One thing worth knowing before you spend money:
heating CBD does not make THC. Decarboxylation only converts CBDA>CBD. You need acid, not heat alone. That trips up a lot of people.
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## The reaction: acid-catalyzed cyclization
CBD is a di-p-menthene. Acid protonates it, the ring closes, and you get THC isomers - mostly D8 with some D9, plus D8-iso-THC, CBN, and unreacted CBD. This is exactly how commercial D8 is made; there's no secret. The [Barrie patent](
https://patents.google.com/patent/US7399872B2/en) is the canonical reference (300 mg CBD + 30 mg p-TsOH in 15 mL toluene, reflux 1 h, claims >=60% yield).
Shopping list: CBD isolate, n-heptane or VM&P naphtha, p-toluenesulfonic acid monohydrate, sodium bicarbonate, Epsom salt, 190-proof Everclear, borosilicate flask, magnetic stirrer hotplate, reflux condenser, thermometer, glass syringe + 0.45 um PTFE filters, separatory funnel or mason jars.
### Procedure, 10 g scale
1.
10 g CBD isolate into 150 mL heptane in a flask. Stir to dissolve.
2. Dissolve
1 g p-TsOH in 10 mL heptane, add it in.
3. Reflux at 85-100 degC for 2-3 h with stirring. Color goes gold > amber > orange. Longer and hotter pushes more D8 and more degradation; shorter and milder keeps more D9.
4. Cool. Add 100 mL water, swirl, separate.
5. Wash organic layer with water, then 5% sodium bicarbonate (kills the acid), then brine.
6. Dry over Epsom salt, filter, evaporate the heptane gently in a hot water bath with ventilation.
You're left with roughly 8-9 g of dark amber oil at
60-75% total THC, 8-15% unreacted CBD, and a pile of iso-THC junk. Clean it up by dissolving in ethanol, freezing 12 h, filtering cold, and evaporating again - that drops the waxes and some color.
Reality check: without vacuum distillation you will not get 90%+ and it will not be pretty. Commercial D8 is distilled; home crude is a tarry mess that tastes like burnt sugar. Short-path glassware plus a two-stage rotary vane pump (water aspirator won't pull hard enough) runs $250-400 and is a genuine skill curve.
Safety: 190-proof is flammable - hot plate, no gas flame, don't seal the flask. p-TsOH burns, gloves and goggles. Heptane is flammable and mildly neurotoxic; do this outside or under a hood.
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## Spraying it on flower
Use ethanol for this step specifically - heptane residue is worse to smoke.
- Dissolve the oil in
190-proof at 1:4 to 1:5 (oil:solvent), warm slightly.
- Fine-mist atomizer or a cheap airbrush. Flower in a wide shallow tub or a big ziplock.
- Weigh the flower. Target
10-15% added oil by weight. Mist thin passes, tumble between each, 3-5 passes total, 5 minutes apart.
- Cure sealed 24-48 h, tumbling occasionally, then air out 12-24 h until the ethanol smell is gone.
What you're signing up for: greasy sticky bud that canoes, needs relighting, burns hot, and buries the Gorilla Glue terps under the oil. Also, once sprayed, the jar fails any total-THC test by a mile - but nobody is testing your personal stash.
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## The box mod question
Crude oil will not work in a sub-ohm tank. Too viscous to wick, and dirty enough to foul the coil in a day.
Three real paths:
-
Thin it. 10-20% CBC (a cannabinoid that's naturally thin and cheap) plus <=5% terpenes, in a ceramic-coil pod - Nord with an RPM ceramic 1.2O, or similar. Terpenes alone at high percentages are harsh and eat plastic tanks, which is why CBC matters.
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Dab it. A Sequoia/Divine Tribe-style dab tank or a wax pen handles raw oil fine. Just chazzes.
-
Distill it. Only route to something that behaves like a real cart.
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## My actual recommendation
Two things, and neither is the conversion.
Stockpile now. Buy 100 g of D8 distillate this week, split into amber syringes, freeze. That's maybe $150-250 and it's shelf-stable for years cold, dark, and oxygen-free. That single move covers the next several years of vaping and dosing, and it beats anything you'll produce in a kitchen.
Then learn the conversion as a hedge against distillate becoming hard to order, and point it at
edibles and MCT tincture - not carts and not flower. Crude oil is genuinely excellent in a dropper bottle where color and harshness don't matter, and that's the one use case where the messy chemistry is a non-issue. Sprayed flower is a fun project, but it's the worst effort-to-payoff ratio of the three.