The interaction of alkaloids with selected polyhaloquinone and polycyanoquinone n-acceptors was found to yield intensely coloured radical ions. This finding was developed into a sensitive spectrophotometric assay for alkaloids of general applicability and with adequate accuracy and precision. 7,7,8,8-Tetracyanoquinodimethane is used as the reagent.
Anwendung von rr-Acceptoren zur quantitativen Analyse von AlkaloidenAkaloide geben mit rr-Acceptoren vom Typ der Polyhalogenchinone und Polycyanochinone intensiv gefirbte Radikal-Anionen. Auf Grund dieser Reaktion wurde eine allgemein anwendbare, empfindliche photometrische Bestimmungsmethode fur Alkaloide entwickelt, die auf der Umsetzung mit 7,7,8,8-Tetracyanochinondimethan beruht.n-Acceptors, such as tetracyanoethylene (TCNE), 7,7,8,8-tetracyanoquinodimethane (TCNQ), chloranil and 2,3-dichloro-5,6-dicyanoquinone (DDQ) are known to yield charge-transfer complexes and radical ions with a variety of electron donors which include amines' -'). This donor-acceptor interaction has not been investigated hitherto for alkaloids as a group of n-electron donors which were recently demonstrated to participate in charge-transfer complexation with iodine4-'). Furthermore, relatively few previous publications concerned the analytical applications of this interaction, and were mainly centered on indoles and aromatic amines with TCNE'-'').