Eichungsfreie (struktur-unabhängige) Photometrie von Aminen und Amin-Hydrochloriden durch Indikator-Deprotonierung und Ionenpaar-Metathese1)

Calibration-Free (Structure-Independent) Photometry of Amines and Amine Hydrochlorides by Deprotonation of an Indicator Acid Combined with Ion Pair Metathesis¹⁾ Quantitative protonation of amines by a large excess of (in methylene chloride) colourless bromthymol blue (BTB) combined with an in situ ion pair metathesis induced by a large excess of N-butylscopolamine bromide generates an equivalent amount of the butylscopolamine salt of BTB. This technique allows a simple and reliable determination by photometry of amines using the standard absorption parameters λ_max = 412 nm and ? = 18620. Arylamines are not determined quantitatively. Amine hydrochlorides can be analyzed in the same manner if their solutions in methylene chloride are shaken with yellow mercury(II) oxide prior to mixing with the combined BTB -butylscopolamine bromide reagent.