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Rosco Bodine
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| Quote: | Originally posted by quicksilver
However you are now activly doing an experiment; viewing a rough titration with PA somewhat similarly. And if this is successful the result would be
[elimination (or great reduction) of residual acidity to form a soluble sodium salt]: to utilize color indictors where they did not exist (or to any
great extent). This then would give you guidlines where none had previously existed. Yes?
Damn baking soda goes a long way!
In the offing one gets to stop wasting PA (the baby and the bathwater or wash-water as it were). Have you tried this as of this writing....??
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Yes it works and it appears to be useful method of recovering the residual content of dissolved picric acid from the supernatant solutions remaining
from the final crystallization from distilled water .
the potassium picrate can be used in synthesis or for other purposes . You get a few grams of a useful material that would otherwise go down the
drain .
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quicksilver
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| Quote: | | Originally posted by Rosco B. You get a few grams of a useful material that would otherwise go down the drain . |
I apprieciate your input in this, a rather diverse thread. Tying all together what you had spoken of helped a great deal. I kept some simple notes
regarding some hobby stuff I did....and had a lot of fun.
Picric Acid Synth using "Color Indicators" to Produce Higher Yield
Having nitrated phenols from various sources and using various techniques I have found that modern chemistry need not overlook what was perhaps a lost
art of nitration. It has been mentioned by others more astute than myself that color changes and solution clarity (a "cloudy" appearance)
may be used as proper indicators of the various stages of both preparation and nitration. I have noticed that when I use such indicators I am now able
to produce a crop of picric acid crystals that match both mp and purity of the "store bought" reagent material. I have been able to
reproduce these results with most any quantity and basic ingredients. I have been surprised that when I use the methods of color change as indicators
rather than precise time and temperature management; the results prove themselves to be best for my efforts. As mentioned previously, perhaps this is
a lost art; I will say that it does hold promise.
With Picric Acid, I used the following:
Format followed basic methodology (Similar to Davis method) but using ASA (Aspirin)
Pure ASA was obtained [In this instance I use a mix of alcohol & acetone at room temperature to extract same]
Sulphonization was as follows:
Example: 25 grams of H2SO4 was used for every 25 grams ASA as per Davis, the initial sulphonization is equal acid for phenol.
Example: 100 grams Phenol is sulphonated w/ 56ml H2SO4 if one is using "drain cleaner" (93%) acid - a simple method of
volume was utilized as 14 mil of H2SO4 is 25 grams; so one may extrapolate
a "quick and dirty" method of finding the volume of acid for one's
initial sulphonization.
However in this synth I used a bit of a twist as I wanted to maintain the acidic acid as much as I could prior to nitration. So I mixed equal parts
H2SO4 w/ the ASA and let the material sit for 6 hours @ 20 C yielding a very thick cream of pink acidic sulfate (I have used this with Styphic Acid
with excellent results). After which I utilized a weight equal amount of 72% H2SO4 and applied heat (80 C) to form a complete sulphonization which
from past experience would be a ruby red solution. I found this method in a very old patent on styphnic acid and it works every time. I have used it
with Indigo and the results were outstanding. A note on color: what I wanted was a deep scarlet solution from the creamy pink sulfate, which was my
starting point. The color became my road map in a sense.
[In this instance I had 42 grams ASA to work with and did the arithmetic necessary]
The nitration was simple and I used 70% HNO3; only because I had it available and did not want to go to the trouble of working with prills of NaNO3 or
KNO3 (which are coated with wax / clay, as are fertilizer grade AN). I wanted to maintain purity and the only time I have had really unacceptable
products I traced the impurity back to the prill. If I use the common sources of KNO3 prill from "Stump Remover" or the NaNO3 from the 40
lbs bags of "Nitre of Soda", they are all coated prills. Some to a lesser degree; some much more. I had found this to be a very common
additive to prill nitrates due to the manufacturing process adopted in both the United States and in northern Europe.
After HNO3 was applied via sep funnel I heated @ 100 C for 2 hours noticing that color was light-orange cloudy with very bright yellow crystal
formation on surface edge of vessel. Solution was removed from heat and set up to crystallize on it's own for 12 hours. No cooling was applied,
In fact insulation was applied to vessel via fiber-glass and it cooled very slowly yielding crystals approx 2mm in length. Care was taken not to stir
of shake the vessel to minimize the crystals from "shaving" themselves against one another. These is an issue here that a "crust"
forms during the time the nitrated solution is allowed to set up. This proved to be no problem as in the past the mp of the crust material was the
same as the beautiful crystals beneath. However, it should be noted that I did not use a mechanical stir bar during this process. had I done so the
crystal size would have suffered due to the "shaving" of the crystals just prior to the elimination of heat. IMO the crystals form that fast
when sulphonation is as complete as it was utilizing the above technique.
Using Buchner funnel and glass filter the initial crop was 79 grams totally dry. The mother liquor was retained but unfortunately it was not
voluminous enough and of course much too acidic to work with. It was added to a corresponding amount of ice and water. A further crop of crystals was
yielded. Then added to it was common sodium bicarbonate; as discussed previously in this thread, another crop of crystals was observed. What I did was
add, portion wise very small amounts observing the reaction. These crystals need to be dried and weighed, however there was definatly some material
recovered. I can’t estimate at this time what it weighs.
I started with 42 grams of ASA and ended with 79 grams initially (and with harvesting from the solution...perhaps as much as 90+ grams), I believe. I
could outline the same synth with specific time-table and temps of course but as I have worked with much larger amounts and smaller I find that the
slight changes will occur and by using COLOR as an indicator, the results reproduce themselves uniquely well. While I have had an opportunity to
duplicate this with appropriate measurement tools and precision; the result varies. These variables are diverse; they include issues related to the
temp, time, weight, & purity of the chemicals, thus the synth as a whole. When I used PHYSICAL INDICATORS despite the variables, the results were
excellent and repeatable.
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Rosco Bodine
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There are some numbers which need to be considered and applied to the process which you are reporting . When you are translating from one method to
another and substituting different precursors , generally what you must do is work on a molar basis so that the stoichiometry and molar proportions
are the same .
For example , mole weights of
phenol = 94.11 grams
aspirin = 180.16 grams
picric acid = 229.11 grams
To maintain the same molar proportions for a reaction involving aspirin substituted for phenol , requires almost doubling the amount of aspirin used
in the same reaction as would be the amount of phenol , 180.16 / 94.11 = 1.914 , so
1.914 grams of aspirin substitutes for 1 gram of phenol in a reaction where aspirin is substituted directly for phenol , in order to preserve the
molar proportions .
Also with regards to maximum yields ,
the theoretical maximum yield from aspirin
with 100% coversion to picric acid is
229.11 / 180.16 = 1.27 , or 1.27 grams of picric acid for each 1 gram of aspirin .
Reaction temperatures are very important for controlling the nitration so that it proceeds at a good rate without surging problems or accumulation of
unreacted material , and reduces the problem with undesired byproducts .
The numbers which apply are as critical to the success of such syntheses as are any visual observations . A nitration is generally not a process
which can be safely or efficiently conducted with any repeatability and predictabilty , except when it is worked out how to do it " by the
numbers " which apply . These reactions are so sensitive to variables that for safety and for the efficiency of the process , there has to be a
reasonable precision about conducting the reactions in a very well measured and regulated set of conditions , particulary as the batch size is scaled
upwards .
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quicksilver
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| Quote: | Originally posted by Rosco Bodine
Reaction temperatures are very important for controlling the nitration so that it proceeds at a good rate without surging problems or accumulation of
unreacted material , and reduces the problem with undesired byproducts .
The numbers which apply are as critical to the success of such syntheses as are any visual observations . A nitration is generally not a process
which can be safely or efficiently conducted with any repeatability and predictabilty , except when it is worked out how to do it " by the
numbers " which apply . These reactions are so sensitive to variables that for safety and for the efficiency of the process , there has to be a
reasonable precision about conducting the reactions in a very well measured and regulated set of conditions , particulary as the batch size is scaled
upwards . |
I know it doesn't present an equal molar weight but what I ended up with was fantastic. And while I wouldn't recommend anyone continue in
that manner in times past, that must have been the technique to a greater degree. What I ended up with was good stuff. Of couse as actual science
goes the whole thing I posted was a rant; but it did produce decient results....
I hate to "back-peddle" but I should have waited before I posted that thing......
Well, the truth is while I was delighted with the initial yield and busily clapping my hands I think that my initial impression of the total was a
poor one. BUT it was still up there! (...Seems what I thought was totally dry could still use some drying, etc). I have to toss out the numbers as it
really needs a desicator to dry properly. In addition the fact is, I should never have even mentioned the recovered material as it was very
fluffy.... But it appears that differing methods of initial sulphonization have a vast difference in end yield. I have no idea what the ratio (as
related to phenol) is with Indego but there again the result is very similar. The starting product being in varience from one batch of indego to
another (some are "whispy", while others are grainular).
I knew seconds after I pressed the "POST" button I should have left off the initial numbers. But, DAMN, the yield WAS great as well as very
good looking in form. What can I say? It was fun.
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Rosco Bodine
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The problem with unmeasured physical observations is they can often be deceiving . The same thing happened to me when I was evaluating methyl
salicylate as a precursor for picric acid , and there was a huge volume of low density crystals which to visual inspection appeared to be a fine yield
. But as the material was filtered and purified and dried the amount kept getting smaller and smaller , and upon weighing ( the scales don't lie
) ....it was known with no uncertainty that the yield was only about a third what would have been gotten from aspirin . You can't really trust
your eyes when it comes to tracking these reactions because the density of the product can cause huge variations in the apparent amount of end product
, so only weight tells the true tale on what you have goten from a synthesis . At certain stages of course visual observations are important , but
not necessarily definitive of what is occurring , so don't place undue emphasis on what you see compared with what you actually measure .
Sometimes your estimates will prove out to be true , but often there will be discrepancies , in which case you have to trust the measurements as being
what is accurate even if the measurements are not what you hoped or estimated .
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quicksilver
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Well...you simply have to look at these snaps....I tried to use a camera that would capture the crystals. The first is the direct yield and next is
the total yield...please check them out. It's really something.
But what I thought of is "what do I really have here?" Di & Ttrinotrophenol are both light yellow....is it possible that a great yield
could come from a lower nitration????? I won't know until I run up to the Univ. and have a friend do a really professional mp on it. But the
yield IS prretty big. (It's now in the desicator)
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quicksilver
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Here is a picture of the total yield...-- I believe even if there is some serious water inside the crystals; I still got a good yield for a
"kitchen synth"..... I will know the truth in a day or so....
[Edited on 10-10-2005 by quicksilver]
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Rosco Bodine
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If you started with 42 grams of ASA ,
then by my experience the best you will get is 42 X 1.27 X .9 = 48 grams total
picric acid .
Okay , truth time , tell us what the scales say you got 
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quicksilver
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| Quote: | Originally posted by Rosco Bodine
If you started with 42 grams of ASA ,
then by my experience the best you will get is 42 X 1.27 X .9 = 48 grams total
picric acid .
Okay , truth time , tell us what the scales say you got
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Oh God.....I wanted to put this off as long as I could. 46 ..... I started with 42 (ASA) It LOOKED like I had about twice that but it was not only
fluffy, there was what seemed like water within the crystal itself. I noticed it when I actually moved it about the table when taking pics of it.  All I can say is that it IS Trinitrophenol and very good looking under the microscope.
It's mp is 123 on the nose. I know that from a quality MP machine at the Univ. and was actually suprised. I thought it was a mix but it's
right on the number.
I thought I could "Kitchen Waltz" my way into turning animal asprin into a 500gr bottle of Spectrum's best......When I used a real
desicator I just kept watching the numbers on the scale drop and drop....
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Rosco Bodine
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Hehehe .....
We all know the disappointing feeling of having to keep moving those counterweights on the triple beams into the next notches going in the wrong
direction to get that beam level .
But what you are getting there is actually about optimal according to my own experience . I can usually predict within
2% of exactly what I am going to get , and if the result varies beyond that , then I start looking hard for the cause of the anomaly .
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