XXXVI.—A reaction of certain colouring matters of the oxazine series

Abstract

BIATI'ERS OF THE OXAZINE SERIES. * The method of nuinbering is that recommended by Kehrmaiin and Gaulie (Ber.

A reinvestigation of a colorimetric method aimed at quantifying minute amounts of carboxylic acids present in polystyrene and poly(n‐alkyl methacrylate)s

“…This observation suggests that an irreversible transformation of either 1 or 1‐H + is taking place in parallel, an hypothesis confirmed by spectrum F that was obtained after one day at 20 °C and exhibits a further drop in absorbance. Previous authors had indicated that Nile Blue A in its acidic form ( 1‐H + ) is not stable hydrolytically and reacts with traces of water in organic solvents to yield Nile Red 2 according to the overall reaction depicted in Scheme (hydrolysis of the reactive iminium salt 1‐H + obtained after protonation of the imine functional group in 1 ) . The observed spectral evolution appears indeed compatible with such an observation and a significant contamination by 2 (λ max at 525 nm in benzene) over time.…”

Investigation of the Nile Red spectra by semi‐empirical calculations and spectrophotometric measurements

“…Nile Red was prepared according to Thorpe 21 and was purified by column chromatography over silica‐gel 60 (Merck), using ethanol as eluent. After drying, the final product was 16% yield and 99.4% purity [determined by high‐performance liquid chromatography (HPLC)].…”

Suberin lamellae of the onion root endodermis: their pattern of development and continuity

“…Nile red is a component of the commercially prepared, nonfluorochome, lipid stain Nile blue (Conn 1961), which has been used as a histochemical stain for lipids since 1908 (Smith 1908;Cain 1947;Dunnigan 1968;Fowler and Greenspan 1985;Greenspan et al 1985;Knight et al 2002). This Nile blue (phenoxazine dye) can be converted to phenoxazones (nonionic red or yellow compounds) by boiling in dilute sulphuric acid (Thorpe 1907). According to Smith (1908), Nile blue itself can either bind to fatty acids, or the Nile red component can partition into the lipids.…”