Cannabinol (CBN) – Formation, Detection and What It Indicates

Fresh plant material contains cannabinol only in traces. It appears when THC that has already formed oxidises, and its share grows with storage time, exposure to air and light. That makes it a chemical marker for age and storage conditions. The common notion that any application of heat produces cannabinol does not hold in that form.

Formation

The starting material is the THC already formed. Cannabinol sits at the end of an oxidation chain that consumes THC, not at the end of decarboxylation. When tetrahydrocannabinolic acid is converted in a vacuum oven with oxygen excluded, the reaction runs stoichiometrically and no by-product is detectable. Cannabinol shows up only once air is involved.

Access to air as the decisive factor

Decarboxylating on an open tray produces both at once: conversion and oxidation. In a nitrogen-flushed sealed vessel the same conversion ran faster while cannabinol formation stayed minimal. Access to air is therefore what decides. A covered vessel skips the detour through the degradation product.

Share of the total loss

Under heavy overheating more compound disappears than can be recovered as cannabinol. After an hour at 160 °C the combined amount of acid, THC and cannabinol had fallen by 78 %. The remainder went into evaporation and into unidentified degradation products. Cannabinol accounts for only part of the loss.

What is known about its effects

Cannabinol is considered markedly less psychoactive than THC. The widespread attribution of a pronounced sedative effect rests largely on experience reports and older small studies, and is not established with the confidence that its chemical origin is. As a marker of ageing cannabinol is well founded; as a compound in its own right, far less so.

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