Isopropylamine extraction from glyphosate herbicide

Isopropylamine, or 2-aminopropane, is an organic amine used mainly in herbicides and as a chemical intermediate. It is a colourless, highly volatile liquid with the strong rotten-fish smell typical of many amines. There are several reactions I plan to try out with isopropylamine in the future.

Isopropylamine can be fairly easily extracted from glyphosate herbicides. The herbicides contain the amine in the form of the glyphosate salt. The glyphosate is precipitated by adding hydrochloric acid, which leaves the isopropylamine in solution as the hydrochloride salt. Sodium hydroxide is then added to the solution to freebase the amine, which is distilled out of the mixture in fairly pure form.

To a 1000ml beaker, I added 500ml of Number 8 Ready To Go Glyphosate 360 Weedkiller (0.789 moles of isopropylamine glyphosate). With stirring, I poured in 88ml of 33% hydrochloric acid (0.789 moles of hydrogen chloride) and left the mixture to stand for 10 minutes. With addition of the hydrochloric acid, the mixture rapidly became cloudy as a dense white precipitate began to form. After 1 minute, a dense mass of crystals had precipitated. The crystals should in theory consist of N-(phosphonomethyl)glycine (glyphosate), however it's possible that the hydrochloric acid may cause the surfactants in the herbicide to precipitate as well. Anyway, I filtered the heavy white precipitate off, collecting the filtrate in a 1000ml conical flask. 40g (1.00 moles) of sodium hydroxide were then added to the mixture in small portions, with swirling of the flask between additions. A fairly violent reaction was observed with each addition and immediately an intense aroma of rotten fish was noticed. Once the addition was complete, I stoppered the flask and allowed it to cool to room temperature. I then poured the contents of the flask into a 1000ml flat-bottom boiling flask. Thankfully isopropylamine does not form an azeotrope with water, so distillation can be used to extract the amine. A stillhead, condenser, vacuum adapter and receiving flask were attached and a distillation was performed. Boiling water was used as the heat source. The isopropylamine gradually came over at 40-50 C as a colourless liquid.

After a while, I decided that just hot water was not a satisfactory heating source, so I placed a hotplate below the water bath to maintain a temperature of around 90 C. The heat was occasionally adjusted so the vapour temperature stayed at 40-52 C. When no more isopropylamine came over at this temperature, the distillation was ended. I dried the isopropylamine over sodium hydroxide, then redistilled it, collecting the fraction boiling at 30-41 C. Finally, I transferred the product to an amber vial for storage. I got 18ml (0.209 moles) of isopropylamine as the dry freebase. This represents a 26% yield. The density of the product was 0.601g/cm³ which is pretty close to the 0.988/cm³ of pure isopropylamine.

The distasteful smell of isopropylamine wasn't quite as bad as I was expecting. However, the foul odour was still quite unpleasant whenever I was working directly with the compound. Fishy ammoniacal, with a slight rancid note is how I would personally describe it.

The addition of hydrochloric acid at the beginning of the procedure is probably not necessary. I only added this step because I wanted to recover the glyphosate in solid form for easy disposal.


C3H9N.C3H8NO5P + HCl ==> C3H8NO5P + C3H9N.HCl

C3H9N.HCl + NaOH ==> NaCl + H2O + C3H9N

Trimyristin from nutmeg

Trimyristin, or glyceryl trimyristate, is an interesting triglyceride that occurs naturally in nutmeg. It doesn't have many uses except in scientific research. Trimyristin can be hydrolysed to glycerol and myristic acid, and in the future I plan to try this out. Ground dry nutmeg typically contains about 25% trimyristin (by weight) so this is a great source of the compound.

The extraction of trimyristin from nutmeg is a classic experiment. Usually diethyl ether is used as the extraction solvent, but I tried using a different method.

To a 250ml conical flask, I added 40g of dry ground nutmeg. To this I added 100ml of hot (nearly boiling) ethanol and stirred vigorously for 15 seconds. I then immediately filtered the mixture through a cloth, collecting the orange filtrate in a 200ml conical flask. I washed the nutmeg on the filter with 25ml more hot ethanol. It's important that the whole filtering process is performed quickly while the ethanol is still hot, otherwise the trimyristin will start crystallizing out. Anyway, the 200ml conical flask containing the filtrate (already starting to precipitate some product) was chilled to about 2 C. A lot more trimyristin crystallized out and the mixture was filtered to collect it.

After filtration, I was left with fine crystals of almost white trimyristin. I decided to perform a recrystallization from ethanol to purify my product. After recrystallization, I was left with 0.84g of trimyristin as very fine white crystals. The product was easily melted by hot water, which is a good sign as trimyristin is said to melt at about 56 C. My guess is the trimyristin isn't extremely pure but still definitely usable for most things.

Left = recrystallized trimyristin   Right = ground nutmeg

This extraction was poorly planned and performed. I probably could have gotten more product by boiling the nutmeg in ethanol at the start. My procedure was loosely based on this.

Thorium dioxide from electrodes

Thorium dioxide (ThO2) also known as thoria is a weakly radioactive compound used in some welding electrodes. Thorium gives off alpha radiation which can't penetrate paper and is very short ranged, so it's only dangerous if inhaled or consumed. Thorium dioxide used to be used in gas mantles but this was stopped due to concerns about the radiation. I plan to use thorium dioxide to make Thorium metal and generally explore thorium chemistry.

Thorium dioxide can be extracted from thoriated tungsten electrodes used in welding.
These are usually 2-4% thorium dioxide.

Two years ago I brought 4 thoriated tungsten electrodes. I added them to a container of 3% hydrogen peroxide and left them there until the electrodes had corroded away.  After this there were lots of yellow crystals were left. I collected the crystals and placed them in a vial.

Yesterday I decided to purify the thorium dioxide. I realized my sample was probably a mix of thorium dioxide and tungstic acid. So I added the the yellow crystals to 5ml of saturated sodium carbonate solution and heated strongly for a few seconds. The yellow tungstic acid began to react away and a white powder (presumably thorium dioxide) remained. Once this had stopped, I filtered the mixture to collect the white thorium dioxide. Then I added the thorium dioxide to another 5ml of sat sodium carbonate solution to make sure all the tungstic acid had gone. After this, I filtered off the thorium dioxide and dried it. I got 0.8g of slightly yellow thorium dioxide.

 

 left = the thoriated electrodes (image from www.ecvv.com)  /  Right = thorium dioxide

H2WO4 + Na2CO3 ==> Na2WO4 + H2O + CO2

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

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

D-limonene from oranges

Limonene, aka 4-isopropenyl-1-methylcyclohexene or dipentene, is a colourless or slightly yellow liquid. Naturally it occurs in many citrus fruits. It's the chemical that gives citrus rinds their wonderful smell.

I had a go at extracting it from orange peel via steam distillation. I started with five oranges and grated all the rinds of them. Next I placed the rinds into a round bottom flask with 150ml water and set up for simple distillation. I kept the distillation going until around 10ml of liquid was left in the round bottom. Once the distillation was complete I transferred the distillate to a graduated cylinder and noticed an oily top layer, which smelled strongly of citrus. Limonene is a nonpolar hydrocarbon so it doesn't mix with water.

I used a pipette to extract the top limonene layer. This was my final product:

 

Dichloromethane from paint stripper

Dichloromethane, also called methylene chloride or simply DCM, is an extremely useful organic solvent with the formula CH2Cl2. It's a very volatile colourless liquid with a heavy sweetish smell, similar to chloroform.

I'm in urgent need of it and I can't find anywhere to buy it cheaply so I thought I'd try extracting it from paint stripper. I purchased 500ml of "Selleys kwik strip". According to the material safety data sheet (MSDS) the stripper contains:

>60% dichloromethane
10-<30% ethanol
1-<10% light aromatic petroleum
1-<5% aqueous ammonia
And "additives" to 100% (presumably cellulose-derived gelling agents)

I poured 250ml of the "kwik strip" into a large round-bottom flask and setup for distillation. I kept the distillation temperature around 60 C and after no more product came over, I stopped the distillation.
I believed the distillate contained mostly ethanol and dichloromethane, so I washed it with twice its volume of water to remove the ethanol. I was left with a nice amount of usable dichloromethane.