Sciencemadness Discussion Board - salicylic + kno3 = tnp ? help!

salicylic + kno3 = tnp ? help!

avi66 - 15-3-2012 at 01:09

hello, today i try make picric acid using salicylic acid with powerlabs guide:
http://www.powerlabs.org/chemlabs/picric.htm
i take beaker with 18g salicylic acid + 30ml h2so4 98%,
i boil it to 100celcius for 1 hour its won't go dark like in the guide, its became bitter like, i put a vent to eliminate gas ... maby the h2so4 get water to dilute its self from the airstream ? ... it could harsh the reaction ?
anyway i put more heat 105c for 30 min ... nothing change.... all this time the magnetic stirrer work, and temperature check constantly, so i change to 70c add in small portion 16 grams kno3, for 90min long.
after this i put 200ml cold water on it, it is tnp now ? or just some of salicylic nitrate complex .... ?
its look like this:

[Edited on 15-3-2012 by avi66]

niertap - 15-3-2012 at 03:47

That's what it should look like. When you heat it with h2so4 it should just turn a little red. If the first part had not worked, you would have just ended up with a beaker full of polymers and carbon.

bbartlog - 15-3-2012 at 03:56

I expect that different conditions would be required. They claim decarboxylation of salicylic acid to phenol as an intermediate in the synthesis, but I believe that is not correct. Salicylic acid is not decarboxylated thermally at 100C (takes temperatures more like 190C even with copper catalyst), rather as I recall there is first sulfonation and nitration which ultimately lead to decarboxylation via some substitution reaction. So a different pathway and conditions should be required and I think the claim that you can use the exact same times and temperatures for salicylic acid as for phenol is basically bullshit.

avi66 - 15-3-2012 at 05:28

i dry it now... its fully yellow, when it settle down the liquid layer was red color.
so, what could it be, maby a nitration at 70c with sulfuric acid + kno3 will nitrate the salicylic acid to tnp?
and why the hell i didn't get dark color after 1:30 hours of heat at 100c+?
thanks for the help.

quicksilver - 15-3-2012 at 05:48

There is a simple and easy method to tell if you have TNP or a lower nitrated (DNP). Take a tiny weight such as a few milligrams (like a matchhead's worth) and wrap it in aluminum foil - place it on a steel anvil (wear GOGGLES) and strike it with a steel hammer. If it pops like a toy cap you're in business. if it does not react to impact stimulation, it is either DNP or has a great deal of DNP in it. Please do NOT place a heavier amount on the anvil. IF you have TNP the bang will be unpleasant.

DNP can me used to synthesis lead salts that are energetic but it DI-NITROPHENYOL not TRI-NITROPHENYOL. LOOKS can be deceiving. The best test is obviously a melting point test (look for 122-123 C) but impact can help a great deal. Picric acid can be a strong yellow (more hydrogen) to a moderately clear yellow crystal that stains MUCH more than it's semi-transparency would seem. DNP is not without value. What's more it shows you how your nitration went. Someone once said "nitration's are like the Big Birtha of chemical synthesis" a lot of things happen collectively and some of them can be difficult to control until you have understood how they function. Get into the habit of REALLY taking notes when you work. Seemingly small incidental issues become extremely important to success. Temp, time, exposure levels, addition weights and volumes all add to success or a learning agenda.

bbartlog - 15-3-2012 at 05:53

I don't know how you worked out your stoichiometry but it looks bad to me:
18g salicylic acid is 130mmol
16g KNO3 is 158mmol

Since picric acid has three nitro groups and you probably need nitric acid in excess in any case to complete the reaction, it would seem like 45 or 50g of KNO3 would be the bare minimum required. You probably have mostly mononitrated salicylic acid. Of course, using that much KNO3 may run in to solubility problems (thick slurries, undissolved KNO3 or what have you), which is why HNO3 or even NaNO3 are used instead.
My earlier comments regarding the feasibility of the nitration may be too harsh, though. It may well work (just not by turning the salicylic acid into phenol as a first step).

quicksilver - 15-3-2012 at 18:36

I agree with bbartlog .[Occasionally] and even if the stoichiometry is on target for a particular popular nitration, some simply don't respond well to some issues (up or down-scaling: you name it).

Additionally, getting a solid nitrate for your mixed acid gets much better results if you are suspect of source for your nitrate to re-crystallize. To me that means reagent grade. "Suspect" to me means unquestionably fert. grade (or designed for other than lab use).
Many moons ago there was a long thread (I don't remember where it was posted however) that had a humorous title such as "Picric Acid & the Red Goop"*. Nitration can be very finicky and if clay or debris (from a prill tower) are not eliminated, it's easy to get frustrated. I have learned that mixing a solid nitrate with your H2SO4 should be done at a low temp (5 C) & until one has a clear mixed acid. Even if you have your math OK, ( & personally I double check, even from organic Synthesis web site) undissolved nitrates can cause problems.
Maintain your solution at a refrigerated level and covered (mixed acids=hygroscopic). On occasion issues such as these are why may appealingly decent patents stay in a lab rather than make it to plant-level.
Power-Labs admin is an intelligent & friendly individual yet his styphnic acid synth didn't cut it: no one is immune from making a mistake now & then & there's nothing wrong with that at all as this is a learning arena. Just keep it safe, grab other sources, retain your notes, and think about what makes sense.

I am very fond of an undergrad textbook "Chemistry, the Molecular Science" Moore, 2002 (is the latest one). I check a great many things there as it's written very understandably (& you can find it really cheap through Amazon).

* Turned out the overwhelming majority of the problems could be traced back to not doing the math or impurities. Many of the REALLY ugly ones were very poor purity levels. Even dirty glassware can ruin an otherwise workable nitration. A stoichiometry miscalculation is a near guarantee.

avi66 - 15-3-2012 at 23:19

thanks very much, me so sad

.
i think i do it again, by using same heating process, with cooling and nitrating with nitric acid.

quicksilver - 16-3-2012 at 08:57

Don't be sad: it's all learning. - and i didn't mean I only agree with "bbartlog occasionally": attach "OCCASIONALLY to the sentence that follows. He's right on the money. But the point is that in so far as source for a synthesis is concerned - do your best to find a synth that's been working w/ no problems for decades or more if you don't feel too comfortable w/ a new one. Check out Davis page 161. You run that lab and you'll have pcicric acid: NO problem!
If you don't have the book you can download it from the SM library.

avi66 - 21-3-2012 at 13:30

... cool, there is no need to cool the acid to below zero, i just nitrate it by slowly addition of nitric acid at 45c, and then boil the whole stuff to 110c for 30 min.... after this add water, and many beautiful yellow crystal form

.
and even at the boil process, there was chunks already formed.

Vikascoder - 28-5-2012 at 00:14

According to COPAE picric acid is synthesize by using 68 % nitric acid could 68% nitric acid be substituted by 50 % nitric acid and the rest of the procedure remains the same.

caterpillar - 28-5-2012 at 16:02

As for me, phenol is better start point than salicylic acid. Phenol + H2SO4 + KNO3 (or NaNo3). Good yield, few amount of nitrogen oxides. I described this synthesis at corresponding tread on TNP.

Vikascoder - 28-5-2012 at 18:23

i am using acetylsalicylic acid extracted from aspirin for preparing picric acid . i want to know whether i can use 50% nitric acid for synthesizing picric acid from acetysalicylic acid . i have no phenol currently. i tried to substitute nitric acid with sodium nitrate but yield was really pathetic .

caterpillar - 29-5-2012 at 01:38

Taken from dear Jared:

Procedure: Place 50 grams of aspirin into a beaker, and then add 350 milliliters of 95% ethyl alcohol (note: about 50 grams of aspirin can be obtained by crushing up 100, 500-milligram tablets of store bought aspirin tablets—these crushed up tablets can be added directly to the 350 milliliters of 95% ethyl alcohol). Thereafter, stir the mixture to fully dissolve the aspirin, and then filter-off any insoluble impurities—such as starch, and other fillers (if using medical aspirin tablets), and then recrystallize the aspirin from this 95% ethyl alcohol solution. Thereafter, vacuum dry or air-dry the collected aspirin crystals. Now, into a clean flask equipped with thermometer, motorized stirrer and powder funnel, place 350 grams of 98% sulfuric acid, and then place this flask into a an ice bath, and chill to 0 Celsius. Thereafter, slowly add in small portions, 115 grams of potassium nitrate, or 95 grams of sodium nitrate to the sulfuric acid over a period of about 1 hour, while rapidly stirring the sulfuric acid, and maintaining its temperature below 5 Celsius. After the addition of the sodium or potassium nitrate, slowly add the dry recrystallized aspirin, in small portions, over a period of about 1 hour while rapidly stirring the sulfuric acid/nitrate mixture, and keeping it temperate below 5 Celsius. After the addition of the aspirin, replace the powder funnel with a condenser, and reflux the mixture for 2 hours at 60 Celsius with rapid stirring. After 2 hours, remove the heat source, and allow the reaction mixture to cool to room temperature. Then gradually add the reaction mixture to 1500 milliliters of ice water, and then allow the entire mixture to stand for 3 hours. Thereafter, filter-off the precipitated picric acid, wash excessively with 10, 250-milliter portions of ice cold water. Note: washing with base to remove traces of acid should be avoided as formation of the corresponding picrate salts may develop. After the washing process, vacuum dry or air-dry the solid product.

Vikascoder - 29-5-2012 at 20:43

Quote: Originally posted by caterpillar

Taken from dear Jared:

Procedure: Place 50 grams of aspirin into a beaker, and then add 350 milliliters of 95% ethyl alcohol (note: about 50 grams of aspirin can be obtained by crushing up 100, 500-milligram tablets of store bought aspirin tablets—these crushed up tablets can be added directly to the 350 milliliters of 95% ethyl alcohol). Thereafter, stir the mixture to fully dissolve the aspirin, and then filter-off any insoluble impurities—such as starch, and other fillers (if using medical aspirin tablets), and then recrystallize the aspirin from this 95% ethyl alcohol solution. Thereafter, vacuum dry or air-dry the collected aspirin crystals. Now, into a clean flask equipped with thermometer, motorized stirrer and powder funnel, place 350 grams of 98% sulfuric acid, and then place this flask into a an ice bath, and chill to 0 Celsius. Thereafter, slowly add in small portions, 115 grams of potassium nitrate, or 95 grams of sodium nitrate to the sulfuric acid over a period of about 1 hour, while rapidly stirring the sulfuric acid, and maintaining its temperature below 5 Celsius. After the addition of the sodium or potassium nitrate, slowly add the dry recrystallized aspirin, in small portions, over a period of about 1 hour while rapidly stirring the sulfuric acid/nitrate mixture, and keeping it temperate below 5 Celsius. After the addition of the aspirin, replace the powder funnel with a condenser, and reflux the mixture for 2 hours at 60 Celsius with rapid stirring. After 2 hours, remove the heat source, and allow the reaction mixture to cool to room temperature. Then gradually add the reaction mixture to 1500 milliliters of ice water, and then allow the entire mixture to stand for 3 hours. Thereafter, filter-off the precipitated picric acid, wash excessively with 10, 250-milliter portions of ice cold water. Note: washing with base to remove traces of acid should be avoided as formation of the corresponding picrate salts may develop. After the washing process, vacuum dry or air-dry the solid product.

basically i would like to go with the procedure mentioned in COPAE . currently buying nitric acid of 50% is extremely cheap to me . I have sodium and potassium nitrates also but due to some reason i dont want to make picric acid from them . i just want to know whether picric acid can be made from 50% nitric acid. So please help me in making picric acid from 50% nitric acid

caterpillar - 29-5-2012 at 21:40

As I know, it is impossible. Only resorcinol can be nitrated with such diluted nitric acid.

Red Ryder - 31-5-2012 at 22:07

I havent done quantitative analysis in about 15 years - could someone tell me the theoretical yield for TNP from aspirin/KNO3? Also, the procedures I'm familiar with ALL treat the ASA with hot H2SO4 and then add the NO3. the above method seems awfully complex and loooong. Of course it may achieve a much better yield?? I have no idea...

Vikascoder - 4-6-2012 at 05:38

I reacted 10 grams of acetylsalicylic acid with 20 ml of 96% H2SO4 and then heated the mixture to 100'c for 1 hour after that i cooled it to 10'c after that i have added 35 ml of 69%nitric acid and the temperature didnt rise more than 15'c now my question is after how much time i should heat the mixture .

Ral123 - 5-6-2012 at 09:41

I can spare wfna and pure analitical sulfiric acid. My question is do I have a chance of making pure tnp? Wont the aspirin yield trinitroacetisalic? They sell pure acetysalic acid quite cheap also. How do you know you got tnp and not the "high molecualr weight tars" or dnp. We all not just want any "detonateable product by motives of tnp" but the nice stable classy explosive.

caterpillar - 13-6-2012 at 00:11

Quote: Originally posted by Ral123

I can spare wfna and pure analitical sulfiric acid. My question is do I have a chance of making pure tnp? Wont the aspirin yield trinitroacetisalic? They sell pure acetysalic acid quite cheap also. How do you know you got tnp and not the "high molecualr weight tars" or dnp. We all not just want any "detonateable product by motives of tnp" but the nice stable classy explosive.

The simplest answer is by MP, of course. It depends on percentage of TNP and DNP. Pure TNP must have MP at 122,5 (I'm not sure about last digit). My recommendation is do not waste wfna nor rfna for such simple compound like TNP, which can be easy obtained using KNO3 or NaNO3- use conc HNO3 for something more interesting like nitramines.