# Structural Elucidation of Azo and Quinoneimine Products Formed in Diazonium-Based Color Reactions of Cannabinoids

## TL;DR

This study identifies the chemical products formed when diazonium salts react with various cannabinoids, revealing how color changes occur during cannabis screening.

## Contribution

The paper provides the first structural elucidation of azo and quinoneimine products formed in diazonium-based color reactions of cannabinoids.

## Key findings

- Azo compounds were formed from cannabidiol, cannabigerol, cannabichromene, and cannabidiolic acid.
- Quinoneimines with positional isomers were produced from cannabinol, Δ9-THC, and hexahydrocannabinol.
- The reaction was ineffective with Δ9-THC acetate and HHC acetate.

## Abstract

Cannabis use is generally restricted worldwide because it contains the narcotic compound Δ9-tetrahydrocannabinol (Δ9-THC). Although cannabis is detected at crime scenes using color-based primary screening methods, the details of the reaction mechanism have not yet been elucidated. In this study, we isolated the products generated during the color reaction between the diazonium salt prepared from para-nitroaniline and nine cannabinoids and determined their structures. Azo compounds 6, 11, 16, and 17 were produced from cannabidiol, cannabigerol, cannabichromene, and cannabidiolic acid, respectively, while quinoneimines 7–10 and 12–15, which contained positional isomers, were produced from cannabinol, Δ9-THC, and hexahydrocannabinol. The reaction barely proceeded with Δ9-THC acetate and HHC acetate.