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9th October 2010 @ 04:16
Determination of the optical rotation of the 2 enantiomers of PZQ in dependence of ee and concentration See also: [url=http://www.ourexperiment.org/racres_pzq/742]Optical rotation of S-(+)-Praziquanamine[/url] [data=size:500x160]511[/data] Enantiopure samples of R-(-)-PZQ and S-(+)-PZQ donated from [url=http://www.intervet.com/]Intervet Innovation GmbH[/url], Germany (Schwabenheim) [b]Separation method:[/b] Chiral column chromatography performed on microcrystalline cellulose triacetate [1]. [b][i]R[/i]-(-)-PZQ:[/b] m.p. 111-112°C (lit.[2] m.p. = 113-115°C). [α]D20 = -139° (c=1, EtOH) (lit. [2] [α]D20 = 126.9 (c = 1, EtOH 99.%) [α]D20 = 135.0 (c = 1, CHCl3)). [b][i]S[/i]-(+)-PZQ:[/b] m.p. 110-111°C. [α]D20 = -136.5° (c=1, EtOH). [b]Determination of the optical rotation in dependence of the [i]ee[/i] (in %)[/b] To a solution of R-(-)-PZQ (c = 1, EtOH) was added a solution of S-(+)-PZQ (c = 1, EtOH) (vol/vol) to give a total volume of 1 mL. [data=size:200x150]513[/data] [i]Chart 1: [/i]Optical rotation α as a function of the [i]ee[/i] [data=size:400x200]825[/data] [b]Determination of the optical rotation in dependence of the concentration:[/b] A solution of R-(-)-PZQ (c = 1, EtOH) was diluted with EtOH to the concentration given in the tables below. 4 dilution series were performed to determine the mean value of the optical rotation α (lage deviations for diluted solutions) [i]Series1- Series4[/i] [data=size:250x150]517[/data][data=size:250x150]519[/data] [data=size:250x150]521[/data][data=size:250x150]523[/data] [i]Chart 2: [/i]Optical rotation α as a function of the concentration c (for[i] Series4[/i]) [data=size:400x200]529[/data] [i]Chart 3: [/i]Mean value of the optical rotation [α] in dependence of the concentration c ([α] = α / l * c, and l=1, α and c are given in tables [i]Series1 - Series4[/i]) [data=size:400x200]527[/data] [b]Results:[/b] - Linear dependence of the optical rotation α of PZQ on the [i]ee[/i] (determined for a concentration c = 1 in DCM) - Linear dependence of the optical rotation α of [i]R[/i]-(+)-PZQ on the concentration [b]References:[/b] [url=http://www.plosntds.org/article/info%3Adoi%2F10.1371%2Fjournal.pntd.0000357][1] "Taste, A New Incentive to Switch to (R)-Praziquantel in Schistosomiasis Treatment", T. Meyer, H. Sekljic, S. Fuchs, H. Bothe, D. Schollmeyer and C. Miculka, [i]PLoS Neglected Tropical Diseases[/i] [b]2009[/b], [i]3[/i], 1, e357[/url] [2] "Enantioselective synthesis of (R)-(−)-praziquantel (PZQ)", P. Roszkowski J. K. Maurin and Zbigniew Czarnocki, [i]Tetrahedron: Asymmetry[/i],[b]2006[/b],[i] 17[/i], 9, 15, 1415-1419. ([url=http://dx.doi.org/10.1016/j.tetasy.2006.04.023]doi:10.1016/j.tetasy.2006.04.023[/url])
Attached Files
Scheme
Table1
Chart Dependency optical rotation - ee
Series1
Series2
Series3
Series4
Chart [alpha] in dependency of c
Chart alpha in dependency of c
Chart: Dependency optical rotation - ee