for determination of sibutramine hydrochloride monohydrate and direct enantiomeric separation on a protein-based chiral stationary phase. J. AOAC Int. 2008; 91(3):572-579. 22. Radhakrishna T, Lakshmi-Narayana C, Sreenivas-Rao D, et al. - LC method for the determination of assay and purity of sibutramine hydrochloride and its enantiomers by chiral

LITERATURE CITED 1. Gadenne, B., Hesemann, P. & Moreau, J.J.E. (2004). Ionic liquids incorporating camphorsulfonamide units for the Ti-promoted asymmetric diethylzinc addition to benzaldehyde. Tetrahedron Lett. 45, 8157–8160. DOI: 10.1016/j.tetlet.2004.09.038. 2. Singh, A. & Chopra, H.K. (2016). New benzimidazolium-based chiral ionic liquids: synthesis and application in enantioselective sodium borohydride reductions in water. Tetrahedron: Asymmetry 27, 448–453. DOI:10.1016/j.tetasy.2016.04.004. 3. Vasiloiu, M., Leder, S., Gaertner, P., Mereiter, K. & Bica, K

References BERKECZ, R., SZTOJKOV-IVANOV, A., ILISZ, I., FORRÓ, E., FÜLÖP, F., HYUN, M. H., PÉTER, A.: High-performance liquid chromatographic enantioseparation of β-amino acid stereoisomers on a (+)-(18-crown-6)-2,3,11,12- tetracarboxylic acid-based chiral stationary phase. J. Chromatogr. A, 1125, 2006, 138-143. BOESTEN, J.M.M., BERKHEIJ, M., SCHOEMAKER, H.E., HIEMSTRA, H., DUCHATEAU, A.L.L.: Enantioselective high-performance liquid hromatographic separation of N-methyloxycarbonyl unsaturated amino acids on macrocyclic glycopeptide stationary phases. J

Abstract

Most ligature cases feature everyday, innately-tied Overhand Knots, Half Hitches and Half Knots. These knots are the result of habitual behaviour and individual tiers demonstrate consistency, except when certain contextual factors come into play. This survey focussed on comparing the chiralities of basic knots to those of Figure Eight Knots, which occur in case evidence and require similar tying actions. It is important to note that real-world Figure Eights are oriented relative to their working ends and are therefore chiral, whereas topological Figure Eights have no ends and are amphichiral. Data summarizing the tying habits of 184 survey respondents were collected and analysed. The majority of volunteers surveyed tied common Overhand Knots and Figure Eights of equal chirality, consistently or nearly consistently, irrespective of any general learning effect. A minority tied knots of opposite chirality. The knots tied by the remaining respondents varied, and the data suggested a potentially complex pattern which may be related to previous findings. Similar but less pronounced patterns were exhibited in the Half Hitch and Half Knot data. This information could be useful when analysing case evidence and making links to suspect samples, provided cautious attention is paid to context and knot function.

References [1]. Y. Hassan, Synthesis of chiral ketopinic acidderived catalysts and their evaluation in asymmetric transformations, PhD Thesis, Rhodes University, pp. 1-173 (2015). [2]. P.G. Hultin, L.M. Geary, The state of the art in asymmetric induction: the aldol reaction as a case study, Tetrahedron: Asymmetr. 20 (2009) 131-173. DOI: 10.1016/j.tetasy.2008.12.030 [3]. A. Córdova, W. Zou, I. Ibrahem, E. Reyes, M. Engqvist, W.W. Liao, Acyclic amino acidcatalyzed direct asymmetric aldol reactions: alanine, the simplest stereoselective organocatalyst, Chem. Commun

References BEESLEY, T.E.: Review of Chiral stationary phase development and chiral applications. LC/GC Europe, 24, 2011, 270-276. BÚČIOVÁ, Ľ., BOROVANSKÝ, A., ČIŽMÁRIK, J., CSÖLLEI, J., ŠVEC, P., KOZLOVSKÝ, J., RAČANSKÁ, E., BENEŠ, L.: Štúdium lokálnych anestetík. LXXXIX. Štúdium vplyvu obmien v spojovacom reťazci na biologickú aktivitu v skupine bázických fenylkarbamátov. Českoslov. Farm., 36, 1987, 339-344. BÚČIOVÁ, Ľ., CSŐLLEI, J., BOROVANSKÝ, A., ČIŽMÁRIK, J., RAČANSKÁ, E.: Štúdium lokálnych anestetík. XCVII. Príprava a účinnosť 1-etoxymetyl-2-/1- pyrolidinyl

.1016/j.aca.2008.03.040. 16. Laroche, M., Pukall, R. & Ulber, R. (2003). Gewinnung und Charakterisierung einer L-Serindehydratase aus dem marinen Bakterium Paracoccus seriniphilus zum Aufbau bioanalytischer Systeme. Chemie Ingenieur Technik 75(1-2), 146-9. DOI: 10.1002/cite.200390012. 17. Son, S.H . & Jegal, J. (2007). Chiral separation of D, Lserine racemate using a molecularly imprinted polymer composite membrane. J. Appl. Poly. Sci. 104(3), 1866-72. DOI: 10.1002/app.25845. 18. Yoshimatsu, K., Ye, L., Lindberg, J. & Chronakis, I.S. (2008). Selective molecular

REFERENCES 1. Poirier L, Tobe SW. Contemporary use of β-blockers: clinical relevance of subclassification. Can J Cardiol 2014;30(Suppl 5):S9–15. doi: 10.1016/j.cjca.2013.12.001 2. Nguyen LA, He H, Pham-Huy C. Chiral drugs: an overview. Int J Biomed Sci 2006;2:85–100. PMID: 23674971 3. Hernando MD, Gómez MJ, Agüera A, Fernández-Alba AR. LC-MS analysis of basic pharmaceuticals (beta-blockers and anti-ulcer agents) in wastewater and surface water. Trend Anal Chem 2007;26:581–94. doi: 10.1016/j.trac.2007.03.005 4. Massarsky A, Trudeau VL, Moon TW. β-Blockers as

Abstract

Panthenol is a biologically active compound closely related to vitamin B5 (pantothenic acid). This work deals with the separation of panthenol enantiomers using high performance liquid chromatography. Different types of chiral stationary phases (β-cyclodextrin, isopropyl carbamate cyclofructan 6, amylose tris(3,5-dimethylphenylcarbamate)) were tested in normal phase separation mode. Effect of mobile phase composition on the resolution and retention of enantiomers was studied. Two types of detectors, low-wavelength UV and polarimetric, were used. The optimal chromatographic system includes a chiral stationary phase based on amylose and a mobile phase of hexane/ethanol (60/40, v/v) where the resolution of enantiomers reached the value R s = 2.49. Suitable chromatographic conditions were applied for the determination of panthenol enantiomers in samples of pharmaceutical preparations with the obtained recovery of more than 92 %. Linearity of the high performance liquid chromatography method with spectrophotometric detection was from 1.0 × 10−3 to 1.3 mg mL−1 (R 2 = 0.998), with the limit of detection of 0.3 × 10−3 mg mL−1 for both enantiomers.