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Correlations between hRF values on thin-layer chromatograms and chemical structure of some tertiary strychnos alkaloids by J.D. Phillipson; N.G. Bisset is a Chemistry article available to read on EtoBox.

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The thin-layer chromatographic behaviour of some thirty compounds of the tertiary alkaloid type found in the genus Strych~zos has been examined, Seven solvent systems have been used to compare behaviour on alumina and silica gel plates and further comparisons have been made by addition of diethylamine to these same solvent systems. It has been demonstrated that RF values cannot be explained solely in terms of pKa values and that for Strychmos alkaloids the factors affecting adsorption are more complicated than for the previously examined heteroyohimbine and oxindole alkaloids. The adsorption processes, although not fully explained for all compounds, can be understood for the majority by considering: (a) The type of aromatic substituent -methoxyl, amino, hydroxyl; (b) The position of the substituent, its inductive effect on the C(IO) carbonyl or hydrogen bond formation to an adjacent hydroxyl; (c) The C(IO) carbonyl most certainly takes part in adsorption, its effect being more marked on alumina than on silica gel: (d) Nb most certainly takes part in adsorption and adsorption is markedly affected by adjacent oxygen atoms at C(16) or C(IS); (e) N-oxides are very strongly adsorbed whe

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Author

J.D. Phillipson; N.G. Bisset

Publisher

Elsevier Science; Elsevier ; Elsevier BV (ISSN 1873-3778)

Published

1970

Language

EN

Field

Chemistry (Physical Sciences)