Nitroglycerin
Nitroglycerin is a clear, viscous liquid with no odor and a sweetish taste. It is a secondary, needing a detonator to set it off, but don't use this to gauge it's stability. It is very unstable (but not as unstable as the peroxides). It's synthesis is fairly easy, but it takes a lot of time and care. It is made by the nitration of glycerin. For legality reasons, I can not show pictures of this synthesis as many chemistry teachers and regular teachers will view my website.
Reaction:
C3H8O3 + 3HNO3 ----> C3H5(NO2)3 + 3H2O
Materials |
Equipment |
| Glycerin | 250ml Beaker |
| 70% Nitric Acid | Graduated Cylinder |
| >94% Sulfuric Acid | 1000ml Beaker |
| Sodium Bicarbonate | Seperatory Funnel |
| Desiccator | |
| Ice Bath | |
| Thermometer |
Into a 250ml beaker, pour 35mls of concentrated (>94%) sulfuric acid. Chill this in an ice bath and measure out 20mls of 70% nitric acid. Add this to the sulfuric acid and stir it up until it is thorougly mixed. You might want to grab a fan at this time and position it to blow air over the top of the beaker. I only do this because I usually get tons of white fumes because of the nitric acid and these piss me off. Stick the thermometer in there and measure out 5ml of glycerin in a graduated cylinder. Remember that glycerin is very viscous and a lot of it will get stuck to the sides of the measuring device so it might be wise to use a graduated pipette instead. Once the nitration bath is down to about 10C (it can go lower if you want it to), you may begin the addition of glycerin. Do this a couple drops at a time and gently stir with the thermometer. Be sure not to tap the sides or bottom of the beaker with the thermometer when stirring as this has been known to detonate the nitroglycerin, though it is unlikely. I have attempted to use the air bubbler method (where bubbling air is used to agitate the nitration mixture to stir the glycerin in) but I was severely dissatisfied with it. It spattered little drops of the nitration mixture on my hands every once in a while and nitrated me. Also, it left quite a bit of un-reacted glycerin laying on top.
When adding the glycerin, be sure not to let the temp rise above 20C. If it does, don't drip any more glycerin in it until it goes back to 10C. A runaway will occur at rougly 30C. If a runaway reaction occurs, carefully take the beaker out of the ice bath and dump its contents into the ice bath. If you had made a reasonable ammount of nitroglycerin by the time this happens (if it does), you can extract it off the bottom of your ice bath. Once all the glycerin is added, leave the beaker to sit in the ice bath for 20-30 more minutes with occasional stirring. Once this period of time is over, it is time to extract your nitroglycerin.
First fill a 1000ml beaker with 500mls of cold, distilled water. Dump the contents of the 250ml beaker into this and leave it for a minute or two. There will be oily blobs on the bottom, this is your nitroglycerin. Decant the majority of the water out of there and pour the remaining ammount including the nitroglycerin into a seperatory funnel (if you have one). Once the nitroglycerin settles out, use the tap to pour it out (it will be the bottom layer). Pour the remaining water out of the seperatory funnel and fill it with 75% of its volume in distilled water again. Add the glycerin to this slowly and again use the tap to seperate the bottom layer once it has settled out. Repeat the last two steps two more times. Now, instead of distilled water, add a 5% solution of sodium bicarbonate and slowly add the nitroglycerin to this. The point of adding it slowly to the water is so that most of it touches the water to remove the impurities. Shake the funnel up a little bit (be sure to vent the gas formed in the funnel to avoid the top from blowing off). Let the nitroglycerin settle out and use the tap to pour it out again. Discard the water in the funnel and then wash the nitroglycerin once more with distilled water. This time, use the tap to pour it into a 50ml beaker. Set this in a desiccator (read my "general chemistry" section for instructions on how to make various DIY desiccators) and leave it in there for 3 days.
After 3 days, you should have a clear, yellowish liquid. This is your nitroglycerin. The last time that I used this synthesis, I got 9.5 grams of nitroglycerin (which is about 8mls). The theoretical yeild for this is 15.55grams which means I got rougly a 61% yeild. This is not bad considering 70% nitric acid was used (the less water, the better the yeild will be).