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Rosco Bodine
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Picric acid is easily made but there are a few places where people may go wrong .
The sulfonation of phenol or acetylsalacylic acid is a heat driven reaction . The subsequent nitration of either sulfonate precursor is also a heat
driven reaction .
Read that as meaning heating to 90 C or better at the end of such reactions for a half hour or more is needed for reasonable completion of those
reactions .
The temperature is regulated by rate of addition and by the
level of supplemental heating . A heating bath is what is needed for picric acid nitration , not a cooling bath .
The nitration should be begun with the precursor mixture still relatively hot from the sulfonation , so that the nitration proceeds smoothly and
maintains the temperature , consuming the nitration material at rate which follows closely the
rate the nitrate is being added . If the nitrate is added to a cool mixture , it accumulates and then as the temperature rises , a surge in the
reaction rate and temperature occurs which is fed by the mass of unreacted nitrate which accumulated at the lower temperature .
So the prevention of a runaway is as simple as beginning the nitration
at a sufficient temperature and maintaining that smooth reaction temperature during the entire nitration . The introduction of each nitro group
requires a higher temperature . A working range would probably be in the area of 70 C to 90 C as a minimum , and upwards to 80 to 120 C at the upper
limit . That is the temperature " window " for the reaction to proceed smoothly at a decent rate and produce decent yields economically .
The higher temperatures are for the folks who can provide good stirring
and temperature control . The lower range is safer for manual swirling . Longer reaction times and slower additions are needed for the manually done
reaction .
The fumes produced by the nitration are deadly poisonous and extreme caution
should be observed to provide some sort
of * steady * ventilation to carry the fumes away . If such ventilation cannot be provided , then the reaction should not be done until that
necessity is met .
Otherwise , the " surprise " for the oversight or carelessness will be
much more serious than some stained fingers . The insidious nature of the fumes is that you won't even realize the exposure in real time as it
occurs , but 12 to 24 hours later , when the unforgiving learning experience is an unexpected visit from the grim reaper chuckling to himself about
how yeah here's another one who just didn't get it . This is one of those perils where " once is enough " ,
no second chances , so respect it for what it is . Accord these sort of nitration reactions with the same seriousness as you would have if poking
around with test probes in an exposed circuit panel known to be energized , no slips nor distractions are permitted .
A good test is to put a lighted stick of
incense near the reaction vessel so you
can observe the streamer of smoke as a
telltale for the draft across your work area . If you can smell the incense ,
then you need to get better ventilation
or back away from that area .
The amount of sulfuric acid on Brainfever's site is more than double what is needed even for a mixture that could be swirled manually , and
although it probably doesn't decrease the yield it is just a waste of acid .
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Quince
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| Quote: | | The fumes produced by the nitration are deadly poisonous and extreme caution should be observed to provide some sort of * steady * ventilation to
carry the fumes away. |
Actually, I did the nitration inside, except for the heating for 3 minutes at 115*C, which I did outside. No brown NO2 was observed, however there
certainly were fumes and I no doubt breathed in some amount. Hasn't been 24 hours yet, but I think, given the very small size of my batch, I
should be fine.
Are these fumes any different from any other nitration procedure? Is there anything else than NOx gasses and HNO3 vapors that's a problem?
I was more worried about the picric acid on my fingers getting absorbed through the skin, as I read that it's very toxic. Time to steal some
more nitrile gloves from the doctor's office...
[Edited on 13-3-2005 by Quince]
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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Rosco Bodine
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I stand by what I said about the nitrous fumes . You can play the roulette on this
and one of these times the ball will fall where you hadn't figured . Maybe the
headstone could be engraved ,
" I should still be alive because it was only a small batch , but here I lay feeding the worms anyway . What was I thinking ! " 
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The_Davster
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The damage from nitric acid/nitrous fumes does the damage to the lungs heal over time or is it accumulative?
I have had a few lungfulls of these gasses (mainly nitric acid fumes) recently. 
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Rosco Bodine
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Maybe you got a whiff or two of air containing a bit of the fumes , but no way did you get a few lungfuls of the stuff ,
because if you did , you wouldn't be telling your own story except in a posthumous publication . There's a few other gases that can do
similar damage
from one good breath of the concentrated
fumes , but most of the fatalities are actually from low level exposure which causes no immediate alarm , so a person just keeps breathing the poison
until they
have gotten a fatal exposure without realizing it at the time . It's like radiation ,
too much in a certain time window and you are done .
Inhaling a bit of ammonia can be antidotal if you get to it soon enough , but of course only low level there because ammonia is toxic too , just a
whole lot less so than the nitrous fumes .
[Edited on 14-3-2005 by Rosco Bodine]
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Mr. Wizard
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Regarding the healing of the lungs, the damage is cumulative, and the lungs do not regenerate. You may pass through an acute inflammation with
chemical pneumonia, edema , or fluid in your lungs, and feel better after it passes, but there was damage done. When it comes to breathing toxic
fumes and dusts, just say no. Emphysema is a long tough way to die.
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Quince
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How is it possible to get a lungful of HNO3 fumes? For me, they cause my airway to immediately close and I'd have to make an effort to breathe
them in.
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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Rosco Bodine
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PATR has several references to the extreme toxicity of nitrogen oxides ,
calling them one of the most insidious toxic gases known to man .
The 30 minute exposure to 100 ppm levels is disabling within 48 hours , causing a cardiopulmonary crisis type of episode which can be life threatening
, and for exposure at 200 ppm for 30 minutes the effect is fatal .
Expressed as percentages in air , 100 ppm is air containing 0.01 per cent ,
and 200 ppm is air containing 0.02 per cent ......so the stuff is * absolutely *
not a material which can be trifled with by
experimenters . Disbelief of the toxicity
provides no protection . Without any exaggeration , the respect of the inhalation hazard potential in the proximity of nitration and nitrosation type
reactions
which evolve nitrogen oxides
is imperative for survival conscious persons working with such processes . The inexperienced may be very watchful and aware of the explosive dangers
to the point of distraction , while being complacent and unconcerned about the
inhalation danger , as if it was somehow okay to take it for granted
that this is sensible or safe .
To summarize this information , it is not excessive to have a regard
for the inhalation hazard of nitrogen oxides that very nearly compares to the respect one should have for " intended " toxins like nerve gas
. Ventilation measures and avoidance of performing such reactions absent some strategy for avoiding inhalation of the nitrogen oxides even at low
levels of exposure ,
is simply a
* NO BRAINER *
[Edited on 17-3-2005 by Rosco Bodine]
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Taaie-Neuskoek
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100ppm is around 188mg/m3, where the odour treshold is 1-6ppm, so you should be able to smell 100ppm as hell...
if I do not smell any NO2, it is fairly ok, if I do smell it --> get the hell out!
Edit: thanks for those instruction about TNP Rosco! I've tried it 2 differend times starting from phenol, and both times I tried to get the temp
as low as possible before the first addition of HNO3.
This is causing a very viscious mixture, and after adding a little HNO3, and a little stirring, a kinda runaway happened, with red stuff being blown
out of the 1L RBF. Heating up the mixture, and adding the HNO3 slow is indeed a good idea, and if one is really afraid of NOx fumes, (I am) you can do
the addition maybe with a reflux condenser on the RBF, cooled with an ice-cold mixture like ice-EtOH. This will trap and liquify some NO2. Though I
won't try this probably, as I HATE the smell of phenol...
[Edited on 29-3-2005 by Taaie-Neuskoek]
Never argue with idiots, they drag you down their level and beat you with experience.
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Taaie-Neuskoek
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I tried the TNP synthesis again, with the procedure as posted by Rosco. I started from fenol, but some strange things happened...
This is what I did:
I added in a 1L RBF 20gr. of fenol, I added 30ml conc. H2SO4, I transferred the flask to a boiling water bath, and left it there for around 30min.
I added 90ml of HNO3 subsequently in small steps, just fast enough to keep the reaction going. The reaction was visible by a lot of bubbling and the
emission of a lot of heat, and a bit of corrosive fumes.
The last 15ml were added at once, and to finish the reaction the flask was transferred to a boiling water bath. The reaction started, went more
vigorous, and a shitload of NO2 fumes were emitted. After 30min. the reaction was over, and I let the solution cool down a bit.
I dropped this solution in 250ml of dH2O, froze it, and tried to filter it. I have (I think) around 5-10gr. of TNP. However, besides the TNP, there
was also some strange black stuff in the filter, which didn’t dissolve in water at all...
I don’t have an idea of the quality of the fenol, it was already a bit old, so may that be a reason for this? I hope there is enough TNP present to
make some azo-clatherate...
Never argue with idiots, they drag you down their level and beat you with experience.
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Lambda
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Finalising the production stages and purification of Picric acid.
There is a way to test the completion of the Sulphonisation stage. If you dissolve a sample in Water, then this should give a transparrent solution.
The Picric acid formation, should be completed on a boiling Water bath. This is the final stage to be applied, after no more Nitrogen dioxide (NO2) is
produced at the end of the so called "runaway reaction stage". The Water bath heating will allso have been competed, after no more visible
Nitrogen dioxide (NO2) is formed.
Picric acid can be purified by:
1. - Washing the filtered crystals with a little amount of cold Water.
2. - These washed crystals are then dissolved in a solution of Sodium carbonate (Na2CO3). A Sodium picrate solution is thus formd.
3. - This Sodium picrate solution is filtered, and Hydrochloric acid is then added. Picric acid then crystalises out as yellow precipitate.
4. - This is then dissolved in the minimum amount of boiling Water, filtered, and then cooled. Picric acid will then precipitate.
5. - The crystaline Picric acid thus obtained, is dried at 30 - 40 degrees C..
Taaie-Neuskoek, you should be able to get rid of that black gunk at stage 3 of purification.
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Taaie-Neuskoek
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I know how purificate the stuff, but thanks for the protocol anyway.
As the gunk is not soluble in water, and TNP is, that is not a big problem.
I am just recristallising the stuff, I've dissolved everything that would dissolve in bioling water + a bit HCl. It is now in the freezer, and
I'll let it thaw in the fridge, to minimise the loss of TNP dissolved in water.
The gunk is on a second look not excactly black, but anyway.
However, the gunk is loss, which is a pity. Anyone any idea what it can be, and is it normal?
Thanks about clarification concerning the 3rd stage nitration, the runaway seems to be normal. That's good, but these amounts of NO2 are rather
nerve wrecking, even with good ventilation.
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Lambda
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Taaie-Neuskoek, did you get the gunk during the sulphonisation stage, or after the nitration stage ?.
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Rosco Bodine
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The synthesis which I have described was starting from purified acetylsalacylic acid ,
not phenol . Phenol is more sensitive to oxidation in the early part of the nitration and becomes less sensitive to oxidation and temperature as the
nitration proceeds .
So the initial to intermediate nitration of sulfonated phenol should be done more gradually at a lower temperature to prevent oxidation losses , and
then the temperature ramped up towards the end of the nitration . Phenol nitrates more easily than aspirin so it requires a gentler approach .
Others have described some very good results for pretty much unattended nitrations involving specific batch sizes , for picric acid from phenol ,
and there are several variations of a general lab method which all give good results .
Simple recrystallization from a slightly less than saturated boiling water solution allowed to cool * slowly * to room temperature , without cooling ,
gives the purest crystals . The remaining 10% of the yield can be gotten by boiling down the filtrate until a slight amount of dark molten solid
precipitates , decanting
the boiling hot solution and allowing it to cool slowly . Artificial cooling of either of these solutions precipitates impurities along with the
picric acid .
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Taaie-Neuskoek
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Rosco Bodino, how would you suggest to keep the temperature of the nitration low when nitrating sulphonated phenol? I’ve tried it a couple of times,
but even when is started with a small amount of cooled HNO3 the reaction is very violent and the temperature of the reaction is very hard to control,
if not impossible. If HNO3 is added, nothing will happen till the temp and the conc. of HNO3 have reached a certain stage, and it is not advisable to
look straight into the flask…
Lambda, The gunk was formed during the last stage of the nitration, before that I could not see any solid material.
Concerning the crystallisation, I know this is not the gentlemen’s way, and will do it the proper way lateron. However, as temperatures are
(sub)tropic here, I consider to cool it down a bit more in a fridge, in order to keep the yield a bit high.
I need to get my hands on some ASA, then I’ll try again.
[Edited on 24-6-2005 by Taaie-Neuskoek]
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Rosco Bodine
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for example
See the attached file page 2 , lines 61 through 115 .
For this old text ,
66 Baume H2SO4 is ~ 95.9% H2SO4
42 Baume HNO3 is ~ 68.7% HNO3
There is an indication in this and some other patents that some water content in the nitration mixture can actually improve the yield beyond what is
gotten with stronger acids . This would seem to be applicable and useful in particular when the source for the nitric acid is a solid nitrate plus
additional sulfuric acid , as the water content would provide a thinner mixture . My own experiments with the nitration of salicylic acid disulfonate
derived from aspirin indicate that somewhat less dilution with water should be used when a nitrate plus sulfuric mixture is used for nitration , than
is described by the patent for the nitration of phenolsulfonic acid using nitric acid . I would guess that the difficulty for the nitration of a
particular phenolsulfonic precursor has a bearing on what concentration is optimum for the nitration mixture , and the concentration may also differ
according to the type nitration mixture used , whether it be using a solid nitrate , or free nitric acid , or some combination . But the process
would seem to be general , and also applicable
to synthesis of styphnic acid and other nitrophenols . The optimum proportions and temperatures and times would vary some for each particular
scenario .
[Edited on 25-6-2005 by Rosco Bodine]
Attachment: US1380186 Picric Acid Manufacture.pdf (301kB)
This file has been downloaded 1738 times
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Taaie-Neuskoek
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Thanks a lot for the patent Rosco!
However, no quantity is given for the amount of HNO3 to be added for the introduction of the 2nd and 3rd nitrogroup, but I assume it must be 2.2 molar
ratio to the amount of phenol.
Never argue with idiots, they drag you down their level and beat you with experience.
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Rosco Bodine
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Honestly I have never looked too closely at methods for picric acid using phenol as the precursor , nor have I ever made any picric acid from phenol ,
simply because it is the least convenient and most expensive precursor . OTC precursors like
aspirin , salicylic acid , and oil of wintergreen , have always seemed more promising as starting materials . And honestly again aspirin is the only
precursor I have ever used for making picric acid , since it is cheap and I get about 90% yield . From what I have read
about the published methods , I would likely just use an adaptation of the method I already use for aspirin . I haven't tried this adaptation to
see how it would perform or know what adjustments would be needed to refine the method . This is purely off the top of my head as a possible
experimental method as I am interpolating and guessing a bit on this adaptation for phenol . I hesitate to describe an untested experiment because of
the unknowns , but anyone having some experience " reading " reactions as they are observed could try this approach and
make their own adjustments as it goes to
pin down the details . So for the got carbolic acid on the shelf but got no aspirin folks , here goes nuttin'
If you just want something different from one of the reported methods known to work , this seems possible , but I am not
entirely certain , this is hypothetical at this point .
This proposed method is untested and
most definitely EXPERIMENTAL :
The reaction contemplated would be performed in a two liter beaker or wide mouth erlenmeyer or flat bottomed florence or a similar sized pyrex teapot
,
sitting upon a stirrer hotplate with a good thermostatic heat control , not a rate controller , and using a three inch or larger
stirbar . A thermometer , addition funnel and wash bottle will also be required .
50 grams of liquified phenol is added slowly with stirring to 200 ml 92% H2SO4 @85 C , regulating the rate of addition to
maintain reaction temperature of 95 C to the end of the addition . The temperature is raised to 115 C and maintained for an additional 30 minutes and
then the heating discontinued .
When the mixture has cooled to 55 C ,
the stirred mixture is cautiously and slowly diluted with 75 ml H2O streamed onto the walls of the vessel from a syringe or wash bottle .
To the stirred mixture is added in small portions dry sodium nitrate , at a rate sufficient to maintain temperature in the
range of 55 C to 70 C , or just less than the temperature at which red fumes appear , until a total of 60 grams sodium nitrate have been added . Then
an additional 200 ml 92% H2SO4 is added at
a rate which maintains the temperature at
65 C . When the addition is completed ,
the temperature is maintained with supplemental heating for fifteen minutes
at 65 C , and then raised to 85 C . In small portions an additional 120 grams of
dry sodium nitrate is added to the stirred mixture as rapidly as the rate of reaction allows without producing red fumes . The
temperature rise allowable should steadily
increase as the nitration proceeds , particularly after the midpoint of the addition . A smooth nitration temperature
may be observed in the range of 95-100 C. At a point towards the end of the addition of the nitrate the exotherm should begin to diminish , and
supplemental heating should be applied to maintain the reaction temperature with an endpoint temperature of 115-120 C ,
held for three or four minutes , before
supplemental heating is discontinued .
Stirring should be continued for the mixture as it cools . After the mixture
has cooled to perhaps 80 C , it is again
cautiously diluted with water streamed
onto the inside wall and allowed to sheet
slowly into the stirred mixture , ~300 ml
of water being used for the dilution .
The still warm mixture is dumped onto twice its volume of ice cubes . After standing for a time all of the ice will be melted and the cold mixture is
filtered to obtain the crude picric acid . The still damp crystals are redissolved in boiling water and recrystallized on slow cooling to room
temperature . The filtered solution is concentrated by boiling until
some dark colored precipitate appears , allowed to cool slightly and decanted from the impurity . Upon cooling slowly a second crop of crystals will
be obtained ,
about 10% of the total yield from the second crop of crystals . The total yeild
should exceed 90% of theory based on phenol , about 110 grams of dried crystals of pure picric acid .
[Edited on 26-6-2005 by Rosco Bodine]
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Quince
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I was using generic ASA tablets. I initially filtered after soaking in a bit of water to dissolve the hydroxypropyl methycelluose. After drying in
air, I dissolved in acetone and evaporated it. However, no crystallization appeared. Instead, a thick, dirty-colored liquid remained, with a smell a
bit like vinegar. My guess is I overheated during evaporation (I was using a heating mantle, so the beaker walls were much hotter than the base with
the fluid, and probably little cooling to the base from evaporation), but I'm wondering what the likely decomposition products are?
[Edit] Fuck, it's impossible to get rid of the sticky shit! I had to scrub my hands with hot ammonia to get rid of it, and I'm still
cleaning the beakers! Motherfucker!
[Edited on 15-7-2005 by Quince]
Oh man, hot ammonia does a number on your skin. My hands are redder than a spanked indian ass.
This sticky goatsassshit is worse than the time I got picric acid dust in my mouth. And I don't know what the hell it is, was it the fact that I
used generic ASA, or what.
[Edited on 15-7-2005 by Quince]
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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Rosco Bodine
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Removing the binders from aspirin
Here is a good method for isolating the pure acetylsalicylic acid .
When aspirins are on sale , you can buy two bottles of 500
325 milligram tablets for under five dollars . After weighing the thousand 325 mg tablets , and doing the math , you may find that you have about 53
grams more weight than the 325 grams of pure aspirin the tablets contain . There are different solvents and methods that can be used for extracting
the acetylsalicylic acid , and I have tried a few
different ways , discovering that denatured alcohol works very well for this .
About 800 ml of denatured alcohol will dissolve your 325 grams of aspirin , if you get the alcohol solvent hot . A procedure I have used that works
well is to first break up the tablets the easy way by letting moisture do the work of breaking the binders . Dump the 1000 aspirin tablets into a
stainless mixing bowl of about one and one half liter
capactity . Put some water into a trigger sprayer bottle and very lightly mist the tablets while stirring them around so that their entire outer
surfaces are moistened , the idea being
to just dampen the all the outer surfaces of all the tablets slightly , but not to soak them . Complete the task of moistening the tablets quickly ,
because
in less than a minute , the tablets will begin disintegrating , and you should not continue misting the powder , or a wet mud will be created instead
of the damp but loose powder desired . The moisture will cause the tablets to disintegrate to a powder as they are stirred . There will be small
pieces that may be a bit stubborn but these can be crushed under the pressure of a spoon after sitting idle a few more minutes in the dampened powder
. The job doesn't have to be perfect , because later the alcohol used to extract the aspirin is going to complete the task of disintegrating any
small chunks of tablets . The loosened damp powder is spread out in a glass tray to air dry . A good method for drying this and other materials is
to get a large retangular glass ovenware baking dish .
Underneath the tray place a heating pad of the sort used for soothing sore joints and muscles .
Beneath the heating pad should be placed a sheet of styrofoam or a stack of newspapers , or a piece of fiberglass insulation batting so the heat path
is to the drying tray and not wasted warming the tabletop instead . An efficent tool for breaking up a dried crystal cake is one of those potato
masher kitchen utensils which has heavy wire formed into a flatted section having U-shaped , back and forth parallels with the wire forming a yoke
which enters a handle . The dried aspirin powder is spooned into a glass jar of about one and one half liters capacity , and having a threaded
closure . Then about 700 ml of denatured alcohol is poured ino the jar and the mixture stirred . The jar is capped lightly and placed into a pan of
warm water then heated further , to a bit less than boiling hot by a hotplate . It is not necessary to get the alcohol hot enough to boil , but do
heat to nearly the boiling point of the alcohol .
The jar of alcohol and powdered aspirin will be brought up to nearly the boiling point of the alcohol and all of the acetylsalicylic acid should
dissolve in the hot alcohol with a little stirring , and the starches and buffers should settle out of the solution into a layer on the bottom of the
jar . The sediment is a very fine dustlike material , and it will be difficult to decant all of the clear solution without disturbing the sediment
and contaminating the supernatant clear solution . Filtering the saturated solution is out of the question without a heated funnel , because the
saturated solution will begin crystallizing immediately on exposure to the air from evaporation
and cooling while pouring , which will instantly plug up any filter . The manipulation should be performed as follows : Carefully decant as much of
the clear solution away from the layer of sediments as possible without stirring up and tranferring sediment along with the
hot solution . The hot solution is decanted into the cleaned stainless bowl which was used earlier for breaking up the tablets . It will serve well
as a crystallizing vessel . Whatever solution cannot be decanted away without being contaminated by sediment , must be diluted with an added 50 ml
portion of alcohol.( in order to lower the saturation and reduce the tendency to crystallize during pipetting ) and the
solution is reheated on the water bath . The solution can be taken up into a large irrigation syringe and transferred portionwise to the bowl for
cooling . Alternately , a pickup wand ( glass tube ) can be used to vacuum pickup the liquid and deliver it to an aspirated receiver bottle , but only
a very gentle vacuum may be used to prevent flash boiling the hot alcohol in the receiving bottle . I have a 100cc syringe that I use for the transfer
. A large rubber bulb, automotive battery filler , or a turkey baster type of utensil would probably work as well for harvesting the supernatant
liquid without disturbing the sediment . Once as much of the solution above the sediment as possible has
been transferred to the crystalizing bowl , a further 50ml portion of alcohol is added to the remaining sediment and swirled with it , then this is
simply dumped through a coffee filter . The filter is twisted down to squeeze the sediment into a ball and press out the alcohol , and the filtered
solution is added to the solutions in the crystallizing bowl . A lump of sediments which is the binders and other inert materials now having been
separated from the original aspirins , will be about the size of a golf ball or slightly larger , a substantial amount of impurities removed . The
cooling bowl of crystallizing pure acetylsalicylic acid should be set if front of a small fan or blower to keep a good stream of air across it , and
the bowl should be warmed gently at the same time . The source of heat should be low power ,
like a water bath of small dimension which does not quite reach the boiling point , a potpourri crock , or a heating pad is adequate , or one of those
heated coasters that are used to keep a coffee cup warm should work fine .
A mound of crystals will form quickly in the bowl and if the crystals are periodically scraped from the sides and piled in the middle of the bowl into
a pile which rises above the surface of the liquid , a wicking effect will cause a small mountain of crystals to grow in the evaporating solution .
Several hours will be required for the crystallization to complete , and then the mass is dumped out into a warmed glass tray , broken up and dried
comletely . The cake of crystals will be most easily broken up while it remains slightly damp with residual alcohol , and if allowed to dry
completely without breaking it up , it will become a very hard rock , a monolith which will require jackhammers and dynamite to reduce to powder . So
save a lot of work and begin breaking up the crystal cake while it is still damp . After the material is fully dry and broken up , store it for later
use by keeping in an airtight container in a cool dry place .
A freezer is good for long term storage of the pure material .
[Edited on 15-7-2005 by Rosco Bodine]
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Quince
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The only high percentage alcohol available here is isopropyl alcohol. However, every time I've tried it, it reacts with something in the aspirin
and makes a sticky mess. This is the first time I've had acetone fail, and I'm not sure what went wrong. Also, aspirin here is about $10
for 100 325 mg tablets.
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Quince
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The aspirin here contains triacetin, which is soluble in alcohol. How would one separate this from the ASA, when alcohol extraction would extract
both?
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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Lambda
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The old fashioned coffee grinder as powder milling machine
An old fashioned coffee grinder can be used to grind the asprin tablets to a fine powder. The blades in such a coffee grinder are blunt-edged, and the
powder formation is based more on impact than on the cutting action. This works out fine for making powders. You must not overburden the grinder with
to many tablets at the same time, for the motor will then overheat rapidly if used in many succesive batches.
Just adding my two cents.
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Quince
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Look here at the aspirin purification part. He crystallizes the ASA by cooling a filtered saturated alcohol solution. I like the idea, since I have
problem with heating decomposing the aspirin. However, to use this alternative procedure, the approximate solubility of aspirin in the alcohol is
needed.
Anyone know what the ASA solubilities in isopropanol and in acetone are? Couldn't find this during my searching.
Also, my triacetin question from the last post didn't get a reply. It's soluble in alcohol, so the impurity remains with the ASA; what
about acetone, or some other way to remove it?
[Edited on 22-7-2005 by Quince]
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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Joeychemist
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US patent 2890240 relates to, and deals with the purification of aspirin via crystallization from acetone, it may help you, if not, it is still very
relative to this thread and the subject at hand.
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