What is Delta 9 THC?

Products claiming to contain delta-9 THC are being sold at gas stations and convenience stores. Are delta-9 claiming products real weed? The answer is no. The only natural delta-9 THC is found in cannabis bred to produce THCA, which is what most people think of as marijuana. Not all cannabis cultivars produce THC: hemp is cannabis bred to produce CBD and fiber. Synthetic delta-9 can be made from hemp, as I’ll explain below.

Cannabis flower sold at dispensaries as medical and adult use marijuana contain THCA, which is biosynthesized by the plant from CBG. THCA is carboxylated tetrahydrocannabinol, which means it is the acidic derivative of delta-9 THC. THCA is not psychoactive and must have the carboxyl group removed. This is done by heating, and the carboxyl group pops off as CO2. We call this decarboxylation. The heat of smoking the flower instantly converts THCA to delta-9 THC, which is then inhaled as vapor. In the same way, THCA containing oil extracted from cannabis is heated to produce delta-9 THC oil. This is what is used, in the regulated market at least, to make vape pens and edible products.

Thus, the only natural delta-9 THC is produced by cannabis stains that biosynthesize THCA.

Synthetic delta-9 is made from the extract of hemp. Hemp contains a good quantity of cannabidiol (CBD) and other cannabinoids, and the CBD can be converted to delta-9. By treatment with a very strong acid and heat, the CBD cyclizes to delta-9. This is an interesting transformation, so let’s go a little deeper.

CBD, either pure isolate or crude oil is mixed and heated with an acid similar to sulfuric acid, which causes the cannabidiol to ring close to form the skeleton of delta-9 THC. Of course, if the starting material is not pure (i.e. crude oil), then the impurities also react to form new impurities. Even when using pure CBD isolate, this harsh treatment produces impurities. As a synthetic chemist, I can personally attest that chemical reactions almost never produce only the one desired product: side reactions always occur, especially when the reaction conditions are not carefully controlled. Reaction streams must be “cleaned up” of impurities, especially if the material you are making is the final product. Black market producers do not carefully control their reaction conditions, and don’t “clean up” their product. It is an impure product, and it may in fact contain little delta-9 THC. That’s because of the delta-8 issue.

When CBD is treated with acid and heat, the initial product formed is indeed delta-9 THC. However, the delta-9 isomer is not stable under the reaction conditions, and converts to the more stable delta-8 isomer. Chemists would call delta-9 the kinetic product, while delta-8 is the thermodynamic product. Thus, to produce pure delta-9, one would have to trap and remove each and every molecule from the reaction stream before it has time to convert to delta-8.

This is obviously impossible to do, so formation of delta-8 is unavoidable unless extremely sophisticated chemical and engineering controls are put in place to minimize delta-8 formation. The simple fact is that nature prefers that the cannabinoid skeleton have the delta-8 structure.

Products from the unregulated market that claim to be delta-9 weed are untested and full of impurities. The major cannabinoid present is likely to be delta-8 THC, plus a bunch of other minor isomers. Always buy from the regulated market, where the products are produced under state supervision, and are tested not only for chemical purity, but also for toxins like heavy metals and pesticides.