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Producing Picric Acid

 

Now that you have prepared 1,6kg of acetylsalicylic acid and 9-10L of 90%+ sulfuric acid you are halfway into manufacturing picric acid.

 

See guide

 

 

I used the following measurement for creating PA. I had a negatively disproportionate amount of sulfuric acid so I used a little more acetylsalicylic acid and sodium nitrate.

 

In a 1L conical flask I heated 600ml (700 is optimal) of 90%+ sulfuric acid in a 1L conical flask up to 60C. I then, over the next 2-4 minutes mixed in 112g of acetylsalicylic acid under stirring (using a hotplate magnetic stirrer). I then turned off the heat as the nitration would ensure enough heating.

I then started the nitration process (adding 190g of sodium nitrate slowly the next 140 minutes. I added 0,3g each 15 seconds for a total of 1,2g per second making sure to keep the temperature between 60-70C. I kept the temperature at around 66C to be precisely. Keeping the temperature stable at around this heat is essential. After about an hour I had to turn up the stirring power to max as the liquid thickened.

 

After 140 minutes the solution was fully saturated (even though I had 24g of sodium nitrate left) and it "bloomed". Blooming is like a reversed melting process in which the solution solidifies and no amount of stirring can stop it. I do not know for sure if this is correct as I have never seen a guide describing it. Regardless, I kept on stirring every 5 minutes for the next 30 minutes, and then every 10 minutes for the next 30 minutes to prevent the increasingly "growing" substance from overflowing. This was one of my "successful" batches which contained approximately 40-50% pure PA crystals. 80% of my batches "bloomed" in this manner. It took around 4-5 hours for the container with the unpurified PA to reach room temperature. The 1L conical flask was 800ml full. At this point, I could continue the process by slowly scraping out 400 ml of semi-clumps of PA into a 2L beaker with 500ml of distilled water and the rest distilled ice cubes (filled up to 1400 ml). After proper precipitation I poured it into 6 x 500ml beakers with the same amount of funnels/filter papers, saving the filtrate and pouring out the liquid into a 100L plastic bucket (which was later to be dumped near a death-sentenced-bush, outside:)

 

Corrections to previous guide based on my own experiences and research while producing 10 batches of unpurified PA. When I first started this production process I assumed I would end up with a relatively pure end product, perhaps 70-80% pure after washing a couple of times. Needless to say; it was significantly more time consuming than I thought and I had to learn the hard way due to significantly lacking and even misleading guides. The positive surprise though, was that handling PA was significantly safer than I thought. I started out as overly careful as regards to PA and metal. Although you have to be careful, know that PA is perhaps the most safe booster you can work with. Unpurified PA isn't, in most cases, even flammable. So you don't need an exceptional fume hood and fan. An improvised version will work just as well for this purpose. After I had bought a fume hood I invested in two fans, one cheap version (it was actually just a dust collector suction fan) retailing for 140 euro. I also invested in a much more expensive fan (especially manufactured to prevent explosion) retailing for 950 euro. It would seem I was way too paranoid as the only dangerous gas you ever need to worry about when manufacturing PA or DDNP is the NOx gas during nitration and also H2S and SO2 during DDNP manufacture when acidifying the sodium picramate solution but these gasses aren't explosive at all. I was somehow worried that the anti-metallic nature of PA would prevent me from using a metallic fan-tube. However, using one is not a problem at all as all the PA remains in the beakers. So don't worry at all about explosive gasses cause there aren't any. And you don't need a hazmat suit either. Just use regular nitril washing-up-gloves and a good 3M face mask with visor and acid filter/vapor gas filter (nr. 60923 - multifilter) and you're more than fine.



 

A few guides states: after you mix in the acetylsalicylic acid with the 90%+ pure sulfuric acid, slowly mix in the sodium nitrite. A few guides did not even specify in more detail than this.

 

1. What many guides failed to mention and which I had to learn the hard way after ruining several batches; it is ESSENTIAL that you do the nitration (mix in the sodium nitrite) between 60-70C. I found out that if you mix in the sodium nitrite below 60C some of it turns into a layer at the bottom of the conical flask which grows ever thicker. This layer can potentially sabotage and ruin your whole batch. If the temperature suddenly rises this layer may suddenly "melt/loosen" and cause a nitration "overdose" as it mixes with the rest of the content which may increase the temperature with up to 20C within minutes and severely deteriorate the yield of the batch. This layer may also affect the magnetic stir bar and cause it to not stir properly. So make sure you prevent this from happening by keeping the temperature around 65C and never let it drop below 60C.

 

2. What ALL the guides failed to mention was the fact that the addition of the sodium nitrate increases the temperature of the content. So basically; as you start the nitration just after you add the acetylsalicylic acid at around 50-60C, you don't need any heat at all during the process as you can keep the heat between 60-70C by adding sodium nitrite (or potassium nitrate). Rapid heat fluctuations is the most severe threat to your batch and temperatures above 70C (not exactly sure about 70C perhaps 75C) will deteriorate your batch and cause a significantly lower yield. By deteriorating I mean lowering your yield of pure PA crystals from an optimal 50% down to 10% in a worst case scenario.

 

3. What all except one guide failed to mention was the importance of the glassware you are using. I used 2 x 1L beakers and 1 x 1L conical flask. All of my beaker batches ended up with a very low yield for the following reason; the magnetic stir bar works significantly better in a conical flask. I had problems in the beaker as the stirring was significantly reduces (even at max power) due to the shape of the container and the fact that I had a glass temperature rod which very presence significantly reduced the stirring output created by the stir bar. In any case; use a conical flask instead of a beaker if possible.

 

4. On my most successful batch I used a 1L conical flask with 600ml of sulfuric acid (90-95%). On average; I added 1,2g of sodium nitrate per minute (for my two most successful batches). Instead of dropping 1,2g in one go each 60 sec, I added aprox 0,3g every 15 sec (in other words 4 times x 0,3g per minute). I sat there for 2 hours and 15 minutes doing that on my most successful batch (with 2 x 5 minute breaks). You can imagine the agony of sitting there with a 3M gas mask on a rotten chair with your back hurting adding 0,3g every 15 sec. Its repetitive, extremely boring and frustrating. You will start to curse the fact that you didn't set up a TV nearby, or the fact that you only bought one hot plate stirrer instead of three. The prospect of doing this 10 times can be psychologically challenging. So take all measures to make your time more efficient. I managed to barely survive with my sanity intact thanks to my iPod<3

 

5. Acquire 3 x hot plate stirrers if possible. The nitration process is an extremely tedious and frustrating process. With three hot plate stirrers you can add 0,3g in three separate conical flasks speeding up this bitch of a task 300%. A hot plate stirrer retails for 300-500 euro so its affordable. Also, its less suspicious to buy 1 than 3:) as three mostly indicates that you are going to resell them<3

 

6. Creating PA proved to be a very unforgiving manufacturing method. Several things can go wrong, and most of these things relate to impatience -> too much sodium added per minute -> temperature rising to fast f example; I took a break a couple of mins too long and came back to see the thermostat at 59C. I tried to compensate with a little extra sodium nitrite, which didn't seem to have any effect on the temp. I added more and suddenly the temperature exploded and ended at 81C. A couple of other times I got too impatient and added too much per minute (although at the time I believed that a temperature above 70C wouldn't make a difference - I eventually learned that it makes all the difference). You need to be rested and focused before you begin this process (I was exhausted on several occasions which made me lose focus a few times and thus ruin the batch). As long as you focus and add the sodium nitrite 2-4 times per minute x 0,2-0,4g you should be fine.

Prepare mentally for the nitration process. Don't start if you are physically tired or if you need to eat any time soon. Just prepare and if possible have a radio, TV or iPod at your disposal.

 

7. Don't assume that the precipitate you end up with will be above 60% purity. Consider the precipitate you end up with grapes, whereas the actual pure PA crystals are the seeds in the grapes. If you do the process flawlessly the seeds will be large, but if you make mistakes, they will be significantly smaller. This will save you the disappointment I encountered:-). Out of 1,2kg of unpurified PA substance I ended up with only 200-300g of pure PA crystals. Had I done everything optimally I would have ended up with 1,5kg of unpurified PA substance and perhaps 0,8-1kg of pure PA crystals.

 

8. You can mix in the acetylsalicylic acid quickly. I never spent more than 5 minutes mixing it in, in the beginning of the process. As soon as you have mixed it in and it has fully dissolved you can start the nitration process. I usually mixed it in at around 60C and started the nitration process at around 60-65C.

 

Washing

 

It says in most guides that you need to wash with ice cold water 2-10 times. Basically, if you want to do this; just pour water over the filter to clean away sulfates. However, as you need to purify your yellow PA substance anyway, it is pointless to wash it! As I didn't know this at that time I washed the PA-substance 2 times, and the batch intended to create DDNP; 4 times.

 

 


Date: 2015-12-17; view: 673


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