Thin-layer chromatography of steroisomeric 2,4-dinitrophenylhydrazones of aliphatic aldehydes.
Abstract The stereoisomeric forms of 2,4-dinitrophenylhydrazones (2,4-DNP) of some aliphatic aldehydes and unsymmetrical detones were separated by several reverse phase thin-layer chromatographic procedures. Evidence indicated that the reaction to produce the 2,4-DNP produces both the syn and anti form, but that repeated recrystallization in ethanol yielded the pure syn crystalline form. Racemizaton of the crystalline syn form could be stimulated by dissolving it in chloroform or by the addition of a small amount of hydrochloric acid to an acetone or methanol solution. Certain thin-layer chromatographic systems separated the homologous series to the greatest extent and the isomers the least (undecane/75% methanol-25% water). Another system separated the isomers to a considerable extent but was not too effective in separating the homologous series (dimethylformamide/heptane). Combinations of these systems should be of value in resolving mixtures of syn and anti forms of mixtures of aliphatic aldehyde 2.4-DNP.
THIN-LAYER CHROMATOGRAPHY OF ALIPHATIC 2,4-DINITROPHENYLHYDRAZONES.
Abstract Thin-layer chromatographic procedures are described for the separation of 2,4-dinitrophenylhydrazones into: 1. Individual members of homologous series by a partition system between 2-phenoxyethanol supported on kieselguhr G and light petroleum (b.p. 100–120°), 2. n-Aldehyde, n-alkan-2-one and n-alk- i -en-3-one derivatives on aluminium oxide G with 4% diethyl ether in light petroleum (b.p. 30–40°) as the solvent, 3. n-Alkanal, n-alk-2-enal, n-alka-2,4-dienal, n-nona-trans-2,trans-6-dienal and n-nona-trans-2,cis-6-dienal derivatives on plates of aluminium oxide G containing 25% AgNO3 (w/w) with 16% diethyl ether in light petroleum (b.p. 30–40°) as the developing solvent. These procedures have been combined in two-dimensional techniques to give a separation of mixtures of the 2,4-dinitrophenylhydrazones of the normal homologous series of alkan-2-ones, alk- i -en-3-ones, alkanals, alk-2-enals, alka-2,4-dienals, and alka-2,6-dienals.
Beiträge zur Papierchromatographie organischer Substanzen
ZusammenfassungUngesättigte Verbindungen, hauptsächlich Olefine C2–C12, werden als Quecksilber(II)-salze mit Hilfe der Papierchromatographie und Dünnschichtchromatographie aufgetrennt. Geeignete Lösungsmittelgemische werden angegeben und die Zusammenhänge mit Fleckengröße und Rf-Werten graphisch dargestellt.SummaryUnsaturated compounds, mainly olefines C2–C12, are separated in form of their mercuric salts by help of chromatography on paper or on thin layers of silica gel. Suitable solvent mixtures are given and their relations to spot sizes and Rf-values are represented in graphs.