Fading of organic artists' colorants by atmospheric nitric acid: reaction products and mechanisms

Abstract

The reaction products formed upon exposure of selected \nartists' colorants to gas-phase nitric acid have been identified \nusing chemical ionization mass spectrometry. The \ntwo organic colorants that were most nitric acid-fugitive \nwere triphenylmethane derivatives: the chloride cationic \ndye basic fuchsin yielded the corresponding nitrate salt, \nand the carbinol pararosaniline yielded the corresponding \norganic nitrate ester. Both also yielded small amounts of \nbenzophenones. Other colorants studied yielded only small \namounts of oxidation (but not nitration) products, i.e., \nphenols and/or ring-opening products: benzoic acid and \nhydroxyquinacridone from acridones, isatin and isatoic \nanhydride from indigo, trihydroxyanthraquinone from \nalizarin, and phthalic acid from Alizarin Crimson. The \ncorresponding reaction mechanisms are outlined. The \nresults are discussed in terms of possible damage to colorants \nin museum collections resulting from exposure to \natmospheric nitric acid.

Cite this work

No public copy is stored for this record, so only the metadata is cited.

Stored only when both papers are in the corpus — 26 citations exist upstream.