A structure–reactivity relationship driven approach to the identification of a color test protocol for the presumptive indication of synthetic cannabimimetic drugs of abuse

Highlights • Synthetic cannabimimetic drugs do not respond to the Duquenois–Levine color test. • The lack of response was rationalized using structure and mechanistic principles. • 2,4-Dinitrophenylhydrazine was investigated as an alternative color test reagent. • The reactivity of 2,4-DNPH with cannabimimetics was correlated with structure. • Naphthoyl, benzoyl, phenylacetyl and cycloalkoyl indoles were tested.