Piperine from pepper

Piperine is the chemical responsible for the smell and spiciness of pepper. It's an amide, which can be hydrolysed to piperic acid and piperidine – my intended use for piperine. In the mouth, piperine activates heat and pain receptors which cause the burning sensation you get from eating pepper. This is similar to capsaicin's role in chillies and allicin's role in garlic.

I tried extracting some piperine from black pepper.

I started with 100g of black peppercorns. Using a food processor, I grinded it all into a fine powder.
I added the powder to a 1000ml conical flask. 150ml of ethanol was added. I heated the mixture on a hotplate until the ethanol started to boil, then quickly took it off the heat. This was repeated 2 times, and the mixture filtered. I poured the brown/yellow filtrate into a beaker and set it aside.
I then got the residue pepper and added 100ml of ethanol (to make sure I had extracted all the piperine). The heating process was repeated and the mixture was filtered.

I added the filtrate to the product from the first extraction. This gave 250ml of ethanolic pepper extract. I distilled off 150ml of the ethanol (this can be used for future runs) and was left with about 100ml of liquid. I then prepared a solution of 5g sodium hydroxide in 40ml ethanol and added this to the liquid. A dirty brown precipitate was observed (consisting of various peptides and resins). The precipitate was filtered off and discarded. I collected the filtrate then slowly added water to it from a dropper. A pale yellow precipitate of piperine formed. I kept adding water until the piperine stopped precipitating, then filtered off the piperine product. It can be recrystallized from acetone but I didn't bother doing this. I didn't weigh it or calculate the yield because I was unable to dry it completely.


 









left = starting black pepper and right = crude moist piperine

Salicylic acid

Salicylic acid, or 2-hydroxybenzoic acid, is a useful chemical with the formula C7H6O3. It's commonly used as a treatment for various skin disorders and a preservative for food. Salicylic acid is also a valuable precursor. It can be used to prepare salicylate esters such as oil of wintergreen. It can be used to prepare salicylamide or it can be decarboxylated to phenol, which in turn can be used to make bisphenol compounds, phenyl esters and picric acid.

It can be made by hydrolyzing aspirin. I tried this myself.

I started with 23g of pure acetylsalicylic acid in a 1000ml flask. To this I added 11g of sodium hydroxide (an excess is best). I then slowly added 400ml of water to the mixture. A vigorous reaction was obsverved. The mixture was then gently heated without boiling for 8 mins and then filtered. The clear, slightly yellow filtrate was transferred to a flask and 33% hydrochloric acid was added slowly. Immediately a white precipitate of salicylic acid formed. I kept adding the acid until no more precipitate was observed forming.

I collected salicylic acid via filtration and washed it a few times with cold water then dried it.
The experimental yield was higher then the theoretical yield. So obviously the product still contains a bit of water.

C9H8O4 + 3 NaOH = C7H4Na2O3 + C2H3NaO2 + 2 H2O

Acetylsalicylic acid from aspirin tablets

Acetylsalicylic acid (ASA), or aspirin, is a common painkiller with anti-inflammatory properties. It's a useful precursor in the home lab. It can be hydrolysed to salicylic acid, which in turn can be decarboxylated to phenol, or used to prepare oil of wintergreen. There are many other uses as well. Before the ASA can be used however, it must be extracted from its off-the-counter tablet form.

To extract the ASA, I pour the tablets (usually 40 tablets containing 300mg each) into a beaker and crush them. Next I add 100ml ethanol to the crushed tablets. Acetone and isopropanol can also be used but the quantities must be changed accordingly. Anyway, I stir the ethanol and crushed tablets for about 2 minutes to dissolve the ASA, then filter the mixture. The filtrate is an ASA solution in ethanol and the residue consists of binders and additives from the tablets.

The ASA-ethanol solution can be evaporated down to yield crystals of acetylsalicylic acid (ASA).

left = starting product and right = extracted acetylsalicylic acid