Caffeine Extraction 101
Here we look at three caffeine extraction methods:
Extracting caffeine from caffeine pills, from coffee grounds, and from tea leaves/bags.
Caffeine is a stimulant and is found within nature in both the tea bush and the coffee plant. Kola nuts and guarana berries also are a rich source of caffeine. Caffeine is excellent for keeping you mentally alert and for warding off drowsiness. Most cultures the world over ingest some form of caffeine-related beverage or food every day.
However, these extraction methods below are impractical and are only for fun. Caffeine is much cheaper (time and money-wise) to buy in caffeine anhydrous powder format.
Method One – Extraction from Pills
Crushing a caffeine pill may seem like the easiest option. Here’s how –
What you need –
A mortar and pestle or a wooden rolling pin
Caffeine pills (any generic kind)
Dichloromethane or other organic solvent such as 95%+ ethanol
Fritted glass filter and vacuum pump
Watch glass or other glass cover for the Erlenmeyer flask
- Begin in a well ventilated area
- Crush up the pills until they resemble a fine powder
- Transfer the powder to the Erlenmeyer flask
- Pour 120mL of DCM (dichloromethane) or ethanol into the flask
- Place the watch glass or cover on top and stir manually (or use a stir stick) until the solids sink to the bottom (only caffeine and povidone will be soluble in the DCM)
- Let the mixture settle until it forms two layers and wait until the solids form in the bottom
- Pour the solution into a fritted glass filter and use a vacuum pump to separate the liquid from the solids
- Repeat this process until the filtrate is almost. But use 50mL of DCM (instead of the original 120mL) in the Erlenmeyer flask each time.
- Stop this process either after four cycles or once the solution is almost clear
- Remove the DCM via distillation. Then break up the left over powder at the bottom of the flask and transfer the powder to a beaker
- Recrystallize the powder by dissolving it in hot water. The impurities should remain soluble while heating and the caffeine should drop out of solution.
- Let the solution cool and then place in a freezer once at room temperature so that more caffeine recrystallizes.
- Pull the caffeine out of the freezer and add it to a Büchner funnel. Once it “deflates”, turn off the vacuum and add cold water.
- Turn the vacuum on again. The caffeine should look purer/whiter than before
- Repeat this Büchner funnel process 1-2 more times until the caffeine stops becoming whiter
- Run the vacuum until the caffeine is dry
- transfer the caffeine to a crystallizing dish and heat (at low temp) in the oven
- Once dry, crush the caffeine into a fine powder. This is your yielded pure caffeine.
Caffeine Pill Extraction Instructional Video
Method Two – Extraction from Tea Leaves
This method requires several more steps and more chemistry equipment. It’s technically more of an extraction than the caffeine pills, since the pill method was more of a separation process.
This video demonstrates the procedure below.
What you need –
6 tea bags
6 grams of Na2CO3 (sodium carbonate)
A Separatory funnel
An Erlenmeyer flask
- Place the tea bags, water, and sodium carbonate while swirling the mixture gently
- Bring the solution to a boil for about 10 minutes
- Introduce a lid to limit water loss. Remove the lid and let the bubbles settle if it starts overflowing.
- Transfer the mixture to an Erlenmeyer flask while keeping the tea bags in the beaker
- Add 60mL of water and repeat the process
- Add this new batch of tea to the existing batch in the Erlenmeyer flask
- OPTIONAL: Filter the tea extract before the separation process
- Transfer the tea extract to a separatory funnel and add DCM (dichloromethane) to the funnel
- Cap the separatory funnel and shake gently
- Allow the layers to settle and drain the bottom DCM layer
- Repeat this process three times and use 15mL of DCM each time
- Set up distillation to remove the DCM
- Remove the crude caffeine from the flask and transfer to a test tube.
- Add DCM to the test tube and boil it off until you are left with caffeine crystals.
- Vacuum filter the crystals and wash them using cold 95% ethanol
- Dry the crystals under vacuum
Method Three – Extraction from Coffee
This is basically the same process as the tea extraction.
What you need –
Watch glass (optiona)
Paper coffee filters
A Separatory funnel
- Add 10g of ground coffee, 4g of sodium carbonate, and 60mL of distilled water to a beaker
- Place a watch glass on top and boil the mixture for at least 15 minutes. To limit foaming, shake the beaker.
- Filter the grinds from the solution using gravity filtration with a paper filter. Place the watch glass on top of the filter to limit heat loss while filtering.
- Wash the original flask with boiling water and refilter. Then add another 100mL of water while filtering. Microwave the gravity filter if it becomes too cool.
- Transfer the coffee to the separatory funnel and add 15mL of DCM.
- Once the caffeine separates at the bottom, pour only the caffeine (the clear layer) into a beaker.
- After filtering the first time, refilter with another 15mL of DCM, then a final, third time with 10mL of DCM.
- You should be left with a cloudy solution. Pour this back into the filter and add a saturated salt solution to pull out the water.
- After filtering, add this solution to a beaker and add a drying agent, such as molecular sieves, to remove remaining water. Do this for 20 minutes.
- Add this solution to a clean beaker. Bring this to a boil to remove DCM the solvent. Be careful not to overheat and burn the remaining caffeine. DCM has a low boiling point.
- You should be left with brown, crude caffeine. Recrystallize this using 95% ethanol and place in a freezer.
- Take the contents out of the freezer and place in a vacuum filter. Dry in the vacuum for 30 minutes. This should yield pure, white caffeine.
Whichever method you choose to do so, do remember that pure caffeine is extremely potent and it is important to read up on the effects in order to know exactly how much to use in your drinks, baking, and so on.